Without interrupting the traffic on the old bridge, the connection of the widening bridge will cause disturbance to the concrete in the splicing position. In order to study the anti-disturbance performance of concrete material, the Normal Concrete (NC) material and the Ultra-High-Performance Concrete (UHPC) material were experimentally investigated by the vertical shaking table and X-ray computed tomography scanning. It can be learnt from tests that the compressive strength of NC and UHPC can be increased by about 10% to 20% after disturbance, while the flexural tensile strength and splitting tensile strength of both NC and UHPC can be reduced by about 20% to 25% and 10% to 20%, respectively. The elastic modulus of UHPC is not significantly affected by the vibration disturbance, and that of NC can be increased by about 20%. The setting time difference of the proposed NC material can be controlled within 100 min, and it can improve its anti-disturbance performance. Excessive vibration disturbance affects the internal structure of NC, while it has little effect on the distribution of steel fiber in UHPC. Due to the high cost of UHPC materials, it is recommended to analyze the joint performance requirements before the selection of splicing materials. If the stress requirement is not particularly high, it is still recommended to apply the proposed NC material for the splicing of widening bridge.

This paper investigates the flexural behavior of CFRP plate-strengthened concrete structures. Specimens of the CFRP plate-reinforced beam were designed and tested by the four-point flexural test. The load-deflection relationship, failure modes, and crack propagation were analyzed. The results showed that the postcracking stiffness and bearing capacity of the test beams can be improved by the additional anchoring measures for CFRP strengthening. The relationship between flexural moment and curvature was analyzed by introducing a MATLAB program. The calculation model between curvature, flexural moment, and stiffness was derived for the CFRP plate-strengthened structure. The recommended calculation model was applied in the analysis of deflection, and the theoretical values were compared with the test results.

With the background of bridge industrialized construction, as a convenient construction form of a joint, a joint with loop connections has been applied in the connection of the precast bridge deck. As a relatively new type of connection structure, the fatigue performance and degradation law of a loop connection joint are still not clear. In this paper, different flexural fatigue specimens are designed based on the application situation of the loop connection joint. After 0 to 2 million fatigue-loading cycles, the fatigue-loading process is suspended and the static flexural performance of the specimen is tested. The load-deflection curves of specimens under static loading remain roughly linear, and the slope changes little. After 200 × 10⁴ fatigue-loading cycles, the failure mode of each specimen is still presented as typical pure flexural failure. In addition, the strain of steel and concrete changes little, as well, and the stiffness degradation of each specimen is not obvious. It is indicated from this experiment that the fatigue-loading cycles has little effect on the mechanical properties of the concrete and loop bars, and the joint with loop connections has good fatigue performance.

For the purpose of splicing widening bridges without interrupting traffic in expressway reconstruction and extension projects, different types of anti-differential disturbance concrete (ADC) were developed. This paper experimentally investigated the mechanical performance of ADC under the influence of traffic–vehicle coupling vibration. The experimental device, with one end fixed and the other end vertically vibrated, was designed to simulate vehicle–bridge coupling vibration on an existing old bridge. Different disturbance degrees were simulated by adopting specimens made with standard molds and integral plate molds. The compressive strength and other performances of normal-type ADC (NADC) and high-performance ADC (HPADC) were tested. Owing to the differential disturbance, the compressive strength of the NADC increased by 10~20%, and that of the HPADC was almost unaffected. The flexural tensile strengths of the NADC and the HPADC were decreased to some extent. NADC and HPADC can both meet the requirement of widening bridge splicing, and the anti-differential disturbance performance of HPADC is superior to that of NADC.

Numerical investigation of mechanical behavior of carbon fiber‐reinforced polymer‐ (CFRP‐) reinforced concrete beam after high‐temperature action of asphalt paving construction was carried out in this study. The debonding failure of the CFRP plate‐concrete interface was simulated by introducing the double debonding criterion. In order to compare with simulation results, specimens with different pavement schemes were tested to obtain experimental data. The load‐deflection relationship, CFRP strain distribution, and crack propagation of specimens were compared with the numerical simulation results. The numerical simulation results showed good agreement with the experimental results. Additionally, the interface bonding stress distribution model and the calculation formula of the debonding bearing capacity were proposed. The proposed calculation model was proved to have good accuracy in predicting the strain of intermediate cracking debonding and the debonding bearing capacity of the CFRP‐reinforced concrete beam after high‐temperature action.