Seismic Performance of RC & Composite Frames with Plan Irregular Configurations

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1 Seismic Performance of RC & Frames with Plan Irregular Configurations Naveen Kumar C N 1, Ramesh B M 2, P S Ramesh 3 1M.tech final year student, Department of Civil, SJBIT College Bengaluru, Karnataka. 2Assistant Professor Department of Civil, SJBIT College Bengaluru, Karnataka. 3Associate Professor Department of Civil, SJBIT College Bengaluru, Karnataka *** Abstract - Steel-Concrete composite structures are very popular & have their advantages over Concrete constructions. Concrete structures are bulky and have more seismic weight and more deflection as compare to Construction, & it combines the better properties of both steel and concrete along with lesser cost, speedy construction, fire protection etc. The aim of the present study is to compare seismic performance of plan irregular configurations of RC, and building frame which is situated in earthquake zone IV. Total number of 12 models been modeled(6 RC & 6 all models are of G+10 storey buildings. All frames are designed for same gravity loadings. Beam and column sections are made of Either RCC and Structural Steel-concrete composite sections. Response Spectrum method are used for seismic analysis. Effect of each building is studied with respect to time period, base shear, storey shear, displacements, drift & axial force. ETABS-2015 Software is used for analysis and results are compared. Key Words: Beam, Column, Response spectrum method, ETABS 1.INTRODUCTION At the present time, many of multi-storey (residential & commercial) buildings have open storeys as salient feature. The composite materials were commonly used for multistorey, industrial buildings or in bridges. The composite structures are made of different materials and they are compatible and complementary to each other, the composite structures have same extension both for thermal & applied loads. The combination of the steel and RCC will have higher strength as steel will take tension forces and the concrete will take compression forces. The concrete also gives corrosion protection and thermal insulation to the steel at elevated temperatures and additionally can restrain slender steel sections from local or lateral-torsional buckling. 1.1 OBJECTIVES The present work done for both RC & structure the total number of model considered is 12 (6 RCC & 6 Steel with the number of storey as 11, which was in zone 4, & the soil type taken is medium soil. I. To analysis the multi storeyed frame of irregular plan of both R.C and frames. II. To perform Equivalent analysis & Response Spectrum Analysis. 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 335 III. To study the performance of both R.C and composite frame w.r.t. different parameters such as story displacement, story drift, base shear, story shear, time period & axial force. 2 STRUCTURAL MODELLING On the analysis a building has been Modeled for G+10 storey building and analysed in ETABS software. Two kinds of the structures were considered one is RCC structure with column of 0.4x0.5m from 1-5 th floor & 0.3x0.4m from 6-11 th floor and beam of 300x350mm kept constant for all the floors and slab of 175mm. And another one is steel composite structure with column of 0.4x0.5m at 1 st floor & 0.3x0.4m encased ISHB250 from 2 nd -11 th floor and beam of 250x350mm and slab of 175mm. 3. DESCRIPTION OF ANALYTICAL MODEL Various parameters such as a number of storeys, the dimension of structural members, storey height, load intensities are mentioned below. Number of Storeys Building Frame system Table -1: Description of model G+10 Reduction Factor SMRF Importance Factor Storey Height 3m Grade of Concrete M25 Seismic Zone Zone 4 Grade of Steel Fe500 Type of Soil Medium Live load 3 kn/m 2 4. TYPES OF MODELS Model 1- Re- entrant Corner (C- shaped RCC & Steel Model 2- Re- entrant Corner (U- shaped RCC & Steel Model 3- Re- entrant Corner (L- shaped RCC & Steel

2 Model 4- Re- entrant Corner (T- shaped RCC & Steel Model 5- Re- entrant Corner (Plus- shaped RCC & Steel Model 6- Diaphragm Discontinuity (Hollow- shaped RCC & Steel 5.2 BASE SHEAR Table-3: Base Shear of both RC & Fig-1: Different types of Models 5. RESULTS AND DISCUSSION 5.1 TIME PERIOD Table-2: Time period of both RC & Fig-3: Base Shear of both RC & The results show that the response obtain in the form of base shear may be due to various earthquakes is more in case of the RC building when compare to the composite building. 5.3 STOREY DISPLACEMENT Table-4: Displacements in X directions of both RC & Fig-2: Time period of both RC & Its observed that mode 1, 2 & 3 of all models of RC building shows slightly higher frequency, than the mode 1, 2 & 3 of all models of Steel composite building. 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 336

3 The displacements of all models in Y directions. From the results its observed that the model 3 model 1 & model 4of composite building shows the higher displacements. The maximum deflection is occurred in the upper most floor & its less than 40mm(the deflections were within limits as prescribed by IS codes) 5.4 STOREY DRIFTS Fig-4: Displacements in X directions of both RC & Table-6: Drifts in X directions of both RC & The displacements of all models in X directions. From the results its observed that the model 3 model 1 & model 4 of composite building shows the higher displacements. The maximum deflection is occurred in the upper most floor & its less than 40mm(the deflections were within limits as prescribed by IS codes) Table-5: Displacements in Y directions of both RC & Fig-6: Driftss in X directions of both RC & Fig-5: Displacements in Y directions of both RC & The drifts of all models in X directions. From the results its observed that the model 4, model 2 & model 3 of composite building shows the higher drifts. The maximum deflection is 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 337

4 occurred in the upper most floor & its less than 40mm(the deflections were within limits as prescribed by IS codes) Table-8: Axial Force of both RC & Table-7: Drifts in Y directions of both RC & 6. CONCLUSIONS Fig-8: Axial Force of both RC & Fig-7: Drifts in Y directions of both RC & The drifts of all models in Y directions. From the results its observed that the model 3 model 1 & model 4 of composite building shows the higher drifts. The maximum deflection is occurred in the upper most floor & its less than 40mm(the deflections were within limits as prescribed by IS codes) 5.5 AXIAL FORCE 1. There are slight changes in time period of both RC & composite buildings, RC buildings has more frequency when compared with composite buildings. 2. Base shear values are more for composite buildings when compared with RC buildings. Because seismic weight of materials, when compared with RC buildings. 3. Base shear and storey shear of composite buildings is high, due to more seismic weight of the building. 4. In the displacements of both RC & structures of all models, it is observed that in few models of the structure has discontinuity in X direction & has less number of bays than in Y direction. Therefore, structure in Y direction is stiffer than X direction. Similarly in the remaining models, Y direction has got discontinuity, so X direction is stiffer than Y direction. 5. The displacements of all plan irregular models is found to be within the limits as per IS The storey drift of the RC building is less as compared to composite building, and all frames are within permissible limit of times the storey height, as prescribed in IS Drift variations are observed for both RC and composite buildings which may be due to differential size of columns. 8. It is observed that the RC buildings have more axial force than the composite buildings. The axial force of RC building has got high value when it was compared with building. 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 338

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