Determination method for pier settlement limits of standard girder bridges in high-speed railways considering adjacent pier height differences

To accurately determine the permissible settlement limit value (PSLV) of high-speed railway (HSR) bridge piers, this paper presents a method that not only considers the typical factors impacting PSLV but also incorporates the nonlinear effects of adjacent pier height differences (PHDs). A train-track-bridge dynamic model is firstly established and validated with measured dynamic data. Subsequently, a method for determining PSLV under all influencing factors coupled with PHDs, is proposed. This method can reasonably identify the corresponding PSLV based on the most unfavorable factor combinations. Finally, using the maximum entropy principle, the statistical representative values of PSLV are obtained under random track irregularities, and the interdependent nonlinear relationship among PSLV, PHDs, and uniform temperature changes is analyzed. The results show that the smallest PSLV reaches under a combination of positive temperature gradient, uniform temperature decrease, and the residual influential factors. Compared to the wheel unloading rate, the train vertical acceleration is more sensitive to the uniform temperature decrease amplitude and pier settlement. When the bridge PHDs are taken into account, the PSLV decreases obviously with increasing PHDs and uniform temperature decrease amplitude. Considering the actual pier settlement requirements of the bridge, the PHDs of the HSR 32 m standard box girder cannot exceed 50 m. The method proposed in this paper effectively considers the impact of unavoidable adjacent PHDs in non-plain regions on PSLV, providing theoretical support for optimizing the design and operation management of HSR standard simply supported girder bridge. • A method incorporating the nonlinear effects of adjacent pier height differences (PHDs) is proposed. • The most unfavorable factor combinations are identified using validated coupled dynamic model. • The nonlinear relationship among PSLV, PHDs, and uniform temperature changes is obtained.