International Journal of Engineering Research in Electronics and Communication Engineering

Seismic Evaluation of Concentric Braced Frames using Nonlinear Static and Dynamic Time History analysis

Author : Jayarajan P ¹ ²

Date of Publication :18th July 2019

Abstract: These Concentric braced frames (CBFs) are frequently used in steel structures as an efficient structural system to resist earthquake loads and control the structural drift. The braced system designed as per code provisions will be subjected to yielding and post buckling failures when acted upon by strong ground motions resulting in excessive interstorey drifts. Eurocode 8 (EC8) presents various guidelines for the design of dissipative elements along with requirements of non-dissipative parts to ensure a predetermined failure mode. The paper presents the results of a study on the seismic evaluation of four most commonly used CBFs namely diagonal, X, Chevron and zipper designed as per seismic provisions of EC8. A nonlinear static (pushover) analysis is first performed to obtain the capacity curve, over strength and the sequence of plastic hinge formation. Nonlinear dynamic time history analysis is then performed using preselected ground motion records to confirm the findings of pushover analysis and assessment of performance levels. The results show that all CBFs met the expected performance levels and ensured intended yield mechanisms. The assessment of behavior factors indicate that zipper configuration is the most efficient followed by the diagonal & X bracings. The Chevron bracings is characterized by the least overstrength.

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