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A platform for research: civil engineering, architecture and urbanism
Seismic Evaluation of RC Stepped Building Frames
‘Stepped building’ frames, with vertical geometric irregularity, are now increasingly encountered in modern urban construction. This chapter proposes a new method of quantifying irregularity in such building frames, accounting for dynamic characteristics (mass and stiffness). The proposed ‘regularity index’ provides a basis for assessing the degree of irregularities in a stepped building frame. This chapter also proposes a modification of the code-specified empirical formula for estimating fundamental period for regular frames, to estimate the fundamental time period of the stepped building frame. The proposed equation for fundamental time periods is expressed as a function of the regularity index. It has been validated for various types of stepped irregular frames. A new approach to determine the lateral load pattern, considering the contributions from the higher modes, is proposed that is suitable for pushover analysis of stepped buildings. Also, a modification to the displacement coefficient method is proposed, based on time history analysis of 78 stepped frames. When the newly proposed load pattern is combined with the modification of the displacement coefficient method of FEMA 356, the target displacement for the stepped building frame is found to match consistently the displacement demand given by the time history analysis.
Seismic Evaluation of RC Stepped Building Frames
‘Stepped building’ frames, with vertical geometric irregularity, are now increasingly encountered in modern urban construction. This chapter proposes a new method of quantifying irregularity in such building frames, accounting for dynamic characteristics (mass and stiffness). The proposed ‘regularity index’ provides a basis for assessing the degree of irregularities in a stepped building frame. This chapter also proposes a modification of the code-specified empirical formula for estimating fundamental period for regular frames, to estimate the fundamental time period of the stepped building frame. The proposed equation for fundamental time periods is expressed as a function of the regularity index. It has been validated for various types of stepped irregular frames. A new approach to determine the lateral load pattern, considering the contributions from the higher modes, is proposed that is suitable for pushover analysis of stepped buildings. Also, a modification to the displacement coefficient method is proposed, based on time history analysis of 78 stepped frames. When the newly proposed load pattern is combined with the modification of the displacement coefficient method of FEMA 356, the target displacement for the stepped building frame is found to match consistently the displacement demand given by the time history analysis.
Seismic Evaluation of RC Stepped Building Frames
Chakraborty, Subrata (editor) / Bhattacharya, Gautam (editor) / Sarkar, Pradip (author) / Menon, Devdas (author) / Prasad, A. Meher (author)
2012-12-06
11 pages
Article/Chapter (Book)
Electronic Resource
English
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