Plate bearings in existing small-span bridges for heavy-haul railways have exhibited corrosion, detachment, and surface cracks under large axle loads, making them inadequate for the “capacity expansion and renovation” of heavy-haul railways. Therefore, identifying new bearings suitable for small-span bridges and developing a rapid bearing replacement method tailored to the operational needs of heavy-haul railways are urgent priorities. This paper takes spherical bearings as an example and proposes a method for rapidly replacing plate bearings with spherical bearings. The bearing replacement tests of six simply supported beams were carried out to verify the effectiveness of the proposed method. Dynamic performance tests of bridges and bearings were performed before and after the replacement. A finite element model was established to analyze the effects of bridge span and pier height. The results show that the entire bearing replacement process for a span bridge could be completed within 4 h using the proposed method. Compared to plate bearings, spherical bearings could improve the lateral dynamic performance of both the bridge and bearings. However, the improvement decreases as bridge span and pier height increase. For 2.2 m diameter cylindrical piers commonly used in heavy-haul railways, the pier height with spherical bearings should be limited to 10 m.

A novel prefabricated strengthening structure (NPSS) is proposed to improve the vertical stiffness and load-bearing capacity of existing short-span bridges for heavier axle-load trains passing through. The strengthening principle of the NPSS is revealed through theoretical derivation. A refined calculation model is prepared to investigate the effects of two important parameters on the structural behavior of the bridge, including the support stiffness and the installation location of the NPSS. The calculation model is also verified with four-point bending test of a bridge removed from a heavy-haul railway. With the calculation model and the response surface methodology (RSM), the functional relationships among the crucial mechanical indexes of the bridge and the two parameters of the NPSS are methodically established. Thus, the optimal values of the parameters are determined via a multi-objective optimization model and the analysis hierarchy process-fuzzy comprehensive evaluation method. Furthermore, the feasibility of the optimal parameters is appropriately verified based on simulations of the vehicle–track–bridge dynamics. The existence of the NPSS with optimal parameters could enhance the vertical stiffness of the bridge by 21.0% and bearing capacity by 19.5%. In addition, it could reduce the midspan dynamic deflection amplitude by 23.4% and vertical vibration acceleration amplitude of the bridge by 25.2%. The results of the study are expected to contribute to the capacity development and rehabilitation of existing heavy-haul railways with low cost and convenient construction without railway outage.

In response to the increasing structural damage, reduced load-bearing capacity, and diminished durability of heavy-haul railway culverts under heavy axle load transportation conditions, this study focuses on the application of assembled corrugated plates to reinforce diseased culverts. Through engineering applications, numerical simulations, and field tests, the research investigates reinforcement techniques, analyzes parameter influences, and evaluates effectiveness. The results demonstrate that the integration of corrugated plates with existing culverts forms a composite structure, enhancing overall stiffness by sharing loads. Under identical conditions of corrugation height, pitch, and grout layer thickness, arc-shaped corrugated plates exhibit smaller mid-span deflections and stresses compared to triangular and rectangular profiles, with arc-shaped plates showing superior reinforcement performance. The sensitivity analysis results indicate that the waveform is the most sensitive parameter affecting the reinforcement performance. With the waveform fixed, the corrugation height has a relatively significant influence on the reinforcement effectiveness, followed by the corrugation pitch, while the influence of the grout layer thickness is negligible. Field trials on 14 diseased culverts with varying spans demonstrate that corrugated plate reinforcement reduces mid-span deflections and steel reinforcement strains by an average reduction exceeding 40%, with deflection reductions slightly outpacing strain reductions. These findings validate the substantial effectiveness of corrugated plate reinforcement in heavy-haul railway culvert rehabilitation.