Study On Mechanical Behavior Of Prestressed Concrete Box-Girder Bonded With Steel Plate

In civil engineering,with the increase of the service life,as well as the influence of various factors such as disrepair,design defects and the increase of load levels,many prestressed concrete box-girders have potential safety problems such as cracks of the bridge and reduction of bearing capacity.Therefore,strengthening the structure has become the main means in the current engineering practice because of the advantages of its economy and convenience.The reinforcement method of bonding steel plates is stronger than other reinforcement methods,and has little influence on the structure.It can make use of the tensile property of steel plates to improve the bending capacity of bridge greatly.Based on the above background,this paper uses the Abaqus finite element software to analyze the mechanical behavior of prestressed concrete slotted box beams bonded with steel plates.The main work includes:(1)This paper analyzes the whole process of prestressed concrete box girders bonded with steel plates,and summarizes the main problems and solutions in the process of numerical simulation of the concrete bridge.(2)Based on the finite element theory and method,combined with the mechanical behavior of concrete box-girder,the finite element model of 30 m prestressed concrete box-girder bridge is established by using the plastic damage model of concrete,and the reliability of the model is verified by comparing with full-scale tests.(3)Based on the above model,cracks were prefabricated on the bottom of the box-girder bridge and the steel plate was bonded.The influence of factors such as the area of steel plate,the height of cracks,and the effective prestressing force of prestressed tendons on the failure modes and mechanical properties of box beams strengthened with bonded steel were investigated.The simulation results show that with the increase of crack height and the decrease of effective prestress,the bending capacity and stiffness of the box girder decreases,and the bending capacity of boxgirders with cracks can be effectively improved by bonding steel plates.(4)A calculation method for the flexural bearing capacity of the prestressed concrete simply-supported concrete box-girder bonded with steel plates is introduced.The influence coefficient of cracks is introduced,and the linear regression analysis is performed on the model calculation results.The functional relationship between crack height and the influence coefficient of the crack is determined.