International Journal of Research and Scientific Innovation (IJRSI) | Volume IV, Issue X, October 2017 | ISSN 2321–2705

Non Linear Static Analysis of 3D Framed Structures with Vertical Irregularities including Steel Bracings and Masonry Struts

Mohd Nazim Raza[1], Syed Jawwad Ahmed[2]
[1 ,2] Department of Civil Engineering, MJCET, Hyderabad, India

Abstract: This study aims at evaluating and comparing the response of G+10, G+15, G+20 systems with vertical irregularities as described by the ATC-40 and the FEMA-440 using nonlinear static procedures, with described acceptance criteria. The methodologies are applied to G+10, G+15, G+20 systems with vertical irregularity with bracings and with masonry struts. The non linear response of structure with vertical irregularity has been done using SAP2000 17 with an intent to evaluate importance of several factors in the non linear static analysis which includes time period, displacement, base shear etc,. It is observed that irregularity in elevation of building reduces lateral forces resisting capacity of the structure which in turn reduces the performance of the building and there is also decrease in deformation or displacement of the building.

Keywords: nonlinear static analysis, vertical irregularity, bracings, masonry struts, base shear displacement.

I. INTRODUCTION

Structures mostly get affected severely when unexpected loads acts on it and these types of loads are often classified into dynamic loads which include wind, earthquake, blasts etc. Non linear static analysis has become widely used performance based design tool for seismic evaluation of existing and new structures. It is assumed that non linear static analysis will provide adequate information on seismic demands induced by the design ground motion on the structural system and its components. The aim of the non linear static analysis is to estimate the expected performance of a structural system by evaluating its strength and deformation demands under the action seismic loads by developing a plot between spectral displacement and spectral acceleration which obtained by using the conversion of ADRS format. These are compared to available capacities at the targeted performance levels. The Non linear static analysis of a structure is a static non linear analysis under permanent vertical loads and gradually increasing lateral loads. The equivalent static lateral loads approximately represent earthquake induced forces. A plot of the total base vs top displacement in a structure is obtained by this analysis that would indicate any premature failure (or) weakness. The analysis is carried up to failure, and then it enables determination of collapse load and ductility capacity.

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