Reliability indices for compression braces in eccentrically braced frames

Abstract

The Eccentrically Braced Frame (EBF) has been accepted by seismic codes as a major seismic load resisting system. EBFs are designed using the capacity design method where all structural members are proportioned for the maximum capacity of the ductile fuse element. Load and resistance factors for code provisions have historically been derived from the actions of external loads and have so far not been derived for capacity design provisions. The first order second moment method is used to derive reliability indices for compression braces in an EBF. Reliability indices derived using design code equation result are non-uniform. Alternatively, the use of a recently proposed statistical equation for computing link overstrength is observed to result in uniform reliability indices. Since the current design provisions are inconsistent and may lead to both conservative and insufficient designs, the proposed statistical equation may be adopted with a reduced value of resistance factor.