High-strength steel frames with SMA connections in self-centring energy-dissipation bays: insights and a multimodal nonlinear static procedure

Abstract

This study explores the effectiveness of shape-memory-alloy (SMA)-based self-centring energy-dissipation bays (SCEDBs) for enhancing the seismic performance of high-strength-steel (HSS) frames. The work commences with the development of an ensemble of prototype HSS frames equipped with SCEDBs, known as HSSF-SCEDB structures. The prototype systems are examined using cyclic-pushover and nonlinear-response-history analyses (NL-RHAs). According to the analysis database, it is found that the cyclic-pushover responses generally show a typical flag shape over a wide deformation range and that the post-earthquake residual deformations are below 0.5%, even following maximum interstorey drifts beyond the codified deformation threshold (i.e. 2%). To offer a practical tool to engineers for damage-control behaviour evaluation and seismic demand estimation, we develop a multimodal nonlinear static procedure based on a modified energy-balance concept. Conventional procedures relating to the fundamental vibration mode are also revisited. The results indicate that a medium-rise HSSF-SCEDB may be appreciably influenced by higher vibration modes. The difference between the average maximum interstorey drifts calculated by NL-RHAs and those obtained using the proposed procedure for an ensemble of earthquake motions is generally below 5%, and the adequacy of the proposed method is confirmed.

Seismic evaluation of friction spring‐based self‐centering braced frames based on life‐cycle cost

“…𝐹 𝑟 = 𝐾 𝑢 ⋅ 𝐷 𝑝𝑟𝑒−𝑐𝑜𝑚𝑝𝑟𝑒𝑠𝑠𝑖𝑜𝑛 (10) where E is the Young's modulus; θ is the taper angle of friction spring; ϕ is the friction angle (tan ϕ = ρ, ρ is the friction coefficient over the tapered surface); n is the total number of the contacting pairs in a friction spring set; D 01 and D 02 are the diameter of the centroid of the cross-section of inner and outer springs, respectively; A 1 and A 2 are the cross-sectional areas of the inner and outer rings, respectively; and D pre-compression is pre-compression deformation of the brace. Then the F I G U R E 4 Plan and elevation of the prototype structure loading stiffness to unloading stiffness ratio (λ) can be calculated using:…”

“…Then, the braces can be designed accordingly. The SCB can be designed based on Equations ( 7)- (10). Besides, the boundary frame should remain elastic under expected inter-story drift.…”

“…In this context, there has been a growing concern for resilience at both building and community levels among the seismic community in recent years. [3][4][5] A variety of self-centering (SC) strategies, such as SC connections, [6][7][8][9][10] braces, [11][12][13] rocking core, 14 and other systems, 15 have been successfully developed to promote structural resiliency by reducing the residual drift/permanent damages following major earthquakes. This improved seismic performance of SC structures has been found experimentally and numerically.…”

“…This improved seismic performance of SC structures has been found experimentally and numerically. [16][17][18] Such SC systems not only ensure life safety but also the safety of our built environment against seismic events warranting complete avoidance of demolition/reconstruction and its associated environmental and social impacts. Among these SC strategies, owing to easy installation and potential commercialization, SC braces (SCBs) seem to be preferable for new structures and upgrades of existing structures.…”

“…A variety of self‐centering (SC) strategies, such as SC connections, 6–10 braces, 11–13 rocking core, 14 and other systems, 15 have been successfully developed to promote structural resiliency by reducing the residual drift/permanent damages following major earthquakes. This improved seismic performance of SC structures has been found experimentally and numerically 16–18 . Such SC systems not only ensure life safety but also the safety of our built environment against seismic events warranting complete avoidance of demolition/reconstruction and its associated environmental and social impacts.…”