Study On The Whole Forced Condition Of Prefabricated Slab Girder Bridge Reinforced By SRC Method With Hinge Joints

The assembled hollow slab girder bridge is the main structural style of medium and small span bridges through hinge joints.However,due to the structure,construction and load,hinge joints are prone to damage,destruction and even the formation of veneer force,which has become the main cause of diseases in the operation of the assembled hollow slab girder bridges and seriously affects the safety and durability of bridges.At present,the main reinforcement method is to take reinforcement measures at the bottom of the beam.Although the reinforcement effect by this method is good,there are inconvenient factors in the construction of the bottom of the beam.In this paper,the research group of the author has proposed a method of strengthening the top surface of the bridge,namely the reinforced method of section steel-concrete composite(SRC),which can improve the whole forced condition of the assembled hollow slab girder bridges.The engineering application has also proved that this method is convenient in construction,and effectively reduce the cost of measures.On the basis of summarizing the previous research,this paper carries out the whole forced condition research of the assembled hollow slab girder bridge reinforced by SRC.The main contents and results are as follows:(1)The reinforcement mechanism of SRC method was systematically explained.SRC reinforcement method is mainly proposed for small hinged assembly slab girders.The principle is to connect the slab girders into a whole through the PBL shear connector formed by section steel-concrete,which plays the role of stiffening and strengthening the hinge joints.After the reinforcement,the hinge joints can bear shear force and bending moment,and the failure state changes from the brittle interface failure to the bendingshear failure in the reinforcement layer,which achieves the effect of improving the bearing capacity and the synergistic mechanical performance between the slabs and girders.In addition,the section steel can prevent the cracks extending to the reinforcement layer and improve the fatigue resistance of the hinge joints after reinforce-ment.(2)The load transverse distribution of the slab girder bridge reinforced by SRC was researched.The influence law of the load transverse distribution of the slab girder bridges reinforced by SRC was studied by the finite element analysis method,and the calculation results were compared with the hinged slab girder method and the rigid slab girder method.The research shows that the load transverse distribution coefficient is between the hinged slab girder method and the rigid slab girder method,and closer to the rigid slab girder method.From the perspective of partial safety,the hinged slab girder method is proposed as a method for calculating the load transverse distribution coefficient of the reinforced slab bridges.(3)The influence of the spacing of section steel on the whole forced condition of the reinforced slab girder bridges was studied.The results show that the channel steel spacing is reduced,and the load transverse distribution of the reinforced slab girder bridges is more uniform.It is determined that the channel steels along the longitudinal direction adopt a variable spacing of 60 cm near the fulcrum and 30 cm near the middle of the span as the optimal layout spacing,and an optimal scheme is proposed to replace channel steels with angle steels..(4)The influence of load position and width-span ratio on the whole forced condition of the reinforced slab girder bridges was studied.The results show that the load transverse distribution of each slab girder tends to be more uniform with the load position is closer to the mid-span section;with the width-span ratio decreasing,the load transverse distribution of each slab girder becomes more uniform,which indicates that the abovementioned load transverse distribution law after SRC reinforcement is consistent with the general hinged and rigid slab girder method.And explore the distribution law of the transverse bridge normal stress on the upper and lower edges of the reinforcement layer and the normal stress on the lower edge of the section steel to further support the reinforcement mechanism of SRC method.