Seismic Design Adequacy of Existing Reinforced Concrete Dual-System Buildings in Rasht, Iran: A Comparative Study of the 3rd and 4th Editions of the Iranian Seismic Code (Standard 2800)
Abstract
This study investigates the seismic design adequacy of residential Reinforced Concrete (RC) buildings with dual systems (moment frame+shear wall) in Rasht, a major metropolis in northern Iran, according to the 4th edition of the Iranian seismic code (Standard 2800). Given Iran’s high seismicity and the occurrence of damaging earthquakes, evaluating existing building stock is critical. A total of 50 existing building plans (1 to 4 stories) were analyzed using Extended Three Dimensional Analysis of Building Systems (ETABS) software under both the 3rd (older) and 4th (newer) editions of Standard 2800. Key parameters compared include base shear, lateral displacement, and internal forces (axial, shear, moment). Results show that the 4th edition imposes stricter seismic demands, leading to an average increase in base shear of 18–35% and up to a 62% increase in displacement demands, depending on irregularity and seismic hazard zone. Approximately 45% of buildings fall into a low-vulnerability category, while 5% require urgent retrofitting or replacement. These findings provide a clear vulnerability map for Rasht and inform urban retrofitting priorities.
Keywords:
Seismic design adequacy, Reinforced concrete dual system, Standard 2800, Rasht, Seismic vulnerability, PushoverReferences
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