Behavior of a Multistoried Building with and Without Infill Walls under Seismic Forces using STAAD.PRO

IJSTE - International Journal of Science Technology & Engineering | Volume 2 | Issue 01 | July 2015 ISSN (online): 2349-784X

All rights reserved by www.ijste.org

195

Behavior of a Multistoried Building with and

without infill Walls under Seismic Forces using

STAAD.PRO

K. Satya Narasimha Rao

M. Tech Student Anirudh Gottala

M. Tech Student

Department of Civil Engineering Department of Civil Engineering

Andhra University College of Engineering Andhra University College of Engineering

Dr. Shaik Yajdani

Assistant Professor

Department of Civil Engineering

Andhra University College of Engineering

Abstract

The effect of masonry infill panel on the response of RC frame subjected to seismic action is widely recognized and has been

subject of numerous experimental investigations, while several attempts to model it analytically have been reported. In

analytically analysis infill walls are modelled as equivalent static approach there are various formulae derived by research

scholars and scientist for width of modelling. Infill behaves like compression between column and beam and compression forces

are transferred from one node to another. In this study the effect of masonry walls on high rise building is studied. Static analysis

on high rise building with different arrangement is carried out. For the analysis G+9 R.C.C framed building is modelled. The

width is calculated by using equivalent static method. Various cases of analysis are taken. All analysis is carried out by software

STAAD-PRO. Axial Force, Shear Force, Storey drift, Nodal displacement, bending moment is calculated and compared for all

models. The results show that infill walls reduce displacement, time period and increase base shear. So it is essential to consider

the effect of masonry infill for the seismic evaluation of moment resisting reinforced concrete frame.

Keywords: RCC Framed Buildings, In Filled Walls, High-Rise Building, Displacement

________________________________________________________________________________________________________

I. INTRODUCTION

It has always been a human aspiration to built earthquake resistant structures. The reinforced cement concrete moment resisting

frames in filled with unreinforced brick masonry walls are very common in India and in other developing countries.

Masonry is a commonly used construction material in the world for reason that includes accessibility, functionality, and cost.

The primary function of masonry is either to protect inside of the structure from the environment or to divide inside spaces.

Normally considered as architectural elements. Engineer's often neglect their presence. Because of complexity of the problem,

their interaction with the bounding frame is often neglected in the analysis of building structures, When masonry in fills are

considered to interact with their surrounding frames, the lateral load capacity of the structure largely increases.

This assumption may lead to an important inaccuracy in predicting the response of the structure. This occurs especially when

subjected to lateral loading. Role of infill's in altering the behavior of moment resulting frames and their participation in the

transfer of loads has been established by decades of research. The survey of buildings damaged in earthquakes further reinforces

this understanding. The positive aspects of the presence of never the less, it may be appropriate to neglect their presence and

declare the resulting design as conservative.

Observed infill induced damage in buildings in the past earthquakes exposes the shortcomings of the current bare frame

approach. In buildings, the ordinarily occurring vertical loads, dead or live, do not much of a problem, but the lateral loads due to

wind or earthquake tremors are a matter of great concern and need special consideration in the design of buildings. These lateral

forces can produce the critical stress in a structure, set up undesirable vibrations and in addition, cause lateral sway of the

structure which can reach a stage of discomfort to the occupants.

In many countries situated in seismic regions, reinforced concrete frames are in filled fully or partially by brick masonry.

Although the infill panels significantly enhance both the stiffness and strength of the frame, their contribution is often not taken

into account because of the lack of knowledge of the composite behavior of the frame and the infill. Infill wall can be modeled in

several forms such as creating a plate element with infill walls properties using stad.pro etc.

For new buildings, infill wall is modeled and designed to provide high rigidity. Also older buildings are rehabilitated with

infills that are compatible with the original frame work. Studies found that infill fails in two main ways, Shear failure and Corner

crushing. The variability of the mechanical properties of infill panels, depending on both the mechanical properties of their

Behavior of a Multistoried Building with and without infill Walls under Seismic Forces using STAAD.PRO (IJSTE/ Volume 2 / Issue 01 / 035)


196

materials and the construction details, introduces difficulty in predicting the behavior of infill panels. Additionally, the overall

geometry of the structure i.e., number of bays and stories, aspect ratio of infill panels and the detailing of the reinforced concrete

members are aspects that should be considered.

The location and the dimensions of openings play also an important role in the evaluation of the strength and stillness of the

infill panels. Despite the aforementioned cases of undesired structural behavior, field experience, analytical and experimental

research have demonstrated that he beneficial contribution of the infill walls to the overall seismic performance of the building,

especially when the latter exhibits limited engineering seismic resistance.

In fact, infill panels through their in-plane horizontal stiffness and strength decrease the storey drift demand, and increase the

storey lateral force resistance respectively, while their contribution to the global energy dissipation capacity is significant, always

under the assumption that they are effectively confined by the surrounding frame.

II. METHODS OF ANALYSIS

Code-based Procedure for Seismic Analysis A.

Main features of seismic method of analysis based on Indian standard 1893(Part 1):2002 are described as follows

Equivalent Static Lateral Force Method

By IS code method for Static analysis B.

By STAAD PRO software Method-for with and without infill walls both. C.

Equivalent Static Analysis: 1)All design against seismic loads must consider the dynamic nature of the load. However, for simple regular structures, analysis

by equivalent linear static methods is often sufficient. This is permitted in most codes of practise for regular, low-to medium-rise

buildings. It begins with an estimation of base shear load and its distribution on each story calculated by using formulas given in

the code. Equivalent static analysis can therefore work well for low to medium-rise buildings without significant coupled lateral-

torsional effects, are much less suitable for the method, and require more complex methods to be used in these circumstances.

III. MODELLING AND ANALYSIS

For the analysis of multi storied building following dimensions are considered which are elaborated below. In the current study

main goal is to compare with and without infill walls (Rectangular) building.

Static and Dynamic Parameters: A.

Design Parameters: Here the Analysis is being done for G+9 (rigid joint regular frame ) building by computer software using STAAD-Pro.

Design Characteristics: The following design characteristic are considered for Multistory rigid jointed plane frames Table - 1

Design Data of RCC Frame Structure

S.No Particulars Dimension/Size/Value

1 Model G+9

2 Seismic Zone II

3 Floor height 3 m

4 Plan size 23.15 x 14.99 m

5 Size of columns 0.6 x 0.6 m

6 Size of beams 0.3 x 0.45 m

7 Walls 1) External Wall =0.23 m

2) Internal Wall =0.115 m

8 Thickness of slab 150 mm

9 Type of soil Type-II, Medium soil as per IS-1893

10 Material used Concrete M-30 and Reinforcement

Fe-415

11 Static analysis Equivalent Lateral force method

12 Earthquake load as per IS-1893-2002

13 Specific weight of RCC 25 KN/m2

14 Specific weight of infill 20 KN/m2

15 Software used STAAD-Pro for both With and Without infill walls

Table - 2

Zone Categories

Seismic Zone II III IV V



197

Seismic intensity Low Moderate Severe Very Severe

Z 0.10 0.16 0.24 0.36

Fig. 1: Plan of Regular Building

Fig. 2: 3-D Model of Regular Building



198

Fig. 3: 3-D Model of Regular Building (With Sections)

Fig 4: 3-D Model of Infill Walls Building



199

Fig. 5: Earthquake Loading

Fig. 6: Deflection Diagram (Without Infill Walls)

Fig. 7: Deflection Diagram (With Infill Walls)



200

IV. RESULTS AND DISCUSSIONS

The above RCC frame structure is analyzed both with and without infill walls and the results are compared for the following

three categories namely Shear Force, Storey-Drift, Axial Force, Displacements and Moment at different nodes and beams and the

results are tabulated as a shown below.

Comparison of Bending Moment for Beams A.

Table - 3

Comparison of Bending Moment

BEAM NUMBER STOREY WITH INFILL(KN-m) WITHOUT INFILL(KN-m)

1228 10 43.46 67.8

1110 9 52.02 137.4

992 8 66.5 162.33

874 7 78.59 184.13

756 6 88.23 200.9

638 5 95.3 212.7

520 4 99.89 219.9

402 3 101.89 222.26

284 2 105.56 226.52

166 1 107.3 230.42

Fig. 8: Comparison of bending moment of with and without infill walls

Comparison of Storey-Drift for both with and without infill walls B.

Table 4 Comparison of Storey-Drift

STOREY HEIGHT WITH INFILL WALL

(DRIFT)(mm)

WITHOUT INFILL WALL

(DRIFT)(mm)

30 1.898 2.625

27 2.59 4.096

24 3.159 5.517

21 3.597 6.681

18 3.905 7.55

15 4.089 8.144

12 4.158 8.46

9 4.095 8.468

6 3.805 7.879

3 2.903 5.857

0 0 0



201

Fig. 9: Comparison of Storey-Drift between with and without infill walls

Comparison of Displacement for both with and without infill walls C.

Table - 5

Comparison of Displacement(+X)


(DISPLACEMENT)(mm)

WITHOUT INFILL WALL

(DISPLACEMENT)(mm)

30 34.755 66.305

27 32.852 63.680

24 30.267 59.584

21 27.108 54.067

18 23.511 47.386

15 19.606 39.835

12 15.517 31.691

9 11.359 23.223

6 7.264 14.755

3 3.459 6.879

0 0.556 1.022

Fig. 10: Comparison of Displacement(+X) between with and without infill walls

Comparison of Shear Force for both with and without infill walls D.

Table 6 Comparison of Shear Force


(SHEAR FORCE)(KN)

WITHOUT INFILL WALL

(SHEAR FORCE)(KN)



202

30 430.054 643.528

27 734.80 1255.30

24 978.776 1745.06

21 1168.71 2126.36

18 1311.38 2412.76

15 1413.53 2617.81

12 1481.91 2755.08

9 1523.277 2838.12

6 1544.38 2880.49

3 1551.98 2895.742

0 1552.813 2897.42

Fig. 11: Comparison of Shear Force between with and without infill walls

Comparison of Axial Force for both with and without infill walls E.

Table 7 Comparison of Axial Force

Column number with infill walls(KN) without infill walls(KN)

591 475876 893943

709 370121 717686

827 272612 544221

945 185768 375775

1063 112095 214650

1181 54272 63377

Fig. 12: Comparison of Axial force between with and without infill walls



203

Nodal Displacements in (1-G-H) Frame: F.

Table 8

Nodal Displacements in (1-G-H) Frame

Node L/C X-Trans mm Y-Trans mm Z-Trans mm RESULTANT (mm)

6 SEISMIC LOADS 0.653 -0.174 0.069 0.679

DEAD LOAD -0.001 -0.152 -0.006 0.152

SEISMIC+DEAD -0.981 0.033 -0.113 0.988

94 SEISMIC LOADS 4.526 -0.4 0.463 4.567

DEAD LOAD -0.008 -0.437 -0.043 0.439

SEISMIC+DEAD -6.8 -0.054 -0.76 6.842

138 SEISMIC LOADS 9.766 -0.536 0.974 9.829

DEAD LOAD -0.031 -0.695 -0.088 0.701

SEISMIC+DEAD -14.696 -0.237 -1.593 14.784

182 SEISMIC LOADS 15.387 -0.63 1.515 15.474

DEAD LOAD -0.057 -0.923 -0.141 0.936

SEISMIC+DEAD -23.165 -0.44 -2.483 23.302

226 SEISMIC LOADS 21.002 -0.696 2.052 21.114

DEAD LOAD -0.085 -1.122 -0.199 1.142

SEISMIC+DEAD -31.631 -0.639 -3.376 31.817

270 SEISMIC LOADS 26.399 -0.738 2.568 26.534

DEAD LOAD -0.117 -1.29 -0.26 1.321

SEISMIC+DEAD -39.773 -0.828 -4.242 40.008

314 SEISMIC LOADS 31.398 -0.757 3.045 31.555

DEAD LOAD -0.151 -1.427 -0.323 1.471

SEISMIC+DEAD -47.324 -1.006 -5.053 47.603

358 SEISMIC LOADS 35.816 -0.754 3.468 35.991

DEAD LOAD -0.186 -1.534 -0.386 1.592

SEISMIC+DEAD -54.003 -1.17 -5.782 54.325

402 SEISMIC LOADS 39.457 -0.73 3.823 39.648

DEAD LOAD -0.221 -1.608 -0.445 1.683

SEISMIC+DEAD -59.516 -1.317 -6.403 59.874

446 SEISMIC LOADS 42.148 -0.692 4.1 42.352

DEAD LOAD -0.263 -1.651 -0.492 1.742

SEISMIC+DEAD -63.616 -1.437 -6.889 64.004

490 SEISMIC LOADS 43.917 -0.665 4.305 44.133

DEAD LOAD -0.341 -1.662 -0.506 1.77

SEISMIC+DEAD -66.387 -1.495 -7.217 66.795

Column End Forces in (1-G-H) Frame: G.

Table 9 Column End Forces in (1-G-H) Frame

COLUMN L/C Node Shear-Y (KN) Shear-Z (KN) Moment-Y

(KN-m)

Moment-Z

(KN-m)

C949 SEISMIC LOADS 357 42.898 -0.624 0.115 44.624

401 -42.898 0.624 1.756 84.07

DEAD LOAD 357 8.241 -1.832 2.725 12.302

401 -8.241 1.832 2.77 12.422

SEISMIC +DEAD 357 -51.985 -1.812 3.915 -48.484

401 51.985 1.812 1.522 -107.472

C950 SEISMIC LOADS 358 21.259 -1.955 1.302 10.768

402 -21.259 1.955 4.564 53.011

DEAD LOAD 358 8.79 6.059 -8.918 13.169

402 -8.79 -6.059 -9.259 13.202

SEISMIC +DEAD 358 -18.704 12.022 -15.331 3.602

402 18.704 -12.022 -20.735 -59.713

C1067 SEISMIC LOADS 401 29.688 0.061 -0.722 22.379

445 -29.688 -0.061 0.54 66.684

DEAD LOAD 401 8.485 -1.834 2.685 12.352

445 -8.485 1.834 2.817 13.104

SEISMIC +DEAD 401 -31.804 -2.842 5.111 -15.041

445 31.804 2.842 3.416 -80.371



204

C1068 SEISMIC LOADS 402 14.104 -1.022 -0.301 -3.271

446 -14.104 1.022 3.368 45.583

DEAD LOAD 402 9.251 6.245 -8.81 13.197

446 -9.251 -6.245 -9.924 14.556

SEISMIC +DEAD 402 -7.279 10.901 -12.764 24.702

446 7.279 -10.901 -19.937 -46.54

C1185 SEISMIC LOADS 445 14.471 0.199 -0.561 3.179

489 -14.471 -0.199 -0.036 40.233

DEAD LOAD 445 8.09 -1.752 2.005 11.305

489 -8.09 1.752 3.25 12.965

SEISMIC +DEAD 445 -9.571 -2.926 3.849 12.189

489 9.571 2.926 4.929 -40.902

C1186 SEISMIC LOADS 446 0.31 0.655 -1.884 -15.466

490 -0.31 -0.655 -0.081 16.398

DEAD LOAD 446 7.957 5.672 -7.646 11.53

490 -7.957 -5.672 -9.371 12.341

SEISMIC +DEAD 446 11.47 7.526 -8.643 40.494

490 -11.47 -7.526 -13.935 -6.084

Beam End Forces in (1-G-H) Frame: H.

Table 10 Beam End Forces in (1-G-H) Frame

Beam L/C Node Shear-Y (KN) Shear-Z (KN) Moment-Y

(KN-m)

Moment-Z

(KN-m)

B993 SEISMIC LOADS 401 -25.561 -0.617 1.154 -51.452

402 25.561 0.617 1.368 -53.094

DEAD LOAD 401 44.827 -0.102 0.185 28.266

402 50.063 0.102 0.234 -38.973

DEAD+SEISMIC 401 105.583 0.771 -1.453 119.577

402 36.752 -0.771 -1.702 21.181

B1111 SEISMIC LOADS 445 -15.652 -0.843 1.571 -31.538

446 15.652 0.843 1.877 -32.477

DEAD LOAD 445 44.956 -0.209 0.372 28.482

446 49.934 0.209 0.482 -38.663

DEAD+SEISMIC 445 90.911 0.951 -1.799 90.03

446 51.424 -0.951 -2.093 -9.28

B1229 SEISMIC LOADS 489 -8.315 -1.009 1.864 -16.134

490 8.315 1.009 2.264 -17.875

DEAD LOAD 489 14.16 -0.482 0.888 7.892

490 18.644 0.482 1.084 -17.062

DEAD+SEISMIC 489 33.712 0.79 -1.463 36.039

490 15.493 -0.79 -1.77 1.219

V. CONCLUSION

The results as obtained using STAAD PRO 2006 for with and without infill walls are compared for different categories

The Bending Moment chart, Table 3of a beams shows a difference between with and without infill walls where without infill walls show the maximum values. The difference in bending moment is Twice of with infill walls

In Table number 4 the storey drift shows a difference between with and without infill walls where without infill walls shows the maximum drift. The difference in storey drift is 50% higher for without infill than with infill walls.

In Table number 5, the Nodal displacement shows a difference between with and without infill walls where without infill walls show the maximum displacement. The difference in nodal displacement is 2 times higher for without infill

than with infill walls

The Shear Force Table number 6 of a beams shows the variations between with and without infill walls where without infill walls will be having maximum amount of shear force than with infill walls

As per the results in Table No 7, We can see that there is not much difference in the values of Axial Forces as obtained by With and Without infill walls of the RCC Structure..

Nodal Displacements and Bending moments in beams and columns due to seismic excitation showed much larger values compared to that due to static loads.



205

REFERENCES

[1] B.Srinavas and B.K.Raghu Prasad The Influence of Masonry in RC Multistory Buildings to Near- Fault GroundMotions Journal of International Association for Bridge and Structural Engineering (IABSE) 2009, PP 240-248.

[2] Indian Standard, Criteria for earthquake resistant design of structures, IS 1893(part 1):2002, Bureau of Indian Standards, New Delhi. [3] Indian Standard, Code of practice for plain and Reinforced Concrete,IS 456:2000,Bureau of Indian Standards, New Delhi. [4] Mehmet Metin Kose Parameters affecting the fundamental period of RC buildings with infill walls Engineering Structures 31 (2009), 93-102. [5] V.K.R.Kodur, M.A.Erki and J.H.P.Quenneville Seismic analysis of infilled frames Journal of Structural Engineering Vol.25, No.2, July 1998 PP 95-102.

Documents

Behavior of a Multistoried Building with and Without Infill Walls under Seismic Forces using STAAD.PRO