Seismic assessment and parametric analysis on a multi-level aseismic simply-supported bridge with cable-restraining composite rubber bearings and dissipative controlled rocking piers

Recent earthquakes uncovered the potential risk of widely-used simply-supported bridges (SSBs) to suffer severe bearing and pier damage, which may not be mitigated efficiently by only enhancing one of these components. Hence, this study proposes a novel multi-level aseismic bridge system (MLABS) comprising cable-restraining composite rubber bearings (CRCRBs) and dissipative controlled rocking (DCR) piers to make improvements at the system level. Deterministic and fragility analyses are conducted to compare the seismic performance of the novel system with that of the other three reference ones. Then, an economy analysis is carried out to evaluate economic efficiency. Finally, the effects of four main influential factors are investigated. The results reveal that the novel MLABS is capable of controlling the response of each vulnerable component within an acceptable range so that it can possess a large seismic capacity and a low system fragility. The economy superiority is also proved by the lowest expected losses under the concerned events and the minimum life-cycle cost. The internal sliding area ratio of the bearings is positively related to the performance and the economy, while the optimal design free displacement of the cables is about 140 mm. The pier capacity can be weakened by increasing the initial prestressing force or the energy-dissipating bar area in this case, which reduces the effectiveness and economy in improving the structural performance.