IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 11, 2016 | ISSN (online): 2321-0613
Linear Static Analysis of Regular Space Frame with & without Fixed Base Ms. Akshaya Ghalimath1 Mr. Mantesh A.Hatti2 Ms. Sheetal More3 Ms. Chaitrali Jamadar4 1,2,3,4 Department of Civil Engineering 1,2,3,4 A.G. Patil Institutes, Solapur, Solapur University Abstract— Due to present increase in the world population people in this world tends to occupy available location present in any zone, which also includes zones falling in the high seismic zone categories. Commonly designers consider the building to be fixed at their bases. Flexibility of the soil causes the decrease in stiffness resulting increasing in the natural period of the structure. Such increases in the natural periods, changes the seismic response of structure hence it may be an important issue for design consideration. The present study provides systematic guideline for determining the natural periods of frame buildings due to the effect of soil-flexibility and identification of spring stiffness for linear building story and various influential parameters such as period, displacement, base shear and column forces have identified for both fixed and flexible base has to be studied for bare frame for all types of soils. Key words: Bare Frame, Fixed Base, Flexible Base, Base Shear, Period, Displacement, Axial Forces In Column I. INTRODUCTION Presently and majority existing of reinforced cement concrete structure has been a tremendous increase in the amount of tall stories in modern localities and the structures do not need the current seismic requirement as they are primarily designed for gravity loads only. Since the structure being tall and slender are subjected to seismic and wind load, if the structure is not stiff enough to resist the loads and vibration cause. Therefore it is important for these structures to resist lateral forces along with vertical forces. As waves from an earthquake a reach a structure, they produce motion in the structure. This motion depends on the structure vibration characteristics and the layout of the structure. For the structure to reach to the motion, it needs to overcome its own inertia force, which results in an interaction between the structure and the soil. The extent to which the structural response changes the characteristics of earthquake motions observe at the foundation level depends on the relative mass and stiffness properties of the soil and the structure. Thus the physical properties of the foundation medium are an important factor in the earthquake response of the structure supported on it. The process in which the response of soil influences the motion of the structure and the motion of the structure influence the response of the soil is termed as soil structure interaction. In the analysis work one model of R.C.C. Space Frame G+ 10 floors are made to know the realistic behavior of building during earthquake. A. Bare Frame: The in-plane stiffness of masonry infill wall is not taken into account in bare frame. Bare frame will deflect under horizontal loads by bending in columns and beams .Nonstructural components such as masonry that are subjected to seismic forces are not normally within the design scope of
the structural engineer, whose responsibility is to provide the seismic safety of the building.
Fig. 1: Bare Frame II. THEORETICAL FORMULATION A. Objective The main objective of this work is to carry out the effect of bases, types of soil on the seismic behavior of R.C.C. building with linear static analysis method. B. Methods of Seismic Analysis Following Flow chart shows seismic analysis methods used for Seismic evaluation:
Fig. 2: Seismic Analysis Methods 1) Linear Static Analysis Equivalent static analysis is the indirect method of considering the effect of ground motion and there is incorporation of dynamic properties of the structure in terms of fundamental period, response reduction factor, soil type, seismic zone and importance factor. Equivalent static analysis were carried out for all the models under the action of Dead load (DL), Live load (LL) and earthquake load (EQ) for different load combination as per IS 1893-2002. This method is limited to regular type of structure whose response is governed by first mode of vibration. As per IS 1893-2002 regular structure up to 40m in height in zone IV and V and up to 90m in zone II and III can be analyzed by Time History and Response Spectrum analysis. 2) SMRF: Special Moment-Resisting Frame, It is a moment- resisting frame specially detailed to provide ductile behavior and comply with the requirements given in IS 4326 or IS13920 or SP6.For the analysis and design purpose one model has been considered namely as bare frame (S.M.R.F frame).
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