Comparing Behavior of Steel Buildings with Diagonal & Chevron Knee Braced Frames under Lateral Loads

Subject Areas : Analysis of Structure and Earthquake

s.mehdi Zahraei ¹ , Saeid Bahram Masjed bari ²

1 - دانشگاه تهران
2 - کارشناس ارشد پژوهشکده زلزله مرکز تحقیقات ساختمان و مسکن

Received: 2016-04-28 Accepted : 2016-10-10 Published : 2016-11-21

Keywords: Diagonal bracing, chevron bracing, knee element, capacity curve, Target displacement, Plastic hinge,

Abstract :

Bracing system is one of typical lateral bearing schemes in steel buildings. If just a limited length of ductile element becomes inelastic, a more controllable behavior is warranted. Knee Braced Frames, KBFs, are among such systems. In this paper, multistory frames (5 and 8-story frames) have been modeled with SAP2000 software and their lateral behavior has been studied. Meanwhile some of their properties have been introduced by using criteria such as target displacement, capacity curve (Force-Displacement), formation of plastic hinge and sample designed sections. Better lateral performance of chevron knee braced frames compared to diagonal knee braced frames has been indicated due to more knee elements and thus higher damping. According to the results of chevron knee braced frames, when the height of the structure increases (from 5 to 8 stories), the target displacement increases 65%, base-shear and spectral acceleration decrease 10% and 40% respectively, while in diagonal knee braced frames the target displacement increases 70%, base-shear  and spectral acceleration decrease 5% and 40% respectively.