Comparative seismic fragility assessment of buckling restrained and self-centering (friction spring and SMA) braced frames

Abstract

In seismic regions, steel braced frames are one of the most commonly used seismic lateral force resisting systems for their reliable performance. This study presents a comparative seismic performance of different braced steel frames at their system levels. Three types of bracings for steel frames are investigated: Buckling Restrained Bracing (BRB), Superelastic Shape Memory Alloy (SMA) bar reinforced Piston Based Self Centering (named as PBSC) bracing, and Friction Spring Based Piston Bracing (named as SBPB). A methodology to evaluate the structural response of the building in a probabilistic framework is used. The procedure to estimate the probability of exceeding certain limit states conditioned on the ground motion intensity is applied to the structures. Emphasis is given to the estimation of the probability of exceedance of peak Interstory Drift Ratios (IDR). The peak interstory drift ratio provides a way to estimate the damage to structural components. For this purpose, four, six, eight, and twelve-story structures, designed with the three bracing types are used. A large number of Incremental Dynamic Analyses are performed to derive three-dimensional (3D) vulnerability functions that involve building heights and bracing types. This versatile 3D format enables the interpolation of results to arrive at the seismic fragilities of structures with different stories. The results show that the SBPB and PBSC frames outperformed the BRB frames in terms of damage probability.

Mainshock-aftershock effect on the seismic performance of multi-story CBFs equipped with SMA-friction damping braces

“…The IM usually refers to the peak ground acceleration and spectral acceleration at the fundamental period. The PSDM relates the IM with the EDP in the logarithmic form (Cornell et al, 2002; Issa and Alam, 2020; Qiu and Zhu, 2016, 2020):…”

Probability seismic demand and fragility analyses of novel SMA-based self-centring eccentrically braced frames

“…The stress-strain relationship of superelastic SMA exhibits a typical flag-shaped loop, whose excellent SC capacity and moderate energy dissipation capacity have been drawing much attention in modern earthquake engineering. Furthermore, the SC capacity of SMAs can be maintained at a large strain (up to 8% strain), and its good fatigue resistance (more than 2000 cycles at 8% strain amplitudes) and excellent corrosion resistance (similar to stainless steel) make it attractive in structural design [12,13]. SMAs are commonly used in the forms of cables and bolts, mainly undertaking tensile stress [14][15][16].…”

Probabilistic seismic evaluation of SMA‐based self‐centering braced structures considering uncertainty of regional temperature

“…Many SC structural systems have been developed and tested in the past few decades, for example, SC bracing (SCB) system, [9][10][11] SC rocking core system, 12,13 and SC modular panel system, 5,14 which could outperform the conventional structural systems. 11,12,15 Among the possible solutions, a novel class of smart metal called shape memory alloys (SMAs) has been widely considered because of their inherent flag-shaped-like nonlinear superelastic behavior. SMAs possess two well-known characteristics, that is, shape memory effect and superelasticity (SE).…”

“…The resilient design strategy aims to achieve rapid recovery of structural integrity and functionality, and self‐centering (SC) technology, which can eliminate the permanent deformation with a typical flag‐shaped hysteretic behavior, has attracted extensive attention. Many SC structural systems have been developed and tested in the past few decades, for example, SC bracing (SCB) system, 9–11 SC rocking core system, 12,13 and SC modular panel system, 5,14 which could outperform the conventional structural systems 11,12,15 . Among the possible solutions, a novel class of smart metal called shape memory alloys (SMAs) has been widely considered because of their inherent flag‐shaped‐like nonlinear superelastic behavior.…”