Construction of multi storey buildings is must in developing countries like India in order to occupy space and also due to increase in population. These constructions of multi storey buildings often have soft stories due to requirement or needs of the occupants in the building. For example, open ground storey for the purpose of vehicle parking or for the commercial use such as showrooms etc. This soft storey due to lack of stiffness fail to resist the lateral loads due to Earthquake forces

more »

... may lead to the damage or collapse of the building. In this project, the study is made to know the behavior of single and multi soft storey at different levels of multi storey building for regular plan for G+14 stories using ETABS for seismic zone V in India during Earthquake and to find the optimum location of the soft storey using "Response Spectrum Method" by using IS 1893: 2002 part 1 codal provision with regards maximum storey displacement, Storey drift and storey base shear. Keywords: Regular plan, G+14 multi storey building with soft storey, stiffness, Response Spectrum Method, IS 1893:2002 part 1 provisions, Etabs software. I. INTRODUCTION Immense evolution in the population of India among various factors is one of the foremost causes for the construction of tall structures in big places. This is the reason for the progress of the nation. A soft storey is defined as "If storey is lesser than 70% stiff than that of the storey just above or less than 80% stiff as the average of three storeys above (As per IS-1893:2002 (part I)) it is recognized as soft storey". Reinforced concrete frame structure in present time has a distinctive role i.e. the ground storey is kept open for the need of parking, etc. These building are usually considered as open ground storey buildings or building on stilts. Such a storey is adopted in multi storied buildings based upon the desires of the occupants of the building. Earthquake generates waves which influences the base of structure through vibrations in various etiquette and directions, due to this reason lateral forces is developed on structure as a result of which shearing of column or even buckling of the whole column occurs finally resulting in collapse of building. Here an attempt was made to inspect the outcome of single soft storey and multiple soft storeys with conventional column and composite column in tall building by varying the position of them along the entire height of the structure having a regular plan. The modeling of G+14 storey building models will be done on the ETABS 2018 software. Post analyses of a building such as drift value, displacement value and base shear values are computed and then compared for structure having soft storey with composite column and soft storey with RCC column. II. LITERATURE REVIEW 1) Mohammed Hamaid Sayeed, , Prof Md Mansoor Ahmed , et al: Building having G+25 is adopted for study. It is studied by taking into account the soft storey at 2nd, 7th, 12th, 17th, 22nd and top most stories. The project has six models belonging to zone 5 and method adopted is "Push over analysis" for analyzing of the building.1.In tall buildings the most suitable position of the soft storey is at higher level. 2. Soft storey at base level is found to yield maximum. 3. Building with soft storey at ground floor along with soft storey at upper floors is found to provide much safety. 4. Nonlinear analysis of the building can be easily explained by pushover analysis. 2) Achyut S. Naphade, Prof. G. R. Patil: The RCC symmetrical building having G+ 10 storey's is considered for the project. The models are prepared for the project in SAP 2000 software. The models were analyzed having soft storey at ground, 2nd, 5th and 8th floor. Push over analysis was adopted to know the performance of the building along with retrofitting by the shear wall. Forming of plastic hinges are maximum due to soft stories although with the increase of base shear. 2. Yielding rate at the soft storey of the building is large. 3. Rate of yielding reduces as the position of soft storey goes to upper floors and after multiple number of pushover analyses the lesser value of hinges are formed. 4. From the pushover analysis and from spectrum curve as the location of soft storey goes to upper floor, the time period value is decreasing from 0.716sec to 0.446sec for 2nd and 8th floor soft storey respectively. This concludes that soft storey at upper floors is better from safer point of view.