Friction dampers are widely used in building seismic protection due to their excellent shock-absorbing performance and reliable operation. To clarify the influence of friction plate material properties on the hysteretic behavior and stability of friction dampers, this study selected three materials with distinct physical properties (density, hardness, and stiffness)—titanium alloy, brass, and zirconia ceramic—as friction plate candidates. Three sets of low-cycle reciprocating load tests were designed to obtain the hysteretic curves of dampers with different friction plates and analyze their energy dissipation capacity and operational stability. Results show that the hysteretic curves of the copper-steel and titanium-steel plate specimens are close to the ideal rectangular shape, with symmetric force–displacement relationships and stable energy dissipation. The copper-steel plate exhibits strong energy dissipation capacity and high cost-effectiveness, while the titanium-steel plate has moderate energy dissipation capacity but stability comparable to that of the copper-steel plate. In contrast, the friction force of ceramic-steel plate specimens shows obvious divergence as displacement increases, leading to poor overall stability. The friction coefficient between the friction plate material and the main plate material exerts a significant influence on the damper’s energy dissipation, and a stable friction mode serves as a guarantee for its normal operation.

As a commonly used support system in highway bridge construction, the deformation of steel-tube-columns-combined-with-Bailey-beams doorway supports is often an indicator for safety and quality control. In this paper, through finite element simulation and theoretical derivation, the main form of deformation of each part of the combined doorway is analyzed, by using the rigid body function of ANSYS. The study shows that when bearing vertical load, the deformation of the combined doorway is mainly caused by the deflection of the Bailey beams; when bearing transverse horizontal load, the deformation of the combined doorway is mainly caused by the rotation of the foundation; when bearing longitudinal horizontal load, the deformation of the combined doorway is mainly caused by the offset bending of the Bailey beams out of the plane. When several loads are applied to the combined doorway at the same time, the deformation in the linear phase follows the superposition principle, and the geometric nonlinearity has little effect on the overall deformation of the structure. The structural deformation caused by different types of loads can be calculated separately, and then the structural deformation under composite load can be calculated by linear superposition, using geometric relationships. The safety and deformation resistance of steel-tube-columns-combined-with-Bailey-beams doorway supports can be effectively improved by choosing reinforced Bailey beams, increasing the width of the foundation, and setting lateral supports between the Bailey beams.

In the design of cantilever method bridge anti-overturning structures, the appropriate gap between the supporting foot and the lower rotating table is a crucial factor. It affects the distribution of the upper load and the friction force of the rotating structure, playing a key role in stability control. Currently, a reasonably defined range for this gap based on engineering practice has not been established. This study, set against the backdrop of practical engineering for large-tonnage rotational bridges, analyzes potential overturning instability forms during rotation. It provides a detailed examination of the stability performance of bridges in unbalanced states under single-side joint support configurations and analyzes the mechanical performance and stability under different gaps and impact velocities during rotation. The result is that the impact acceleration, angular acceleration of rotation, and tilt angle (gap) increase displacement and stress in the support system, posing a significant safety risk. The present research demonstrates the safety and rationality of the proposed unbalanced rotation and provides control limits for tilt angle and rotation acceleration during the rotation process. These results demonstrate that the proposed support mode ensures safety requirements during unbalanced rotation, offering insights for the design and construction of large-tonnage rotational bridges.

To assess the influence of the spherical and supporting radius of swivel hinges on the anti-overturning capability of T-structures and the safety of lower turntables, this study focuses on large-tonnage rotary bridges spanning the South-to-North Water Diversion Project along the Jiaozuo to Tanghe Expressway. The research involved theoretical analysis and numerical simulations to evaluate the stability of the rotary structures and the load-bearing capacity of rotary platforms with varying spherical and supporting radii, and we generated 15 numerical models. The results indicate that the critical eccentricity for T-structure anti-overturning increases with larger supporting and spherical radii, with diminishing returns as the supporting radius decreases. The critical eccentricity for spherical hinges is consistently lower than that seen for flat hinges. The lower turntable’s failure characteristics divide it into four zones, as follows: main compressive stress failure at the bottom under the hinge, main tensile stress failure at the top around the hinge, and two other regions less prone to failure. The supporting radius significantly influences compressive and tensile stress failures, while the spherical radius mainly affects the tensile stress area. These results offer insights for the design and construction of large-tonnage rotational bridges.

Pipe-insulating joints are common cathodic protection devices in long-distance oil and gas pipeline infrastructures. To ensure safety, they are often designed too conservatively, resulting in large dimensions, high self-weight, and substantial costs. This study analyzed an insulating joint under the most unfavorable conditions to identify the component of the maximum stress in the insulating joint, which is the right flange. Then, using parameterized finite element calculations, five independent dimensions of the right flange were combined and arranged to obtain a dataset of the right flange dimensions and their maximum stress. Subsequently, four different fitting algorithms were trained with this dataset, and the ridge regression algorithm, which showed the best predictive performance, was used to establish a surrogate model for calculating the maximum stress of the right flange. Finally, the surrogate model was combined with a genetic algorithm to determine the optimal design dimensions of the right flange. This study also provides examples verifying the accuracy and reliability of the surrogate model and genetic algorithm. In these examples, the maximum stress under the design dimensions given by the optimization algorithm has a maximum error of 8.98% and an average error of 4.63% compared to the preset maximum stress target, while the stress predicted by the surrogate model has a maximum error of 9.65% and an average error of 5.33% compared to the actual stress. This improves the computational efficiency of the optimization algorithm by establishing a surrogate model, which can be used to optimize the dimensions of insulation joints.