effect of brick infill panel in design of high rise · pdf fileeffect of brick infill panel in...

Effect of Brick Infill Panel in Design of High Rise Building

Sachin R Patel#1, Sumant B patel*2

#1P.G.Student, Structural Engineering Department

Gujarat technological UniversityBirla Vishvakarma Mahavidhyalaya Engineering College

V V Nagar, Gujarat#[email protected]

*2Professor, Structural Engineering Department, B.V.M Engineering College, V V Nagar.*[email protected]

Abstract— Earthquakes are natural hazards under which

disasters are mainly caused by damage or collapse of buildings and other man-made structures. Due to accommodation of vehicles and their movements at ground levels infill walls are generally avoided, which creates soft storey effect. It should be noted that 70 to 80 % of buildings of urban areas in India fall under the classification of soft storey according to IS 1893 (2002) Part-I. In analysis and design of the high rise building generally we do not consider the effect of the brick masonry infill panel and design it by considering bare frame. Here to observe the effect of brick masonry infill panel and without infill panel in analysis of plane frame. Brick infill panel is modeled as diagonal strut and they are placed at all above the ground plus level. also check out stiffness of building.

Keywords- brick infill panel, bare frame, strut, stiffness

Introduction- In many countries situated in seismic regions, reinforced concrete frames are infilled fully or partially by brick masonry panels with or without openings. 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 behaviour of the frame and the infill.

Performance of buildings in the recent earthquakes (2001 Bhuj earthquake) clearly illustrates that the presence of infill walls has significant structural implications. Therefore, the structural contribution of infill walls cannot simply be neglected particularly in regions of moderate and high seismicity where, the frame–infill interaction may cause substantial increase in both stiffness and strength of the frame in spite of the presence of openings. Generally, presence of these openings decreases stiffness and strength of infilled frames. A review of analysis and design provisions related to masonry infilled RC frames in seismic design codes of

different countries shows that only a few codes have considered the effect of infill in analysis and design of masonry infilled RC frames. On the other hand, the stiffness and strength of the infilled frames with opening are not taken care of by most of the codes. Hence, the behavior of infilled frames with openings needs to be studied extensively in order to develop a rational approach or guidelines for design.

The masonry infill is very stiff and has considerable strength, meaning that the load capacity of masonry infilled frames increases substantially. In the case of horizontal loading due to wind or seismic action, it is usual to assume that an equivalent compression strut can replace the action of the masonry panels.

Width of strut- Diagonal strut modelling is most popular. Researchers have tried to model the brick masonry in multiple diagonal struts, i.e. single strut, two diagonal struts, and three diagonal struts. Observing the results on this trial they conclude that the single diagonal strut is the most effective method of modeling for the masonry infill panel that work best.

It is therefore important to compare the width of diagonal strut of solid infilled frames obtained from several empirical relationships are available.

=0.175(λH)0.4d (Mainstone 1971)

(Paulay and Priestley1992)

(Holmes 1961)

National Conference on Recent Trends in Engineering & Technology

13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India

=

= 1.79 m

Where, λ is characteristic of infill,

h is height of story, c/c of beam

d is diagonal length of strut

Modulus of Elasticity of the Masonry infilled panel (Em): this parameter represents the initial slope of the strain-stress curve and its values exhibit a large variation. Different approaches can be found in the literature for the calculation of Em, most of them relating the modulus of elasticity of masonry walls with the compressive strength of the material. These empirical equations result in their majority in a range of values between 400fm<Em<1000fm

Em = kfm (Drysdale 1993)

=500×

=935.41 N/mm2

Where, fm is the compressive strength of masonry prism in MPa and k lies between 500 to 600. In the present study, this expression is used with k taken as 550 to model the initialstiffness of the infilled frames with openings.

Em = 4000 (fm)1/2 (Dayaratnam 1987)

Em=750fm (Pauly and priestly 1992)

= 750×

= 1.403×10+6 KN/m2

The effect of opening on the lateral stiffness of the infilled frame can be represented by a diagonal strut of reduced width. This reduction in strut-width can be represented by a factor (ρw), which is defined as ratio of reduced strut-width to strut-width corresponding to fully infilled frame, i.e.,

Strut − width reduction factor (ρw) =

The presence of central opening can be considered by reducing the effective width through a reduction factor.

ρw = 1 − 2.47αo Opening-Area-Ratio (α0) =

Strut width reduction factors for various opening-area-ratios for all the frames are obtained. A sharp decrease of initial stiffness has been observed when the opening is extended up to full height or full width of the panel. Except such extreme cases, it is observed that the area of opening is important for initial lateral stiffness of infilled frame. Therefore, the cases in which the openings are extended up to the full height or full width of the panel are excluded in regression analysis as they do not reflect the strut action adequately.

Example: Plan dimension : 4m × 5m

Height of building :

G.F., , & 3rd floor : 3.6m

Parapet wall : 0.9m

Numbers of bays in X-direction : 2 Nos.

Numbers of bays in Z-direction : 1 Nos.

Column size : 450 mm × 300 mm

Grade of Concrete : M-25

Density of Concrete : 25KN/m3

Density of Masonry : 20 KN/m3

Dead Load : 3 KN/m2

Live Load : 4KN/m2

Slab thickness : 120 mm

Floor Finish : 1 KN/m2

Size of Beam :

420 mm × 230 mm

Wall Thickness :

230 mm



Fig1: Without infill panel

In that model it has done that the displacement of with infill panel is decrease as compare to without infill panel. It has analysed by earthquake load. See below table comparation of displacement

TABLE 1 DISPLACEMENT OF EARTHQUAKE LOAD WITH AND WITHOUT INFILL PANEL IN X AND Z

DIRECTION

.

Fig2: with infill panel

Take a Same model to apply load for check stiffness. In that below table displacement of applied load at the roof level.

TABLE 2A DISPLACEMENT OF APPLIED LOAD AT ROOF LEVEL

with infill in x-direction

without infill x-direction

Node L/C X mm Z mm X mm Z mm

9 PT 50 3.343 -0.735 100.491 0

10 PT 50 3.632 -0.737 100.491 0

19 PT 50 3.06 -0.27 100.087 0

20 PT 50 3.449 -0.269 100.087 0

31 PT 50 2.989 -0.124 99.944 0

32 PT 50 3.361 -0.119 99.944 0

Node 32 With infill panel Without infill panel

L/C X mm Z mm Xmm Z mm

1.5(DL+LL) -0.051 -0.142 0.064 -0.137

1.2(DL+LL+EQ X) 10.423 17.46 145.611 308.924

1.2(DL+LL+EQ Z) 10.423 17.46 145.611 308.924

1.2(DL+LL-EQ X) -10.505 -17.686 -145.508 -309.143

1.2(DL+LL-EQZ) -10.505 -17.686 -145.508 -309.143

1.5(DL+ EQ X) 13.035 21.829 182.014 386.155

1.5(DL+ EQ Z) 13.035 21.829 182.014 386.155

1.5(DL- EQ X) -13.125 -22.104 -181.886 -386.429

1.5(DL- EQ Z) -13.125 -22.104 -181.886 -386.429

0.9DL+1.5EQ X 13.053 21.884 181.988 386.21

0.9DL+1.5EQ Z 13.053 21.884 181.988 386.21

0.9DL-1.5EQ X -13.107 -22.049 -181.911 -386.374

0.9DL-1.5EQ Z -13.107 -22.049 -181.911 -386.374



TABLE 2B DISPLACEMENT OF APPLIED LOAD AT ROOF LEVEL

with infill in z-direction

without infill z-direction

Node L/C X mm Z mm X mm Z mm

9 PT 33.33 -0.861 4.992 0 180.282

10 PT 33.33 -0.831 4.836 0 180.053

19 PT 33.33 -0.861 4.743 0 180.282

20 PT 33.33 -0.798 4.59 0 180.053

31 PT 33.33 -0.865 4.925 0 180.282

32 PT 33.33 -0.759 4.767 0 180.053

In that table it has saw stiffness of with infill panel is increase as compare to without infill panel.

TABLE 3A STIFFNESS OF ROOF LEVEL

with infill panel x-direction

without infill panel x-direction

Node L/C Xmm Xmm

9 PT 50 29.91325157 0.99511399

10 PT 50 27.53303965 0.99511399

19 PT 50 32.67973856 0.999130756

20 PT 50 28.99391128 0.999130756

31 PT 50 33.45600535 1.000560314

32 PT 50 29.75304969 1.000560314

TABLE 3B STIFFNESS OF ROOF LEVEL

with infill panel z-direction

without infill panel z-direction

Node L/C Zmm Zmm

9 PT 33.33 20.03205128 0.554686547

10 PT 33.33 20.67824648 0.555392023

19 PT 33.33 21.0837023 0.554686547

20 PT 33.33 21.78649237 0.555392023

31 PT 33.33 20.30456853 0.554686547

32 PT 33.33 20.97755402 0.555392023

CONCLUSIONS

In many countries, multistory buildings are commonly built with reinforced concrete frame and masonry infill walls. Such buildings are usually designed assuming the infill walls to be nonstructural and ignoring their strength and stiffness. By considering infill wall panel the stiffness of building increase by 30.388% in x-direction And in z-direction 20.81%. Maxmimum roof displacement of the building 100.174mm without infill And 3.31mm with infill.

REFERENCES

[1] Goutam Mondala and Sudhir K. Jain, M.EERI “Lateral Stiffness of Masonry Infilled Reinforced Concrete (RC) Frames with Central Opening” Department of Civil Engineering, Indian Institute of Technology Kanpur, India 208016.

[2] Holmes, M., 1961. Steel frames with brickwork and concrete infilling, Proceedings of the Institution of Civil Engineers 19, 473–478 (eISSN 1753-7789).

[3] Paulay, T. and Priestley, M. J. N., 1992, Seismic Design of Reinforced Concrete and Masonry Buildings, John Wiley & Sons Inc., 744 p.

[4] C.V.R. Murthy, Indian institute of technology Kanpur,india earthquake tips.

[5] C V R MURTY And Sudhir K JAIN “BENEFICIAL INFLUENCE OF MASONRY INFILL WALLS ON SEISMIC PERFORMANCE OF RC FRAME BUILDINGS” 12WCEE 2000,paper 1790, pg. 2-5



effect of brick infill panel in design of high rise · pdf fileeffect of brick infill panel in...

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