Research On Key Influencing Factors And Migration Problems Of Static Load Failure Mode Of Composite Dowels In High-performance Composite Bridge Deck

As orthotropic steel decks(OSDs)have many outstanding advantages such as light weight,high bearing capacity,convenient transportation and erection,and fast construction speed,it has been widely used.However,it is determined by the structure characteristic in lifting,manufacturing process and service environment.Pavement damage and the fatigue cracking at welded joints are the main problems.One of the most effective solutions to address the presented issues in the structure system is to ehance the local stiffness of the traditional OSDs by using an innovative composite deck.The innovative composite deck is composed of corrugated steel and a high performance concrete layer.The composite dowel has realized the connection and cooperative force between corrugated steel and high performance concrete.The foundation and key to investigate the static performance of the composite dowel are: determine static load failure mode;explore the typical failure modes and the changes of the main mechanical characteristics during the whole process of stress;expound the bearing mechanism of failure modes.The failure mechanism of the composite dowel is investigated by model tests and theoretical analysis.The main research contents and conclusions are completed:(1)By conducting push-out tests to verify the correctness of nonlinear finite element numerical simulations.On this basis,the typical failure modes of composite dowel and the variation rules of the main mechanical properties in the whole process of loading are defined,and the bearing mechanism of different failure modes is expounded.(2)Through the nonlinear finite element parametric analysis,the influence of the thickness of dowel,the thickness of concrete and the strength of concrete on the shear capacity and the transfer of failure mode of composite shear connector are systematically studied.According to the results of the finite element,an equation for calculating the shear strength of composite dowels embedded in UHPC is derived,which can describe the influence of the main factors.(3)On the basis of the clarifcation of bearing mechanism of static failure mode,the effect of key influencing factors on the shear resistance of the combined dowel was quantified to derive an equation for calculating the shear strength of composite dowels embedded in UHPC.Finally,the accuracy of the formula is verified by experimental data.