Performance-based comprehensive functional damage probability assessment framework for high-speed railway bridge under earthquake

• • Under frequent earthquakes, HSRSSB designs satisfy all three functional performance requirements (PTF, SBF, CRF), confirming that current seismic design provisions ensure operational continuity and structural safety for typical simply supported bridges. • • Under design-level earthquakes, the structural bearing function (SBF) remains in a slight damage state, while the post-earthquake traffic function (PTF) exhibits varying degrees of damage that worsen as pier height increases; this height-dependent degradation directly impacts post-earthquake traffic resumption decisions and requires height-specific mitigation strategies. • • The pier structure satisfies seismic demands even under rare earthquake conditions, demonstrating adequate collapse resistance function (CRF) and validating the effectiveness of current ductile detailing for HSR bridge piers in high-seismicity regions. • • The proposed framework integrates the probability density evolution method and vulnerability method to compute damage probabilities at three functional levels, enabling quantitative assessment of operational, structural safety, and structural integrity requirements for HSRSSBs.