Structure Design Criteria-final

8/19/2019 Structure Design Criteria-final

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DARIYAH VILLA

Structural Design Criteria15/5/2013


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STRUCTURAL DESIGN PAGE NO.

1. INTRODUCTION…………………………………….………………..3

2. GENERAL OBJECTIVE .......................................................... 3

2.1 Safety and Strength .................................................... 3

2.2 structural stability …………………….………………….3

2.3 Durability ..................................................................... 3

2.4 Economy ..................................................................... 4

2.5 Serviceability ............................................................... 4

2.6 Constructability ............................................................ 4

2.7 Spesifecation ............................................................... 5

3. STRUCTURAL DESIGN PARAMETERS ................................. 5

3.1 Design codes and refrences ...................................... 5

3.2 Design load ............................................................... 5

3.3 Load combinatons ...................................................... 6

4. MATERIALS ............................................................................ 7

4.1 Concrete ................................................................. 7

4.2 Reinforcement ........................................................ 8

4.3 Structural Steelwork ............................................... 8

4.4 Block Work Walls ................................................... 8

4.5 Timber .................................................................... 8

4.6 Fill Material ............................................................. 8

5 STRUCTURAL SYSTEM ......................................................... 8

5.1 Substructure ........................................................... 9

5.2 Superstructure ..................................................... 10

7 EXTERNAL WORKS……………….. ................................. 19

8 FUTURE VERTICAL EXTENSTION……………….. .......... 19

9 THERMAL INSULATION……………….. ........................... 19

11 SOFTWARE PROGRAMS………………............................20


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LIST OF FIGURES PAGE NO.

Figure 9:: Economy beam depth, depends on Mu, beam width.................17

Figure 10:: Economy beam reinforcment, depends on Mu, beam width.....17

Figure 11:: Columns Schematic Sizes, depends on Pu, % of steel............18

LIST OF TABLES PAGE NO.

Table 1:: Concrete Grades & Basic Mix Requirements........................ . .......7

Table2:: Structural Software's...................................................... ................20


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1- Introduction:

The purpose of this report is to clarify the design criteria, design parameters and structural system.

The structural systems adopted for the proposed project compatible with the architectural design

philosophy. The design reflects the particular needs of any special functional parameters of the

project. The structural elements designed generally in accordance with Saudi Building Code(SBC)

and American Building code and there standards.

Project Description:

The project consists of two basements, ground, first and roof mainly it is containing living rooms,

bed room, and other services rooms, for more details please refer to arch drawings.

2- General objectives:

The objective of the structural design is to achieve the optimum structural system and requirement

as stipulated in the relevant codes and standards that will satisfy the following criteria:

2.1 Safety and strength:

Shall be as defined by the current (SBC) codes in terms of loading and strength, the design

method for all structural elements will be in accordance to Limit State Design.

2.2 Structural Stability:

The structure should be designed to adequately transmit the design ultimate dead, live,

wind, earthquake and imposed loads safely from the highest supported level to the

foundations.In addition, lateral stability of the structure shall be achieved for all critical load cases which

includes seismic and wind forces. Limit of lateral drift shall be according to the code

requirement for all load types, In order to check the lateral stability of the building, a three

dimensional finite element model has been created using a well-known computer program

Etabs-V9.7.4. Also the provisions of section 7.13 of SBC 304 for structural integrity should

be achieved.

2.3 Durability:

Concrete mixes and cover are to be provided to protect reinforcements against corrosion for

the soil exposure conditions to be determined based on geotechnical testing, to avoid attack

of deleterious salts on concrete, it is recommended that foundation, basement, and other

structure coming on contact with the soil or groundwater be constructed using ASTM Type

"V" cement .

2.3.1 Concrete Cover:

Concrete cover to steel reinforcement shall be provided to protect the reinforcement against

corrosion and fire according to SBC clause 7.7.

Cast-in-place concrete (Non-Prestressed)


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a) Concrete cast against and permanently exposed to earth = 75mm

b) Concrete exposed to earth or weather

Diameter 18 mm and smaller = 40mm

Diameter larger than 20 mm = 50mm

c) Concrete not exposed to weather or in contact with ground

Slabs and Walls = 20mm

Beams and Columns = 40mm

Structural steel works shall be coated by protective coating in order to achieve a minimum

fire rating of two hrs.

2.3.2 Waterproofing of structures below ground:

Waterproofing materials: at least two layer of bitumen coating should be applied to the

exterior of all the foundation and other concrete coming in contact with soil.

2.4 Economy:

Shall be achieved by establishing a practical structural system that will yield the simplest

structural forms in terms of geometry and logic and will be well suited for existing local

practices, The structural system shall be conceptualized to emphasize the architectural

concept. The self-weight of the structure also designated, as dead load is an important

element in the economic structural design of building. This dead load accounts for

approximately (70%) of the total strength design of structural elements, An economic

structural design must therefore seek to reduce dead loads as much as possible, simplicity

of form reduces the cost of shuttering and labor.

2.5 Serviceability:Serviceability as defined by relevant codes of practice SBC shall be checked and accounted

for in the design. Serviceability affects deflection of members, crack control, limitation of

vibration, acoustics and fire protection.

2.5.1 Deflection criteria:

The structure will be designed& checked according to SBC 304.

2.5.2 Fire resistance:

The following fire resistance periods in accordance with ACI regulations are to be applied to

the structural elements.

Load bearing walls & columns = 4 hrs fire rating

Floor construction including beams = 2 hrs fire rating

Shafts and stair walls = 4 hrs fire rating

2.6 Constructability:

Ease and economy of construction will be high among the designer's priorities.

2.7 Specification.

Material and workmanship specification shall be based upon relevant SBC and American

standards.


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3- Structural design parameters:

3.1 design codes and references.

The structural design, in general, will be in accordance with the following codes of practice.

ACI-318-05: Building Code Requirements for Structural Concrete (318M-05).

ASCE 7-05: Minimum Design Loads for buildings and other Structures, for wind load.

IBC 2003 : International Building Code, for seismic load.

SBC 301 : Saudi Building Code, Minimum load requirements for the design of buildings and

other structures.

SBC 304 : Saudi Building Code, concrete structure requirement.

AISC-ASD: American Institute of Steel Construction – Allowable Stress Design.

3.2 Loadings:

Design dead load and live load as per ASCE 7-05 and SBC 301.

3.2.1 Dead loads:

Principle dead loads to be carried by the structure (except self-weight) are cladding,

floor finishes, partitions and landscaping loads. Allowance for these loads is to be

taken in consideration in the design.

Reinforce concrete = 24 KN/m³

Ceramic or quarry tile (20 mm) on

25 mm = 1.1 KN/m2

Water = 10 KN/m³

Sand =15 KN/m3

Services = 0.5 KN/m2

Weight of hollow blocks ≥ 30 kg

- Reference: Table 3-1 and Table 3-2 SBC 301

3.2.2 Live loads:

The Minimum live loading will be as specified in ASCE 7-02 and SBC 301 is 2.0 KN/m2

- Reference: Table 4-1 SBC 301

3.2.3 Wind loads:

Wind load calculation shall be done using ASCE 7-05 and SBC 301 according to the

following Criteria

Wind Speed = 170 Km/hr. Figure 6.4.1 SBC 301

Exposure Type = B

Importance Factor = 1.15

Topographical Factor = 1.00

Gust Factor = 0.85

Directionality Factor = 0.85

Windward Coefficient = 0.80Leeward Coefficient = -0.50


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3.2.4 Seismic loads:

According to the IBC 2003 and SBC 301; the seismic coefficient for Riyadh

are Ss=0.271g and S1=0.098g, and according to soil investigation report soil profile

type =C, so SDs=0.415g and SD1=0.228g these factors should be used in the

design of the proposed project, and the importance factor equal to 1.25.

3.3 Load combinations:

The load combinations shall be in accordance with ACI318-05, the following

combinations shall apply:

Ultimate limit state (strength) Loads:

The principal load combinations for strength are:

U = 1.4 (D + F) (3-1)U = 1.4 (D + F + T ) + 1.7(L + H ) + 0.5 (Lr or R ) (3-2)U = 1.2D + 1.6 (Lr or R ) + (1.0 L or 0.8 W ) (3-3)

U = 1.2D + 1.6W + 1.0L + 0.5(Lr or R ) (3-4)U = 1.2D + 1.0E + 1.0L (3-5)U = 0.9D + 1.6W + 1.6H (3-6)U = 0.9D + 1.0E + 1.6H (3-7)

except as follows:

(a) The load factor on L in Eq. (3-3) to (3-5) shall be permitted to be

reduced to 0.5 except for garages, areas occupied as places of public

assembly, and all areas where the live load value of 5 kN/m2 to be

consistent with the Saudi Building Code for Loading (SBC 301).

(b) The load factor on H shall be set equal to zero in Eq. (3-6) and (3-7) ifthe structural action due to H counteracts that due to W or E. Where lateral

earth pressure provides resistance to structural actions from other forces, it

shall not be included in H but shall be included in the design resistance

Vertical Seismic Components:

The load effect resulting from the vertical component of the earthquake

ground motion and is equal to an addition of (0.2SDSD) to the dead load

effect, D, for Strength Design, and may taken as zero for Allowable Stress

Design.

Serviceability Limit State:

Combinations of actions for serviceability limit states shall be those

appropriate for the serviceability condition being considered. Appropriate

combination may include one or a number of the following loads:

1) D + L

2) D + L+S ± W or 0.7 E

3) D + L ± 0.5 W

4) 0.9D ±0.7E

Where:D: Dead Load

L: Live Load


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E: Earthquake Load in Both Directions (EX & EY)

W: Wind Load

4- Materials:

In general, the main structural components and materials will comply with the following outline

specifications:

4.1 Concrete:

All reinforced concrete shall have minimum characteristic cubic strength of 40

N/mm2 at 28 days.

Slabs on grade, shall have minimum characteristic cubic strength of 20 N/mm2 at 28

days.

Blinding concrete shall have minimum characteristic cubic strength of 18 N/mm2 at

28 days.

Admixtures will be used to improve certain properties of concrete admixtures should

comply with the ASTM standard.

The Following Table of Concrete Grades and Basic Concrete Mix Requirements:

Concrete

Grade (Cube)

Cube strength

(fcu) (MPa)

Cylinder

strength (f ’c)

(MPa)

Minimum Cement

Content (Kg/m3)

Maximum (W/C)

ratio

C20 20 16 210 0.60

C40

40

32 350 0.40

Table 1:: Concrete Grades & Basic Mix Requirements.

- Ordinary Portland cement (OPC) type "I" will be used for superstructure

reinforcement concrete.

- ASTM type "V" will be used for substructures (foundation, basement, and other

concrete structure contact with soil.

- Maximum aggregate size shall be of 20 mm for all concrete.

4.2 Reinforcement:

All main reinforcing bars including mesh reinforcement shall be deformed high

strength steel bars complying with ASTM standard having minimum yield strength of

420 MPa and minimum elongation a gauge length 14%.

4.3 Structural Steel Work:

Minimum Yield Strength

Fy =250 MPa for ASTM A36 hot-rolled steel structural sections.

Fy =345 MPa for ASTM A514 cold-rolled steel structural member.

Bolts connections

ASTM A325 high strength bolts for primary connection and ASTM

A307 for secondary connections and anchor bolts Weld connections


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ASTM E70xx low hydrogen welding electrodes. All welds shall conform to

AWS A5.1 and D1.1 Structural Welding code.

Steel roof deck minimum yield strength

Fy=225 MPa for ASTM A611 or ASTM A446.

4.4 Block Work Walls:

The minimum strength of all non-load bearing hollow concrete blocks shall not be

less than 7 N/mm2 expressed as force per unit of cross sectional area.

The minimum strength of all load bearing concrete blocks shall not be less than 10

N/mm2 expressed as force per unit of cross sectional area.

4.5 Timber:

All timber used for architectural purposes, such as pergolas, shall be class SC5

Hardwood with minimum grade strength of 7 N/mm2.

4.6 Fill Material:

All fill shall be from selected, well-graded material and shall be placed in layers not

exceeding 200mm. Each layer shall be adequately compacted to a minimum 95%

maximum dry density (Proctor Test) and shall be tested.

5. Structural System:

An important part of the total responsibility of the structural engineer is to select from

the alternatives the best structural system for the given project. The wise choice of

structural system is far more important in its effect on overall budget and

serviceability than the refinement in proportioning the individual members.

The close cooperation with the architect in the early stage of the project is essential

in developing a structural that not only meet functional and esthetic requirements butexploits to the fullest special advantages of the reinforced concrete which include the

following:

1. Versatility of form: Usually placed in the structure in the fluid state, the

material is readily adaptable to a wide variety of the architectural and

functional requirement.

2. Durability: with proper protection of the steel reinforcement. The structure

will have long life, even under highly adverse climatic or environmental

conditions.

3. Fire resistance: with proper protection of the reinforcement, a

reinforcement concrete structure provides the maximum in fire protection.

4. Speed on construction: in terms of the entire period, form the date of

approval of the contract drawings to the date of completion; a concrete

building can often be complete in the less time than a steel structure.

Although the filed erection of steel building in more rapid, this phase must

necessarily be preceded by prefabrication of all part in the shop.

5. Cost: in many case the first cost of concrete structure is less than that of a

comparable steel structure. In almost every case, maintenance cost is less.

6. Availability of labor and material: it is always possible to make use of

local source of labor, and in many inaccessible area s, a nearby sour of


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good aggregate can be found, so that only the cement and reinforcement

need to be brought in form a remote source.

The structural concrete elements in the system can be summarized as follows:

5.1 Substructure:

5.1.1 Foundations:

Introduction:

Footings are structural members used to support columns and walls and

transmit their loads to the underlying soils, Reinforced concrete is a material

admirably suited for footing and is used as such for both reinforced concrete

and structural steel buildings, bridges, towers and other structures.

Not only is it desired to transfer the superstructure loads to the soil beneath

in manner that will prevent excessive or uneven settlements and rotations,

but it is also necessary to provide sufficient resistance to sliding and

overturning.

The closer a foundation is to the ground surface, the more economical it will

be to construct. There are two reasons, however, that may keep the

designer from using very shallow foundation. First, it is necessary to locate

the bottom of a footing below the ground freezing level to avoid vertical

movement or heaving of the footing as the soil freezes and expands in

volume. Second, it is necessary to excavate a sufficient distance so that a

satisfactory bearing material is reached, and this distance may on occasionbe quite a few feet.

Types of footing

Among the several type of reinforced concrete footing in common use are

the wall, isolated, combined, raft and pile cap types.

1. Wall footing, Simple an enlargement of the bottom of a wall that will

sufficiently distribute the load to the foundation soil. Wall footing are

normally used around the perimeter of a building and perhaps for some the

interior walls.

2. An isolated or single column footing is used to support the load of single

column. These are the most commonly used footing.

3. Combined footing, is used to support two or more columns, it is economic

where two or more heavily loaded columns are so spaced that normally

designed single column footing would run into each other.

4. Mat or raft foundation, is a continuous reinforced concrete slab over a

large area used to support many columns and walls. This kind of foundation

is used where the soil strength is low or where column loads are large but

where piles or caissons are not used.

Types of loads on foundations:


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Dead, live, wind, inclined thrusts and uplift, water table and earthquake

forces.

Types of settlements:

Uniform and differential, Differential settlement must be minimized, depends

on site soil conditions and distribution of loads on columns that supporting

the building.

Foundation design:

In this project depend on the soli investigation with soil bearing capacity

=400 KN/m2 the designer will be use wall footing and isolation footing .

5.1.2 Ground water:

Ground water table effect will be taken in consideration according to soil investigation

and recommendations

5.2 Superstructure:

5.2.1 Slabs:

Considering the architectural layouts and configurations, it is expected to use Ribbed

Slab (two ways and one way) and Solid Slabs within project buildings, where the

thickness of slabs according to length of spans supposed to be 37 cm.

Mixed of drop and hidden beams will be used throughout slabs and again thickness

varies according to spans. Drop beams expected to be between (60-150) cm.5.2.2 Columns:

Concrete columns are provided to suit Architectural layout and structural integrity, the

columns dimensions, In general, from 25x60 cm to 30x150cm.

5.2.3 Bearing walls:

Concrete bearing walls will be provided at elevator shafts and wherever needed,

distribution of bearing walls are fit with Architectural layout as needed.

5.2.4 Lateral Force Resisting System (LFRS):

In order to take benefits for the presence of concrete columns and shear walls and

considering the irregularity in the building geometry, dual system from shear walls

(bearing) and ordinary frame system will be used. Response modification factor expected

to be 5.5 special care of steel reinforcement distribution and details shall be provided

according to IBC in order to ensure ductile performance of the LFRS.

5.2.2 Beams:

In-situ beams provide support: they transfer loads from slabs to columns and

walls. They offer strength, robustness and versatility, e.g. In accommodating

cladding support details. In overall terms, wide flat beams are less costly to

construct than narrow deep beams; the deeper and narrower, the more

costly they are. Beams and columns of the same width give maximum


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formwork efficiency as formwork can proceed along a continuous line.

However, used internally, these relatively deep beams result in additional

perimeter cladding and tend to disrupt service runs. Deep edge beams may

limit the use of flying form systems on the slab. Up stand perimeter beams

(designed as rectangular beams) can reduce overall cost. Parapet wall

beams are less disruptive and less costly to form than deep down stand

beams.

The intersections of beams and columns require special consideration of

reinforcement details. Sufficient width is required to get both beam and

column steel through; end supports need to be long enough to allow bends

in bottom reinforcement to start beyond half the support length yet maintain

cover for links and/or lacers.

Initial beam size and reinforcement

In this project the designer will be use cubic concrete strength equal to Fcu

40N/mm2 (f'c= 32N/mm2) and reinforcement steel with Fy=420 N/mm2, the

next chart describes the economical beam schematic design (the

reinforcement ratio =0.5ρmax) depends on Mu, d and the percentage of steel

parameters, for example if the beam carry load=1200 KN.m and using

width=500 mm then the economy beam depth=800 mm with steel

reinforcement= 4820 mm2.

Figure 9:: Economic beam depth, depends on Mu, beam width.


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Figure 10:: Economic beam reinforcement, depends on Mu, beam width.

5.2.3 Columns:

In-situ columns offer strength, economy, versatility, mouldability, fire

resistance and robustness. They are often the most obvious and intrusive

part of a structure and judgment is required to reconcile position, size,

shape, spans of horizontal elements and economy. Generally the best

economy comes from using regular square grids and constantly sized

columns. Ideally, the same size of column should be used at all levels at all

locations. If this is not possible, the alternative to keep the number of profiles

to a minimum, for example, one for internal columns and one for perimeter

columns. Certainly up to about eight stories, the same size and shape

should be used throughout a column’s height. The outside of edge columns

should be flush with or inboard of the edges of slabs. Chases, service

penetrations and horizontal offsets should be avoided. Offsets are the cause

of costly transition beams which can be very disruptive to site progress.

High-strength concrete columns can decrease the size of columns required.

Smaller columns occupy less let table space and should be considered on

individual projects. However, up to about five stories the size of perimeter

columns is dominated by moment: concrete strengths greater than Fcu

35N/mm2 appears to make little difference to the size of perimeter column

required. Rectangular columns can be less obtrusive than square columns.

Initial column size

In this project the designer will be use concrete strength equal Fcu 40

N/mm2 (f'c=32 N/mm2) and reinforcement steel with Fy=420 N/mm2, the next

chart describes the columns schematic sizes depends on Pu andpercentage of steel parameters, for example if the column carry load =2500


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KN and using reinforcement ratio=2% then the column area=105050 mm 2,

so if we assume the column width =250 mm then the depth =450 mm.

Figure 11:: Columns Schematic Sizes, depends on Pu, % of steel.

5.2.4 Bearing walls:

Concrete bearing walls will be provided at elevator shafts and wherever needed,

distribution of bearing walls are fit with Architectural layout as needed.

5.2.5 Lateral Force Resisting System (LFRS):

In order to take benefits for the presence of concrete columns and shear walls and

considering the irregularity in the building geometry, dual system from shear walls

(bearing) and ordinary frame system will be used. Response modification factor expected

to be 5.5 special care of steel reinforcement distribution and details shall be provided

according to IBC and SBC301 in order to ensure ductile performance of the LFRS.

6- External works:

Retaining walls, water tanks, water ways, water features, and other structural works will be

designed as required by the landscape requirements and will be designed as watertight concrete

elements in accordance BS 8007 " Design of concrete structures for retaining aqueous liquids " to

reduce cracking and thus reducing corrosion of steel.

7- Future vertical extension:

No vertical extension will be taken into consideration in the design.

8- Thermal Insulation:

Thermal expansion of concrete roofs caused by solar radiation is a common cause of distress to

buildings. Such stresses shall be minimized by applying thermal insulation on top of the roof toreduce the temperature differences. This material may include the application of foam or

lightweight concrete to the top of the roof.


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9- Software programs:

The next table shows the structural software's which the designer of the project shall made the

calculations by.

Software Program Adoption contents Remark

PROKON VW2.0.1

Structural analysis and

Design for different

structural elements.

Prokon Software Consultants Ltd. Mainly

used for foundations and earth retaining

structures.

SAFE V12.3Slab analysis by the

finite element method.

Computers and structures Inc. (CSI).Used to

model slabs and rafts.

ETABS V9.7.4Structural analysis and

design program.

Computers and structures Inc. (CSI). Used

for analysis and design of 3D models.

Table2:: Structural Software's.

Documents

Structure Design Criteria-final