Civil Insight: A Technical Magazine Volume 3 | Page 50

Karki G. and Bhatt M.R.
Civil Insight (2019) 45-50
building, even cof 2 was not sufficient to achieve beam hinge mechanism, where most of the columns were
yielded before the beam. However, in a 9-storied building, a significant beam hinge mechanism was
observed for higher column overdesign factors greater than 1.2.
Thus, from the study, it is seen that for lower-story building columns are generally under estimated due to
the low axial loads on columns. But for higher-story buildings, axial loads on the columns are larger due to
which stronger columns are to be designed. It requires columns to be relatively stronger from the
consideration of column-to-beam moment capacity ratio. For the same reason, in case of higher-story
buildings, smaller value of cof like 1.4 can provide better performance taking into account the energy
dissipation, but for lower story, it is not satisfactory. The Clause 7.2 of IS code 13920 (2016) recommends
single cof value 1.4, which cannot meet the philosophy of strong column-weak beam for buildings of
various stories.
Recommendations
The authors’ research is totally based upon the deterministic analysis approach. If the cof values are
recommended based on the deterministic analysis, it will be larger value like 2 or 2.5, which can make the
buildings uneconomic. To recommend the best value, probabilistic analysis of failure and economic
consideration are necessary.
References
Agrawal, P., & Shrikhande, M. (2011). Earthquake Resistant Design of Structure. New Delhi: PHI Learning
Private Limited.
ATC-40 (1996). Seismic Evaluation and Retrofit of Concrete Buildings. Redwood City, CA: Applied
Technology Council.
FEMA-356 (2000). Prestandard and Commentary for Seismic Rehabilitation of Buildings. Washington,
D.C: Federal Emergency Management Agency.
IS 13920: 1993 (2016). Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces –
Code of Practice. New Delhi: Bureau of Indian Standards.
Krawinkler, H., & Seneviratna, G. (1998). Pros and cons of pushover analysis on seismic evaluation.
Engineering Structures, 20(4-6), 452-464. https://doi.org/10.1016/S0141-0296(97)00092-8
MATLAB (Version R2015a) [Computer software]. (2015). The MathWorks, Inc. Available from
https://www.mathworks.com/products/matlab.html
Mistri, A., & Sarkar, P. (2016). Capacity Desing of Reinforced Concrete Framed Building For Earthquake
Loading. Indian Journal of Science and Technology, 9(30), 1-8. doi: 10.17485/ijst/2016/v9i30/99225
SAP2000 (Version 20.1.0) [Computer software]. (2018). Computers and Structures, Inc. Available from
https://www.csiamerica.com/products/sap2000
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