In this study, finite element numerical simulations were used to investigate the deformation of critical vehicle components and the damage characteristics of the retaining wall at the end of the emergency escape ramp after the impact of a Ford 800 truck on the retaining wall of the refuge lane. A finite element model of the reinforced concrete retaining wall of the truck was created using the LS-DYNA (R11.0) program and the correctness of the constructed finite element model was confirmed by tests. The parameters of the reinforced concrete retaining wall were determined using orthogonal tests. Finite element numerical simulations of vehicle impact on the retaining wall were carried out, and the results showed that two stages of deformation occurred at the front and rear sides of the cockpit during the impact process, and the damage of the retaining wall increased with the increase in the vehicle speed, the impact angle, and the bumper stiffness. Punching shear damage occurred in the impact region of the wall and shear damage occurred at the corners of the wall.

Lightweight design and crashworthiness of protective structures are critical for battery safety in electric vehicles (EVs). This study addresses the limited research on cross-sectional shape design of high-strength steel double-cell roll-formed tubes (DCRFTs), widely used in EV bumper beams, battery boxes, and electric bus frames. A parametric design method is proposed based on three parameters: middle flange offset (o), upper deflection angle (α), and lower deflection angle (β). Under the constraints of constant cross-sectional height and enclosed area, this method systematically generates diverse shapes, including square, trapezoid, hexagon, re-entrant hexagon, and various hybrid shapes. Validated finite element models were employed to analyze the deformation modes and crashworthiness of DP980 steel DCRFTs under idealized lateral three-point bending with simple supports. The results indicated that the re-entrant hexagon section reduced maximum deformation (Disp) by 2.95%, peak crushing force (PCF) by 9.53%, and improved crushing force efficiency (CFE) by 13.88% compared to the baseline square section. The parametric study and sensitivity analysis confirmed that the offset (o) was the most critical parameter, contributing over 80% of the variance in Disp, PCF, and CFE. Multi-objective optimization using an RBF surrogate model and the NSGA-II algorithm yielded Pareto optimal solutions. Compared to the baseline, three representative solutions achieved Disp reductions of 11.83–25.10% and CFE improvements of 15.63–22.26%, each with distinct trade-offs among objectives. This work establishes a methodological framework for parametric cross-section design of roll-formed profiles; its extension to realistic boundary conditions will further facilitate practical EV protective structure design.