Optimized seismic retrofit of steel-concrete composite buildings

Abstract

This work is focused on comparatively assessing the cost-effectiveness of three seismic retrofit approaches for non-code-conforming frame buildings with steel-concrete composite columns.The first two of the assessed retrofit approaches aim in indirectly enhancing structural system performance by strengthening individual composite columns using reinforced concrete jackets or concrete-covered steel cages. The third retrofit approach considered aims in upgrading the composite building frame at hand by installing steel bracings at selected bays. A specially developed structural optimization procedure is used to perform an objective comparison of the cost-effectiveness of the three retrofit approaches. The objective of the optimization procedure is to minimize the total retrofit material cost, while constraints are imposed to ensure the satisfaction of design requirements for the retrofitted structure regarding member capacities (according to Eurocodes 3 and 4 for steel beams and composite columns, respectively), structural system performance under horizontal loading (based on interstorey drifts calculated by pushover analyses) and fundamental periods (obtained from eigenvalue analyses). By defining 30 cases of under-designed 2-storey, 4-storey and 6-storey composite buildings (i.e. buildings with steel-concrete composite columns), an extensive numerical investigation involving 120 retrofit optimization runs was conducted. The results obtained provide insight into the relative cost-effectiveness of the three seismic retrofit approaches and reveal certain conditions under which each approach is economically most viable.

Experimental Investigation of ECC Jackets for Repair of Pre-Damaged R.C. Members under Monotonic Loading

“…In a state-of-the art review of strengthening applications with ECC, Shang et al 2019 [23] concluded that the strain-hardening property of ECC renders it an ideal retrofitting material; the interfacial resistance is adequate to ensure monolithic behavior between core and jacket, which is a finding that is also supported by inclined interface shear tests between plain and ECC concrete, particularly if the substrate is roughened prior to the strengthening application. It is also worth mentioning that the results of the present work are in line with the findings of Papavasileiou et al 2020 [24], who demonstrated that implementing a thin jacket layer to a deficient member is an effective retrofit technique that can be competitive to other strengthening methods (such as conventional thicker jackets or bracings at frame bays), provided that the thin jacket is composed of appropriate material(s) to develop sufficient confinement of the core and the additional strength required for the retrofitted member.…”

Prediction of Properties of FRP-Confined Concrete Cylinders Based on Artificial Neural Networks

“…Many researchers have done work for estimating the axial strength and strain of externally confined concrete members [17][18][19][20][21][22][23][24] based on empirical techniques [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], i.e., Karbhari et al, Miyauchi et al. [42,43], Lam and Teng [44], and Mander et al [45], as described in Table 1.…”

Vibration control of seismic forces using viscous dampers and buckling restrained braces in irregular composite buildings

“…In addition, considerable work on the structural behaviour of CFST has been reported in the literature [17] compared three seismic retrofit strategies for building types with steel-concrete composite columns to find the most efficient strategy. [18] investigated G+7 high-rise buildings with the composite structural system and compared them with RCC structures with the same building plan and design data.…”