Experimental verification and probabilistic assessment of self-centering damper with adjustable activation force to mitigate seismic risk of existing multi-bent bridges

This study presents a detailed experimental and numerical investigation aiming to assess the effectiveness of a self-centering damper with adjustable activation force (SDAAF) in enhancing the seismic performance of multi-bent RC adjacent bridges (RCABs) prone to various damage modes at both the superstructure and substructure levels by adjusting the precompression force and energy dissipation. Following a detailed assessment framework proposed to upgrade substandard RC bridges, the SDAAF is designed and fabricated, and its self-centering and hysteretic behavior is experimentally verified through quasi-static cyclic reversed-loading tests conducted at different activation levels. The test results confirmed that increasing activation forces from 10% to 40% significantly improved energy dissipation by 60–230% relative to zero precompression, highlighting its critical role in improving energy dissipation efficiency. A simple yet effective numerical model for the SDAAF is subsequently developed and successfully validated against experimental hysteretic responses obtained at different activation levels. The close alignment between the numerical and experimental results confirms the reliability and applicability of the proposed modeling approach for subsequent seismic performance evaluations at the structure level. The SDAAF damper is then implemented in a three-dimensional fiber-based model of a benchmark RCAB at the substructure (SBR), superstructure (SPR), and both the substructure and superstructure (SBSPR). The preliminary analyses, conducted to determine appropriate SDAAF activation forces and configurations, indicate 35% improvement in the bridge’s lateral strength, along with a notable delay of local damage indicators. The fragility analysis across different seismic scenarios confirms that the SDAAF implemented at SBSPR significantly reduced all damage probabilities and ensured 75%-100% continuous functionality of the bridge. This comprehensive investigation demonstrates the effectiveness of the proposed SDAAF in mitigating various seismic damage modes observed in both the substructure and superstructure by adjusting the activation force and energy dissipation, thereby ensuring safety and continued serviceability of RCABs following seismic events.