Vulnerability analysis of high-strength steel-reinforced UHPC frame structures

To investigate the shock resistance of ultra-high performance concrete (UHPC) structures with high-strength steel, eight earthquakes were selected for the incremental dynamic analysis of the normal reinforced concrete frame structure (model Frame-C) and the high-strength steel-reinforced UHPC frame structure (model Frame-UHPC). Taking the maximum story drift ratio and spectral acceleration as the structural demand and ground motion intensity parameters, respectively, the probabilistic seismic demand model was fitted to calculate the seismic susceptibility curves of the two models, thus deriving the risk prediction and damage assessment results. The results reveal that compared with model Frame-C, the ground motion intensity of model Frame-UHPC is higher when the maximum probability of moderate or severe damage is reached, thus indicating that the model Frame-UHPC has better seismic resistance under the action of strong earthquakes. Furthermore, under the action of small earthquakes, the vulnerability index of the model Frame-UHPC is significantly lower than that of model Frame-C, thereby reflecting the high-strength advantage of the UHPC structure. However, when using the normative performance points, the difference between the vulnerability indices of the two models under moderate or maximum earthquake is small, and the model Frame-UHPC cannot maximize the advantages of UHPC and high-strength steels. Therefore, the suggested performance points suitable for model Frame UHPC are given by sorting out and analyzing the data of reinforced UHPC columns in the literature. Compared with the normative performance points, the probability of Frame-UHPC reaching the ultimate state is lower, and the vulnerability index is significantly reduced when using the suggested performance points. Furthermore, the vulnerability indexes for frequent and moderate earthquakes are reduced by 19. 5% and 42. 3%, respectively, showing that model Frame-UHPC can better maximize its material advantages by using the suggested performance points. © 2024 Editorial Board of Journal of Harbin Engineering. All rights reserved.