Arman Hossain Patwary, Taukir Ahmed, Tamzid Islam Zarir, Md Manik Mia, and Ann Nazmun Sakib

Abstract: To combine knowledge and advances in structural engineering over the past two decades, significant changes have been introduced at BNBC 2020. Modifications regarding design parameters and analysis methodology have been proposed which mainly revolve around seismic load analysis. In case of seismic loads, a number of parameters, such as, maximum lateral deflection, section classification, site class comparison, rebar percentage have been considered and reformulated. Seismic zoning has been subjected to recalibration of PGA values. It has been observed that the response reduction factors for structural systems, structural importance factors and soil factors vary. In order to obtain a clear understanding of these modifications, this research has been conducted in a controlled parametric study of RC structures based on previous codes (BNBC 1993) and new (BNBC 2020) using finite element analysis in this study. The study has been conducted by analyzing the 8-story RC building located in the city of Barishal, Cumilla, and Sylhet. It has been observed that the basic differences between codes are seismic base shear and maximum lateral displacement. In BNBC 2020, the seismic base shear is found to be higher than that of BNBC 1993 by factors of 1.33 times, 1.38 times, and 1.82 times for low, moderate, and high seismic zones, respectively. In this study, the changes in similarities and differences between the parameters, and seismic demand for RC buildings in different zones, have been outlined. It has been observed that demand has significantly increased when the building is designed according to the BNBC 2020 than when the building has been designed according to the BNBC 1993. In all cases, the inter-storey drift in the high seismic zone has been found 0.00169 according to BNBC 2020, which is 1.24 times greater than that of BNBC 1993.Abstract: To combine knowledge and advances in structural engineering over the past two decades, significant changes have been introduced at BNBC 2020. Modifications regarding design parameters and analysis methodology have been proposed which mainly revolve around seismic load analysis. In case of seismic loads, a number of parameters, such as, maximum lateral deflection, section classification, site class comparison, rebar percentage have been considered and reformulated. Seismic zoning has been subjected to recalibration of PGA values. It has been observed that the response reduction factors for structural systems, structural importance factors and soil factors vary. In order to obtain a clear understanding of these modifications, this research has been conducted in a controlled parametric study of RC structures based on previous codes (BNBC 1993) and new (BNBC 2020) using finite element analysis in this study. The study has been conducted by analyzing the 8-story RC building located in the city of Barishal, Cumilla, and Sylhet. It has been observed that the basic differences between codes are seismic base shear and maximum lateral displacement. In BNBC 2020, the seismic base shear is found to be higher than that of BNBC 1993 by factors of 1.33 times, 1.38 times, and 1.82 times for low, moderate, and high seismic zones, respectively. In this study, the changes in similarities and differences between the parameters, and seismic demand for RC buildings in different zones, have been outlined. It has been observed that demand has significantly increased when the building is designed according to the BNBC 2020 than when the building has been designed according to the BNBC 1993. In all cases, the inter-storey drift in the high seismic zone has been found 0.00169 according to BNBC 2020, which is 1.24 times greater than that of BNBC 1993.

Keywords: Seismic load, BNBC, lateral displacement, RC structure

References

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