Research On The Design And Calculation Method Of External Pre-stress Strengthening

External pre-stress strengthening is a new kind of reinforcement method for bridge using pre-stress steel wire bunch or pre-stress tie rod(bar reinforcement).External pre-stress reinforcement method is widely used in field of old bridge maintenance and reinforcement,for its obvious effect in improving load,little damage to the original bridge structure,simple construction,easy to check and maintenance,etc.Although the external pre-stress strengthening has had extensive research both at home and abroad,many technical problems still exist in design theory and in practical application.Especially the calculation method of transverse distribution coefficient for main girder considering the role of bridge deck pavement is not yet found in the relevant reports.In order to analyze the stress state of the bridge reinforced with external pre-stress method under vehicular loads,finite element solution and analytical solution considering the role of bridge deck pavement were derived based on the theories of internal statics and contact combined with finite element methods.Solving methods for displacement and stress state of main girder considering the stiffness contribution of pre-stress steel and the effect of slippage on interface between concrete slab and steel beam under vehicular loads were derived.And the concrete expression of the transverse distribution coefficient solved by the improved eccentric pressure method is derived based on the analytical solution.The influence of pre-stress steel on the overall mechanical performance of the main beam is obtained and the results were compared with the results of ANSYS and field test.It is showed that the finite element solution,the analytical solution and the method of calculating the transverse distribution coefficient derived in this paper were correct and reasonable.The results show that the existence of external pre-stress can greatly improve the carrying capacity,improve the overall mechanical performance of bridges,and the design theory of this paper can be effectively used to calculate the displacement and stress state of the main girder of the bridge strengthened with external pre-stress method.It provides a reliable technical support for external pre-stressing reinforcement design.