## 1 Introduction  
In recent years, advancements in finite element analysis have significantly enhanced the precision and accuracy of structural seismic demand assessments. Numerous studies conducted both domestically and internationally indicate that the seismic demand on bridge structures is influenced not only by the uncertainty associated with seismic motions but also by uncertainties in the structural parameters [1]. An increasing number of scholars have begun to investigate the sensitivity of uncertainty factors in seismic demand analysis. [PERSON] et al. [2, 3] classified these uncertainties into three categories: structural-level uncertain parameters, material-level uncertain parameters, and boundary condition uncertain parameters, ultimately identifying thirteen critical uncertain parameters. [PERSON] [4] considered seismic motion uncertainty while employing Latin hypercube sampling to address uncertainties in structural parameters. This resulted in the development of fragility curves for a seismic isolation and movable bearing continuous beam bridge system; however, his investigation into structural parameter uncertainties was neither comprehensive nor thorough, lacking an in-depth analysis and discussion regarding aspects such as the yield displacement and hardening coefficient of the seismic isolation device. [PERSON] [5] proposed a more comprehensive evaluation based on a separable seismic isolation and movable bearing beam bridge, expanding the previously mentioned studies by including additional uncertain factors such as the width of expansion joints, scaling factors for dead load, and collision stiffness. [PERSON] et al. [6] performed a seismic fragility analysis on steel continuous beam bridges designed according to New York State regulations, taking into account uncertainties associated with material strength, structural mass, bearing friction coefficients, and gap sizes in expansion joints through Latin hypercube sampling techniques. Additionally, [PERSON] et al. [7] conducted seismic performance studies on multiple bridge structures in the southeastern and central regions of the United States, assessing a broader range of uncertainty factors, including geometric dimensions, material strength characteristics, and boundary characteristics such as bearing properties, abutments, and expansion joints. [PERSON] et al. [8] extended the investigation of uncertainties in soil parameters based on prior literature, focusing on a steel box girder continuous beam bridge and considering material strength parameters (concrete, steel, and soil strengths), boundary parameters (bearing gaps, abutment fill pressures), and the uncertainties associated with ground motion inputs, thereby studying the seismic performance of bridge structures situated on liquefiable soils. [PERSON] et al. [9] assessed the impact of corrosion on the fragility of existing prestressed concrete girder bridges under traffic loads by quantifying the effects of varying levels of corrosion on structural performance. They integrated this uncertain parameter of corrosion severity into their evaluation of structural vulnerability. Additionally, [PERSON] et al. [10] employed MTInSAR technology for monitoring bridge deformations while considering both systematic and random errors. This approach enables the consideration of uncertainties arising from geological phenomena during the data processing phase, which can significantly influence seismic calculations for simply supported concrete girder bridges. Currently, sensitivity analysis methods are widely applied in the analysis and design of seismic isolation systems. [PERSON] et al. [11] designed a seismic isolation system utilizing multi-level sliding friction adaptive isolation bearings by considering uncertain mechanical parameters such as shear stiffness, horizontal sliding distance, and horizontal friction coefficients. Their study validated the effectiveness of this design in improving seismic isolation performance. [PERSON] et al.