One issue to consider while designing and constructing steel girders reinforced with carbon fiber-reinforced polymer (CFRP) plates in bridges is debonding failure. Previous studies showed that the parameters such as characteristics of material, load, adhesive, and CFRP plates have an effect on the failure probability of steel girder, which is represented by the reliability index. Therefore, this study analyzes the reliability indices of steel girders in bridges strengthened with CFRP plates to clarify the effects of debonding failure. Debonding and strength limit states are used to compare differences in reliability indices of different design scenarios. Strength and debonding margin the functions for the strength limit state and debonding limit state will be established in this study. The probability of failure is determined by a Monte Carlo simulation (MCS). It is found that the reliability index of debonding limit state is much lower than that of the strength limit state. This shows that the debonding failure should be considered significant in the reliability analysis of steel bridge girders strengthened with CFRP plate.

This study investigates the effects of wind-barrier design parameters on the aerodynamic performance of bluff box girders and the near-deck wind environment for vehicles on long-span bridges. The experimental program includes aerodynamic force measurements, two-degree-of-freedom aeroelastic tests for vortex-induced vibration (VIV) and flutter, and near-deck wind-velocity measurements to assess the impact of barrier porosity, perforation orientation, height, installation configuration, and VIV-mitigation strategies. Two box-girder sections with B/D = 3.44 and 4.98 were tested to explore the role of deck geometry. Results show that the thin girder is more sensitive to wind-barrier-induced aerodynamic effects, experiencing higher near-deck wind speeds and larger vertical VIV amplitudes. Wind barriers effectively reduce wind speeds and improve vehicle stability but may also increase drag, amplify vertical VIV, and reduce flutter stability depending on configuration and girder type. Mitigation strategies are more effective for the thick girder, with limited benefit for the thin girder. Among the configurations studied, 50%-porosity barriers provide the best balance between wind shielding and aeroelastic performance, offering reductions in wind speed while maintaining acceptable VIV and flutter margins.

This study presents a comprehensive comparative analysis of two stochastic system identification methods—SSI_data and SSI_cov—for extracting flutter derivatives (FDs) of a trussed deck suspension bridge section under turbulent wind conditions. Numerical simulations and wind tunnel experiments were conducted to evaluate each method's robustness to noise, identification accuracy, and computational efficiency. Results show that while both methods reliably estimate natural frequencies, SSI_data achieves greater precision in damping ratio identification and offers a significant computational advantage—reducing runtime compared to SSI_cov. A detailed signal-to-noise ratio (SNR) analysis reveals that SSI_data excels in vertical mode identification, while SSI_cov is more resilient in estimating torsional damping under low SNR conditions. Experimental validation confirms that the critical flutter wind speeds estimated using both methods under turbulent flow conditions closely match the results observed in wind tunnel tests. These findings provide practical guidance for selecting suitable identification strategies and underscore the potential of SSI methods—particularly SSI_data—for real-time aeroelastic analysis of long-span bridges operating in complex, turbulence-prone wind environments.

Stay cables are slender and lightly damped structural members that are highly sensitive to wind action. Although the aerodynamic effects of rain rivulets, ice accretion, snow accretion, and surface roughness on bridge cables have been widely investigated, the influence of architectural illumination attachments installed along stay cables remains insufficiently understood. Such attachments modify the original circular cable cross-section and may alter aerodynamic force coefficients, vortex-shedding characteristics, wake structure, and galloping tendency. This study investigates the aerodynamic characteristics of bridge stay cables modified by illumination attachments with different shapes, dimensions, and installation gaps. Large-eddy simulation was performed using OpenFOAM 5.0 to resolve the unsteady flow around a reference circular cable and ten illumination-modified cable configurations at a representative subcritical Reynolds number of R_e = 9.42 × 10⁴. The numerical model was first verified using benchmark aerodynamic properties of a circular cylinder and then validated against force measurements obtained from closed-circuit wind-tunnel experiments. The results show that illumination attachments significantly affect the drag and lift characteristics of stay cables, particularly at oblique wind attack angles. Among the representative wind attack angles considered, the drag coefficient generally increases when the attachment is exposed laterally or obliquely to the incoming flow, whereas the lift coefficient is strongly affected by attachment shape and angular orientation. Rectangular and double-rectangular attachments produce stronger wake disturbance, greater pressure asymmetry, and more complex vortex structures than circular attachments. The preliminary Den Hartog analysis further indicates that sharp-edged and direct-contact attachments may increase galloping susceptibility, whereas smaller circular attachments and separated-gap configurations show more moderate aerodynamic behavior. These findings indicate that illumination systems should not be treated as purely architectural accessories, but should be considered in the aerodynamic assessment and wind-resistant design of cable-supported bridges.