Research And Experiment On Bending Behavior Of Wet Joints In Lightweight Composite Deck System Composed Of Orthotropic Steel And UHPC Layer

Orthotropic steel deck bridges are inevitably plagued by two inherent issures,which are easy to suffer from fatigue cracking and damage issue of wearing surface.A lightweight composite bridge deck system composed of an orthotropic steel deck and Ultra High Performance Concrete(UHPC)layer is proposed to solve this problem effectively.Aimed at technical problems of cast-in-place maintenance of lightweight composite bridge deck,to advance its engineering application scientifically and rationally,it is necessary to propose a reasonable and excellent performance wet joint form of steel-UHPC lightweight composite bridge deck s ystem,and so far very limited knowledge is available regarding the wet joint form.In this paper,the wet joint of steel-UHPC lightweight composite bridge deck is studied.Experimental research and theoretical analysis were carried out on the static bendin g properties of the steel-UHPC dense reinforcement-enhanced wet joint 、 the strengthening steel plate-enhanced wet joint、the tongue-and-groove wet joint and the special-shape steel plate-enhanced wet joint.The location of the wet joint in real bridge and its calculation safety of anti-cracking are analyzed.The major contributions are provided as follows.(1)Based on the traditional orthotropic plate bending differential equation and its classical analytic form,the techniques to reduce the internal force and deformation of the orthotropic steel bridge surface are analyzed.According to the composition characteristics of light composite deck,the main factors affecting the flexural performance are analyzed,and the performance of UHPC material and the cracki ng strength calculation method of fiber reinforced concrete based on the theory of composite mechanics are introduced.Then the main cable force and the stress control points are analyzed which based on the calculation results of the steel-UHPC lightweight composite bridge deck system of the real bridge when the bridge deck changed.(2)The steel-UHPC dense reinforcement-enhanced wet joint static bending tensile performance.By configuring the dense reinforcement to strengthen the ability to combine the UHPC between the joints,taking UHPC joint reinforcement ratio as variable parameter,a steel-UHPC composite structure including one kind of conventional plane interface wet joint and four different kinds of dense reinforcement-enhanced wet joint is designed and manufactured,and static bending test was carried out.Based on the test results,the mechanical behavior and anti-crack performance of static bending tensile of the steel-UHPC composite structure wet joints are analyzed.Based on the force model of the steel-UHPC dense reinforcement-enhanced wet joint,a formula for calculating the crack width of the UHPC joint is established which suitable for the steel-UHPC composite structure dense reinforcement-enhanced wet joint under bending tension.(3)The strengthening steel plate-enhanced wet joint static bending tensile performance.By setting strengthen steel plate in the joint to improve the bending tensile performance of the wet joint,a negative bending test beam containing three kinds of strengthen steel plate-enhanced wet joints is designed and manufactured,and static bending test was carried out.Based on the test results,the mechanical behavior and anti-crack performance of static bending tensile of the steel-UHPC composite structure wet joints are analyzed.Based on the force model of strengthen steel plate-enhanced wet joint,the calculation method for the crack width of UHPC joints is proposed which suitable for steel-UHPC composite structure welded reinforcement form-enhanced wet joints under bending tension.(4)The tongue-and-groove wet joint static bending tensile performance.Through the "bite" to enhance the joint ability between UHPC joints,one piece of 3 U ribs were fabricated,and the static bending test was carried out.One piece of tongue-and-groove wet joint assembly test beam with three U-ribs was designed and manufactured,and the static bending test was carried out.The mechanical behavior and anti-crack performance of static bending tensile of the steel-UHPC composite structure wet joints are analyzed.Based on the UHPC tongue-and-groove wet joint mechanical model and finite element analysis,the calculation method for the crack width of UHPC joints is proposed which suitable for steel-UHPC composite structure tongue-and-groove wet joint under bending tension.(5)The special-shape steel plate-enhanced wet joint static bending tensile performance.The bending performance of wet joints is improved through the "rigid locking" effect of the special-shape steel plate.One pieces of experimental beam was designed,including types of three special-shape steel plate-enhanced wet joint and one mesh reinforcement-welded wet joint,and the static bending test was carried out.The mechanical behavior and anti-crack performance of static bending tensile of the steel-UHPC composite structure wet joints are analyzed.Based on the special-shape steel plate-enhanced wet joint mechanical model,the calculation method for the crack width of UHPC joints is proposed which suitable for steel-UHPC composite structure special-shape steel plate-enhanced wet joint under bending tension.The mechanical properties and anti-cracking of the typical wet joints were compared,which provides reference for bridge design of different types of wet joints considering dura bility.Taking the Humen-bridge as an example,the setting position of the wet joint and the corresponding anti-cracking safety are also analyzed.