In order to address the difficulty in determining the seismic damage probability of continuous girder bridges under construction, the seismic vulnerability analysis method of the construction state is proposed in this study. Firstly, taking a long-span prestressed concrete composite box girder bridge with corrugated steel webs (OSW) as an example, the finite element models (FEMs) of dynamic calculation in different phases of cantilever construction are simulated by OpenSEES. Secondly, by selecting reasonable seismic waves and seismic intensity measures, the non-linear time-history analysis is carried out, followed by the demand parameters and damage indexes suitable for the construction state proposed. Finally, the probabilistic seismic demand model (PSDA) of the continuous box girder bridge during the construction stage is constructed by using the “cloud method”, and the seismic vulnerability curves of the piers and temporary bearings are established to evaluate the seismic performance during the construction stage. The results indicate that the damage probability of piers and temporary bearings increases with the progress of construction. The initial formation of the cantilever structure and the sudden change in the size of the construction segmental girder correspond to a high probability of damage, and seismic protection measures should be strengthened during this construction state. Moreover, significantly higher damage probability of the components under construction compared to the completed bridge after it is built.

This study aims to investigate the seismic behavior of concrete-filled steel tubular (CFST)-laced piers; after verifying the model through engineering tests, the simplified finite element models (S-FEM) and refined ones (R-FEM) with CFST-laced piers are developed in this manuscript, respectively. Through comparison, it is found that the S-FEM can effectively improve analyzing efficiency while meeting the requirements of engineering analysis accuracy. In addition, the seismic response of assembled flange-connected CFST-laced piers bridge was studied based on the S-FEM, and different structural parameters, including pier height, axial compression ratios, steel ratios of CFST columns, steel lacing tube arrangement, and longitudinal slope, are considered to optimize the bridge design scheme. Results indicate that the parameters of 0.1 axial pressure ratios and 1:30 longitudinal slope show superior seismic performance. Meanwhile, the peak axial force and peak bending moment of CFST column limbs occur at the pier bottom, and the flanges, which are subject to larger bending moments, are generally located at the two connection positions above the pier bottom.

In highway expansion and reconstruction projects, existing slopes often lead to significant variations in pier heights, forming Irregular Slab-Column Bridge Structures (ISCB). When subjected to seismic loading, such structures exhibit complex mechanical behavior, thereby highlighting the necessity of seismic mitigation design. This study is based on an irregular double-column slab-column highway bridge structure (with a short column of 3 m and high columns of 4 to 9 m) and conducts seismic response analysis using a finite element model. Subsequently, buckling-restrained braces (BRBs) were introduced to evaluate the influence of BRB force ratio on seismic mitigation performance. On this basis, an optimization design method was proposed based on the relationship between the BRB stiffness factor and force ratio. By adjusting the ratio between the BRB force ratio and the computed BRB stiffness factor KF, optimal seismic mitigation and self-centering performance of the structure can be achieved under earthquake loading. This approach effectively prevents local over-deformation and unbalanced responses, enhancing overall seismic performance. The results indicate that the short column exhibits a larger seismic response. When the short column is 3 m and the high column is 6 m, the disparity in seismic responses between the two columns tends to diminish with increasing high column height. The incorporation of BRBs can significantly reduce the structural base shear, reinforcement strain at the column base, and displacement at the column top. Moreover, the reduction in seismic response becomes more pronounced with increasing BRB force ratio. The proposed optimization design method takes into account both the seismic mitigation performance of the BRBs and the self-centering capability of the ISCB. Using this method, the optimal BRB design parameters for the example ISCB are determined (FR _BRB =0.3, KF = 3.3). The proposed method for integrating BRB components into bridge pier design can significantly enhance the seismic performance of the prototype structure, promote rapid functional recovery following strong earthquakes, and serve as a novel strategy for the seismic mitigation design of ISCB structures.

Prefabricated cantilever systems (PCSs) are essential for mountainous road infrastructure, yet their structural behavior under traffic loads remains insufficiently studied. This study innovatively integrates scaled experiments, finite element simulations, and field test data to develop and validate a full-scale PCS model under extreme traffic conditions. The results reveal that the beam–column junction is highly vulnerable to stress concentrations, risking concrete cracking. To address this, a novel prestressed reinforcement design is proposed, optimizing rebar placement to reduce local stresses and enhance structural integrity. Ultimate load analysis confirms that prestressing improves stiffness, load resistance, and ductility. This study provides a systematic framework for PCS optimization, promoting its application in complex engineering environments.

To investigate the impact of temporary structures on the mechanical behavior of shaped bridge towers during the construction process, the Dianbu River Special Bridge was selected as the engineering background. A finite element model of the middle tower column during the construction stage was established using ABAQUS to analyze the effects of key parameters, including the angle and pretension of temporary cables, as well as the wall thickness and diameter of temporary diagonal braces. The study examines how these parameters influence the stresses at the tower-girder consolidation. The results indicate that the angle of temporary cables significantly affects the tensile stresses at the tower-girder consolidation, while its impact on compressive stresses is minimal. Among all parameters, the pretension of temporary cables has the most pronounced effect on the stresses at the tower-girder consolidation. In contrast, the wall thickness of temporary diagonal braces has only a minor influence, whereas the diameter of temporary diagonal braces has an almost negligible impact. These findings provide valuable insights for optimizing the design and arrangement of temporary support structures in similar bridge construction projects.