Comparative Study on Structural Efficiency of Diagrids with Beam Column, Shear Wall and Steel Bracing Lateral Load Resisting Systems

Abstract

Choosing the most efficient and economical lateral load resisting system is a crucial question in designing high rise buildings, especially in high seismic zones. Shear walls and steel bracings are most popular lateral load resisting systems. Recently the use of diagrids for structural efficiency and architectural elegance has generated renewed interest from architectural and structural designers. These structures are emerging as popular structural systems in many developed and developing countries of the world, but in context of our country they are yet to get importance. To transfer the technology of using diagrids as lateral load resisting system to our country , it is very crucial to study the advantages of them over the well-known lateral load resisting systems. This research is a comparative study, considering a symmetrical G+30 office high rise RC building laterally strengthened by 14 lateral load resisting systems collectively of six different types of shear wall, six different types of steel bracing, rigid frame and four module diagrid. Modal response spectrum analysis for seismic zone IV was carried out based on ESEN 1998-1:2013 using finite element software ETABS v9.6.0. Every independent variable that can affect lateral load resistance of high rise buildings was kept constant except the lateral load resisting systems. The comparison was in terms of four critical parameters; storey displacement, storey drift, time period and base shear. As per the comparisons made, diagrids have showed a reduction of 7.8% in the X direction and 6.9% in the Y direction in storey displacement, 9.74% in the X direction and 7.31% in the Y direction in storey drift and 8.87% in fundamental time period as compared to the most efficient lateral load resisting system considered in the study. They showed a reduction in base shear of 8228.79KN in the X direction and 9418.25KN in the Y direction as compared to the system with the least base shear considered in the study (bare frame). These results show the best performance of diagrids in terms of reduction in storey displacement, storey drift, time period and base shear for every case and from every lateral load resisting system considered in the study. Therefore, diagrids, in addition to their inherent aesthetic quality and geometrical versatility, are the most efficient lateral load resisting systems in the range of many lateral load resisting systems known.