Study On Mid-span Deflection Of Continuous Rigid Frame Bridge With Corrugated Steel Webs And Improvement Measures

Firstly,the structural characteristics of continuous rigid frame bridge with corrugated steel webs were summarized,the influencing factors and basic theory of deflection of corrugated steel webs rigid frame bridge were briefly introduced.Then the influence of shear deformation,interface slip,shrinkage creep,prestress loss and other factors made on the midspan deflection was studied.Finally the improvement measures of midspan deflection were discussed.The main contents include the following aspects.The influence of shear deformation was discussed.Firstly,with the idea of transforming statically indeterminate structure into statically indeterminate structure,the edge and midspan of corrugated steel webs rigid frame bridge were separated into several statically indeterminate structures,then the deflection formulas considering shear deformation were deduced.Finally,based on a real bridge,the Midas/Civil model and FEA model were established,and the theoretical calculation value was compared with the finite element calculation value.The analysis results show that the derived deflection formula considering shear deformation can calculate the mid-span deflection and shear deformation accurately,and the deduction method adopted was reasonable.However,as the influence of diaphragm was not taken into account and the assumption that all the shear force of the cross section was bore by corrugated steel web,the theoretical calculation value is larger than the finite element result,so it is safe to use the derived formula in practical engineering.By changing the boundary restraint of continuous rigid frame bridge with corrugated steel webs,a continuous beam bridge with corrugated steel webs of the same span is established.The characteristics of mid-span deflection,web shear stress and bearing-shear ratio were analyzed.At the same time,steel webs were replaced by concrete webs,and corresponding prestressing tendons were added,the characteristics of shear deformation,web shear stress and shear ratio were compared and analyzed.The effect that interface slip made on the deflection of corrugated steel webs rigid frame bridge was studied.Based on slip deformation theory of simply supported beams with steel webs,a proportional coefficient was proposed,and a formula for calculating sliding additional deflection of corrugated steel webs rigid frame bridge was established.The formula was also verified with a bridge model.The results show that the proposed proportional coefficient is reasonable and can be used to estimate the additional deflection of mid-span slip conservatively.At the same time,aiming at the common shear connector forms,the influence of different shear connector combinations made on the additional deflection of sliding of corrugated steel webs rigid frame bridges was studied.The results show that the additional slip deflection is obvious when the bolt connection was used,but the the additional slip deflection is very small when Twin-PBL shear key and the embedded shear key were used.For rigid frame bridge with corrugated steel webs and PC rigid frame bridge,the effects that shrinkage and creep,prestress loss,bulk density and relative humidity made on the deflection were studied.The results show that the deflection of PC rigid frame bridge is obviously larger than that of rigid frame bridge with corrugated steel web,and the influence of these factors is more obvious for PC rigid frame bridge.Finally,the measures to improve the deflection of rigid frame bridge with corrugated steel webs were studied,such as changing the thickness,wave length and wave height of corrugated steel webs.The results show that shrinkage,creep and prestress loss are still the main factors affecting the deflection of corrugated steel webs rigid frame bridges.Changing the design parameters of corrugated steel webs has no significant effect on improving the deflection.