Analysis Of Shear Behavior Of Prestressed Continuous Steel Beams

The prestressed steel bundle can play the role of improving the structural stress state in the steel structure,increasing the structural rigidity,saving steel and reducing the cost.The research work on prestressed steel structures is mainly concentrated on prestressed steel trusses and simply supported beams,but there are few studies on prestressed continuous beams.The continuous beam can play the role of reducing the mid-span bending moment,and exerting the pre-stress on the continuous beam foundation,can continue to reduce the bending moment of the bridge and achieve the effect of improving the stress state.The characteristics and types of prestressed steel structures and the development at home and abroad are summarized.A 1:10 scale model test of a three-span prestressed continuous steel beam was carried out without considering the deck pavement.The simplified calculation method of prestressed continuous steel beam based on equivalent load method is verified,and the influence of the cable method on the stress state of continuous beam is discussed.Through the three-dimensional finite element nonlinear analysis of ANSYS,the influences of the tensile force,shear span ratio,web thickness,steel beam bending angle and stress state on the shear performance of the prestressed continuous steel beam are discussed.The theoretical calculations are basically consistent with the experimental results.The main conclusions are as follows:(1)The pre-stress increases the shear stiffness of the continuous beam by 9.1%,and the reduction of the side-span deflection of the continuous steel beam is greater than that of the mid-span.For the continuous steel beam,the single-span double-fold cable should be used,and the folding point at 1/4 of each span is beneficial to the rigidity of the continuous beam.(2)The increase in tensile force and the reduction in shear span ratio all increase the shear resistance of the continuous beam.The thickness of the web is uniform for the stiffness of the continuous beam,while the prestressed steel beam is not uniform for the stiffness increase,and the effect of the side span is higher than the mid-span.The increase of the bending angle of the steel beam near the middle support can improve the shear resistance of the continuous beam,but will reduce the bending rigidity of the beam.(3)When the load acts on the one-side span of the prestressed continuous beam,the prestressing effect on the flange restraint effect is weakened.Two vertical stiffeners are provided at the support of the continuous beam,which is beneficial to the strength of the web.