Improving the Earthquake safety of Ghana’s Schools PDF... · 2015-12-29 · Improving the Earthquake safety of Ghana’s Schools An EERI Housner Fellows Report ... Proposed Updates

Improving the Earthquake safety of Ghana’s Schools

An EERI Housner Fellows Report

Dr. Syed Mohammad Ali, Ph.D.; Director Earthquake Engineering Center, University of Engineering and Technology; Peshawar, Pakistan;

[email protected]

Cale Ash, PE, SE; Degenkolb Engineers; Seattle, Washington, USA; [email protected]

Ing. Carlien D. Bou-Chedid, FGhIE; Consulting Structural Engineer; Accra, Ghana; [email protected]

Danielle Hutchings Mieler, PE; Association of Bay Area Governments; Oakland, California, USA; [email protected]

Lindsey Maclise, PE, SE; Forell/Elsesser Engineers; San Francisco, California, USA; [email protected]

Hassan Mdala; Geological Survey of Malawi; Zomba, Malawi; [email protected]

Vivek Rawal; People-in-Centre Consulting; Ahmedabad, India; [email protected]

Kate Stillwell, PE, SE; GEM Foundation; Oakland, California, USA; [email protected]

Improving the Earthquake Safety of Ghana’s Schools

An EERI Housner Fellows Report

Dr. Syed Mohammad Ali, Ph.D.; Director Earthquake Engineering Center, University of Engineering and Technology; Peshawar, Pakistan;

[email protected] Ash, PE, SE; Degenkolb Engineers;

Seattle, Washington, USA; [email protected]. Carlien D. Bou-Chedid, FGhIE; Consulting Structural Engineer;

Accra, Ghana; [email protected] Hutchings Mieler, PE; Association of Bay Area Governments;

Oakland, California, USA; [email protected] Maclise, PE, SE; Forell/Elsesser Engineers;

San Francisco, California, USA; [email protected] Mdala; Geological Survey of Malawi; Zomba, Malawi; [email protected] Rawal; People-in-Centre Consulting;

Ahmedabad, India; [email protected] Stillwell, PE, SE; GEM Foundation;

Oakland, California, USA; [email protected]

AcknowledgmentsThe authors of this report would like to express our sincere gratitude to the many EERI members and colleagues who have assisted and mentored us. We would like to thank the Housner Fellowship Management Committee and EERI staff for their vision in creating this program and for the support they have provided. We would like to thank our Ghanaian colleagues for their collaboration and shared interest in protecting school children in their classroom building. Last but certainly not least we want to thank Lucy Arendt for her nurturing mentorship over the course of the program.

© 2015 Earthquake Engineering Research Institute, Oakland, California 94612-1934.

All rights reserved. No part of this publication may be reproduced in any form or by any means without the prior written permission of the publisher. All opinions, findings, conclusions, or recommendations expressed in this report are the authors’ and do not necessarily reflect the views of EERI or other named organizations. While the information presented in this document is believed to be correct, neither the authors, nor EERI, nor any organization named or acknowledged, nor any of their officers, staff, or con-sultants make any warranty, expressed or implied, or assume any liability or responsibility for any use of this report’s opinions, findings, conclusions, or recommendations. The material presented in this report should not be relied upon for any specific application without competent review by qualified profession-als. Users of this document assume all liability arising from their use.

Table of ContentsExecutive Summary 1

Acknowledgments 5

1. Overview 6

1.1. When, Not If 6

1.2. Organization of the Report 6

2. Schools in Ghana 7

2.1. Why Schools? 7

2.2. Background 7

2.3. Typical Structure & Construction 8

3. Earthquake Hazard in Ghana 10

3.1. Seismicity 10

3.2. Seismic Hazard Maps for Ghana 10

3.3. Probabilistic Seismic Hazard Assessment 12

3.4. A New Earthquake Hazard Assessment for Ghana 12

3.5. Earthquake-Related (Secondary) Hazards 12

4. Seismic Design of New Schools 14

4.1. Architectural Review of Standard School Design 15

4.1.1. Architectural Form 15

4.1.2. Spatial Functionality 15

4.1.3. Toilets 15

4.1.4. Site Layout 15

4.2. Proposed Updates to Standard Drawings 16

4.2.1. Structural Updates 16

4.2.2. Architectural Updates 17

4.3. Proposed Updates to Current Seismic Design Code 18

4.4. Adopting and Enforcing Code Changes 19

5. Seismic Evaluation of Existing Schools 20

6. Earthquake Preparedness Curricula 21

7. Stakeholder Engagement 22

7.1. Stakeholder Groups 22

7.2. Ministry of Education 23

7.3. The Architectural and Engineering Services LTD (AESL) 24

7.4. The Ghana Earthquake Society (GhES) 24

7.5. The National Disaster Management Organization (NADMO) 25

7.6. The Ghana Institution of Engineers (GhIE), Engineering Council, and Ghana Consulting Engineers Association 26

7.7. The Association of Building and Civil Engineering Contractors in Ghana 26

7.8. The Ghana Institute of Architects / Architects Registration Council 27

8. The Housner Fellows Program 27

8.1 Saving Lives (one step at a time) 27

8.2 Limitations of this Report 28

Appendix A – Architectural Design Standards and Requirements 29

A.1. Architectural Form 32

A.2. Spatial Functionality 32

Appendix B – Understanding the Seismic Hazard in Ghana 32

B.1. Problems with Existing Seismic Hazard Maps 33

Appendix C – Probabilistic Seismic Hazard Assessment 34

C.1. SourceDefinition 35

C.2. Magnitude Frequency Relationship 35

C.3. Active Faults Data 36

C.4. Magnitude Frequency Relationship 36

C.5. Ground Motion Prediction 37

C.6. Probability of Exceedance Calculation 37

Appendix D – A Strategy for Existing Schools 37

References 40

IMPROVING THE EARTHQUAKE SAFETY OF GHANA’S SCHOOLS

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1. OverviewGhana’s extraordinary economic development in recent decades is a testament to the Ghanaian people. Such forward thinking has also led Ghana-ians to build 200 new schools in the next decade, and to consider the safety of those schools in earthquakes. It is particularly notable that school seismic safety measures are being considered in advance of a catastrophic earthquake.

For this report, the EERI Housner Fellows reviewed the design and construction standard of practice for school buildings in Ghana, with a focus on the Accra region. This included reviews of pub-lished building codes (not yet formally adopted), studies of sample school designs to understand code implementation, and collaboration with engineers and builders in Ghana to assess con-struction practices and material quality.

1.1. When, Not IfGhana has a history of infrequent, ‘moderate’ earthquakes, with magnitudes ranging from 4 to an estimated 7.1. Unlike regions where earth-quakes are frequent and remain in recent mem-ory, in Ghana the population’s memory of major earthquakes, and their destructive power, can be expected to have dimmed over time. Ghana’s last damaging earthquake was in 1939.

However, children are the future of any soci-ety. If mandating their education is a collective investment in Ghana’s future, ensuring their safety at school is a necessary step toward Gha-na’s continued growth. This report identifiesthe most effective steps for improving the safety of current and future schools, and the children in them:

• Change current practices for school de-sign and construction in Ghana

• Expand knowledge of the seismic hazard in Ghana

• Improve design of new schools, and in-crease safety of existing schools

• Teach earthquake preparedness to school children, in particular, and to teachers as well as the general public

1.2. Organization of the ReportThe organization of the report is listed below.

• Section 2 describes current practices for school design and construction in Ghana.

• Section 3 explains the seismic hazard, the potential ground shaking that build-ings must resist.

• Section 4 details earthquake-resistant measures for the architectural and struc-tural design of new schools.

• Section 5 outlines an approach to evalu-ating and improving the safety of exist-ing schools.

• Section 6 outlines ways to teach students and teachers about earthquakes and protective responses to them.

• Section 7 suggests next steps for stake-holder groups.

• Section 8 describes the Housner Fellows Program, the authors of this report.

Four appendices contain technical information for design professionals, engineers, and earth scientists.

2. Schools in GhanaOver the next few years, the government of Ghana plans to build 200 new schools, the largest infrastructure development for the country since gaining independence. Ensuring the seismic safety of these schools is critical. The future of Ghanaian society depends on protecting school children from earthquakes. Some engineers in Ghana are trained in earthquake-resistant design


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for schools, but the relevant building codes are not formally adopted, and the associated design and construction practices are not widespread.

2.1. Why Schools?In the past decade, tens of thousands of children worldwide have lost their lives in school buildings that collapsed in earthquakes (Rodgers, 2012). As a point of comparison, Pakistan’s school build-ings are typically constructed with unreinforced masonry, similar to schools in Ghana (EEFIT, 2006). In the 2005 magnitude 7.6 earthquake in the Kashmir region of Pakistan and India, about 7,000 school buildings collapsed, killing 19,000 children (Maqsood and Schwarz, 2008).

School buildings will continue to be damaged inearthquakesunlessgovernments,schooloffi-cials, families, communities, engineers, and sci-entists devise solutions to the problem. In 2005 the Organization for Economic Cooperation and Development recommended that member countries take steps to establish and imple-ment programs of school seismic safety (OECD, 2005). Improving the seismic safety of schools is often the first step to amore resilient com-munity because schools not only house children during the day, but they also typically serve as neighborhood gathering spots and post-disas-ter relief centers.

Making schools earthquake resistant is most cost-effectiveduringdesign,andmoredifficultand expensive for schools that are already built, but Ghana has an unparalleled opportunity with its new school construction to save lives and build community resilience.

2.2. BackgroundGhana has a population of about 25 million peo-ple. In1957, itbecamethefirstAfricannationto declare its independence from European (British) colonization. Since 1993, it has been a constitutional republic, with an elected pres-

ident and a multi-party parliament. Though still considered a developing nation, Ghana is rich in natural resources and maintains the high-est GDP per capita in West Africa. Over 95% of school-aged children attend school, with a nearly equal ratio of boys to girls. Literacy has increased in the past ten years, from less than 50% to nearly 70%.

Basic school education in Ghana takes 11 years (two years of kindergarten, six years of primary school, and three years of junior high school), with children starting at the age of six. After basic school, students may enter senior high school (SHS) for a three-year course, which pre-pares them for university education. According to the 2010 Ghana Census, over 900,000 chil-dren are currently enrolled in basic and second-ary schools in the Accra region.

There are approximately 13,305 Kindergar-tens, 14,112 primary schools, 8,818 Junior High Schools and 535 public Senior High Schools1 in Ghana. There are several other privately-owned and operated schools at all levels. Most second-ary schools are boarding schools, which mean that students spend the majority of their time during the year in school structures (class-rooms, dormitories, assembly halls, and dining halls). Primary schools tend to be single-story buildings, while secondary school buildings tend to be two- and three-story structures.

Most schools in Ghana are commissioned and designed by the government. The Architectural and Engineering Services Limited (AESL) is a consulting firm wholly owned by the govern-ment and currently working on several school projects. The AESL oversees standard designs for government schools; these designs are also used by non-governmental agencies for school buildings. The AESL is also often called upon to advise on the rehabilitation of existing school buildings.

1 Source: Speech by Deputy Minister of Education during Special Forum held Monday, January 6, 2014 under the theme “Advancing the Better Ghana Agenda: Prospects for 2014”


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Other groups that construct school buildings include Parent-Teacher Associations, nongov-ernmental organizations, communities, philan-thropists, and local government authorities. Schools in poorer areas are often built with informal labor and locally available materials of unknown strength, and without engineered designsorconstructionspecifications.

2.3. Typical Structure & Con-structionSchool buildings are typically poured-in-place concrete-framed buildings with unreinforced

masonryinfillwalls.Theintermediatefloorsaretypicallyreinforcedconcreteconstruction, and the top floor roofconsists of a pitched roof on timber trusses. School buildings in Ghana have traditionally been designed for a 100-year lifespan, and the majority of them have been built with little or no resis-tance to seismic forces. Vulnerabili-ties of these structures, and suggested design and construction improve-ments, are described in Section 4. For more detail about design standards and requirements, see Appendix A.

The 2006 Code is the most current local design standard for the seismic design of reinforced concrete structures. It follows a similar code published by the Building and Road Research Institute in 1990. Neither the 1990 nor the 2006 Code were legally adopted or enforced, and the usage of the 2006 Code varies from engineer to engineer. Some engineers reference other avail-able standards such as the Eurocode, ACI 318, and ASCE 7 in their design practice.

Figure 1. Typical School Block (source: Cale Ash)

Figure 2 (top). Concrete frame with masonry infill observed at school construction site (source: Cale Ash)

Figure 3 (right). Typical school construction with cantilever walkways at elevated floors (source: Cale Ash)


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As shown in the foreground of Figure 1, school blocks in the Accra urban region are generally two- or three-story buildings with structural bays repeated at classrooms and minor varia-tions at stairwells and toilet rooms. AESL uti-lizes a “standardized” design practice whereby previous school block designs are reused in future projects and adapted to the local site conditions. The inherent repetition of the standardized buildings offers the advantage

that any improvements made to the design standard will improve all future schools based upon it.

Each school block usually consists of poured-in-place reinforced concrete construction (see Figure 2). Elevated floors are one-way slabs spanningbetween beams and girders, which are supported by square or rectangu-larcolumns.Thefirstfloorismostfre-quently an elevated, structural floorof similar construction to the floorsabove. As shown in Figure 3, cantile-

vers are used to support the exterior walkways and consist of a horizontal extension of the floor beams and one-

way slabs. Expansion/contraction joints are usually located every three to four structural bays and are approximately 25-50 mm in width.

Roofs consist of un-topped, lightweight metal deckroofingsupportedbytimbertrussesspan-ning between perimeter concrete beams (see Figure 4). The trusses apparently serve as out-of-planebracingforthemasonryinfillwallsasthere is generally not an independent concrete

Figure 4. Timber roof trusses with metal deck roof, note lack of con-crete diaphragm at top of wall elevation (source: Cale Ash)

Figure 5 (left). Masonry infill walls placed in tight contact with surrounding concrete frame (source: Cale Ash)

Figure 6 (top). Typical 75x150x300mm sandcrete masonry block as produced on construction site (source: Cale Ash)


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diaphragm at the top story ceiling level.

As shown in Figure 5, party walls consist of unreinforced masonry blocks constructed in tight contact with the perimeter concrete frame. Common design practice is to assume that the masonryinfillwallsarenonstructuralelements.However,thisconfigurationcouldaffectseismicperformance and is discussed in more detail in Section 4.

As shown in Figure 6, the sandcrete blocks2 are produced onsite using forming/compaction equipment (Figure 7). The masonry blocks are batched using simple volumetric ratios of the constitutive materials.

2 Sandcrete blocks are made from cement and sand (usu-ally river sand) and are a common construction material in the former British colonies in West Africa. Sandcrete blocks are different than concrete blocks, which use crushed aggregates.

Concrete is typically site-mixed for school construction projects. Site-mixing concrete is common in many developing countries (espe-cially on small projects like school buildings). This involves volumetric portioning of materi-als, which can cause variability in compressive strength. Local contractors and practitioners told us that reinforcing steel suppliers some-times provide bars of smaller diameter than specified. This can result in construction thatdoes not conform to the design drawings and can weaken the structure. Sometimes steel rein-forcing bars also lack the desired level of ductil-ity—which allows them to bend without break-ing in earthquake shaking. A study by Kankam and Adom-Asamoah (2002) found that locally manufactured bars in Ghana usually were not sufficientlyductile.

3. Earthquake Hazard in GhanaThis section describes the potential ground shak-ing which buildings must be designed to resist.

3.1. SeismicityGhana is a region of low to medium seismicity. Ghana is situated far away from any tectonic plate boundary, but the southern part of the country has some faults and is seismically active (Amponsah et al., 2012). Historical seismicity records in Ghana date back to 1615. The seis-miccatalogueshowsthatthereweresignificantearthquakes near Accra in 1862 and in 1939 (Amponsah et al., 2012). Since 1939, there have been several earthquakes of magnitude 4.5-5.0, and many earthquakes with magnitude 3.0 or less (Kulhanek, 1989). Most of these events were clustered in the area surrounding Accra, with a few located in the sea or further inland (Figure 8). The largest event since 1940 had a magnitude of 4.8 (Amponsah et al., 2012).

Figure 7. Compaction equipment used for forming sand-crete masonry blocks (source: Cale Ash)


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The 1862 earthquake caused great damage, even to the most strongly built stone masonry houses; most of the public buildings were ren-dered unusable, and three people were killed. The earthquake was assessed by Ambraseys and Adams (1986) to be greater than or equal to MF 6.5, but was later reassessed by Ambra-seys (1988) to be MS 7.1. The 1939 earthquake (6.3 magnitude) caused widespread damage to adobe houses as well as better-constructed buildings (Ambraseys and Adams 1986); 22 people were killed.

Two major tectonic features in the Accra region contribute to the seismic activity in the area: the coastal fault zone and the Akwapim fault zones. The seismic events in this region are caused by the normal faulting in the coastal area (Figure 9) (Amponsah et al., 2012). The NNE-striking Akwapim thrust system (Figure 9) might be in its juvenile stage and become much more active (Burke, 1969).

3.2. Seismic Hazard Maps for GhanaA seismic hazard assessment provides informa-tion on the level of earthquake ground motion that can be expected at various locations. Because this information helps in determining the likely earthquake effects on structures, seis-mic hazard maps are important parts of build-ing codes.

All the seismic hazard maps produced for Ghana so far have been deterministic in approach, whichis,basedonidentifiedsources:maximumhistorical earthquakes and their estimated locations. However, deterministic methods are unable to be very precise about seismic sources. In areas like Ghana, where there are likely active faults thatarenotknownorwelldefined (theAkwapim fault zone, for example), the whole area is treated as a source. This does not allow forspecificenoughestimatesoffuturesources.

The deterministic method is also unable to be very precise about the maximum possible earthquake. In Ghana, the maximum histori-cal earthquake appears to have been used as the basis for most of the maps; however, even the size of it is uncertain. The 1862 earthquake was estimated initially by Ambraseys (1986) to

Figure 8 (left). Seismic map of Ghana – Note the high seismicity around Accra region (area in red circle). Source: Digitized from Geological Map of Ghana. Earthquake epicen-ters were taken from seismic catalogue of Ghana.

Figure 9 (top). A model for seismic events in southeast Ghana showing down-sagging of heavy ocean floor causing normal faulting in the coastal area (Amponsah et al., 2012).


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have been greater than or equal to MF 6.5. In the same paper, Ambraseys estimated the Accra earthquake of 1939 to have been MF 6.3. Later, Ambraseys reassessed these events to have been MS 7.1 and MS 6.5, respectively (1988). Because Ghana does not have the benefit of alongperiodofseismicrecording,itisdifficulttodetermine whether earthquakes of magnitude 7.1 and larger are possible.

For more discussion of deterministic methods of hazard analysis, see Appendix B.

3.3. Probabilistic Seismic Hazard Assessment The Probabilistic Seismic Hazard Assessment (PSHA) method is now standard international practice for seismic hazard assessments. PSHA is often used in combination with deterministic methods because it considers not only earth-quakes producing the largest magnitude, but also more likely, moderate-magnitude events which, at a closer distance, can produce larger ground motions. The results of PSHA are used to develop regional seismic hazard maps for use in building codes, which in turn basic information for the seismic analysis and design of structures.

For more discussion of PSHA, see Appendix C.

3.4. A New Earthquake Hazard Assessment for GhanaWe recommend that a robust probabilistic seis-mic hazard analysis be conducted for Ghana. Fortunately, systems have been developed that make it possible to use that method, even in a region like Ghana with limited data on seismic activity. The richest probabilistic scenarios can be selected for deterministic analysis. Seismic hazard maps based on a PSHA can be developed for use in engineering and planning. They can also be used for the development of seismic design standards.

Our examination of the earthquake hazard in Ghana showed that Accra was the most vulnera-ble location because it is situated at the junction of two major earthquake source systems, the Akwapim fault zone and the Coastal Boundary fault. All seismicity maps show concentrated activity in the Accra area. Engineers need guid-ance on the level of peak ground acceleration to be employed in the design of buildings. During the Housner Fellows visit to Ghana, we learned that engineers are using different values for peak ground accelerations. Some use values given in the BRRI 1988 code, while others use the BRRI 1990/2006 values. Some felt that a value between the two would be more reason-able. Using the 1939 magnitude 6.5 Accra earth-quake as a scenario, Amponsah et al. (2009) esti-mated peak ground accelerations for Accra that ranged from 0.14g- 0.57g. This report therefore endorses the peak ground acceleration of 0.35g, as recommended by the 2006 Code for Accra.

3.5. Earthquake-Related (Sec-ondary) HazardsIn addition to shaking-related damages, strong earthquakes can cause secondary hazards such as liquefaction, landslides, and ground rupture.

In areas of loose sandy soils saturated with water, earthquake shaking can trigger liquefac-tion.Liquefiedsoilsbehavelikeliquidandlosetheir bearing strength, allowing buildings to sink or slump, underground pipes to break, and roadways and railways to buckle. Liquefaction is particularly likely in low-lying areas along theseaandnearriverfloodplains.Inthe1939Accra earthquake, sand vents and mud volca-noes—signs of liquefaction--were observed along the western and southern sides of the Sakumo Lagoon. Similar phenomena were seen near the rivers at Aplaku, Tetegu and Nakwa (Junner et al., 1941).

Landslides and rock falls often result from strong ground shaking. Landslides are likely in


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the sedimentary formations of the Akwapim Mountains. Landslides can be very damaging to buildings built on hillsides and below them. In the 1939 earthquake, cracks appeared in the ground at the villages of Nyanyanu and Aplaku (Junner et al., 1941). Cliffs slid along the shore between the lighthouse at Accra and Christians-borg castle. West of Accra, a boulder fractured a water main at Weija (Junner et al., 1941).

In some cases, the rupture of a fault during an earthquake can reach the surface and dam-age underground pipelines and buildings that straddle the rupture. In the 1939 earthquake, fissuresinthegroundbetweenWeijaandFetepassed through thebeatenmud floors of fish-ermen’s huts. Fissures up to 4.57 meters wide were also observed (Junner et al., 1941).

Earthquake ground motion at various locations can be magnified by certain soil conditions.Areas with soft soils tend to amplify the ground motions. The intensity IX shaking estimate for the 1939 earthquake took place in an area far from the epicentral region (see Figure 10).

Any of the hazards described above can cause substantial damage to nearby buildings. Each potential site for a school should be evaluated by a geologist or geotechnical engineer to deter-mine whether any of these secondary hazards

is possible. In some cases, an engineer can con-sider these hazards in the design of the building and plan to accommodate them.

Mapping secondary hazard zones will point to areaswhereadditionalsite-specificevaluationsare needed. Such an exercise would require a detailed knowledge of the soils and geology of the areas to be mapped.

Ayetey and Andoh (1988) undertook an earth-quake site response study of the Accra area and produced a geotechnical map from borehole data, showing surface soil deposits. They found that Accra was mainly founded on clays and sands. They suggested that, in some areas, the bedrock topography, soil cover, surface topogra-phy and groundwater relationships combined with numerous faults in the area increased the potential damage to structures there. They pro-duced a map (see Figure 10) identifying areas with high, medium and low damage potential for Accra.

The map provides initial information, but researchers in Ghana might wish to consider improving on it and perhaps extending the exer-cise to other areas. The following zones of inves-tigation are recommended:

• Landslides and rock falls: Akwapim Mountains• Liquefaction: Low-lying shoreline areas and in existing and historic riverfloodplains• Surface fault rupture: Near identi-fiedonshoreseismicsourcezones,particularly the mapped active faults in the Akwapim fault zones• Shaking amplification: Faultedand folded regions in the Akwa-pim Range, shales and interbedded shales and sandstones of the Accra Series, all fault contacts between different formations, the Accraian Basin, Keta Basin, Tallus conglom-erate and continental sediments.Figure 10. Earthquake Risk Potential Zones in the Accra Area showing in-

tensity zones of the 1939 Accra Earthquake (Ayetey and Andoh, 1988, p. 23).


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Because subsurface conditions can change rap-idly and dramatically across a zone, it is recom-mended that all potential school building sites within the zones be evaluated by a geologist or geotechnicalengineer.Theirfindingsshouldbetaken into account when deciding the suitability of each site.

4. Seismic Design of New SchoolsDuring detailed conversations with various stakeholders in Ghana, there was considerable discussion of the seismic performance desired for schools. Many discussants wanted to avoid putting children’s lives at risk, and there was interest in higher-than-standard seismic per-formance.

Similarly, the Ministry of Education recognizes that schools not only should protect children, but will be used for a number of post-disaster func-tions, including temporary hospitals, shelters, or community centers. The buildings are expected to remain functional post-quake. The Ministry is in a position to adopt and enforce higher stan-dards for the design of public school buildings—a level of seismic performance that matches the “Safe and Usable during Repair”3 category as defined in the2008SPURResilientCityreport.Engineers acknowledged that increasing seismic performance comes with an increased construc-tion cost, but if higher seismic performance is desired, this cost must be factored into the con-struction budget for projects.

In various meetings with engineers, architects, emergency managers, associations of con-

3 “Safe and usable during repair” describes the perfor-mance needed for buildings that will be used to shelter in place and for some emergency operations. Buildings will experience damage and disruption to their utility services, but no significant damage to the structural system. They may be occupied without restriction and are expected to be deemed safe for occupancy after an earthquake with mag-nitude having 10% chance of being exceeded in 50 years.

tractors, and government officials, all gener-ally understood the need for a legally adopted Ghanaian building code. As evidenced by the construction techniques observed in high rise buildings in Accra, which mainly consists of rein-forcedconcreteflatplatesystems,theconstruc-tion industry of Ghana is capable of supporting good quality school construction. Importantly, various professionals – including those in the contractors association – stressed the need for continuous professional development courses and training to keep Ghanaian construction professionals aware of current trends around the world.

If school buildings continue to be designed and constructed as they have been, their seismic performance will not be at the desired level. In order to analyze the seismic performance of a typical new school building, we conducted a Tier 1 evaluation for Life Safety4 performance, per the American Society of Civil Engineers Standard for the Seismic Evaluation of Existing Building (ASCE 31-03). This evaluation revealed anumberofpotentialdeficiencies:

• The shear stresses in moment frame col-umns exceed safe limits. This can lead to excessive lateral deformations, degrada-tion of concrete within the columns, and possible loss of gravity capacity. In past earthquakes, such buildings performed

4 The Life Safety performance level was chosen for this evaluation as this more-closely aligns with the 2006 Code’s intent. Life Safety is a common code-required minimum seismic performance level and describes the post-earth-quake damage state where there may be severe damage to some structural elements and to nonstructural com-ponents, but this has not resulted in large falling debris hazards within or outside the building. As the building re-tains a margin against onset of partial or total collapse the overall risk of life-threatening injury is expected to be low, although injuries may occur during the earthquake. Exit routes within the building are not extensively blocked, but may be impaired by debris. Repair of the structure should be possible but may not be economically feasible, and the building may be unusable for a period of several months while repairs are completed. This represents a lower perfor-mance level than “Safe and Usable during Repair” category.


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poorly, with some frames partially col-lapsing.

• Expansion/contraction joints between adjacent blocks and between stairs and the building are not sized to function as true seismic separation joints, so some pounding damage is expected. Since the floor diaphragms align, this damage isnot expected to pose a collapse risk al-though it could damage stairways and inhibit the exit of occupants.

• There is inadequate separation between infillwalls and structural columns. Theinteraction between the structural frame and the non-structural masonry wall is not considered in the design of the frames. This leads to a short or captive column condition in which the lateral de-formation of a story is concentrated over the reduced free height of the concrete column. In past earthquakes, this condi-tion has led to column shear failure and partial structural collapse.

• The reinforcing detailing does not meet the design requirements for a ductile structure. The following details are inad-equate: tie spacing in columns; location of reinforcing laps; shear reinforcing in beam-column joints; and a number of problemswithmasonryinfillwalls—theyare unreinforced, lack positive anchorage to the structural concrete frame, and are not adequately braced at the roof level.

4.1. Architectural Review of Stan-dard School DesignMany architectural features affect school earth-quake safety: overall layout and siting, and design elements such as parapet walls, balco-nies,lightfixtures,ceilingtiles,andbookshelves.

4.1.1. Architectural FormFor improved seismic performance, the L- and U- shaped designs should be separated with expansion joints to create more regular rectan-gularconfigurations.Alternately,itmaybepos-sibletoreinforcethecornersufficientlytomini-mize damage at these locations.

In Options 1 and 2, the staircase extends out-side of the regular rectangular layout and could result in torsional response to lateral load-ing. Since the stairs are critical for evacuation after an earthquake, this configuration shouldbedetailedsufficiently toavoiddamageat theentrance to the stair, and the lateral system must besufficienttoeliminatetorsion,toensurethatthe stairs remain functional.

4.1.2. Spatial FunctionalityThe circulation space on elevated floors isdesigned as a cantilevered slab. During the mid-day breaks or school closing times, it is likely all students might be concentrated in that space.

4.1.3. ToiletsIn some cases (e.g., Option 1), male toilets are accessible only though a long narrow passage, which could compromise exiting during an earthquake. Since all the toilets should have direct daylight and ventilation, it may be desir-able to change the functional layout of toilet rooms.

4.1.4. Site LayoutWhile site layout is important from a climate and functional perspective, safety concerns must also be a priority. Hazards such as landslides and rock falls should also be considered in siting a school building. In addition, exit routes must be taken into account so a damaged building does not block exit from an adjacent one.


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4.2. Proposed Updates to Stan-dard DrawingsAs a result of meetings between AESL and the Housner Fellows, and subsequent correspon-dence between these groups, several items wereidentifiedaspossibleimprovements.Eachrecommendation below would incrementally improve the seismic performance of school buildings. Once the recommendations are fully implemented, the buildings will approach a per-formance category of “Safe and Usable during Repair.”

4.2.1. Structural UpdatesS.1. Design buildings to resist the minimum

base shear prescribed in the 2006 Code, with Accra being in Zone 3. Eventually, site seismicity will be characterized on probabilistic seismic hazard maps.

S.2. Provide separation between masonry (‘sandcrete’) infill and concrete frames(e.g., foam filler) to avoid unintendedstructural/nonstructural interaction for in-plane behavior. This may be accom-plished by using foam material at the

joint between masonry walls and the sur-rounding concrete frame members. As shown in Figure 11, masonry infill mayhave negative effects on the intended seis-mic performance by creating a “short” or “captive” column which may then experi-ence a shear failure.

S.3. Reduce tie spacing in columns to the pro-visions of ACI 318-11 Section 21.5.3 and provide seismic hooks at bar ends. This increases the ductility of the concrete frames when resisting seismic forces. As shown in Figure 12, larger tie spac-ing may lead to shear failure of columns which results in a loss of vertical load car-rying capacity for the column.

S.4. Consider increasing all column sizes to minimum of 300mm X 300mm so as to provide reserve capacity to support grav-ity loads during and after an earthquake.

S.5. Locate longitudinal reinforcing lap splices away from potential plastic hinge loca-tions (within middle one-third of column height or beam span) and comply with ACI 318-11 Section 21.5.2.3. As shown in Figure 13, structural damage may con-

Figure 11 (top). Short column effect due to masonry infill interac-tion with building structure (source: Cale Ash)

Figure 12 (right). Inadequate shear tie reinforcement spacing which led to shear failure (source: Cale Ash)


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centrate at lap splice locations so these splices should be located away from joints which are highly-stressed regions of the frame. Lap splice lengths should be designed per ACI 318-11 Section 21.7.5.

S.6. Secure masonry (‘sandcrete’) walls to the surrounding concrete frame to restrain the blocks from falling out-of-plane during an earthquake. This may be accomplished by providing steel dowels which are cast into the concrete frame members and then embedded in the masonry wall joints. This approach would be compatible with the foam recommended in item S.2 as both are required to achieve the desired structural and non-structural perfor-mance. As shown in Figure 14, these walls may separate from the structural frame. Securing the walls is especially important at exits to protect occupants as they leave the building.

S.7. Clearly specify material properties for construction. This includes specifying ductility and strength of reinforcing steel and compressive strength of concrete. In

Figure 13 (left). Concrete joint failure due to presence of lap splices adjacent to joint (source: Cale Ash)

Figure 14 (bottom). Masonry walls which have separated from the concrete building frame (source: Eduardo Fierro and EERI)

addition, quality assurance testing stan-dardsshouldalsobespecifiedandtrainedon-site supervision should be provided to enforce quality control measures.

4.2.2. Architectural UpdatesA.1. Provide adequate separation between

adjacent buildings to ensure that exits and stairways are not blocked and there is sufficient space for students to safelycongregate. As shown in Figure 15, pounding between buildings may lead to increased seismic damage to both build-ings. A minimum separation of 10 cm is recommended.

A.2. Require expansion joints at the corners or bends in L and U shaped buildings to minimize seismic damage at these loca-tions.

A.3. Evaluate building contents for objects that could block exits or injure occupants during an earthquake. As shown in Figure 16, building contents frequently experi-ence the most damage in earthquakes.


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This evaluation should consider all build-ing spaces such as classrooms, toilets, corridors, library, and laboratories.

A.4. Strive for simplicity in architectural design that also results in desired build-ing structure configuration. Attempt toavoid cantilever framing and discontinu-ous vertical elements such as walls and columns as damage can concentrate in these locations.

A.5. Evaluate building exit pathways (cor-ridors, stairs, and doorways) to ensure their continued functionality after earth-quake damage has occurred.

4.3. Proposed Updates to Cur-rent Seismic Design CodeThe following recommended revisions to the 2006 Code are intended to provide the desired seismic performance level. They are not pre-sented in a prioritized order; rather, all should be incorporated by the governing body (Ghana Institute of Engineers - GhIE) into a future code so as to become enforceable design require-ments for engineers such as those working for AESL:

Figure 15 (left). Pounding between adjacent buildings (source: Cale Ash)

Figure 16 (top). Seismic damage to building contents (source: Cale Ash)

• Provideacleardefinitionofthebuildingcode’s intent with respect to seismic per-formance objective (e.g., “Safe and Us-ableduringRepair”).Adefinitionofthebuilding code’s intent provides a basis of understanding for practitioners, own-ers/users, and the general public.

• Provide a table showing correspondence of “Class” assignment for buildings with “Ductility Level” assignments. Currently the code states that “Class 1 structures to be built in high seismicity areas shall be preferably designed to ductility level III.” We recommend that the word “pref-erably” be removed; use mandatory lan-guage.

• Reviseimportancefactordefinitionsforcritical building structures: schools, hos-pitals, and religious centers. Importance factors are typically used to provide in-creasing levels of seismic performance for important buildings. Currently the 2006 Code classifies school building as“Class 1” critical structures. In order to achieve a “Safe and Usable during Repair” performance level, we recommend that the code be updated to state that Class 1 structures should be horizontally and


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vertically regular. Similarly, this recom-mendation could be extended to prohibit vertical setbacks in Class 1 buildings.

• Update characterization of seismic haz-ards using probabilistic seismic hazard analysis methods and also include both short- and long-period seismic design values.

• Add requirements for designing lateral systems for bi-directional loading (e.g., 100% + 30% orthogonal loading combi-nation).

• Provide lateral system-specific designparameters that consider the displace-ment ductility capacity of each system, especially when considering local con-struction practices and material & quali-ty control limitations. The building code currently provides this through the use of K factors. The K-factors for structures having poor detailing, low concrete strength, and lower ductility should be assigned conservative values of K-factor.

• Developmaterial-specificdesignandde-tailing requirements that align seismic hazard, lateral system, and occupancy considerations to achieve the desired seismic performance. The levels of de-tailing may be dependent on the code classificationforbuildings.

• Add quality control and inspection lan-guage to ensure the proper materials and construction techniques are applied throughout the construction process.

• Include provisions for adopting and updating future code requirements through a consensus-based process that equally considers input from engineers, researchers, governmental officials,contractors, and suppliers. This process should be considered in the develop-ment of a legally adopted code. See Sec-tion 4.4.1 for further discussion on a pro-cess of code implementation.

4.4. Adopting and Enforcing Code ChangesThe lack of a legally adopted and enforced build-ing code allows for wide variability in the design of new buildings. Since development and imple-mentationofabuildingcodedifferssignificantlybetween developing and developed countries, the process used in developed countries might not be the most relevant. Generally, codes are developed through joint efforts of industry, research institutions (e.g., universities), profes-sional bodies, and regulatory bodies.

Developing countries could face numerous chal-lenges in this regard:

1. Lack of legal framework or loose and dor-mant legal regulation of the engineering profession.

2. Lack of coordination between the various stakeholders of the country to address this issue.

3. Financial constraints that decelerate code development activities.

4. Lack of training, awareness, and advocacy.

As a point of comparison, Pakistan, also a devel-oping country, recently adopted and imple-mented a seismic building code. This process was precipitated by a damaging M7.6 earth-quake in 2005, which claimed more than 80,000 lives, left more than 4 million homeless (EERI, 2006), and caused direct economic losses of US$5 billion.

Until the 2005 earthquake, Pakistan did not have a legally binding building code; however, work started on preparing a building seis-mic code after the earthquake. The new code, which was supported by organizations such as the International Code Council and the Ameri-can Concrete Institute, was completed in 2007 (Pakistan Engineering Council, 2007; Shabbir and Ilyas, 2011).


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Some of the lessons from Pakistan might guide the adoption and enforcement of a seismic building code for Ghana:

1. Sensitize people and start a dialogue in Ghana related to seismic issues – some initialfirststepshavealreadybeentakenthrough the formation of the Ghana Earthquake Association (GhES) and by the Housner Fellows who visited Ghana in August 2013 to meet with numerous stakeholders. The continuing presence of one Housner Fellow in Ghana could facili-tate sustained stakeholder motivation.

2. Form a consortium of stakeholders, including but not limited to AESL, GhIE, GhES, the National Disaster Management Organization (NADMO), universities, professional licensing bodies, Contrac-tor Association, School Administration, Ministry of Education, Law Ministry, local and international NGOs, and EERI. The consortium can be helpful in sensitizing people and starting background work for initiating national code adoption.

3. Review existing laws related to regula-tion of the engineering profession in Ghana. This could reveal a way forward that would build common ground among stakeholders.

4. Seek funding from local and international sources to support the first legal codeadoption process. This should involve all stakeholders including experts from other countries. The process would require reg-ular meetings of all stakeholders, and the lead should be a representative of the country’s engineering regulatory body.

5. Set a timetable for completion. A reason-able expectation would be that in two to three years a code would be adopted and enforceable.

6. Plan to revise the code on a regular basis toincorporatenewscientificinformation.

Ideally, this would be done approximately everyfiveyears.

5. Seismic Evaluation of Existing SchoolsA comprehensive program on school seismic safety includes reducing risk to existing school buildings. Experience suggests that this is an expensive, long-term process with many eco-nomic, political and social challenges. The goal of this section is to outline a potential process for evaluating and retrofitting existing schoolbuildings, recognizing that such an effort would likely require many years to implement.

The fact that most schools follow a standard design in Ghana provides a unique opportunity to assess broad segments of school buildings uniformly, and to develop uniform plans for detailedevaluationandretrofit.

Other countries with contexts similar to Ghana’s have made concrete steps to understand the vulnerability of school buildings and to reduce it. Governments that have undertaken programs at the national or state level include New Zea-land, California, Venezuela, Nepal, and Iran.

In Iran, frequent significant earthquakeshave had devastating consequences, and have prompted the evaluation and retrofit of“important buildings and lifelines.” According to the Iranian code, school buildings are import-ant, and the Iranian parliament granted $4 bil-lion to demolish seismically dangerous schools and retrofit vulnerable ones. Between 2005and 2011, 40,000 classrooms were demolished and rebuilt, and an additional 9,000 classroom buildings retrofitted (Mahdizadeh, 2011). Inaddition, an estimated 60,000 classrooms were demolished and reconstructed by provincial governments.

Similarly, seismic risk in New Zealand and an update to the building code in 1991 prompted


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officials to ensure compliance of school build-ings with new seismic standards (Mitchell, 2004). Between 1998 and 2001, the Ministry of Education commissioned a structural survey of 2,361 public school buildings. A walk-through survey was conducted to determine the most structurally defective buildings or site struc-tures (e.g., retaining walls). Potential defects that could cause death and injury were identi-fied and retrofit costs estimated. Some build-ings were evaluated in greater detail following the walk-through study.

In addition to these two examples, Rodgers (2012) has documented a number of examples of school building evaluation programs on all continents around the world:

• The Algiers Province of Algeria evaluated 526 buildings at 190 school sites across nine municipalities using a simplifiedevaluation form.

• The Lamjung District in Nepal screened 636 school buildings and performed a detailed structural evaluation of some of them. In the Kathmandu Valley, 643 schools were inventoried and a vulnera-bility assessment was completed for 378.

• In Delhi, India, experienced structural engineers conducted a detailed evalua-tion of ten government school buildings. Oneofthebuildingswasretrofittedasaresult.

• The Engineering School at the Univer-sity of Peshawar in Pakistan conducted a third-party validation of 100 schools that were built in years 2010-11 with the help of a grant from the World Bank in the Azad Jammu and Kashmir region.

The GFDRR Guidance Notes on Safer Schools (Global Facility for Disaster Reduction and Recovery (GFDRR), 2010) recognized that a “one size fits all” approach to school seis-mic safety is not appropriate given the unique contexts of each nation and unique challenges

that must be addressed. Political will, existing infrastructure, technical capacity, availability of resources, and project scale must be addressed in school seismic safety programs (GFDRR, 2010).However,severalfinanciallyfeasibleandsustainable strategies and guiding principles were proposed:

• Raising awareness• Fostering community ownership• Cultivating innovation• Encouraging leadership• Evaluating the process for improving

practice• Assuring quality• Continuing assessment

For a detailed discussion of the strategies, see Appendix D.

6. Earthquake Pre-paredness CurriculaA key element of any program on school seis-mic safety is to educate school children and the general public on what to do before, during, and immediately after an earthquake.

School children are the target audience for the curriculum described here, but children bring the lessons back to their parents and the larger community. In addition, when they become par-ents with children of their own, they will under-stand the vulnerabilities and act to protect the next generation. While school children in Ghana regularly perform fire drills, earthquake drillsare not generally performed.

ShakeOut is a global earthquake drill and cur-riculum which provides an opportunity to prac-tice what to do during an earthquake: “drop, cover and hold on” (Figure 17). ShakeOut also teaches children what to do immediately follow-ing an event. The program is geared towards a


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broad audiencewith specific drill instructionsavailable for schools, businesses, government agencies, and many other groups. For schools, engaging annually in the ShakeOut drill pro-vides a great opportunity to review the earth-quake response plan, make any updates where needed, and consider simple mitigation mea-sures such as securing falling hazards within the school.

The ShakeOut website (http://www.shakeout.org/) outlines the activities and educational materials for various groups and individuals. ShakeOut has a strong global brand as over 26.6 million individuals and organizations regis-tered to participate in 2014. ShakeOut provides a regular opportunity for earthquake safety advocates to engage the public in a dialog about earthquake hazards and the options available for mitigation.

Students and administrators at the St. Kizito Basic School in Nima Accra participated in the Inaugural ShakeOut Drill in Ghana on October 17, 2013. The event was a direct outcome of the HousnerFellows fieldvisit toGhana inAugust2013, when they met with school administra-tors about bringing the ShakeOut event to the local area. Participants at the school joined 9.6 million Californian participants and 24.8 mil-lion global participants as they practiced the drop, cover, and hold on exercise at 10:17 a.m. (Figure 18). While it was suggested by the Hous-ner Fellows, the Inaugural ShakeOut Drill was organized in Ghana by the Ghana Earthquake Society (GhES). The Fellows also worked with

ShakeOut.org to publicize5 the larger shakeout drillforGhana.AGhana-specificShakeOutpageis in development, to continue to promote the drill in future years. By providing teachers with the tools and resources to educate children on seismic safety, the ShakeOut program can con-tinue to act as a tool to promote seismic safety and education in Ghanaian schools. The Fellows intend to follow up with the teachers and advo-cates that they met during their trip to promote ShakeOut in the coming years.

7. Stakeholder Engage-mentThe Housner Fellows are eager to see this proj-ect on school seismic safety in Ghana make progress toward implementation. This section proposes ways in which specific stakeholdergroups can contribute to the successful imple-mentation of the project. Improvements to school safety in Ghana cannot be made without continuing collaboration among the responsible parties.

7.1. Stakeholder GroupsStakeholdergroupsidentifiedduringthecourseof this project include the following:5 http://allafrica.com/stories/201308281072.html

Figure 17. Students Practicing Earthquake Drills, at Mwanza Secondary School (source: Hassan Mdala).

Figure 18. Figure 18: Students practicing earthquake drill at St. Kizito School (source: GhES and Douglas Asante-Nyarko)


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• The Ministry of Education• The Architectural and Engineering Ser-

vices Ltd (AESL)• The Ghana Earthquake Society (GhES)• Community members, parents, adminis-

trators & teachers• The National Disaster Management Or-

ganization (NADMO)• The Ghana Institution of Engineers

(GhIE)• The Ghana Consulting Engineers Associ-

ation • The Engineering Council• The Association of Building and Civil En-

gineering (ABCE) Contractors of Ghana• The Ghana Institute of Architects/ Archi-

tects Registration Council• The Geological Survey Department

With the exception of the Engineering Coun-cil of Ghana, the Ghana Institute of Architects/ Architects Registration Council, and the Geo-logical Survey Department, all the stakeholders named above were engaged during the Hous-ner Fellows’ visit to Ghana in August 2013, and they showed commitment to seismic safety. The sub-sections that follow summarize ideas developed together with each stakeholder group, specifying goals, actions, messages, and methods that could increase earthquake safety in Ghanaian schools. These are not meant as prescriptive recommendations, but rather as possible ways for each stakeholder group to accomplish its own goals. These suggestions are meant to spark and continue conversation and collaboration among stakeholders toward com-mon objectives.

7.2. Ministry of EducationGoalEstablish expectations for the seismic perfor-mance of school buildings in Ghana and ensure

that design and construction meet these perfor-mance standards.

TargetConsultants engaged in design of new school buildings, developers of private schools, school administrators, and NADMO.

Message Schools must remain safe during earthquakes and beyond so that children are not hurt or killed and buildings can be used in post-disaster situations, e.g., for temporary hospitals or com-munity resource centers.

Key Issues• Seismic safety must be considered in the

design of all new schools in Ghana.• Existing schools should also remain safe

in an earthquake.• Children in schools must know what to

do in event of an earthquake.Methods & Tools:

• Commission the AESL to produce “Guide-lines for the Design of all New School Fa-cilities in Ghana.”

• Formally adopt a policy on performance requirements for all schools (e.g., “Safe and Usable during Repairs” perfor-mance).

• Make appropriate budgetary provisions to enable construction of seismically safe schools.

• Institute a program to inspect and classi-fyexistingschoolsandprioritizeretrofit-ting of unsafe schools.

• Work with NADMO to institute an earth-quake safety day in schools.

Evaluation MeasuresConsider the introduction of a peer review system for new school designs with specificrequests that reviewers check for seismic safety. In a peer review system, new school designs will be checked by other design professionals


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as a means of assuring that the required stan-dards are maintained. Coordinate unannounced earthquake drills in schools to ensure that chil-dren have learned the appropriate responses.

7.3. The Architectural and Engi-neering Services LTD (AESL)Goal To ensure the design and construction of seis-mically safe schools in Ghana

TargetArchitects and engineers engaged in school designs, the Ministry of Education

MessageDue consideration must be given to the min-imum performance requirements for schools in earthquakes so that schools are designed to meet these requirements.

Key Issues• Ensure the consistent use of uniform

and appropriate criteria for the design of seismically safe school buildings.

Methods & Tools• Work with the Ghana Earthquake Society

(GhES) to develop guidelines for the de-sign of new school facilities. The guide-lines may contain information on:

o Codes and standards to be appliedo Seismic performance objectives for

school structures and furnishingso Architectural guidelineso Engineering analysis approacho Material strengthso A requirement for peer review

• Encourage the Ministry of Education to adopt the guideline for all schools.

• Provide professional development train-ing on the guidelines to architects and engineers employed by AESL.

• Improve standard school designs by im-plementing the guidelines.

Evaluation Measure Adopt a Peer Review System within AESL to check the designs of school buildings, and pro-vide inspection during construction.

7.4. The Ghana Earthquake Soci-ety (GhES)Goal To carry out advocacy actions and engage var-ious stakeholders in promoting earthquake safety in schools.

Target All stakeholders named in Section 7.1 above

MessageThe Government of Ghana is to build 200 new schools by 2016. The construction of new schools provides the best opportunity to incor-porate seismic safety into new school design. School children need to learn what to do in an earthquake. Existing schools might not be seis-micallysafe,but retrofittingcan improve theirperformance during earthquakes.

Key Issues• Advocate for the adoption of a legally

binding building code.• Promote earthquake safety activities in

schools.Methods & Tools

• Organize a one-day meeting with all identified stakeholders to present anddiscuss the findings from the HousnerFellows Report.

• Hold a meeting with the Ghana Institu-tion of Engineers (GhIE) to agree on a procedure for development and adop-tion of a legally binding building code; monitor the progress to assure timely completion.


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• Hold a meeting with the Ghana Geolog-ical Survey Department and GhIE to ob-tain their support for a probabilistic seis-mic hazard assessment for Ghana.

• Collaborate with the GhIE to seek fund-ing for the development of a new seismic hazard map and code. Funding may be sought from agencies such as the Busi-ness Sector Advocacy Campaign Fund.

• Work with GhIE, Ghana Standards Board, Engineering Council, and other relevant bodies to ensure adoption of the seismic code as a legally binding document.

• Hold a meeting with NADMO to encour-age it to collaborate with the Ministry of Education to institute an Earthquake Safety Day for Schools in Ghana. This could be held around the annual Shake-Out Event. Incorporate other activities as part of the Earthquake Safety Day to sen-sitize the public and all key stakeholders.

• Assist the AESL to prepare appropriate guidelines for the design of schools.

• Work with the Architects Registration Council and the Ghana Institute of Ar-chitects to organize training programs in seismic design for architects.

• Advocate for the teaching of seismic de-sign principles to architects and engi-neers.

Evaluation Measures• Number of stakeholders newly sensi-

tized to the need for seismic safety of schools

• Progress made in the adoption of a legal-ly binding seismic code

• Guidelines for the design of new schools developed

• Guidelines for the design of new schools adopted by the Ministry of Education

• Earthquake Safety day adopted and pro-moted by the Ministry of Education

• Knowledge of seismic design principles a requirement for architects and engi-neers practicing in Ghana

7.5. The National Disaster Man-agement Organization (NADMO)GoalTo promote earthquake safety awareness in schools

TargetThe Ministry of Education

MessageEarthquake preparedness pays as it can lead to fewer casualties in an earthquake.

Key Issues• Ensure that children in schools, their

teachers, and school administrators are adequately prepared for a major earth-quake and have minimized the associat-ed hazards.

• Advocate for the adoption of an Earth-quake Safety Day in schools.

Methods & Tools• Work with the Ministry of Education to

institute an Earthquake Safety Day for schools.

• Use the window of opportunity present-ed by the Earthquake Safety Day to in-crease awareness of earthquake hazards.

• Tap into resources provided by Shake-out. Coordinate regular earthquake “drop, cover, hold on” drills.

Evaluation Measures• Earthquake safety drills become a regu-

lar feature in Ghanaian schools.• Earthquake Safety Day is adopted by

Ghanaian schools


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7.6. The Ghana Institution of En-gineers (GhIE), Engineering Coun-cil, and Ghana Consulting Engi-neers AssociationGoalTo ensure that members understand the need for incorporating seismic safety in their designs, and that members are equipped with the knowl-edge and tools to do so. One such tool is a mod-ern and legally binding seismic code.

TargetEngineers

MessageSchool buildings must be designed using mod-ern seismic codes for appropriate levels of seis-mic force so that they can perform as required in an earthquake.

Key Issues• Ensure that members are sensitized to

the need for seismic design in Ghana, and are properly trained to apply mod-ern principles of seismic design.

• Advocate for the adoption of a legally binding building code.

Methods & Tools• Hold a meeting with the Ghana Earth-

quake Society (GhES) to agree on a pro-cedure for adoption of a legally binding building code.

• Support the GhES in efforts to perform a new probabilistic seismic hazard assess-ment for Ghana.

• In meetings with legislators and relevant government officials, emphasize theneed for a new seismic hazard assess-ment and for the adoption of a legally binding building seismic code.

• Collaborate with the GhES and explore avenues for the funding of necessary steps to the seismic code becoming le-

gally binding.• Work with the GhES to organize training

programs in seismic design for engineers Evaluation Measures

• Number of engineers trained to apply modern principles of seismic design

• Progress made in the seismic hazard analysis and the adoption of a legally binding seismic code

7.7. The Association of Building and Civil Engineering Contractors in GhanaGoalTo ensure that members are adequately sensi-tized to the need to ensure seismic safety in con-struction.

TargetContractors

MessageMaterials that conform to engineering speci-fications, and adherence to modern detailingrequirements, are key to ensuring adequate seismic performance of school buildings.

Key IssuesEnsure that members:

• Are properly educated on the construc-tion techniques associated with earth-quake-resistant construction.

• Understand the importance of quality control and quality assurance in the con-struction industry.


and the Ghana Institution of Engineers to hold training workshops for members.

Evaluation Measure Number of contractors trained in principles of modern earthquake-resistant construction.


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7.8. The Ghana Institute of Ar-chitects / Architects Registration CouncilGoalTo ensure that architects are adequately sen-sitized about the need to incorporate seismic safety in their designs and have the knowledge to do so.

TargetArchitects

MessageArchitects have a key role to play in ensuring the seismic safety of schools because the basic formofabuildinginfluencesitsabilitytoresistearthquake damage. Nonstructural elements of the building can also become a hazard to the occupants.

Key Issues• Ensure that members understand the

need for seismic design in Ghana and are properly trained in the principles of modern seismic design.

• Ensure that architects educated in Ghana are trained to apply modern seismic de-sign principles.


and the Ghana Institution of Engineers to hold training workshops for members.

• Work with universities teaching archi-tecture and encourage them to make training in modern seismic design prin-ciples part of their curriculum.

Evaluation Measures• Number of architects trained in the prin-

ciples of modern seismic design• Modern seismic design principles part of

the curriculum for architects

8. The Housner Fellows ProgramThe Earthquake Engineering Research Insti-tute(EERI) isanonprofit,professionalsocietyof engineers, geoscientists, architects, plan-ners, public officials, and social scientists. Themission of EERI is to reduce global earthquake risk by (1) advancing the science and practice of earthquake engineering; (2) improving under-standing of the impact of earthquakes on the physical, social, economic, political, and cultural environment; and (3) advocating comprehen-sive and realistic measures for reducing the harmful effects of earthquakes.

The EERI Housner Fellows Program recognizes and equips promising and motivated young to mid-career professionals with the confidence,skills and sense of responsibility needed to become lifelong leaders and advocates for earthquake risk reduction.

The program was made possible through a sub-stantial gift to EERI from Professor George Hous-ner, an educator, a leader in the engineering pro-fession, and an advisor on public policy. He was a founding member of EERI and served as its president for many years. He advanced earth-quake safety through his research and writing, by training students, and as an advisor to gov-ernment agencies. Additional support for the program is provided by the Federal Emergency Management Agency and the Global Facility for Disaster Reduction and Recovery (GFDRR) of the World Bank. The GFDRR supported the par-ticipation of three Fellows.

8.1 Saving Lives (one step at a time)The goal of this Housner Fellows project is to improve school seismic safety in Ghana in order to protect children’s lives in a future earth-


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quake.Asafirststep,thisreportprovidesprag-matic guidance to enable Ghanaian engineers and architects design new schools to be earth-quake-resistant.

The 2012 Housner Fellows chose this project because of its great potential for reducing seis-mic risk. The project allowed the Fellows to take a holistic, multidisciplinary view of seismic safety issues by engaging with a cross-section of key Ghanaian school stakeholders. During these meetings, the Fellows enhanced their leadership skills, especially those related to advocacy and effective communication. The project has the potential to increase awareness of the need for earthquake safety; indeed, it has already begun to increase as a result of publicity the Fellows helped generate during their visit to Ghana.

Because one of the Fellows is an active member of the engineering community in Ghana, there was a local connection. Second, the potential for real and medium-term implementation is high, given the large number of new schools planned for construction.

The Housner Fellows collaborated carefully with Ghanaian stakeholders, starting with con-sensus-driven project selection, and extending through regular conference calls among the group, regular correspondence with local stake-holders, and engagement of a review committee.

The project consisted of three phases: research, a visit by the Fellows to Ghana in late August 2013, and synthesis.

• Prior to their visit to Ghana, the Fellows reviewed the standard school plans and building code.

• While in Ghana, the Fellows met with many stakeholder groups:

o The Architectural and Engineering Services Ltd. (AESL), contracted en-gineers who design Ghana’s public schools.

o The Ministry of Education, the entity

that commissions public schools.o The National Disaster Management

Organization (NADMO), the group responsible for disaster prepared-ness and response in Ghana.

o The Ghana Institution of Engineers (GhIE), the licensing board and pro-fessional organization for practicing engineers.

o The Ghana Earthquake Society (GhES), the professional organiza-tion for practicing engineers, aca-demia, and seismologists, similar to EERI.

o The Association of Building and Civ-il Engineering Contractors in Ghana, the professional organization repre-senting Ghanaian contractors.

• After visiting Ghana, the Fellows synthe-sized prepared the recommendations here.

Throughout each phase, bi-weekly conference calls invited each Fellow to report on progress, and allowed the group to address problems or constraints. The regular calls maintained individ-ual accountability for the group’s achievements.

8.2 Limitations of this ReportThis report was developed with the following limitations:

• This report focuses on schools in great-er Accra. Its recommendations cannot necessarily be generalized to outlying regions of Ghana. In particular, this re-port cannot be generalized to locally or informally-built schools.

• This report is not an exhaustive review of all school designs.

• This report is based on information avail-able to and understood by the Fellows at the time of its writing.


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Appendix A—Architec-tural Design Standards and RequirementsDuring discussions with AESL, it was men-tioned that Neufert Architect’s Data is used as standard for design of the schools. As shown below, all options in the design standards vary in terms of facilities and services, even though all designs have six classrooms. Option 1 has only classrooms and toilets and no rooms for staff or a library. Option 2 has rooms for teach-ers, staff, and library but no toilets. Option 3 has all of these rooms but does not include a head teacher room like in Option 2. Finally, Option 3B does not have toilets. AESL explained that each block is adapted to suit the design requirements established for any given school. For some schools it is possible that an existing toilet block issufficientandthereforeanewblockmightnot

require the same. The variations in plan provide appropriate options to be used in different sit-uations.

Theoverallschoolconfigurationsareeitherrect-angular block (Options 1, 2, 4, and 5), L-shaped (Option 3), or U-shaped (Option 6).

• Design Option 1: This option has three classroomsandtoiletsonthe first floorarranged in a single row. The second floorcontainsfourclassrooms.Thestair-case has been designed as an add-on in front of the classrooms and verandah.

• Design Option 2: This option is simi-lar to Option 1 in terms of overall form. This option contains three classrooms, a head teacher’s office, and storage/com-monsroomson the first floorarrangedinarow.Thesecondfloorcontainsfourrooms as in Option 1 except one of the rooms is to be used as library. The stair-case has also been designed as an add-on in front of the classrooms and verandah.

First Floor—Option 1 Second Floor—Option 1



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First Floor—Option 3A Second Floor—Option 3A

First Floor—Option 3B Second Floor—Option 3B

• Design Option 3: In Option 3A there are three classrooms, a common staff room, storage, and toilets on the firstfloor.TheseroomsarearrangedintoanL-shaped form with the staircase locat-

First Floor—Option 4

ed between the classrooms. The second floorhasthreemoreclassrooms,toilets,and a library. Option 3B is similar except the stair location is relocated and there are no toilets in this layout.


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• Design Option 4: This single story design op-tion has seven rooms located in a single row. This design option appears to have been developed by put-ting two independent classroom blocks adja-cent to each other. This results in toilets being divided into two loca-tions. One set of toilets is between classrooms and the other set is on the end of the build-ing. A recreation room on one end is to be used as reading room or library and the re-maining six rooms are to be used for classrooms.

• Design Option 5: This is a two-story option with three classrooms on both floors.Classrooms,staircase,andtoiletshave been arranged in a single row con-figuration.Asinothertwostoryoptions,the second floor verandah is a cantile-vered slab and is used for circulation.

• Design Option 6: This is also a single

storydesignoptionconfigured intoaUshape with three classrooms on two op-posite sides facing the common central open space. These two wings of class-rooms are connected with a block con-taining a teacher’s room and a library. This is one of simplest design options, as the layoutnotonlyhaswell-defined in-teriorspacesbutalsowell-definedexte-rior open space in the central courtyard.

First Floor—Option 6


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The 1988 Ghana Building Code included a seis-mic hazard map which divided the country into four zones with peak ground accelerations of 0g, 0.02g, 0.04g, and 0.08g for zones 0, 1, 2 and 3, respectively (see Figure B1b). The next revi-sion of the seismic hazard map was published in the 1990 BRRI Code for the Seismic Design of Concrete Structures. In this revision, the coun-try was again divided into four zones but the peak ground accelerations assigned to these zones were much higher. Peak ground acceler-ations of 0g, 0.15g, 0.25g and 0.35g were now assigned to zones 0, 1, 2, and 3 respectively. The 1990 code had limited circulation and it was not until 2006 that a new code was proposed by the BRRI. The seismic hazard map, however, remained unchanged.

The seismic hazard map in the 1988 code was largely guided by the isoseismal map of the 1939 earthquake with some modification toaccount for the effects of the 1906 Ho earth-quake. The 1990/ 2006 seismic hazard map is also very similar. It is predominantly influ-enced by the 1939 earthquake except that some smoothing has been done for the zone with the highest peak ground acceleration and this zone now includes the whole of the Akwapim fault zone, an area believed to be a major source of earthquakes. Areas along the coast which fell within isoseismals of VII, VIII and IX in the 1939 earthquake have also been included.

Other attempts to characterize the seismic haz-ard of Ghana have been made by Amponsah et al. (2012) and Kutu (2013) (see Figure B1c and Figure B1d). Amponsah et al. (2012) produced an earthquake catalogue for Ghana covering theperiod1615-2003.Theareadefinedforthecatalogue lay between latitude 2.0°N and 14°. They then used the database to produce an epi-center map and superimposed isoseismal maps from the different earthquakes. The result was an epicenter map with intensity isolines. This gave an indication of the maximum intensity expected at each location (Figure B1c). Peak ground accelerations were to be estimated from the expected intensities.

A.1. Architectural FormThe architectural design follows a uniform structural grid and the architectural layout has been adjusted within this grid. The width of this grid varies from 3900mm-4150mm and the depth varies from 7500mm-9075mm.

A.2. Spatial FunctionalityThe school buildings are designed with regu-lar bays and classrooms, toilets, library, storage rooms, and other spaces have been created by joining one, two or more bays. This seems to have posed restrictions in terms of the shape of the spaces and therefore their utility. This is particularly obvious for toilets.

Common spaces like the verandah have been planned only as corridor space, but these are also spaces for informal interaction outside of common services like toilets or library rooms. Instead of a long linear space, verandahs could be designed with some variation to facilitate their connecting functions better. The circu-lationspaceatelevatedfloors isdesignedasacantilevered slab. During the mid-day breaks, school closing times, or during an emergency requiring evacuation, it is likely that all students could be crowding in that space.

Appendix B—Under-standing the Seismic Hazard in GhanaThe earliest known attempt to characterize the seismic hazard in Ghana was presented in the Draft Ghana Building Code published by the Building and Road Research Institute, Ghana (BRRI) in 1988 (see Figure B1a). The 1960 West African Building Code, which has been used in Ghana, Nigeria and Sierra Leone, did not specif-ically deal with earthquakes.


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B.1. Problems with Existing Seismic Hazard MapsAll the Seismic Hazard Maps produced for Ghana so far have been deterministic in approach. They are based on the maximum response expected from an identified source. This response is afunction of the size of the earthquake chosen, the distance from the source, and the ground conditions. Mathematical relationships known as attenuation relationships are developed for

(a) Earth-quake risk-lev-el zones. Zone 0 is 0g, Zone 1 is 0.02g, Zone 2 is 0.04g and Zone 3 is 0.08g (source: BRRI, 1988)

b) Earth-quake risk-level zones. Zone 0 is 0g, Zone 1 is 0.15g, Zone 2 is 0.25g and Zone 3 is 0.35g. (source: Amonoo- Neizer, 2011).

(c) Epicentre map with intensity iso-lines (source: Amponsah et al., 2012).

(d) Plot of major earthquake epicenters, and the general earthquake risk-level zones of southern Ghana (source: Kutu, 2013).

Figure B1. Seismic Hazard Maps of Ghana – Note that Accra falls in the highest risk zone in all cases.

different regions and are used to estimate the response from a source.

The maps have generally been based on maxi-mum historical earthquakes and their estimated locations. The 2006 Code map (Amonoo-Neizer, 2012) and the map produced by Kutu (2013) appear to have taken into account the possibil-ity of earthquakes similar in size to the maxi-mum historical earthquake occurring within the Akwapim fault zone and the Coastal Boundary faults. The differences that appear between these


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twomapslikelystemfromthedefinitionofthesource. The map by Amponsah et al. (2012) has considered the activity that occurred outside Ghana’s borders within La Cote D’Ivoire. This does not appear to have been factored into any of the other maps. Also, none of the maps appears to have considered earthquakes that have struck on the Northern border of Ghana in Burkina Faso.

The use of deterministic methods of hazard anal-ysispresentsanumberofdifficulties.Determin-istic methods are unable to account for uncer-tainties in thedefinitionof seismicsources. Inareas like Ghana where there are probably active faultsthatarenotknownorwelldefined,suchas within the Akwapim source zone, the source must often be treated as an area source. In other words the whole area is treated as a source. The boundaries of the area source might not be well defined. InGhana, incidentsofseismicactivitywithin the Akwapim source zone are not neatly bounded within a particular geological for-mation.Thedefinitionofanareasourcecouldlead to conservative results if it includes areas that are unlikely to experience similar levels of earthquakes within the time period under con-sideration, or less conservative results if areas that need to be included are not included. The method is unable to account for the fact that the area around Accra is far more active than other areas.

The value chosen for the maximum earthquake to be used in analysis also profoundly affects the results. In Ghana, the maximum historical earthquake appears to have been used as the basis for most of the maps. The maximum his-torical earthquake occurred in 1862 and was estimated initially by Ambraseys (1986) to have been greater than or equal to MF 6.5. In the same paper, Ambraseys estimated the Accra earth-quake of 1939 to be MF 6.3. The MF scale was introduced by Ambraseys (1986) to describe a felt Magnitude Scale. These events were later reassessed by Ambraseys (1988) to be MS 7.1 and MS 6.5 respectively (MS refers to a surface wave magnitude scale). None of the authors of

the maps described in this section appear to havehadthebenefitofthisinformation.Ghanadoesnothavethebenefitofalongperiodofseis-mic recording. Usually, several hundred years of recordings are required for inactive regions likeGhana.Thismakesitevenmoredifficulttodetermine whether earthquakes of magnitude 7.1 and larger can occur and how often. The deterministic method is unable to model all the uncertainties associated with the choice of the maximum earthquake used.

Appendix C—Probabi-listic Seismic Hazard As-sessmentThe Probabilistic Seismic Hazard Assessment (PSHA) method consists of four basic steps:

• Sourcedefinition• Magnitude-frequency relationship• Ground motion prediction• Probability of exceedance calculation

These steps are represented graphically in Fig-ure C1 and described in more detail in the fol-lowing sections.

Figure C1. The four steps of Probabilistic Seismic Hazard Analysis, after Cornell 1968.


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C.1. Source DefinitionThe location and recurrence of earthquakes rel-evanttothesiteofinterestisdefinedfromseis-micity catalogues, active fault data, and, increas-ingly, geodetic strain rates derived from GPS data.Sourcesareclassifiedasfaultsourcesandareal sources, also referred to as background or distributed seismicity. Fault sources are com-monly modeled as planar features with a given length and depth. PSHA usually considers fault sources within 100-200 km of the site. Sources at greater distance generally produce ground motions too low to be considered for seismic design. Areal sources are used to model seismic-ity away from known fault sources (Abraham-son, 2011). Areal sources can capture seismicity from sources that lack surface expression and have previously been undetected by geologists. Areal sources are commonly modeled as a vol-ume represented by a geographic area and a depth based on the seismogenic thickness.

Two major seismic sources are capable of pro-ducing large earthquakes in Ghana. The Coastal Boundary fault lies parallel to the coast (in the Atlantic Ocean) (Figure C2). The Akwapim fault zone is a highly folded and faulted formation that forms the Akwapim mountain range. The faults in this zone are numerous and it is likely that not all of themhave been identified. In ahazardassessmentforGhana,thewell-defined

Figure C2. Earthquake source zones in Accra – southeast-ern Ghana (Akwapim fault zone top; Coastal Boundary fault bottom). Source: Digitized from Microseismic activity Map of Southern Ghana

Coastal Boundary fault could be characterized as a planar feature, while the Akwapim fault zone would be characterized as an areal feature.

C.2. Seismicity CatalogsThe datasets most commonly used are seismic-ity catalogues, which provide a record of the timing, location, size (magnitude), and depth of earthquakes. Information on the seismicity of Ghana from 1636 to 1995 can be obtained from the Ghana Geological Survey Department. Other sources of information include the United States Geological Survey National Earthquake Infor-mation Centre (NEIC) and the International Seismological Centre (ISC), but such external sources provide only recordings of larger mag-nitude earthquakes. Small earthquakes are generally only fully recorded in Ghana. Instru-mental recordings began in Ghana in 1914 with the installation of a Milne-Shaw seismograph. Recordings were made for 16 years until 1933 when they were discontinued due to a lack of funds. Recordings were begun again in 1973, but operations were again discontinued after a few years. In July 1987, a new nine-station network was set up. It is unclear how long this network operated, but it was still in operation in 1999, thus producing the longest period of complete recording for the region. A new digital seismic network was commissioned for the Ghana Geo-logical Survey Department in December 2012. Stations are located within the southern sector of the country and news reports indicate that seismic activity has been recorded.

The most comprehensive catalogue for Ghana can be extracted from the catalogue prepared by Ambraseys and Adams (1986) and updated by Amponsah et al. in 2012. This catalogue covers the period from 1615 to 2003. The area examined was bordered approximately by lat-itudes 2.0°N and 14.0°N and longitudes 5.0°W and 3.0°E. There is a large gap in in data from 1636 to 1788, but it is likely that there were earthquakes, though the size is speculative. It


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is now more than a decade since the catalogue was prepared and there is a need to update it. Different magnitude scales have been used in the catalogues and there will be a need to con-vert them all to a uniform magnitude scale.

C.3. Active Faults DataActive faults data are used to develop input to seismic hazard modeling. Active fault datasets provide a means of extending the historical earthquake catalogues to include larger, less frequent earthquakes (e.g., prehistoric earth-quakes). Active faults are the surface expres-sion of large fractures in the Earth’s crust, and they accommodate slip between crustal blocks. Some of the world’s largest earthquakes strike on active faults. The GEM Faulted Earth proj-ect has provided a starting point for acquiring fault source model information. It is working to build a global active fault and seismic source database for the purposes of global hazard and risk assessment. The project has provided a tool and procedure for acquiring fault source model information, as well as an explanation of meth-ods to convert active faults data into active fault source models.

Ghana has an updated geological map produced in 2010 that stands at the scale 1:1 million and replaces the previous geological map from 1955. The new map was prepared by The Ghana Geo-logical Survey Department (GSD) with technical cooperation from the Federal Institute for Geo-sciences and Natural Resources (BGR) of Ger-many. Data used in the preparation of the new map include the 1962-1966 geological work by the GSD-Zarubezhgeologia (of the former USSR) on the Voltaian Basin, systematic mapping for programs sponsored by the Mineral Develop-ment Fund (MDF) and an EU-sponsored Mining Sector Support Program (MSSP). The new map is available in digital format, thereby making it morepossibletodefineandlocateactivefaultsand source zones.

C.4. Magnitude Frequency Rela-tionshipA magnitude frequency relationship uses the dimensionsandsliprateofafaultsourcetodefinethe mean magnitude of an earthquake on the source and its frequency of occurrence. The mag-nitude of a characteristic earthquake on a fault source is represented by the general equation,

M_w=log(A)+b (1.1)

Where A is the fault area and b is a constant that is controlled by factors such as fault type, geology, regional tectonics, and stress drop. For areal sources, a range of earthquakes are usu-ally considered, using the Gutenberg-Richter relationship (1944):

LogN(M)=a-bM (1.2)

Where N(M) is the activity rate, M is the magni-tude and a and b are empirical constants.

Attempts have been made to derive a recur-rence relationship for Ghana. Bacon and Ban-son (1979) used instrumental records for the periods April 1973 to September 1974 and Feb-ruary 1977 to July 1978. They obtained a good fit formagnitudesgreater than3anddeduceda B value of 1.05 from their results. Bacon and Quaah (1981) also made an estimate for the B value using data for the periods April 1973 to October 1974 and February 1977 to May 1980. They obtained a b value of 0.70 ± 0.16.

The lack of sufficient data on Ghanamakes itdifficulttoobtainreliableresults.Toovercomethis problem, a number of general relationships have been developed for various fault types and tectonic environments across the globe. In Ghana, the tectonic environment and the slip type of the relevant faults is an important fac-torinfluencingthechoiceofregression.Stirlinget al. (2013) provides a global compilation of regressions, along with recommendations on the use of regressions according to plate tec-tonic region, and the characteristics of faulting (slip rate and slip-type).


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C.5. Ground Motion PredictionGround motion prediction equations (GMPE), also called attenuation relations, are used to model the attenuation of ground motion from the source with distance and its associated uncertainty. Modern GMPEs typically take into account style of faulting (e.g., reverse, strike slip), soil conditions (e.g., soil versus rock), and magnitude. GMPE have been developed for shallow crustal earthquakes in active tec-tonic regions (e.g., California), shallow crustal earthquakes in continental regions (e.g., Central and Eastern North America), subduction zone earthquakes (e.g., Japan), and others. In Ghana, selection of the appropriate GMPE will require consideration of the tectonic environment, the likely slip type of faults in the region, and the soil conditions. The Global Ground Motion Prediction Equations Program (http://peer.berkeley.edu/globalgmpe/) is selecting existing GMPEs for each major tectonic environment in the world and these can be used to guide selec-tion of an appropriate GMPE for Ghana, when a relevant PSHA model is created.

C.6. Probability of Exceedance CalculationThe outcome of the PSHA is a hazard curve which gives the annual probability of exceeding a given ground motion. The curve is developed by integrating overall relevant sources, for all magnitudes, distances and standard deviations. The ground motion produced at the site by each scenario is calculated using a GMPE, as is the probability that the ground motion exceeds a specific level.Uniformhazardspectracanalsobe calculated from the hazard curve by plotting the hazard curve for a suite of different spec-tral periods. At a chosen annual frequency, the spectral acceleration for each spectral period is measured from the hazard curve and plotted on a separate graph. The spectral shape varies with differing local soil conditions and the mix of

sources and distance contributing to the hazard at the site. The hazard spectra provide useful input to engineering design for structures. An important part of the PSHA process is selecting the appropriate hazard level or return period. The return period considered for engineered buildings is typically 475 years. This corre-sponds to a hazard level with a 10% chance of being exceeded in 50 years (the building’s lifes-pan).

Appendix D – A Strategy for Existing SchoolsStrategiesforassessingandretrofittingexistingschools, detailed in Table 1 below, are primarily about capacity building and creating an environ-ment in which knowledge is continually gained and shared, and steps are taken to address iden-tifiedissues.Followingtheseguidingprinciples,GFDRR also recommends a general process for enhancing the resilience of many existing schools that prioritizes the schools at greatest risk, assures quality in design and implemen-tation, and engages the community throughout the process.

The steps below outline one possible commu-nity driven development approach outlined by GFDRR for establishing a program to assess andretrofitexistingschoolbuildings.Researchhas found this approach to be most effective in Africa and Asia. The engineering community typically initiates this approach, as it has the technical capacity for assessment, design, and supervision/inspection of buildings. Funding for the work is typically allocated in install-ments to a community and then managed by the Ministry of Education or similar institution. Thisapproachhasbenefitsbeyondseismicallysafe schools, including those to the local econ-omy through new construction. The table below follows the recommended process by GFDRR. More detail on each of the following steps is pro-vided in GFDRR (2010).


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Step Objective Notes

Identifying key partners

To identify potential collaborators who can contribute to a safer schools initiative, and form a coordinating group to lead the initia-tive.

Convene an advisory committee of key stakeholders and decision mak-ers to provide guidance and oversight while also promoting buy-in of theoverallprocess.Althoughindividualmembersmayservespecificterms, the committee should provide continuity throughout the life of the program. Members should have the necessary skills, knowl-edgeandresources.Theycouldincludeschoolofficials,teachers,par-ents, community members, students, members of local governments, builders, engineers and scientists. Advisory committee members can engage the support of the broader community through public meet-ings and word of mouth to build awareness of the program.

Determining risk

To calculate an approx-imate measure of risk within a given geo-graphical area in order to determine those existing schools in need of urgent intervention.

Risk is a product of hazard and vulnerability. This step can help to identify schools in need to urgent attention. Section 3 of this report, Earthquake Hazard in Ghana, provides guidance on the seismic haz-ard across Ghana and can be for prioritization of school buildings for assessment. The vulnerability of buildings to the hazard can be esti-mated based on the general characteristics of buildings from different periods and construction types.

Definingperformance objectives

To assign performance objectives for the mit-igation of damage, loss and disruption to important school assets and services.

Together with input from the local community and experts, the advi-sory committee can set objectives. Some possible performance objec-tives might include, 1) as a minimum, that no children or teachers are killed or injured inside or near a school building during an earthquake; 2) that buildings are usable as community gathering places after an earthquake.

Adopting building codes and retrofitguides

To identify a set of building codes or retro-fit guidelines that pro-vide technical design and implementation guidance on making a school more resilient to hazards.

A number of guidance documents and standards are available for the retrofit of existing buildings. The engineering community in Ghanashould select the appropriate standard, or develop one, that meets their needs. Update and formalize standard that have already been published, and determine their relevance for existing schools.

Assessing a school site

To conduct a detailed assessment of site-spe-cific hazard charac-teristics and any con-ditions that make a site more or less vul-nerable.

This phase includes evaluation of the potential for landslides, liquefac-tion, fault rupture,and floods,orothernon-earthquakerelatedhaz-ards that might exist at the site. In Ghana, little information is currently available on these hazards, but soil conditions can be assessed at a site todeterminewhethergroundshakingwillbeamplified inanearth-quake or whether liquefaction might be triggered. As faults are better identifiedandmapped,determinationcanbemadewhetherschoolsare located near active faults. Conduct geologic hazard studies for each site, per previous recommendations.

Table D1. Process for addressing seismic safety of existing school buildings (based on GFDRR, 2010).


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Step Objective Notes

Assessing the vul-nerability of existing school build-ings

To conduct a detailed vulnerability assess-ment of the structural and non-structural components of an exist-ing school in a hazard prone area.

Assessments would be made for a representative sample of school buildings to estimate vulnerability of entire stock. When many buildings have similar designs, an evaluation of a small sample of buildings would provide an indi-cation of vulnerability for the overall building stock. A screening tool that determinesyearbuiltandafewotherfactorsmightbeenoughifsufficientinformationisavailableaboutthestructuraldesignofthatera.Thefindingsfrom sample evaluations may also be useful in building support for future phases, if the program is phased. A number of simple screening tools can beadoptedforuseinGhana.ManyofthesetoolsaremodifiedfromFEMA154 (Rapid Visual Screening of Buildings for Potential Seismic Hazards). This tool and an associated handbook are available online (https://www.fema.gov/media-library/assets/documents/15212). It should be noted that FEMA 154 does not address some of the typologies found in Ghana, especially adobe masonry and bamboo buildings. EERI has resources avail-ableforretrofitandconstructionofearthquakeresistantadobebuildingsthrough the World Housing Encyclopaedia (http://www.world-housing.net/tutorials/adobe-tutorials). Bamboo and other types of vernacular con-struction can have good seismic performance, but structural evaluation is needed (Sharma, 2010).The assessment program might be phased based on hazard, vulnerability or occupancy. For example, secondary schools might be given priority, given that secondary schools tend to be boarding schools and these buildings tend to be multiple stories. Engineers should be involved in the assessment, but secondary and university students can also assist. For example, in a sidewalk assessment of existing residential buildings in San Francisco, stu-dents and professional engineers were paired together (ATC, 2009). This is a good way to engage students in evaluation of the buildings in their own community and is an opportunity to educate students about earthquakes and earthquake engineering.

Detailed evaluation

The evaluation of a representative sample might reveal that some buildingdesignswouldbenefitfromamoredetailedevaluationbyastructural engineer. If many buildings were designed using the same standarddesign,findingsfromevaluatingasmallnumberofbuildingsmay be used to characterize the performance for the whole class of buildings.

Preparing a retrofittingplan

To design a retrofittingplanthatsatisfiestheper-formance objectives and school design criteria.

Choosingasmallnumberofbuildingstoretrofit,asapilotphase,willadd visibility to the existing school building program and is another opportunity for education of the entire community about earthquakes and the importance of good building practices. Funding from non-prof-itsandNGOsmaybeavailabletofundtheseretrofits.

Assuring quality of construction andretrofitworks

To retrofit an existingschool to higher safety standards

Theretrofitwillonlymeetitsintendedobjectivesiftheplaniscare-fully followed in construction. Training for builders on proper tech-nique and careful monitoring and inspection of construction will help ensure quality construction.


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