Response Reduction Factor for Industrial Structures

Author Name(s): Udaysingh Patil, Nakul Kabra, Ankush Asati, Dr. Prashant D. Hiwase
Author Email: patil.udaysingh4@gmail.com

Abstract

The Seismic design makes use of concepts of energy absorption and dissipation to reduce the design forces in order to achieve the economy. The behavior of Response Reduction factor (R) assumes a central role in the seismic design process, since design forces are the quotient of elastic forces. R factor is used in the seismic coefficient method for calculating base shear. This factor allows the structure to behave elastically. Response reduction factor (R) can be obtained by multiplication of over strength factor, ductility factor and redundancy factor and it can be calculated from the actual capacity curve of the structure. For finding out capacity curve we need to analyze structure by nonlinear static analysis method. Indian standards provides guideline for the values of response reduction factor of concrete structure like special moment resisting frame, ordinary moment resisting frame etc. and for steel structure like ordinary concentrically frames, special concentrically frames, eccentrically braced frames, ordinary moment frames, special moment frames. Composite industrial structures are getting more popular nowadays in construction industries due to minimization of cost. Indian standards don’t give any guidelines regarding R factor for industrial structures. Present study is focused to evaluate this factor for composite industrial structure for both single bay and multiple bay systems.

Introduction

In IS 1893:2002, value of response reduction factor is 3 for OMRF and 5 for SMRF for RCC building design. It does not specify any values for industrial and composite structures. Higher the value of response reduction factor means higher will be the ductility. This factor is incorporated in [2] seismic coefficient method for calculation of base shear. Thus it is necessary to understand the optimum value of [1] response reduction factor for designing industrial and composite structures. In this study industrial building having RCC column with steel trusses are analyzed and designed and its response reduction factors are calculated by using push over analysis in SAP 2000.

Conclusion

Indian standard code does not specify value of response reduction factor to be used in seismic coefficient method for industrial structures. In this paper Study of single bay and multiple bay industrial structure of 30 m span are carried out. From the obtained results it can be observed that the value of response reduction factors increases with increase in bay. Also it can be concluded that lateral dimension of structural system influences the value of R factor. The R value for single bay industrial structure is 5.3 and for multiple bay industrial structure is 4.53. Furthermore research is required to conclude the optimum value of R factor for various configurations

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