A reasonable and efficient loading scheme is needed to guarantee the success of large-scale bridge tests. In this study, an array-type, self-balancing pulley-group loading system was designed based on the world’s largest spanning arch bridge using a 1:10 scale model test. Automatic statistics of the required load at each loading point were realized using ANSYS, and a load optimization algorithm for loading points at different construction stages was proposed. Tests were carried out separately for the loading system using a single set of pulley groups and an array-type pulley group. Finite element models of the model bridge and the original bridge were established separately using ANSYS, and the stress results of different components during different construction stages of the main arch ring were compared. The research results show the following: (1) The load magnification factor of the single-pulley-group loading device is approximately 6.6 times, with a mechanical efficiency of 94.26%. (2) In the array-type loading system, the actual load at each loading point can reach the design value. The self-balancing characteristic of this system can eliminate the impact of vertical deformation of the structure on loading accuracy, verifying the reliability of the system. (3) The simulation results of the original bridge and the model bridge coincide well, and the stress of each component during the construction process has the same trend. At key construction stages, the maximum relative errors of the stress results of the rigid steel frame and the concrete inside the pipe of the two bridges are 8.33% and 9.34%, respectively, and the maximum absolute error of the bottom plate concrete is 0.66 MPa, verifying the correctness of the counterweight-optimization method. The loading scheme proposed in this paper can provide a reference for the design of loading systems with the same type of scale model test.

To seek a proper way to calculate the preoffsetting value of saddle on a suspension bridge, some influences of structural parameters on the preoffsetting are considered, then a new method for the preoffsetting value of saddle is proposed. On the basis of the relationship of the main cable and saddle, equilibrium equations, geometric equations, and physical equations are deduced. Then, the equations are solved by the Newton-Raphson iteration method to derive the Jacobian influence matrix of preoffsetting. For convergence of the numerical calculation, constraint conditions and the range of initial values are given. Through comparison of the measured value in a 1/30-scale model test and the calculated value, the reliability of the new method is confirmed. Finally, parametric analysis of preoffsetting shows that (1) with an increase of the saddle radius, saddle preoffsetting increases in the middle-span direction; (2) with increases of the side/middle-span and rise/span ratios, saddle preoffsetting in...

The stiffening girder of self-anchored suspension bridge (SSB) is subjected to huge axial force because the main cable is directly anchored on the end of the stiffening girder. To obtain a simple model and accurately understand the mechanical behavior of the whole structure in preliminary design, this paper proposed an analytical calculation method considering the combined effects of the main cable-suspender-stiffening girder. On the basis of the deflection theory of the stiffening girder, the relation between the girder shape and the suspender force was explored. The relation between the main cable end force (MCEF) and the suspender force was derived through segmental catenary theory, and iteration method was further improved to avoid the divergence condition. Finally the solution was obtained through satisfying the compatibility condition. The proposed method does not need to iterate manually and can save calculation time. Examples are introduced to verify the applicability of this method, with the result that this method considers the combined effects of the main cable-suspender-stiffening girder, and the finished bridge state satisfies the minimum strain energy of the stiffening girder. Results also indicate that this method has fast convergence speed and high precision.

In recent years, with global warming and frequent natural disasters, existing offshore bridges are facing the risk of extreme wave action. The research on disaster prevention and mitigation measures of the box-girder superstructure of offshore bridges under extreme wave action is still scarce. In this paper, a numerical model based on the RANS equation and k-ε turbulence model is established to study the wave forces on the box-girder superstructures of offshore bridges with the influence of a floating breakwater. A numerical method for studying the interaction of waves and structures is proposed and verified through experimental data. The effects of many parameters of the floating breakwater on wave attenuation are investigated and a prediction model of the wave reduction rate based on neural network algorithm is proposed. The results show that the reduction rate of wave forces for fixed breakwaters can reach more than 30%, which indicates that a floating breakwater has a significant effect in reducing the wave forces on the box-girder superstructure. The wave reduction performances of the displacement-restricted breakwater and the fixed breakwater are better than that of an elastic restricted breakwater. The prediction model proposed based on the BP neural network is accurate in estimating the maximum wave forces on the box-girder superstructure with the influence of the floating breakwater.

To investigate the reasonable range of the inclination angle of arch ribs, a spatial finite element method was employed based on a concrete-filled steel tube (CFST) basket-handle through an arch bridge with a span of 360 m. A spatial finite element model was established using Midas/Civil software, which was verified with actual bridge data. The effects of different arch rib inclination angles were investigated under static loads. The structural natural frequencies, linear elastic stability coefficients, internal forces, and displacements were comprehensively considered to determine the reasonable range of the inclination angle. The results show that when the inclination angle ranges between 8° and 10°, the first, third, and sixth natural frequencies of the structure are increased. It effectively improves the lateral and torsional stiffness of the arch ribs while ensuring optimal out-of-plane stability of the arch ribs. Compared with the parallel arch, the stability is improved by 20.2%. The effects of angle variation on displacement and internal force of the arch ribs were not significant. Considering all indicators, the optimal range of the inclination angle for the arch ribs of 300-m-level highway CFST arch bridges is suggested to be 8~10°.