| Due to weak transverse connection,the assembly hollow slab bridge with small hinge joints is prone to hinge joints damage,pavement cracking and single slab bearing.The commonly used reinforcement methods have poor practical application effect.Based on the concept of steel-concrete composite structure,this study puts forward the Anchor Steel-Concrete Reinforcement(A-SCR)technology and carries out the corresponding experimental and theoretical research.Firstly,the bearing capacity test of RC Beams strengthened by A-SCR,the transverse connection performance test of hollow slab and the full-scale test of the whole bridge are carried out.Secondly,based on the test results,the theoretical research on the calculation method of transverse distribution coefficient and the bearing capacity after reinforcement is carried out.Thirdly,through finite element numerical calculation,the influence of reinforcement parameters on reinforcement effect is analyzed.Finally,A-SCR reinforcement technology design,construction method and complete set of technology on testing and evaluation has been formed through the application research of real bridge.The main achievements are as follows1)In order to study the calculation method of the bearing capacity of RC beams strengthened by A-SCR,the reinforcement test and theoretical research are carried out.By analyzing the influence of loading history,anchor bolt spacing,steel plate area and reinforcement scope on the bearing capacity after reinforcement,it is verified that the section strain after reinforcement still conforms to the plane section assumption.Based on the elastic-plastic theory,the calculation method of the flexural bearing capacity of RC beams strengthened by A-SCR is proposed and verified.The results show that the method proposed in this paper can be used to calculate the flexural capacity of RC beams strengthened with A-SCR.2)In order to study the transverse mechanical performance of hollow slab strengthened by A-SCR,transverse segment specimens strengthened by steel reinforced concrete with different heights were made.Through single point and two-point loading tests,the effects of strengthened steel reinforced concrete height on the transverse load distribution,bending stiffness,vertical shear capacity and shear stiffness of hollow slab are comparatively analyzed.The results show that the A-SCR reinforcement can enhance the hinge joint stiffness,greatly improve the shear capacity between slabs,and bear the transverse bending moment.However,the height of A-SCR has little influence on bending capacity and stiffness of hollow slabs.3)In order to study the transverse load distribution and mechanical performance of the bridge after reinforcement,a full-scale test is carried out.The test results show that using A-SCR to reinforce the hollow slabs with broken hinge joints can effectively restore the force transfer between slabs without repairing the hinge joints,and greatly improve the overall stiffness of the beam and slab.4)In order to solve the calculation method of transverse load distribution coefficient of the bridge strengthened by A-SCR,a modified calculation method of transverse load distribution coefficient of rigid-joint slab is proposed based on considering the vertical shear stiffness and bending stiffness between plates.The transverse distribution coefficient of the full-scale test bridge is calculated by the measured joint rotational stiffness coefficient and shear stiffness coefficient and the modified rigid-joint slab method.Comparing the measured values of full-scale test,the calculation results of transverse distribution coefficient of hinged method,rigid joint method and modified rigid joint method proposed in this paper,it is found that the modified rigid connection plate method proposed in this paper is more in line with the measured values of full-scale test,which shows that the modified rigid-joint slab method can be used as the calculation method of transverse load distribution coefficient of assembly hollow slab strengthened by A-SCR.5)Based on the finite element analysis method,the influence of different reinforcement length and height by A-SCR method on the reinforcement effect is analyzed.The results show that increasing the reinforcement length can improve the overall stiffness of the bridge,but has little influence on the stress in the span of the hollow slab and the transverse distribution of each slab.A-SCR reinforcement can significantly reduce the main tensile stress of cast-in-place layer and hinge joints,and effectively improve the working performance of bridge deck pavement and hinge joints,which reveals the mechanism of preventive reinforcement of fabricated hollow slab bridge by A-SCR method.By changing the parameters of reinforcement structure height,it is found that the change of reinforcement structure height in the range of 10cm～15cm has little influence on beam slab stiffness,transverse load distribution coefficient and longitudinal stress.When the reinforcement structure height is too small,the reinforcement structure will be damaged,and excessive reinforcement height will easily cause stress concentration damage.6)Aiming at the engineering application of A-SCR reinforcement hollow slab bridge,the application research of real bridge reinforcement engineering was carried out,and the relatively simple reinforcement design and construction method were formed.Through the comparison of load tests before and after reinforcement of the real bridge,it is found that the lateral transfer is restored and the overall stiffness of the bridge is greatly improved after reinforcement,which indicates that the reinforcement method proposed in this paper has remarkable effect. |
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