tailieunhanh - Collapse safety margin in iranian seismic design code: Case studies of RC frame structuress

The study includes RC moment resisting frames with 3, 6 and 10 stories considering two types of soil classifications (Type II and III) and two alternatives of ductility levels (intermediate and high), as defined in standard 2800. | JSEE Vol. 19, No. 1, 2017 Technical Note This is an extended version of the paper presented in SEE7 conference, peer-reviewed again and approved by the JSEE editorial board. Collapse Safety Margin in Iranian Seismic Design Code: Case Studies of RC Frame Structures Ali Reza Manafpour1* and Maryam Tohidian 2 1. Assistant Professor, Urmia University, Urmia, Iran, * Corresponding Author; email: 2. . Graduate in Structural Engineering, Urmia University, Urmia, Iran. Received: 08/02/2016 Accepted: 15/03/2017 ABSTRACT Keywords: Collapse Margin Ratio (CMR); Incremental Dynamic Analyses (IDA); RC Frames; Iranian Seismic Standard According to the modern seismic design codes, the structural collapse is a catastrophic state which is not acceptable, even under very rare earthquakes. Hence, evaluation of collapse safety margin for structures design based on code requirements is very important. The paper tackles this issue considering RC frame structures designed according to Iranian seismic standard (Standard 2800). Incremental Dynamic Analysis (IDA) is carried out using 22 natural ground motion records. The study includes RC moment resisting frames with 3, 6 and 10 stories considering two types of soil classifications (Type II and III) and two alternatives of ductility levels (intermediate and high), as defined in standard 2800. It is concluded that while all structures on the sites with soil class II demonstrate sufficient margin against collapse, taller structures on soil class III show lower than acceptable collapse margin. It is also noted that the collapse margin is generally reduced with the increased height of the structure. 1. Introduction Providing sufficient energy dissipation capacity through plastic deformation is the main goal considered in designing seismic-load-resisting systems for a reduced seismic load. Seismic performance factors (SPF), namely overstrength force reduction factor (R) and deformation amplification .