Modelling and Comparison of Plastic Performance in Ten Types of New Steel Braces under Pushover Analysis

Abstract

Safe design of the structure in earthquake increases the ability to absorb and dissipate energy by the bracing system. Also, one of the new methods to reduce earthquakes is the formation of plastic hinges in the flexible members of the structure. By creating plastic hinges in structural, the distribution of forces in other structural members is improved. Therefore, in the current research, using a questionnaire (6 criteria), the opinions of university professors and doctoral students were collected about the most important criteria for evaluating the plastic performance. The data was analyzed and prioritized by hierarchical analysis method in Expert Choice software. The plastic hinge with a statistical weight equal to 0.424 was introduced as the most important plastic criterion. Then, 10 bracing systems of steel structure including diagonal, gate, V, invert V, knee, rhombus, forward concentrically, zipper, cross, concentrically and steel moment frame were modelled with Sap2000 software. Steel frames have 4 and 8 story. The structures were analyzed and finally compared with nonlinear static analysis. The results showed that concentrically braces (4-story) and zipper (8-story) have the greatest ability to create plastic hinges. The use of all bracing systems in the steel frame increased the number and performance level of plastic hinges. Increasing the height of the structure increased the effects of braces on the steel frame.

Keywords

• steel frame
• pushover analysis
• hierarchical analysis
• plastic hinge
• bracing system