final year project-acedemic block a case study

DEPARTMENT CIVIL ENGINEERING

N.W.F.P. UNIVERSITY OF ENGINEERING & TECHNOLOGY PESHAWAR

DESIGN OF ACADEMIC BLOCK, CASE STUDY

SUPERVISED BY:

ENGR. FAISAL UR REHMAN

SUBMITTED BY: BILAL AKBER

HUMAIRA MANSOOR AHMAD ABDI HASSAN

Session 2008

DEPARTMENT CIVIL ENGINEERING

N.W.F.P. UNIVERSITY OF ENGINEERING & TECHNOLOGY PESHAWAR

DESIGN OF ACADEMIC BLOCK, CASE STUDY

SUPERVISED BY:

ENGR. FAISAL UR REHMAN

SUBMITTED BY: BILAL AKBER

HUMAIRA MANSOOR AHMAD ABDI HASSAN

Chairman Adviser

Prof. Dr. Akhtar Naeem Engr. Faisal-ur-Rehman

-------------------------- ------------------------

DIDICATIONSDIDICATIONSDIDICATIONSDIDICATIONS

DedicatedDedicatedDedicatedDedicated ToToToTo ourourourour

BELOVED PARENTSBELOVED PARENTSBELOVED PARENTSBELOVED PARENTS

After ALLAHAfter ALLAHAfter ALLAHAfter ALLAH

Who, with their very limitedWho, with their very limitedWho, with their very limitedWho, with their very limited Resources,Resources,Resources,Resources,

Provided us every thingProvided us every thingProvided us every thingProvided us every thing

That enabled us to reach at this pointThat enabled us to reach at this pointThat enabled us to reach at this pointThat enabled us to reach at this point

And complete the project workAnd complete the project workAnd complete the project workAnd complete the project work

And to all Our teachers Who Guide usAnd to all Our teachers Who Guide usAnd to all Our teachers Who Guide usAnd to all Our teachers Who Guide us

And Teach SincerelyAnd Teach SincerelyAnd Teach SincerelyAnd Teach Sincerely....

ACKNOWLEDGMENT

First of all we would like to express our deepest gratitude to Almighty and

Merciful Allah, Who gives us the power to do, the sight to observe and mind to

think, judge and analyze. We were not able to perform and face this task, but it

was He Who gives us the courage, power and ability.

We are paying special thanks to our punctual, kind, cooperative, hardworking

and ingenious supervisor Engr. Faisal ur Rehman for his occasionally and

constantly Guidance, Encouragement, Supervision and help that enable us to

complete our Final Year Project.

It was a very beneficial and practical experience for us to learn the modern

techniques of designing efficient irrigation channel and use of modern software

relating designing of watercourses and canals

Finally, we are thankful to our beloved parents for encouraging and morally

supporting us for the completion of our study work.

Contents

Abstract ............................................................................................................................... 1

Chapter 1 Literature Review ............................................................................................... 2

Introduction ..................................................................................................................... 2

Types of Analysis ........................................................................................................... 2

Cycle of Structural Analysis and Design ........................................................................ 3

Chapter 2 Analysis, Loads and Softwares .......................................................................... 4

Response Spectrum Analysis .......................................................................................... 4

Time History Analysis .................................................................................................... 4

Softwares Used ............................................................................................................... 4

Etabs ............................................................................................................................ 5

SAP 2000 V. 11 .......................................................................................................... 5

Safe ............................................................................................................................. 5

Chapter 3 Methodology ...................................................................................................... 6

Steps Followed for Analysis and Design in Etabs .......................................................... 6

Layout ............................................................................................................................. 6

Modeling ......................................................................................................................... 6

Material Properties .......................................................................................................... 6

Concrete ...................................................................................................................... 6

Steel............................................................................................................................. 6

Brick ............................................................................................................................ 7

Soil Pressure................................................................................................................ 7

ACI – 318-02 .................................................................................................................. 7

Load Factors.................................................................................................................... 7

Structural Elements ......................................................................................................... 7

Loads ............................................................................................................................... 7

Earthquake Loads UBC 97 ............................................................................................. 8

Earthquake Loads UBC Response Spectrum Analysis (RSA) ....................................... 8

Load Cases (RSA)....................................................................................................... 8

Define Piers and Spandrels ............................................................................................. 9

Analysis of Walls ............................................................................................................ 9

Design of Shear Wall and Core Wall .............................................................................. 9

Check Demand / Capacity Ratio ..................................................................................... 9

Brick walls can be used for Brick Masonry Performance in Earthquake Resistant

Building........................................................................................................................... 9

Retaining Wall .............................................................................................................. 10

Ramp ............................................................................................................................. 10

Stairs ............................................................................................................................. 10

Import the model from Etabs ........................................................................................ 10

Detailing and Structural Drawings................................................................................ 10

Define GAP element (Links element)........................................................................... 10

Time History Analysis .................................................................................................. 11

Chapter 4 Results and Comparison ................................................................................... 12

Chapter 5 Observation, Conclusion and Recommendations............................................. 14

Observation ................................................................................................................... 14

Conclusions ................................................................................................................... 14

Recommendations ......................................................................................................... 14

Reference ...................................................................................................................... 14

Appendix ........................................................................................................................... 15

Design of Academic Block, Case Study

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ABSTRACT

Earthquake analysis of Acedemic Block N-W.F.P UET Peshawar was carried out using

UBC97, Time History and Response Spectrum Analysis. ETABS and SAFE were used

for analysis and design.

It was observed that ratio of Beam to Column x-section is very high i.e., large beam

section w.r.t small column sections. Also the ratio of Length of Beam to that of Column

is very high. This creates a problem of resisting more moment by beam instead of

transferring effectively to columns.

It was concluded that The Building is designed for damage limit state. Steel of our

analysis is less than actual steel used. Less steel is because we have included Brick

Masonry in analysis so the structure is more stiff in spite of earthquake forces.

It is recommended that the model should be also designed for Time History Analysis.

Pounding Action at expansion joint should be observed by using nonlinear GAP element.

Forces need to be check at different time steps.

Keywords: Time History Analysis, Response Spectrum Analysis, UBC97 Earthquake

Analysis, Brick Masonry Modeling, Shear Wall Modeling.


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CHAPTER 1 LITERATURE REVIEW

INTRODUCTION

The basic job of a Structure Engineer is to know the available tools and materials and

employ those tools to make economical structures, which can resist and withstand by

natural forces.

The case study of Academic Block is not just analysis and design but it is about studying

different methods and techniques. These techniques enable us to analyze and design

frame, slabs, footing, stairs, shear wall, confined brick masonry and retaining walls.

The Academic block is situated on Road-2 adjacent to Mechanical Engineering

Department N-W.F.P University of Engineering and Technology Peshawar.

The project of Academic Block was started in 2006. The consultant is Naveed Aslam &

Associates Islamabad while the contractor is Nawab Brothers Karachi. The client is

N.W.F.P University of Engineering and Technology, Peshawar.

The building is concrete frame of five stories with basement. The building is a

symmetrical about its transverse axis and divided into three blocks. Two blocks are

symmetrical while third block separates them. There is expansion-joint between the

blocks to cope with soil settlement.

As discussed in the start of chapter, aim of Structural Engineer is to design a structure

that is economical, sound in architecture and fulfill its purpose.

TYPES OF ANALYSIS

Analysis means finding axial, shear , moment and displacement in the structure.


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The two basic methods for structural analysis are Force and Displacement. The word

“Force” represents all applied and resisting load like axial, shear, bending moment and

torsion. Similarly the word “Displacement” includes deflection, rotation and settlement.

In force method, the primary unknown is Force. For finding theses forces different

methods were developed. After finding forces we find the displacement. Examples are

Unit Load Method, 03 Moment Equation, Virtual Work Method and Direct Flexibility

Method. In contrast to Force Method, Displacement is the primary unknown in

Displacement Method, from which forces are calculated. Different displacement methods

are Slope Deflection Method, Moment Distribution Method, Direct Stiffness Method.

CYCLE OF STRUCTURAL ANALYSIS AND DESIGN

Following is the cycle for Structural Analysis and Design:

1. Analysis of Structure: We solve structure using either force or displacement method

to find axial, shear, moment and displacements.

2. Design of Structure: Based on given forces and displacements which comes after

analysis, we find the appropriate dimenstion of structural cross section and the

amount of steel required.

3. Detailing of Structure: We make drawings containing dimension of structural

elements like beam, column and slabs as well as the required amount of steel.

Design Code: It is the guideline for Design Engineer to choose the appropriate

dimension and steel amount which is safe enough to withstand the forces of nature.

Available Softwares : There are many softwares available in market for analysis and

design of structures. Some of them are opensource and available for free like excel spread

sheets, opensees( a finite element analysis solver) while other are properiety softwares

like SAP2000 and STAAD Pro.


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CHAPTER 2 ANALYSIS, LOADS AND

SOFTWARES

UBC 97 Earthquake Loads: It is the equivalent static laod of earthquake applied on

structure at floor levels. It is found from the ratio of givend floor weight to the total

weight of the structure multiplied by the given base shear. Base shear is fixed from

Earthquake Zone, Importance factor, Ductility factor, and Time Period factor

RESPONSE SPECTRUM ANALYSIS

It is method of finding base shear from:

1. Ca and Cv

2. and from Time Period of the structure.

using ubc97 response spectrum curve envelope.

This base shear is then distributed at floor levels as a proportion of the floor weight to the

total weight.

TIME HISTORY ANALYSIS

It is the method of finding earthquake force at each time step from the input of

acceleration time history of given earthquake.

SOFTWARES USED

For this project, ETABS (Extended 3D Analysis of Building Systems), SAFE (Slab and

Foundation Analysis Using Fininte Element Method), SAP2000 (Structural Analysis

Program) and Excel sheets are used.


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Etabs Etabs is chosen for analysis and design as it is made specifically for buildings. There are

built-in tempaltes for building systems. Furthermore it is very easy to analysis and design

shear walls in Etabs.

SAP 2000 V. 11 Sap2000 is a general purpose finite element program. It was used just only to explore the

feature of import from Etabs. The solver of SAP2000 is much more faster the etabs hence

it analyzes the structure quickly.

Safe SAFE is used to find the detailing drawings of beams and foundations as well as to find

the quatity estimate.


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CHAPTER 3 METHODOLOGY

STEPS FOLLOWED FOR ANALYSIS AND DESIGN IN ETABS

The Building Model in Symmetrical model about longitudinal axis. Two symmetrical

portions are separated by Middle block with Expansion Joint 2” wide.Right Half Portion

contains Stair well while Left Half Portion contains Core Wall for lift

LAYOUT

1. Formation of Grid line of Right Half Portion

2. Beams, Columns and Slab

3. The section of Beams along x- direction is ConcBeamX (18”x12”) while that

along y-direction is ConcBeamY (27”x12”)

4. All columns are 24”x12”

5. Slab is 6” thick

MODELING

Beams and Columns were modelled as Line Element. Slab, foundation and Shear Walls

as modeled as Area Element (Shell) while Brick Masonry wall was modelled as line

element as well as Area Element (Shell).

MATERIAL PROPERTIES

Concrete 1. Modulus of Elasticity, E = 3600 ksi

2. Compressive Strength, fc’ = 3ksi

3. Unit weight = 0.15 ksf

Steel 1. Yield Strength (Longitudinal bars), fy = 60ksi

2. Yeild Strength (Stirrup), fs = 60 ksi


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Brick 1. Unit weight = 0.12 ksf

2. Modulus of Elasticity = 240 ksi

3. Compressive Strength = 600 psi

Soil Pressure 1. Allowable Soil Pressure, qa = 5 ksf

ACI – 318-02 LOAD FACTORS

1. Dead Load = 1.2

2. Live Load = 1.6

3. Moment = 0.9

4. Shear = 0.75

STRUCTURAL ELEMENTS

1. Beam and Columns as Line Element

2. Brick masonry, Shear Wall, Slab and Foundation as Shell Element

3. Stairs and Ramp as Shell

LOADS

1. Self Weight (Program Calculated)

2. Super Imposed Dead Load (DL)

3. 0.036 ksf

4. Live Load (LL)

5. Ground Floor = 0.1 ksf

6. Intermediate Floors = 0.08 ksf

7. Top Roof = 0.03 ksf


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EARTHQUAKE LOADS UBC 97

1. UBC –97 Auto Lateral

2. Two load Cases EQX and EQY were defined

3. Soil Profile Type = SD

4. Seismic Zone Factor = 0.2

5. Ca = 0.28 (program Calculated)

6. Cv = 0.24 (program Calculated)

7. Time Period factor , C(t) = 0.03 (for Concrete frames)

8. Over Strength Factor = 5.6, for Building Frame System and Ordinary Braced

Frame Concrete

9. Importance Factor, I = 1

10. Eccentricity of Resultant of lateral force = 5%

EARTHQUAKE LOADS UBC RESPONSE SPECTRUM ANALYSIS

(RSA)

1. Function = UBC 97 Spectrum (User Defined)

2. Function name = RS

3. Ca = 0.28

4. Cv = 0.24

5. Function is adjusted for the maximum ordinates of acceleration so that the time

period of our structure lies in Peak Acceleration

Load Cases (RSA) 1. RSX

2. Function = RS

3. Scale factor = 386.4 (g in inches)

4. Direction = U1 (for x-axis)


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5. Eccentricity of Resultant force = 5%

6. Damping = 5%

7. RSY

8. Same as RSX but Direction = U2

9. Load Combination (Program Calculated)

DEFINE PIERS AND SPANDRELS

The wall portion were selected and vertical members were defined as pier while

horizontal members were defined as spandrals.

ANALYSIS OF WALLS

After analysis of walls integrated into whole structural system, shear forces were

observed in piers and spandrals. The shear force for wall is shown as that of line element.

Minimum and maximum shear in piers were calculated.

DESIGN OF SHEAR WALL AND CORE WALL

Based on analysis result, software showed the steel required in each wall.

CHECK DEMAND / CAPACITY RATIO

Based on analysis result, software showed the Demand/Capacity ratio in each wall. All

demand capacity ratio were less then 1 means the capacity of shear wall is ok.

BRICK WALLS CAN BE USED FOR BRICK MASONRY

PERFORMANCE IN EARTHQUAKE RESISTANT BUILDING

The effect of masonry wall was also considered into account. Masonry wall was firstly

modeled as line element cross bracer then it was modeled as shell element. For linear

analysis, the shell element gives better results for design.


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RETAINING WALL

Walls at Basement were designed as both Shear Wall and Retaining Wall

Retaining Wall is designed by Excel Sheet using ACI-318-02

RAMP

Ramp is designed for LL of 500 psf

STAIRS

There are two types of Stairs in Building:

1. Stair Slab Spanning Horizontally

2. Stair Case Spanning Longitudinally

3. Stairs were also design using Excel Spreadsheet

IMPORT THE MODEL FROM ETABS

Model from Etabs was imported to SAP2000 and SAFE. In SAP2000, the model was

only imported to have a cross check on analysis of etabs. The results were matching. In

SAFE the Analysis for Slab and Foundation was carried out.

DETAILING AND STRUCTURAL DRAWINGS

After analysis in SAFE, Detailing Drawings were generated as well as quatity estimate of

rebars was calculated.

DEFINE GAP ELEMENT (LINKS ELEMENT)

There is an expansion joint of 2 inches. It was modeled for a study perpose using the

GAP element. In main analysis, gap element was not considered.


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TIME HISTORY ANALYSIS

1. The time history analysis was carried out:

2. For Pounding Action

3. For Forces and Displacement

4. Video for Time History and pounding Action


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CHAPTER 4 RESULTS AND COMPARISON

The detailing drawing of typical beam is shown below:

Rebars

Column

Design As per Actual

Bars = 8#7 + 4#6 - As = 6.5 sq. in Bars = 6#8 + 6#6 - As = 7.38 sq. in

Stirrup = #3 @ 12" c/c Stirrup = #6 @ 6" c/c

Beams

Beam along x - axis

Corner Edge Mid Contin Edge Corner Edge Mid Contin Edge

Top 2#8 2#8 2#8 Top 3-#6 + 3#8 3-#6 + 3#8 3-#6 + 3#8

Bottom 4#8 4#8 4#8 Bottom 3-#6 + 3#8 3-#6 + 3#8 3-#6 + 3#8

Stirrup # 3 @ 7" c/c Stirrup #3 @ 6"c/c


Beam along Y - axis


Top 2#8 - 1.58 2#8 2#8 Top 6-#6 - 2.48 3-#6 6-#6

Bottom 2#7 - 1.20 2#7 2#7 Bottom 3-#6 - 2.64 3-#6 3-#6

Stirrup # 3 @ 7" c/c Stirrup #3 @ 6"c/c


Slab


x #3 @ 6" c/c #3 @ 6" c/c #3 @ 6" c/c x #3 @ 6" c/c #3 @ 6" c/c #3 @ 6" c/c

y #3 @ 6" c/c #3 @ 6" c/c #3 @ 6" c/c y #3 @ 6" c/c #3 @ 6" c/c #3 @ 6" c/c



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Shear Wall at Basement


Bars along the height =#3 @ 5" c/c Bars along the height = #3 @ 3" c/c

Bars along the length =#3 @ 12" c/c Bars along the length = #3 @ 8" c/c

Core Wall


Bars along the height =#4 @ 11" c/c Bars along the height = #4 @ 6" c/c

Bars along the length =#3 @ 12" c/c Bars along the length = #3 @ 8" c/c


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CHAPTER 5 OBSERVATION, CONCLUSION AND

RECOMMENDATIONS

OBSERVATION

1. Ratio of Beam to Column x-section is very high i.e., large beam section w.r.t

small column sections.

2. Ratio of Length of Beam to that of Column is very high. This creates a problem

of resisting more moment by beam instead of transferring effectively to

columns

3. In modern design, Cracks are avoided in Column but above criteria makes the

column more severe to cracks

CONCLUSIONS

1. The Building is designed for damage limit state.

2. Steel of our analysis is less than actual steel used.

3. Less steel is because we have included Brick Masonry in analysis so the

structure is more stiff in spite of earthquake forces.

RECOMMENDATIONS

1. The model should be also designed for Time History Analysis.

2. Pounding Action at expansion joint should be observed by using nonlinear GAP

element

3. Forces need to be check at different time steps.

REFERENCE

1. Reference Manual of ETABS, SAP2000, and SAFE

2. UBC97 Design Code

3. ACI 318-02 Design Code

4. Brick masonry infills in seismic design of RC framed buildings: Part 1 Cost

implications by Diptesh Das and C.V.R. Murty


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APPENDIX

Limit States:

� Serviceability Limit State

� 50% probability of the design Earthquake

� Cracks need no repair

� Return period of that earthquake = 72 years

� Drift = 0.5 %

� Bricks are intact

� Damage Control Limit State


� Cracks need repair but should have less cost


� Drift = 2%

� Survival Limit State


� Damage beyond repair


� Drift = 2%

� SD = Stiff soil with shear wave velocity of 600 to 1200 ft/sec


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Model of Acedemic Block in Etabs


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Views of Acedemic Block:

final year project-acedemic block a case study

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