The Effect of Architect Shape of Building under Seismic Load

International Journal of Engineering & Technology IJET-IJENS Vol:20 No:02 14

202602-5353-IJET-IJENS © April 2020 IJENS I J E N S

The Effect of Architect Shape of Building under

Seismic Load Luma Ahmed Aday 1*, Mohammed Ghazi Abbas 1, Yasir W.Abduljaleel 1

1 Al-Iraqia University/ Collage of Engineering / Iraq

*Corresponding author E-mail: [email protected]

[email protected]

Abstract-- The main objective of the research is to identify the

least earthquake-affected architectural forms as well as the

desired building behaviour during earthquakes. To achieve

these goals, we must understand the behaviour of the materials

involved in construction. The ductile materials are more

resilient to earthquakes, while brittle materials are less

refractive and less resistant to earthquakes. The project

involves analysis and designs a multistoried building (3-

Dimensional frame) with architectural forms different for

buildings using the parameters for the design as per the UBC-

97 SAP2000 software and by adopting a Time History Analysis

Method. There are several factors which affect the behaviour

of building and Play a key role in understanding the behaviour

of structure including storey drift and displacement, which

have been studied in this research and results are expressed in

form of graphs.

Index Term-- Seismic Effect, Displacement, Storey Drift,

Analysis & Design by SAP2000.

1. INTRODUCTION

Earthquake experiments have shown that a lots traditional

buildings and building ways do not have the basic resistance

to seismic forces. Also follow Simple rules will not block

harm in mild or big earthquakes, but prevention of collapse

and repairable harm should be restricted ratio. Where some

general rules stand out resistant design for earthquake [1]:

Must be the building well connected to a good the earth

and foundation.

Commitment to provide in both directions as well as

from top to bottom, resistive components such as

bracing or shear walls equally across the construction.

All materials used must be of ideal quality and must be

shielded against insects, rain, sun and other weakening

measures so that they do not lose their power.

Not used Structures brittle or which collapse suddenly.

Rather, they should be strong. As categorized structural

components based on the form-efficiency connection. Its

aim is to assist in understanding the role of structural

components in determining full structure performance.

2. INERTIA FORCES IN BUILDINGS AND STRUCTURES

Ground vibration generates ground motion on the base of

buildings and installations. The movement of the base of the

building with the direction of the movement of the ground,

but the ceiling has a tendency to stay in its original position

(According to Newton's first law) [2].

This is very similar to the case of the passenger standing in

a moving device at its sudden start, as the legs move, but the

upper part of the body tends to stay in the back which leads

to fall back!! This phenomenon to continue to stay in the

previous situation known as the phenomenon of inertia,

although the walls and columns may behave ductile, the

behavior of the roof will differ from the behavior of those

elements affected by the ground motion as in Fig. 1.

According to Newton's Second Law of Motion , F = m × a )

Assuming that the mass of the ceiling is equal to m and is

subjected to a land acceleration equal to a ( [2] ,the inertial

force F1 is the mass of the ceiling m multiplied by the earth

acceleration time and its direction opposite the earth

acceleration, Here, it is clear that increasing the mass means

an increase in inertia force, which means that lightweight

buildings have the ability to withstand ground vibration

better than heavyweight buildings.

3. DUCTILITY AND DAMAGEABILITY

The buildings resistant to earthquakes, especially the main

elements, prefer to be built of ductile materials. Such buildings

have the ability to swing forward and backward during

earthquakes; Ductility and damageability are among the desired

earthquake-resistant design characteristics. Ductility is a notion

interrelated with the capacity of the structure to afford

significant deformations without collapse [1]. The parts must

be proportioned in order to achieve a ductile impact in the

component's behaviour so that they come into contact and are subjected to yield [3]. Therefore, adequate ductile materials at

points of tensile stress are a necessity for a good earthquake-

resistant design, Fig. 2 shows this Some materials are ductile,

such as forged iron, steel and wood, other materials are not

ductile (this is called brittle), such a simple masonry, cast iron

and concrete, that is, they suddenly break without warning [4].

mailto:[email protected]



Fig. 1. The effect of inertia on buildings when exposed to vibration at their base.

Damageability: indicate to the ability of a structure afford large

damage, without partial or total collapse [2]. This is good

because those structures can ingest more damage, and also it permits the deformations to be observed and repaired, prior to

collapse [5].

Fig. 2. Ductility buildings are designed and detailed to develop favourable

failure mechanisms.

4. BASIC IDEA TO ACHIEVE RESISTANT EARTHQUAKE

PERFORMANCE

The basic idea is to make the building shape as regular and to

ensure its structural frame, where the construction is

unbalanced in terms of height or plan, is prone to the

earthquake damage, The RC frame take part in resisting the

earthquake and gravity forces as illustrated in Fig. 3 [1, 3].

Whereas load due to contents and self-weight on buildings cause RC frames to curvature, also the buildings with

symmetrical Shape such as the rectangle, cross and Z-shaped

structures shown in Fig. 4 are structures that do not generate

torsion owing to eccentricity, since the middle of gravity and

the center of stiffness correspond, while structures with forms

T, L, U and arc-shaped structures are unbalanced structures that

generate high torsion owing to eccentricity between the middle

of gravity and the center of stiffness [6].

Fig. 3. Earthquake vibration reverses tension and compression in members

– reinforcement [3].

On the other hand observed the shorter columns in Reinforced

concrete frame structures with columns of varying heights on

one floor suffer harm compared to larger columns on the same

floor, where the short column is stiffer than the long column.

Stiffness of the column is its resistance to deformation the result of exposure to large Strength needed to deform it. If the

brief column is not intended for such a big force, during an

earthquake it may suffer eloquent damage [3]. This conduct is

called the "short effect of the column" as in Fig. 5.



Fig. 4. Construction form and center of gravity and center of rigidity.

Fig. 5. Short columns are stiffer during earthquakes and attract bigger forces.

5. BUILDING DRIFT CAUSED BY LATERAL FORCE

The horizontal displacement that happens for building is

called drift. Because of resulting stress in structural and

non-structural seismic elements which it renders them in

distorted shapes, where Maximum drift commonly occurs at

the top of a building, but each story level is subjected to

story drift as shown in Fig. 6 [7].

The building codes specify maximum drift boundaries and

story drift limits to regulate a building's displacement during

an earthquake. Due to the rise in drift and acceleration to the

top of a construction, drift is considered important for the

columns and connections of heavy prefabricated cladding parts whose failure could result in harm. So all structural

seismic elements must be designed to avoid failure and to

containment the expected drift.

Fig. 6. Drift in a building subjected to lateral earthquake forces.



6. LITERATURE REVIEW

Sazzad M. and Azad [8] Studied the impacts of building

shape on drift and displacement owing to wind and

earthquake loads by the Bangladesh National Building Code

(BNBC), It found that, Maximum displacement and

maximum floor drift owing to earthquake in construction

shape type C, and Rectangular Building with hollow room,

is the safest model taking into account all circumstances.

Pawade et.al. [9], presented a paper to study the structural

behavior of multistory RC Structure for different plan

configuration such as rectangular building along with L- shape and C- shape and H-shape in accordance with the

seismic provisions suggested in IS: 1893-2002 using

STAAD Pro V8i. They found Maximum storey drift is

occurring on top storey of L-shape building while the

minimum storey drift occur on Rectangular shape of

building. Maximum bending moment in H-shape of

building. Result has been proved that C-Shape building is

more vulnerable compare to all other different shapes of

building.

Ravi V.S. and Lekshmi S. [10], Through their studies on a

building with a single regular plan and an irregular plan (C,

E, H, L, T, PLUS shapes), the Building with a regular square plan has the same maximum base shear value

compared to other plan shapes and the lowest base shear

value for the ' L ' shaped plan, static and dynamic analysis

performed on a computer with the help of the STAAD-Pro

software using the parameters. For the design as per IS-

1893-2002-Part-1, as well as for the Regular Square

Building, there is a minimum displacement and a maximum

displacement "L" shape compared to other shapes.

7. TIME HISTORY ANALYSIS

Dynamic analysis using the time history method calculates

the response of the building at discrete times using discrete recorded time history as the basis movement, Time History

analysis has been carried out using the Elcentro earthquake

record of May 18, 1940; it is a detailed analysis in which

response is calculated for each time step. It requires more

time but gives a good result.

Steps for using Time History method of analysis in SAP

2000: Step 1: Defining the time history function by adding a

function from file, the Elcentro earthquake record as shown

in Fig. 7. Step 2. Defining the target response spectrum.

Step 3. Assigning time history as a load case. Step 4. Next

run the analysis and get the result.

Fig. 7. Defining time history function (Elcentro, 1940).

8. DETAILS OF THE MODELS AND ANALYSES

To study the effect of shape configure ration we have

developed 4 models in SAP2000 software. Various types of

input data to model the all the 4 models were kept same to

obtain the predicted behavior, total numbers of storeys are 7

for all types of buildings frames. The elevations are same for all the 4 models as shown in Fig. 7. The specifications of

models are shown in Table 1, The buildings consist of 400

mm x 400 mm square columns, all 450 mm x 250 mm size

beams. The elasticity module and concrete compression

strength were taken as E = 3.05 ×107 kN/m2 and fc =

41Mpa. The SAP2000 finite element analysis software is

used to create a 3D model and perform all analyzes. The

software can predict the geometric conduct of space frames

under static or dynamic loads, accepting static loads (either

forces or displacements) and has the ability to perform

eigenvalues, The self-weight of beams and columns (frame members) are calculated automatically, by the program.

And the seismic load values were calculated as per UBC-97

[11, 12].

Table I

Details of buildings components.

Buildings Components Details

Beam 450×250mm

Column 400×400mm

Floor Height 3m

Total Height 21m

-0.4

-0.2

0

0.2

0.4

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Acc

ele

rati

on

(m

/s)2

Time (s)



(a) 3D Elevation and plan of Rectangular Building.

(b) 3D Elevation and plan of Z- Shape Building.

(c) 3D Elevation and plan of U-Shape Building.

(d) 3D Elevation and plan of Cylinder Building.

Fig. 8. Types of buildings frame.



9. ANALYSIS RESULTS

In this research we done compared analysis results Storey Drift

and Displacement for models .whereas can easily observe the

performance of building and we can predict the good building

frame which performs well against earthquake forces. The

analysis results showed the displacement for 4 buildings as

shown Figs. 9-12 , where Peak roof displacement of rectangle

building which obtained from time history analysis in SAP2000 is 9.2 mm, while Peak roof displacement of z-

building reached 9.1 mm and Peak roof displacement recorded

for u-building and cylinder building were 10.2 mm, 9.6 mm

Respectively.

Fig. 9. Displacement time history of top rectangle shaped.

Fig. 10. Displacement time history of top floor– floor–Z shape.

Fig. 11. Displacement time history of top floor –U shape.

Fig. 12. Displacement time history of top floor –Cylinder.

Fig. 13 and Table 2 are showing that for the rectangle building

the base shear is bigger than for other buildings. As higher

stiffness of building results in substantially higher base

shear[12] ; while Z-building have less base shear .

Table II

The result of the SAP2000 analysis of the shear base (KN).

-10

-5

0

5

10

0 5 10

Dis

pla

cem

en

t (m

m)

Time (s)

-10

-5

0

5

10

0 5 10

Dis

pla

cem

en

t (m

m)

Time (s) Rectangle

Shape Z-Shape U-Shape

Cylinder

Shape

327 237 252 283

-10

-5

0

5

10

0 5 10

Dis

pla

cem

en

t (m

m)

Time (s)

-10

-5

0

5

10

0 5 10

Dis

pla

cem

en

t (m

m)

Time (s)



Fig. 13. Base shear time history; 4 models building.

Drift story is a very complicated point in structural engineering.

Large story drifts affect the structural elements, Design For the

moment frame structures have requirements to confirm the

ability of the structure to maintain inelasticity resulting from

deformation and drift. If the deflections of any structure

become too large, (P-Δ) effects may cause instability of the

structure and cause collapse of the structure. [12,

13].According to UBC97 story drifts shall be computed using

the maximum inelastic response displacement, Story Drift

Limitation was calculated the following equation and which

illustrated by the Fig. 14.

∆𝑀= .7 𝑅 ∆𝑆 (1)

Where; ∆S:: Design Level Response Displacement, R: is the

structural system coefficient (8.5) from (table K-16) [11].

Of the conditions for structure with a period less than 0.7

seconds, the maximum story drift is limited to;

∆𝑚 ≤ 0.025ℎ (2)

While for structure with a period greater than 0.7 seconds;

∆𝑚 ≤ 0.02ℎ (3)

Where, h is the story height; the structure period was calculated

using formula 4, was the result T = 0.29, this formula may be

used for all framing systems.

𝑇 = 𝐶𝑡(ℎ𝑛)3

4⁄ (4)

Defined Ct= 0.030 for concrete moment frames, hn = the height of the building [11].

Fig. 15 show that the buildings shapes does corresponds to the

seismic code requirement; the inter storey drifts don't exceed

the inter storey limitation provided by the seismic code and

shown the convergence of results among the four buildings, the

maximum design inter-story drift are reached 1.7 mm , 1.19

mm at third storey for Z building and U- building, respectively

for design story drift ratio can calculation from relative

difference of displacement between the top and bottom of a

story, divided by the story height, the Fig.14 shows story drift

ratio for all buildings.

-400

-300

-200

-100

0

100

200

300

400

0 1 2 3 4 5 6 7 8 9 10 11

Bas

e S

he

ar (

KN

)

Time (s)

rectangle shape

U-Shape

Cylinder Shape

Z-Shape



Fig. 14. Drift Limitation (mm) vs. Storey level.

Fig. 15. Drift ratio vs. Storey level.

10. CONCLUSION

The objective of this study has been to analyse seismic

effects between various shape buildings and to watch the

structural behaviour:

The maximum displacement due to the earthquake is observed in the U-shaped building whereas building

Z, rectangle and cylinder shapes buildings were record

the results of converging displacement.

The disparate story drift results are observed for the Z

and U buildings at the first, second and third storey

and become converging at the storey levels last

whereas the rectangle and cylinder shapes buildings

analysis result were regular for all storey levels.

Base shear is calculated by using time history analysis for all four buildings in the Fig.13 illustrate

the comparison of base shear. The lower base is

getting in Z-shape building and the higher base shear

is getting in rectangle shape building.

Result has been proved that rectangle and cylinder

shapes buildings better behave during earthquakes

compared to Z and U shapes of building.

1, 0.35

2, 0.83

3, 1.19

4, 1.19 5, 1.19

6, 0.59 7, 0.59

1, 0.83

2, 0.95

3, 1.78

4, 0.59 5, 0.59

6, 0.237, 0.23

1, 0.83

2, 0.95

3, 1.19

4, 0.59 5, 0.596, 0.29

7, 0.17

1, 0.89

2, 0.893, 1.07 4, 0.83 5, 0.83

6, 0.597, 0.23

0 1 2 3 4 5 6 7

Rectangle shape Z-shape U-shape Cylinder shape

1, 0.002

2, 0.004

3, 0.006

4, 0.0065, 0.006

6, 0.003 7, 0.003

1, 0.004

2, 0.005

3, 0.001

4, 0.0035, 0.003

6, 0.00137, 0.0013

1, 0.004

2, 0.005

3, 0.006

4, 0.0035, 0.003

6, 0.0016

7, 0.001

1, 0.005 2, 0.005

3, 0.006

4, 0.004

5, 0.003

6, 0.002

7, 0.0013

0 1 2 3 4 5 6 7

Rectangle Shape Z-Shape U-Shape Cylinder Shape



ACKNOWLEDGEMENTS We would like to present many thanks of gratitude to

colleagues who helped to complete this project within the

limited time. The authors declare that they have no

conflict of interest.

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https://doi.org/10.4324/9780080518060

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The Effect of Architect Shape of Building under Seismic Load

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