Jordan Journal of Civil Engineering

Controlling the torsional response of asymmetric low-rise special truss moment frame structures through truss elements modification


Mahyar Mardokhpoor; Houman Ganjali; Mohammad Reza Mansoori; Karim Laknejadi;


Special truss moment frame (STMF) is a seismic force-resisting system which dissipates the energy of an earthquake in specific predefined regions of the truss member called special segment. Past studies have shown that the STMF system is suitable for seismic regions. However, there is a need to evaluate and improve the seismic performance of asymmetric STMF buildings. This paper presents mass, stiffness, and strength centers arrangements for improving the overall seismic behavior of asymmetric STMF buildings and controlling the undesired torsional responses of such structures without using any supplemental devices. Different scenarios of modifying chord, column, and diagonal members are studied and the sensitivity of the performance of the structures to proper stiffness and strength distribution is investigated. According to the results, modifying chord elements has the greatest impact on the overall strength capacity of the frames. Nonlinear pushover and time history analyses were adopted to evaluate the seismic performance of low-rise asymmetric and modified asymmetric STMF buildings. Results show that the performance of the modified models considerably improved in terms of the deformations of the special segments, drifts of both stiff and flexible edges, torsional indices, and the dissipated energy during the earthquakes.


Special truss moment frame, Asymmetric building, Non-linear time-history analysis, low-rise building