In this paper, a numerical simulation is used to establish a three-dimensional model, which considers the height of buildings, the relative position between buildings, and foundation pits. These were studied in detail to investigate the changes in settlement of adjacent buildings and the displacement and internal force of piles caused by deep foundation pit excavation. The results indicate that the number of floors in the building, along with the angle and distance between the building and the excavation pit, have a significant impact on the settlement of the building and the deformation and internal force variation in the piles. For example, when D = 0.1 H, with the increase in the number of floors, the increase in the bending moment of pile 1 at the pile shaft is 62.63 kN·m, and the increase in the bending moment at the pile head is 224.72 kN·m. At this point, the maximum horizontal displacement of the pile shaft occurs at approximately 1.27 H. When $\theta$ = 45${}^{\circ }$, the maximum difference between the maximum and minimum deformations of the building is 9.71 mm. When D ≤ 1.0 H, the majority of the building is in the primary influence range of surface settlement behind the wall, and the building undergoes a combined deformation of ‘upper convex’ and ‘concave’. When D > 1.0 H, the building predominantly resides in the secondary influence range, and the building undergoes a deformation of ‘upper convex’.

To address complex connections in prefabricated concrete structures, a novel joint connecting a prefabricated concrete-filled steel tubular column and a composite beam is proposed. Pseudo-static tests on six scaled specimens and ABAQUS finite element analyses were conducted to investigate seismic mechanisms, focusing on slab effects and beam-bottom configurations. Experimental results show the joints exhibit plump hysteretic curves. The composite beams displayed distinct shear-dominated failure, while the stiffened column remained intact. With an average ductility coefficient of 2.84 and an ultimate equivalent viscous damping coefficient of 0.207, the specimens demonstrated excellent deformation and energy dissipation capabilities. The slab’s flange effect significantly enhanced negative bearing capacity, causing mechanical asymmetry. Comparatively, the steel plate beam bottom configuration offered superior stiffness and stability over the reinforcement beam bottom configuration. Sensitivity analysis revealed that bearing capacity is highly sensitive to beam parameters (e.g., longitudinal rebar strength, connector length) but less sensitive to column parameters. Notably, the bearing capacity of the beam bottom configuration using reinforcement increases significantly with concrete strength and reinforcement ratio, whereas the beam bottom configuration using a steel plate shows marked insensitivity to these factors. These findings clarify the load transfer mechanism and support the seismic design of prefabricated structures.

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.