حالت ارتجاعی ساختار پل جدا با اثر متقابل ساختار خاک Seismic resilience of isolated bridge configurations with soil– structure interaction

Background Seismic resilience (SR) can be defined as the ability of a system to reduce the chances, to absorb, and to recover after of a natural event, such as an earthquake shake [4]. There are many components or dimensions that have to be considered: first, technical and economic, related to the functionality of physical systems, such as lifeline systems and essential facilities; second, organizational and social, more related to the community affected by the physical systems [4]. Several studies have been carried out subsequently, with the goal to define the concept of resilience, especially in case of extreme events when the drop of functionality, or loss, is sudden [6–8]. More specifically, a resilient system should be analyzed to capture some key factors, such as assessment of failure probabilities, evaluation on consequences from failures (in terms of lives lost, damage, and economic and social consequences), and recovery costs and time to recovery (restoration to the ‘‘original’’ level of functionality). Many studies have recently been focused on resiliency of communities affected by natural disasters, such as Miles and Chang [30], and Chang and Shinozuka [9]. When the concept is applied to infrastructure arena, economic impacts should be defined in terms of many parameters. In particular, the losses should include both direct and indirect costs [3, 14]. The paper aims at to assess SR by considering first the probabilities of failures induced by the effects of soil– structure interaction (SSI) on several isolated bridge con- figurations. Second, the presented study wants to consider the damage in terms of economic consequences and, finally, to calculate recovery costs and time to reset the ‘‘original’’ level of functionality. Since the Northridge earthquake, research studies have proved the significant role that soil–structure interaction (SSI) can play during seismic excitations especially on isolated bridges, as reported in Forcellini [15]. In particular, past earthquakes all over the world have proved the benefits of isolation technique for pier protection. These effects can be strongly modified by soil deformability and energy dissipation in the ground, as shown in Vlassis and Spyrakos [33], Tongaonkar and Jangid [31], Ucak and Tsopelas [32], and Forcellini [15]. The paper aims at evaluating the relationships among various characteristics of a benchmark bridge, including ground motion, superstructure, foundation, and isolation devices. The target is to assess the performance of various isolated configurations adopting a performance-based earthquake engineering (PBEE) methodology developed by the Pacific Earthquake Engineering Research (PEER) Center (http://peer.berkeley.edu). SSI effects are assessed by comparing different configurations where isolation technique is applied. Responses are assessed in terms of repair costs and time.