Carbon-fiber-reinforced polymer (CFRP) has gradually become a new material to replace traditional steel due to its outstanding advantages. Because of its poor transverse stress performance, there is a reduction effect on the tensile strength in the bending state. To study the mechanical properties of CFRP tendons subjected to combined tension and bending at the saddle of a suspension bridge, a series of bond-type anchorages were made. Specimens with different diameters of CFRP tendons were tensioned on the device with different bending radius saddles. The test results revealed that the tensile properties were significantly affected by the severity of the bending of the CFRP tendons, including the failure mode, fracture force, and stress distribution. The highest reduction in fracture force was found at the bending radius of 3 m, of up to 38.05%. Furthermore, the tensile properties were also found to be influenced by the diameter of CFRP tendons. It was found that increasing the bending radius was more conducive to improving the performance of CFRP tendons with a smaller diameter. When the bending radius increased from 3 to 12 m, the efficiency coefficient (the ratio of the fracture force to the ultimate force) of D8, D10, and D14 increased by 11.21%, 7.74%, and 2.26%, respectively. Decreasing the bending radius leads to unevenness of the stress distribution and increasing the diameter of the CFRP tendon leads to brittleness and difficulties in anchoring, thus resulting in the decrease in the efficiency coefficient. In addition, the ratio of the bending radius to the tendon diameter was less than 2.4, the efficiency coefficient of the specimen was less than 80%, and the specimen mostly suffered shear failure. Furthermore, the finite element (FE) models validated by the test results were used to reveal the stress state and study the effect of contact friction on the properties of CFRP tendons. The FE results show that the CFRP tendons with a smaller bending radius presented higher shear stress concentrations. As the contact friction increased, the load-bearing capacity of CFRP tendons decreased significantly.

CFRP has the potential to replace steel cables in large-span cable-stayed bridges due to its high strength and lightweight material properties. However, the weak lateral force performance of CFRP material creates the challenge of anchoring. This study introduces a new inner cone + arc + straight cylinder bond-type anchorage system to optimize CFRP tendons’ force state. Experimental and finite element analyses verified the new anchoring system’s performance. In static load tensile tests, six groups of seven CFRP tendon anchorage systems with different sleeve grooves were used to study the failure mode and load–strain variation law. The difference in mechanical properties between the new and traditional anchorage is evaluated in the finite element analysis. The results indicate that the new anchorage system can lower the stress concentration in the anchorage zone and enhance anchorage performance. The groove design of the sleeve can effectively increase the anchoring efficiency, where the groove depth is proportional to the anchoring efficiency and the groove spacing is inversely proportional to the anchoring efficiency. The magnitude of the stress inhomogeneity in the multi-tendon anchoring system during tensioning is proportional to the beginning conditions and the load size. When the inner wall of the sleeve becomes more abrasive, the force heterogeneity of the anchorage system reduces. The tests and finite element analysis show that the new anchoring may improve stress distribution and anchorage efficiency. In engineering practice, it can be utilized as a dependable anchorage system.

To study the mechanical properties of steel–concrete joints during construction, the Mao Port Bridge in Shanghai is used as a case study. The mechanical properties of the bridge and the joint under the construction conditions were studied based on the site construction monitoring results, the finite element calculation of the entire bridge and the refined model of the joint. The results show that the finite element analysis of the bridge and the stress analysis of the joint during the construction phase agreed with the measured values, the end of block 0# of the main span remained in compression during construction and the compressive stresses varied in a zigzag pattern with the progress of construction. The lifting of the mid-span steel beam is a critical construction condition where the side spans of the girders are stretched upwards by 20.9 mm and the main spans are stretched downwards by 32.3 mm. When the steel beam was lifted, the joint was compressed as a whole. At the joint, the longitudinal stresses in the steel structure gradually decreased from the front bearing plate to the joint face, while the longitudinal stresses in the concrete structure gradually increased.

Hybrid cable-stayed suspension (HCSS) bridges enjoy broad application prospects due to their excellent stability and economic benefits. The mechanical response of the transition section between the two subsystems of this novel bridge type is a common concern in the design and use stages. This paper took the design scheme of an HCSS bridge with a main span of 1440 m as the research object. A global finite element model (FEM) of the example bridge and local finite element models of the transition section were established, and the mechanical performance of the subsystem and components of the transition section was investigated. Moreover, parametric studies were conducted to investigate the influences of varies structural parameters on the mechanical performance of the transition sections of HCSS bridges. The results show that the mechanical behavior suddenly changes significantly at the transition between the cable-stayed section and the suspension section. Performance mutations in the transition section of a HCSS bridge can be improved by changing structural parameters, such as the transition section length, the number of cross cables, the area of the outermost cables, and the distance between the outermost cables and adjacent cables. The present findings may provide a reference for the better understandings and design of HCSS bridges.

The hybrid cable-stayed and suspension (HCSS) bridge is known for its stability and cost-effectiveness, with significant application potential. This study examined the static performance of an HCSS bridge with a 1440 m main span. A finite element model (FEM) was developed to assess key parameters, such as the span-to-rise ratio, cable-to-hanger ratio, pylon stiffness, steel–concrete interface, and cable stiffness. Through FEM analysis and parameter optimization using the zero-order and first-order optimization methods in an ANSYS module, key design variables were optimized. The results show that an inappropriate span-to-rise ratio negatively impacts mid-span girder forces, while increasing the cable-stayed area enhances the overall stiffness. Main cable stiffness plays a crucial role in load-bearing and deformation control. Significant force differences were observed between stay and hanger cables, with axial force in the main girder increasing from the side span to the pylon under dead load. Bending moments in the transition region varied widely under combined loads. Optimizing parameters, such as the span-to-rise and cable-to-hanger ratios, significantly improved the mechanical performance of HCSS bridges, offering valuable insights for future designs.

In this study, a refined model of the Shanghai Damaogang Bridge’s (hybrid beam type) box deck joints is established. The correctness of the model is verified by construction monitoring. For the front and back bearing plates, the force performance of the joint members under the most unfavorable loads is investigated, and the force transmission mechanism is analyzed. The influence of the bearing plate thickness and the joints’ stiffness on the stress distribution of the joint members, the internal force of the joints, and the force-transfer efficiency is investigated by the method of controlling variables, and the optimal structural parameters of the nodes are also studied. The results show that, within the proximity of the back bearing plate, the thickness of the back bearing plate affects stress distribution in the joint. The increased stiffness of the welding studs makes the range of shear force along the bridge direction of the top and bottom welding studs larger, and the longitudinal distribution of welding stud shear force is more uneven. The concrete structure bears a higher proportion of the internal force in the joint compared to the steel structure.