Investigation of the Error Rate of Seismic Analysis Methods in Mid-Rise Structures with Lateral Stiffness Irregularity

Basically, among the various stages that are considered to design a building for earthquake resistance, the decision stage regarding the building configuration is of fundamental importance. One of the important factors that has a significant impact on the seismic performance of the structure is its regularity or irregularity in plan and height. Most buildings with irregular configurations are more damaged by the earthquakes. Therefore, determination of the criteria for detecting various types of irregularities in structures is of particular importance. In this study, in order to investigate the error rate of seismic analysis methods (static equivalent, spectral and time history) in mid-rise structures with stiffness irregularity, four 5-story steel samples with 4 states of stiffness irregularity in height including dual moment frame and bracing system are modeled in SAP software. The results revealed that the equivalent static analysis method always provides conservative and somewhat uneconomical values ​​compared to other methods, so it can be said that for mid-rise buildings, equivalent static analysis is reliable. However, time history analysis is better than spectral analysis for structural behavior during an earthquake.