Experimental Study On Flexural Performance Of Steel Plate-UHPC Composite Beams And Shear Capacity Of Studs

As an important part of my country’s bridge construction,small and medium-span bridges play an important role in the country’s economic development and are also convenient for residents to travel.Precast concrete structures are widely used,but they have several problems such as easy cracking of the main girder,easy deflection,damage to the pavement of the bridge,uneven prestressed inverted arches,easy damage to the transverse connection,and high maintenance costs.With reference to the advantages of steel-concrete composite beams and combined with the ultra-high mechanical properties and durability of UHPC,the establishment of a new steel plate-UHPC composite structure system provides the possibility to solve common problems of small and medium-span bridges.At the same time,the steel plate-UHPC composite structure can greatly reduce its own weight,which is conducive to assembly construction,and has a significant role in promoting the factoryization and standardization of small and medium-span bridge construction.In the paper,experiments and analytical methods are used to study the flexural performance of the steel plate-UHPC composite beam,as well as the shear capacity of the stud.The main work content and conclusions are as foll ows:(1)The bending performance test of 7 steel plate-UHPC composite beams and 1reinforced UHPC beam has been completed,and the test parameters are the degree of shear connection and the form of reinforcement.The test results show that the combination of steel plate and steel reinforcement can not only improve the flexural bearing capacity of the composite beam,but also better limit the crack development of the composite beam.(2)The characteristics of the interface slip distribution of steel plate-UHPC composite beams are that they increase sequentially from the middle of the span to the quarter of the cross-section,and then decrease sequentially at the fulcrum.At the same time,increasing the degree of shear connection of the studs can effectively reduce the interface slip of the composite beam.(3)Using the equivalent rectangular stress diagram method,the simplified calculation formula for the flexural bearing capacity of the steel plate-UHPC composite beam is derived.The theoretical value is in good agreement with the experimental value,which verifies the applicability of the formula.(4)The shear bearing capacity of the studs in the steel plate-UHPC composite beam is analyzed and calculated,and the reduction method for the calculation of the stud shear capacity in the tension zone of the(do uble)steel plate-concrete composite beam is referenced in the literature.According to the test results,The reduction factor is used to establish a calculation formula for the shear bearing capacity of the studs in the tension zone of the steel plate-UHPC composite beam.The theoretical value is in good agreement with the experimental value,which verifies the applicability of the formula.(5)Based on the principle of minimum potential energy,reduced stiffness method and width reduction coefficient,the deflection calculation formula of steel plate-UHPC composite beam considering the slip effect is deduced and established,and all of them are in good agreement with the test results.Among them,the calculation formula of the width reduction coefficient method is the simplest,and the meaning of each parameter is clear,which has important reference significance for engineering applications.