Experimental Study On Bearing Capacity Of Continuous Composite Box Girder With Corrugated Steel Webs

Continuous composite box girder with corrugated steel webs has light self-weight,larg span capacity,better aesthetic appearance,excellent seismic performance and high prestressed efficiency,which could be applied as large-span bridges in high seismic intensity regions and scenic spots.Based on beam model test and theoretical analysis,the mechanical characteristics and failure mechanism of continuous composite box girder with corrugated steel webs were studied.Based on the above,the conclusions can be drawn as follows:(1)With the beam model test in elastic stage,the mechanical properties of box girder were analyzed.The results show that the longitudinal strain distribution along the section height of beam model accords with the "quasi-plane assumption".The vertical shear stresses along the height of corrugated steel web are basically the same and show a linear relationship with load.The external prestress increment is linearly associated with load,whose trend is similar to the mid-span deflection.The steel-concrete composite interface shear slip between the concrete top flange and steel web essentially equals to that between the concrete bottom fange and steel web.(2)With the beam model test under failure load,the mechanical properties and the failure mechanism of box girder with corrugated steel webs were studied.The results show that compared with externally prestressed continuous concrete box girder,the continuous composite box girder with corrugated steel webs shows better ductility,meanwhile its shear performance is less affected by section cracking and failure.The failure process of beam model can be divided into four stages:elastic stage,the mid-span section cracking stage,the mid-support section cracking stage and the reinforcements in bottom flange of mid-span section yield stage.The concrete cracking is relative with the steel-concrete composite interface shear slip between concrete slabs and steel webs.(3)Combined with experiment and relevant literatures,the calculation method of external prestress increment of continuous composite box girder with corrugated steel webs was deduced using the mid-span deflection.Considering the steel-concrete composite interface shear slip between concrete slabs and steel webs,external prestress increment and steel flanges,the formula calculating the flexural capacity of continuous composite box girder with corrugated steel webs was revised according to the classic bending theory.