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Masonry Structural Design Competition for Civil Engineering and Architecture Students

Final Report Wednesday, May 15th, 2013

Name of University Clemson University Contact Name Sez Atamturktur, PhD Contact Title Assistant Professor Mailing Address Clemson University, Glenn Department of Civil Engineering Lowry Hall, Clemson, SC 29634-0911 Phone (864) 656-3003 Fax (864) 656-2670 E-Mail sez@clemson.edu

Masonry Design at Clemson University

In continuation of Clemson University’s longstanding history with masonry research and design,

the Glenn Department of Civil Engineering has put together a course offering students the

ability to learn about masonry design and construction. This course will help further the

awareness of masonry topics amongst students within the department, many of whom have

chosen studies in the fields of structural engineering, construction planning and materials

research. The class also offers those in related fields such as architecture and construction

science a chance to venture outside their traditional curriculum in an effort to become well-

rounded graduates more prepared for the working environment. Not only will these students

learn about the historical tradition and relevance of masonry design and construction but they

will be given chances to learn through hands-on demonstrations and activities outside the

classroom in addition to lectures given by relevant industry professionals.

The course is based on the principles laid out by the Masonry Society Joint Committee (MSJC) in

its 2011 code. The students are introduced to the historical traditions of masonry throughout

the world before being guided into modern design through coursework which involves

examples and discussion from the point of view of the practicing design engineer. Work is

assigned and students are expected to expand their knowledge of masonry throughout the

course. The topics evolve through the introduction of materials and technical notes through

simple unreinforced design to that of more advanced, reinforced shear and curtain wall design.

Through the semester the students are given examples through Allowable Strength Design

(ASD) as well as Load and Resistance Factor Design (LRFD) which together provide exposure to

both common and future design practices. Finally, the students are given a chance to research

individual topics and present a summary of their findings to the class. The final presentations

provide both a wonderful opportunity for students to practice their speaking skills as well as a

concluding discussion on more advanced topics within masonry such as acoustic considerations,

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thermal design, masonry accessories and detailing, sustainability, fire resistance and impact

resiliency.

Project Purpose and Description

In an effort to supplement the topics discussed within this course, students this semester were

given the opportunity to participate in a competitive project in which they were tasked with

designing, constructing and testing masonry walls. This semester-long project pushed students

in all facets of what they learned in the course and charged them with not only the design but

also the construction of an actual masonry project. Students were given the opportunity to

compete for monetary prizes and plaques which signified the most outstanding masonry

performances.

The task called for students to design a wall of required dimensions that would be tested for

strength at the end of the semester. In addition to dimensions, students were allowed the use

of a limited quantity of reinforcing bar and grout. They were also asked to design their walls

such that 33% of the surface area was left open. Through the course of the semester students

often made progress on the project through the completion of homework assignments which

involved designing and analyzing their own masonry walls.

Class & Competition Advertising

In November 2012, posters advertising the class as well as the design competition were

distributed throughout the campus – specifically in Lowry Hall (Civil Engineering department

main building) and Lee Hall (Architecture department main building). See page two for a snap-

shot of the poster (Figure 1). The spring semester began on January 9th 2013.

The initial classroom capacity assigned for this course was 30 students. Due to high demand,

the classroom location was modified and a total of 45 students have been accommodated.

Eighteen of these are undergraduate students enrolled in CE 404 while twenty-seven are

graduate students enrolled in CE 604. Students were asked to form groups of five to participate

in the design competition. Groups have mixed undergraduate and graduate students (Table 1).

Project groups have completed the preliminary design of their masonry wall through hand

calculations. Project teams will soon start developing numerical models of their wall in finite

element packages. Further updates regarding the progress of the design competition will be

delivered throughout the semester.

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Figure 1: Poster distributed to advertise design competition and student enrollment to the

masonry class.

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Table 1: Design Competition groups. Green indicates graduate students and yellow indicates

undergraduate students.

Exposure to Masonry Practices

In preparation for the masonry wall construction, it was necessary to provide the students with

some hands-on experience and training working with masonry. The majority of the students

had no prior experience in masonry construction. To provide exposure for the students,

multiple out-of-class trips were organized that gave the class an opportunity to witness walls

being constructed by trained masons. In addition, the students were given a chance to interact,

ask questions and finally build small walls as practice. During the process, the class took away

valuable information about the mixing and preparing of mortar, how best to apply it to the

concrete masonry units and how to construct a wall properly with careful attention to each unit

and course. These trips visited the TD Expo Center in Greenville, South Carolina for the Masonry

Skills Competition and the Pickens County Career and Technology Center where masonry skills

were demonstrated and taught (Figures 2 and 3).

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Figure 2: Masonry Skills Competition at the TD Expo Center hosted by Byard Stevens, Greenville,

SC (above)

Figure 3: Masonry instructor Jeffery Stephens at the Pickens County Career & Technology

Center, Liberty, SC (shown above)

Construction & Testing Logistics

Wall testing took place at Clemson University’s Structural Research Laboratory which lies just

off-campus approximately five minutes from the center of the University campus. The testing

procedure was designed to examine a masonry walls flexural capacity. To do this, it was

decided that a lateral pressure would be applied to the one side of the wall being test with the

other side braced continuously in a simply-supported fashion. This was done sequentially

through the use of an inflatable air bag and a test frame which was fabricated specifically for

this project. The use of air bags is a common practice in structural research reflected in

numerous reports and official ASTM test standards although no official test procedure was

followed for this project. The inflation process created a means of progressively loading the

walls. This process was carefully structured and thus the testing was completed in a slow and

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deliberate fashion. Records were taken of the maximum air bag pressure and wall deflections

during testing. The primary concern for this project was of the maximum pressure withstood

before flexural failure. The walls deflections could be easily monitored from just feet away so it

should be noted that future tests could involve more elaborate failure criteria which may

reflect a maximum allowable deflection, maximum rate of deflection or some other

consideration of flexural capacity.

The testing process for a single wall lasted only minutes once the test was initialized and so the

completion of testing, which involved a total of nine masonry walls, lasted only hours in total.

However, the testing spanned multiple days so that an even curing time could be given to each

wall according to when it was completed. During this testing it was necessary to replace the

inflatable air bags after approximately 3 to 4 walls had been loaded and broken. Carefully

attention should be put on the condition of such things as they can influence the result of the

testing and in a situation such as this, it would be highly impractical to fail a wall accidentally or

through improper testing. Thus, the slow, deliberate testing procedure is and should remain a

vital ingredient in any future project of this nature.

To allow for these tests to take place, the walls required a rigid support system that would

sufficiently brace the upper and lower courses in a simply-supported fashion to allow for the

recordation of accurate flexural strength and deflection measurements. Thus, a medium-sized

test frame measuring approximately 6.5 feet (198.1 cm) in height was designed by Dr.

Atamturktur in conjunction with graduate assistant Gregory Roche who served in a number of

capacities throughout the duration of this project. The frame was designed such that it could be

transported safely over short distances via the use of a department-owned forklift, which

meant that careful observation had to be taken of the frame’s overall dimension and weight as

these limitations were stipulated by the forklifts capacity for safe and efficient lifting. Below are

shown two sample AutoCAD visuals used in guiding the students (Figures 4 and 5).

Figure 4: AutoCAD drawings were created that displayed to the students how the testing would

take place and just how the frame was being designed. In many cases, this affected the students

wall designs.

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Figure 5: Another figure shown to the students. It demonstrates the continuous lateral bracing

of the wall (outlined in red) and where the lateral pressure would be applied (outlined in blue).

The students were also tasked with removing 33% of the surface area without compromising the

outer 88” x 56” dimensions.

Design & Construction of Testing Frame

The creation of a portable test frame was necessary in that it ensured the walls would not have

to be moved individually which would have been a very delicate and dangerous process in

which the walls structural capacity could easily have been comprised, particularly in such a

competition where each wall’s geometry was encouraged to be unique. There are obvious

safety risks as well in this type of process so it was decided that the wall testing should take

place without any relocation demands upon the walls either during or after construction.

Conceptual input and consultation on the general design of the test frame was also provided by

the department’s technical supervisor Danny Metz and his staff. Much of their role within the

department is in the supervision and technical support of projects such as this. Careful

consideration should, and in this case was, given to the abilities and limitations of any

department’s resourcefulness in the design and fabrication of research- or project-oriented

demands. In this instance, the construction of the frame was handled by the Seneca-based

fabrication Blue Ridge Welding and Machining who accurately interpreted both hand-drawn

structural sketches as well as detailed AutoCAD drawings of the test frame. Special attention

was given within the design and outline of the frame to its future use in similar applications

both for class projects as well as masonry research. The completed frame will prove to be a

departmental asset for years to come. See Figure 6-8 below.

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Figure 6: Picture taken after the test frame components had been received, assembled and

painted at the Clemson University Structures Laboratory.

Figure 7: The test frame was designed as a portable, one-piece apparatus. This kept the testing

simple with no complex assembly of the frame required and no relocation of the walls

necessary.

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Figure 8: The frame was transported from wall to wall during testing. It was raised about six

feet in the air and lowered carefully onto each wall before the air bag was installed and

pressurized.

Wall Construction

When the designs were finalized, a construction zone was selected on the grounds of the

Clemson University Structures Laboratory. There, the students were supplied with tools and

hardware to construct the designs they had submitted for approval. All the necessary

components of the walls including the concrete masonry units, the mortar and the grout were

donated by local manufacturer Adams (formerly Cemex). The rebar was purchased from a local

supplier as well. The students were provided with 1 week in which to build their walls. Because

of time constraints, the curing process was shortened with a maximum of approximately 5-6

days being the longest duration possible. Groups were encouraged to plan their construction to

maximize variables like curing time. Because of the competitive nature of the project however,

where circumstances allowed groups were encouraged to plan on their own and requirements

were kept to a minimum. See figures 9 and 10 below.

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Figure 9: Construction began the afternoon of Wednesday, April 24

th (above).

Figure 10: Construction continued over the next several days before walls were left to cure

(above).

Judging Overview

An assessment of the students’ masonry walls was carefully conducted with the help of a panel

of expert reviewers. The judging took place on Monday, April 29th, approximately one week

after construction had begun and shortly before the testing procedures were initiated. During

this review process a number of local officials were on-hand to evaluate the nine walls (Figures

10 and 11). This expert panel was comprised of representatives from Adams Products (supplier

of masonry materials for this project), the National Concrete Masonry Association (NCMA), the

Carolinas Concrete Masonry Association (CCMA), The Masonry Society (TMS), the Pickens

County Career and Technology Center as well as Clemson University. Amongst these individuals

were industry professionals with large amounts of experience in the design and construction of

masonry. In addition, representatives from the Masonry Society and Clemson University

brought a wealth of experience and knowledge involving masonry research, testing and

university-level instruction.

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The results from the judging were combined with the results of the testing as well as the

students predictions to tabulate and overall group score. The best three overall group scores

were recognized with certificates and congratulations as well as prize money provided through

the donations from the National Concrete Masonry Association’s Education and Research

Foundation. Monetary prizes in the amounts of $1,500, $1,000 and $500 were awarded to the

first, second and third place groups, respectively in accordance with their overall project score.

The primary goal for the student competitors in this project was in constructing a wall of

maximum performance under lateral loading and so $1,000 was also awarded to the group

whose wall had achieved the highest ratings when tested for flexural strength. This seemed a

very sensible reward as the focus of the project was directed almost entirely towards this end

from the students end. In addition, a $1000 reward was given to the group whose flexural

capacity prediction had most closely matched the actual test results of their wall. This reflected

the group’s ability to carefully consider, predict and estimate the various parameters which

influenced their walls ultimate capacity in addition to the structural techniques taught in the

course. The effects involved were largely unknown to the groups, at least in detail, and so

careful research and consideration was necessary in making accurate adjustments to the typical

structural engineering techniques involved in practical masonry design. It was considered

important to reward the diligent efforts of the most exemplary group in this category.

Figure 11: A panel of expert reviewers was on-site to judge the walls before they were tested.

From left: Dr. Russell Brown, _________, Todd Cox and Byard Stevens. These represented

Clemson University and The Masonry Society, _______, Adams Products and the Carolina’s

Concrete Masonry Association, respectively.

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Figure 12: The judges carefully reviewed each of the free-standing masonry walls. They noted

and graded each group’s wall according to the criteria of constructability, aesthetics and the

functional use of masonry materials.

On-Site Testing

Finally, the students were asked to diligently construct their walls at designated stations which

had been determined such that the test frame could be safely relocated from station to station

as the testing was completed. Groups were instructed prior to their arrival that they should

begin their preconstruction activities at the next available station. These stations were clearly

marked and numbered at the Structures Laboratory. This station arrangement reflected the

testing order and helped ensure that each wall would have roughly one week of curing time. In

this way, the first walls constructed were the first walls tested. Conversely, the last wall built

was the last wall tested. To make sure this was the case students were reminded at multiple

intervals both during class as well as via electronic reminders. They were also managed

carefully while at the Structures Laboratory where they built their walls. Class instructor and

project leader Dr. Atamturktur in addition to graduate assistant Gregory Roche and technical

supervisor Danny Metz all made sure that at any point proper supervision and guidance was

available on-site. See figures 12-17.

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Figure 12: Shown from one end, the test frame supported the top and bottom courses. A large

piece of plywood was placed between the walls and the air bag. This protected the bag and

ensured consistent pressure across the wall.

Figure 13: A side-view taken during test shows the wall flexing under severe lateral pressure.

The beginnings of flexural failure can be seen in the middle portions of the wall were cracks in

the mortar joints are forming.

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Figure 14: The test was considered complete when additional pressure in the air bag caused

limited or no change in the walls deflection. Here, a failed wall remains in its final deflected

shape.

Figure 15: Deflection measurements were taken after the walls were failed in flexure. A simple

tape-measure sufficed. Here, the wall shows a 4” deflection which happened to be the

maximum seen during testing.

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Figure 16: Failure of the walls was not identical in each specimen. Here, multiple joints have

failed and vertical cracks have moved through many of the 4-inch CMUs.

Figure 17: The failure of each wall was carefully examined and noted after testing by all who

were on-site. This included the group members, the testers, the judges, etc. Here, Clemson

University emeritus faculty member and The Masonry Society President Dr. Russell Brown

closely inspects a walls failure.

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Group Scoring

The walls were evaluated according to a rubric with five primary areas of focus. Most important

in evaluating each wall was its structural performance during the out-of-plane load tests which

were conducted the week following construction. These tests were completed over 3 days to

balance curing times and to allow students some flexibility during exam week to attend the

scheduled wall tests.

The breaking strength of each wall contributed to a total of 35% of the overall group score. This

was the highest weighting given to any of the five criteria. This high weighting was given

because it reflected the structural design developed by the students, the craftsmanship of the

construction and the competitive creativity which was encouraged throughout the project.

To complement the structural performance of their walls, groups were asked to estimate what

they thought to be their walls actual breaking strength. Students began by estimating their

walls capacity according to MSJC 2011 code requirements. To reflect the nature of the project,

groups were encouraged to adjust their predicted strength based on the many variables that

would have an effect during testing. Student construction, limited curing time and conservative

code requirements all contributed to variances in the predicted strengths which students

estimated according to their own predictions. The predictions each group made were measured

against the test data. The importance of this category reflected a variety of project goals.

Students were able to measure the accuracy of their calculations, the impact of masonry

craftsmanship and the basis for many of the MSJC code requirements.

The final three judging criteria were given equal weight. Each was worth 15% of the overall

group score. These were the constructability of the walls, the aesthetics and craftsmanship

displayed as well as the functional use of masonry materials. The first of these, the

constructability, measured how efficiently the wall could be built. The complexity of the unit

layout, the void spacing in the wall and the construction time were all considered as factors in

this measurement. The second criteria, which measured the quality and aesthetics of each wall

was based on a visual inspection done following construction by the judging panel. The visual

appeal of the wall design was also considered in this category. The final criteria which involved

the functional use of materials reflected the thoughtfulness of the design and the practicality of

the construction. The placement of rebar and the groups’ use of masonry units were important

factors in this category.

Test Results

Table 1 shows the scoring associated with the first two categories. This involved the flexural

testing capacity (category 1) as well as the strength prediction accuracy of the group (category

2). Highlighted are the two groups (1 &3) which tied for the maximum wall capacity during

testing and the group (9) whose predictions most closely matched the actual strength of their

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wall when tested. Shown in table 2 are the results of the judging. The panel of 5 judges which

included industry experts and university faculty was asked to individually score each wall

between 1 and 15 based on their opinion of the wall’s performance in each associated

category. Tables 4 through 8 show the winning groups. Listed are the group achievements, the

group members, and the prizes they earned in the competition.

Test & Prediction Results

Station # 1 2 3 4 5 6 7 8 9

Group # 1 5 3 8 2 7 6 4 9

Category 1 (Max Capacity, PSI) 2.64 2.49 2.64 1.45 2.28 1.43 1.14 1.93 1.00

(Maximum Deflection, in) 4" 2.5" 2 1/4" N/A 1.5 1 3/4" 1 1/8" 7/8" 1.5"

Category 2 (Prediction Error, %) 0.76 0.92 0.27 0.58 0.65 0.47 0.82 0.37 0.19

Table 2 – Results from Testing

Judges Scoring (Average of 5)

Station # 1 2 3 4 5 6 7 8 9

Group # 1 5 3 8 2 7 6 4 9

Category 3 - Constructability 15.0 13.4 12.2 14.6 15.0 14.4 14.8 14.6 14.6

Category 4 - Aesthetics 15.0 14.8 10.6 15.0 14.8 13.6 10.8 13.8 11.4

Category 5 - Use of Materials 13.8 15.0 13.4 15.0 15.0 15.0 15.0 14.4 15.0

Table 3 – Results from Judging

Best Overall Design

Group

3

Zachary Graham

$1,500

&

Certificate

Vaughn Hayduk

Evan Mantilla

Christopher Mattison

Rohith Pamraj

Table 4 – The best overall design award was given to group 3. This was based on a summation

of their performance in all 5 scoring criteria.

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Best Overall Design (Runner-Up)

Group

1

Jordan Fiedler

$1,000

&

Certificate

Cornelius Bolling

Andrew Lisicki

Matt Egeberg

David Matheny

Table 5 – An award was also given to the runner-up. This group produced a wall that tied for the

maximum flexural capacity. However, their total score was slightly lower than the winning

group.

Best Overall Design (2nd Runner-Up)

Group

2

Thomas Alexander $500

&

Certificate

William Beadles

Richard Hooke

Thomas Taylor

Table 6 – An award was also given to the 2nd

runner-up. This group produced a wall that

performed well under testing and scoring highly in all areas of the judging.

Best Wall Performance

Group

1 & 3

(Tie)

Group Members

Listed Above

$1000

&

Certificate

Table 7 – Two groups (1 & 3) produced walls which withstood 2.64psi of pressure during testing.

This was the maximum value seen, so the groups divided the purse.

Most Accurate Predictions

Group

9

Yaw Bonsu

$1000

&

Certificate

Christopher Gerding

James Jackson

Kyle Mcdonough

Jessica Stamey

Table 8 – This group (9) produced relatively accurate wall strength predictions. Their prediction

of 0.81psi was slightly lower than the 1.00psi it took to fail their wall however this was the most

accurate prediction amongst the groups.