To compensate the incapability of traditional cable force adjustment methods to automatically optimize cable forces, this paper proposes Midas/Civil and MATLAB as a structure calculator and a cable force optimizer, and external memory as a data transfer. Initial solutions from conventional methods can be optimized by internalizing the influence matrix into the multiobjective particle swarm optimization algorithm with mutation operation and constructing the mathematical model of cable force optimization, and then, a series of Pareto frontier solution sets are obtained. For the first time, fuzzy set theory is introduced for selecting Pareto presolution set for the optimization of cable-stayed bridges, to solve the final reasonable dead load state of bridges. By using this method, the peak vertical displacement of a main girder of the optimized cable-stayed bridge decreased from −11 mm to −6 mm, with a reduction of 45%. Before and after optimization, the difference of peak negative bending moment at the top of the pier was 34.8%, indicating that the main beam was more evenly stressed and the alignment was more reasonable.

Purpose: Reinforcement of reinforced concrete (RC) beams in-service have always been an important research field, anchoring steel plate in the bottom of the beams is a kind of common reinforcement methods. In actual engineering, the contribution of pavement layer to the bearing capacity of RC beams is often ignored, which underestimates the bearing capacity and stiffness of RC beams to a certain extent. The purpose of this paper is to study the effect of pavement layer on the RC beams before and after reinforcement. Design/methodology/approach: First, static load experiments are carried out on three in-service RC hollow slab beams, meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Last, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility. Findings: The experimental results showed that pavement layers increase the flexural capacity of hollow slab beams by 16.7%, and contribute to increasing stiffness. Ductility ratio of SPRCB3 and PRCB2 was 30% and 24% lower than that of RCB1, respectively. The results showed that when the steel plate thickness was 1 mm–6 mm, the bearing capacity of the hollow slab beam increased gradually from 2158.0 kN.m to 2656.6 kN.m. As the steel plate thickness continuously increased to 8 mm, the ultimate bearing capacity increased to 2681.0 kN.m. The increased thickness did not cause difference to the bearing capacity, because of concrete crushing at the upper edge. Originality/value: In this paper, based on the experimental study, the bearing capacity of hollow beam strengthened by steel plate with different thickness is extrapolated by finite element simulation, and its influence on ductility is discussed. This method not only guarantees the accuracy of the bearing capacity evaluation, but also does not require a large number of samples, and has certain economy. The research results provide a basis for the reinforcement design of similar bridges.

Purpose: The flexural reinforcement of bridges in-service has been an important research field for a long time. Anchoring steel plate at the bottom of beam is a simple and effective method to improve its bearing capacity. The purpose of this paper is to explore the influence of anchoring steel plates of different thicknesses on the bearing capacity of hollow slab beam and to judge its working status.Design/methodology/approach: First, static load experiments are carried out on two in-service RC hollow slab beams; meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Finally, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.Findings: When steel plates of different thicknesses are adopted to reinforce RC hollow slab beams, the bearing capacity increases with the increase of the steel plate thickness in a certain range. But when the steel plate thickness reaches a certain level, bearing capacity is no longer influenced. The displacement ductility coefficient decreases with the increase of steel plate thickness.Originality/value: Based on experimental study, this paper makes an extrapolation analysis of the bearing capacity of hollow slab beams reinforced with steel plates of different thicknesses through finite element simulation and discusses the influence on ductility. This method not only ensures the accuracy of bearing capacity evaluation but also does not need many samples, which is economical to a certain extent. The research results provide a basis for the reinforcement design of similar bridges.

Reinforced concrete (RC) beam–column joints are vulnerable to brittle failure under seismic actions due to their limited deformation capacity, posing a threat to the overall safety of RC frames. To address this issue, this study proposes and evaluates a novel strengthening strategy for RC joints using an engineered cementitious composite (ECC) shell, forming a beam–column joint with an ECC shell (BCJES). The mechanical behavior of the BCJES under cyclic loading was investigated through a refined finite element (FE) model. The FE model, validated against test results, enabled a systematic parametric study to quantify the effects of ECC shell height and thickness, longitudinal reinforcement ratio (at the beam region), and axial compression ratio on seismic performance. Results demonstrate that the proposed ECC shell markedly enhances the seismic capacity of RC joints. Increasing the longitudinal reinforcement ratio from 0.05% to 0.2% improved peak load from 33.87 to 85.58 kN (152%), while increasing shell thickness from 30 to 90 mm enhanced peak load by 11.9%. However, a saturation effect was observed, as further thickening the shell to 150 mm resulted in only a 2.46% gain. Based on the parametric results, this study, for the first time, establishes a quantitative predictive model for the ultimate bearing capacity of BCJES using multiple linear regression (R²= 0.943). Furthermore, a new theoretical shear–capacity model incorporating both main and lateral diagonal bracing mechanisms is developed. Theoretical predictions agree well with FE simulations and experimental results, with maximum deviations of only 7.5% and 7.9%, respectively, confirming the reliability of the proposed approach. These findings highlight the potential of the ECC shell as an effective and practical seismic-strengthening solution for RC joints, offering new insights for performance-based design and retrofit strategies.

Based on the main bridge of the Paira Bridge in Bangladesh, this paper studies the behavior of multispan extradosed bridge subjected to variation of cable-free segment length. First, a finite element simulation model was established, and linear analysis was performed. The accuracy of the finite element model was verified by comparing the measured data with the finite element analysis. Then the influences of the cable-free segment length in the midspan and the pylon root on the horizontal displacement of the pylon top, the vertical deflection of the midspan, and the bending moment of the main girder were analyzed, respectively. The results showed that the variation of the cable-free segment length put a significant impact on the horizontal displacement of the pylon top and the vertical displacement of the middle of each span. The increase of positive moment was greater than negative moment when the cable-free segment length in the middle of the span increased. However, when the cable-free segment length of the pylon root increased, the negative bending moment of the main girder increased more than the positive bending moment.

An optimized evaluation method of the bearing capacity of reinforced concrete beam based on the Bayesian theory was proposed in this paper. This evaluation method optimized the traditional Markov Chain-Monte Carlo (MCMC) sampling method, and proposed an improved Metropolis–Hastings (MH) sampling method and a transitive MCMC (TMCMC) sampling method based on the MCMC theory. These two derived sampling methods solved the problem that the traditional MCMC algorithm makes it difficult to achieve convergence when the number of modified parameters is large. Therefore, on the basis of obtaining the measured sample information and the prior information of uncertain parameters, this paper first used multiple “model components” to form a model sample, then carried out a sensitivity analysis based on the relevant response indicators and selected the key parameters that had a great impact on the bearing capacity, carried out static load tests, and extracted and analyzed the experimental data. Then, based on a large amount of analysis data, the improved MH sampling method and TMCMC sampling method were used to establish a posterior probability distribution database. Finally, multiple posterior probability distributions were used to identify and predict the bearing capacity. The results showed that the method was feasible and effective for the evaluation of the bearing capacity of reinforced concrete beam.