Evaluation and Comparison of Seismic Performance in Irregular Steel Structures with Modern Concentrically Braces

Abstract

Irregular structures have special seismic performance during earthquakes. Major irregularities in structural standards include geometric, torsional, diaphragm, out-of-plane and non-parallel. In the present paper, 5, 8 and 11-story steel structures with mass and height irregularities were modeled with SAP2000 software. The structures were subjected to 11 scaled earthquakes (near and far-fault) by nonlinear time history analysis method (direct integration). Steel structures have three types of concentrically braces including Gate, Inverted V and Knee. The results showed that the Knee brace has the best performance in the acceleration and displacement parameters of the structure. Inverted V brace has the best performance in shear force parameter. The average displacement reduction of irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 39.26%, 23.15%, and 49.65%, respectively. The average acceleration reduction of irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 28.56%, 17.23%, and 45.98%, respectively. The average reduction of column shear force in irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 14.11%, 24.48%, and 9.51%, respectively.

Keywords

• irregular steel structures
• concentrically braces
• nonlinear time history analysis
• seismic performance
• code 2800