Comparison between Elastic and Plastic Design of 2D Unbraced Multi-Storey Steel Frames

Abstract

In this research, the elastic and plastic analyses of unbraced 2D steel frames were carried out in order to study their structural behavior. The first and second order elastic and plastic analysis 2D frames were considered in this research. The first and second order analysis of plane frames were carried out using Mastan2 and SAP 2000 and the comparison of analysis results was done. The critical load factors were determined using mechanism method, which was programmed in MATLAB code. The results of these factors for each 2D frame using MATLAB code were compared with that obtained by Mastan2 and SAP 2000.The plastic analysis of unbraced frames were carried out using elastic-plastic hinge method. The elastic and plastic design of plane frames were done using Excel spread sheet. The comparison of analysis results between the Mastan2 and SAP 2000 was about (-22.79 – 16.25) % for bending moments,(-11.06 – 4.56)% for shear forces,(-18.89 – 24.61)% for deflections and (-6.35 – 2.56)% for axial forces. The plastic design of plane frames gives sections smaller than elastic one.