| With the great development of national transportation,the application of long-span steel truss suspension bridges and even multi-tower multi-span steel truss suspension bridges is increasing.In order to solve the problem that traditional large hinges need to be designed,manufactured and installed in advance and participate in beam segment pre-splicing,and ensure the safety when steel truss beams with increasing weight are hinged,Hangrui Dongting Lake Bridge adopts temporary hinges of bolts as the hinged members between steel truss beams.The temporary bolts do not need to be manufactured and installed in factories in advance,thus realizing the three-dimensional multi-operation flour construction in the erection stage of stiffening beams,reducing many quantities,improving the construction progress and creating considerable economic benefits.At the same time,bolt temporary hinge is an innovative semi-rigid temporary connection component,and relevant research is still relatively scarce.The influence of various factors of bolt temporary hinge on force transmission and deformation mode is still unclear.As the local model of bolt temporary hinge is a solid model considering contact nonlinearity and material nonlinearity,finite element calculation requires a lot of time,so in order to consider the role of bolt temporary hinge in the overall model of the whole bridge,a reasonable simplification method should be proposed to improve analysis efficiency.The influence of different temporary hinge simplification methods on construction analysis results also has no relevant data for reference,which is not conducive to the application of bolt temporary hinge to other steel truss suspension bridges.Based on this,the following work has been carried out in this dissertation:(1)This dissertation introduces two calculation theories of the ultimate bearing capacity of eccentric shear bolt groups,and verifies the accuracy of ABAQUS finite element simulation results through a simple example.Then it introduces the application of temporary hinge of bolt in the construction of stiffening girder of suspension bridge.Several important links of finite element simulation of temporary hinge are discussed,including ABAQUS nonlinear theory,material characteristics of the model,and ABAQUS finite element model of bolt temporary hinge is established.Finally,the bearing capacity and stiffness of temporary hinged members are analyzed in detail.(2)The distribution characteristics of bolt group forces with initial fit clearance under the action of axial force and shear force are analyzed,and a calculation formula suitable for the most unfavorable bolt shear force of any bolt temporary hinge is proposed.(3)The whole stress process of bolt group under bending moment only is analyzed,and the calculation formula of rotation center considering the impact of punching nails,the calculation formula of the most unfavorable bolt shear force under bending moment only,and the reverse calculation formula of bolt shear force according to rotation angle are put forward.(4)The influence of three main factors on the temporary hinge performance of bolts is analyzed in turn: the size matching relationship between bolts and bolt holes,the arrangement of common bolts,and the number relationship between punching nails and common bolts.(5)Taking Hangrui Dongting Lake Bridge as the background project,the design process of temporary hinge and the corresponding preliminary design formula are summarized at first.Secondly,it introduces several important links in establishing the whole finite element model of suspension bridge,and puts forward a simplified method of temporary hinge in the whole model of suspension bridge.Then the plane model of the whole bridge is established by using ANSYS life-and-death element,and the construction stage analysis is carried out.The construction joint force is extracted,the temporary hinge is preliminarily designed,and the bridge deck collision problem is discussed in combination with the position of the rotation center.The force of the designed temporary hinge in the construction process is calculated by using the nonlinear spring element.The results show that the preliminary design is reasonable and the temporary hinge does not exceed the limit.(6)Taking Wenzhou Oujiang Beikou Bridge as the background project,the plane model of the whole bridge is first established and analyzed at the construction stage.The hinged position of the bridge is calculated,and the stress of chord and sling is checked.The nodal force at hinged position and the opening amount of lower chord are extracted.Then the preliminary design of the temporary hinge is carried out,and the layout of the temporary hinge is proposed in combination with the analysis content in chapter 4.The force transmission ratio calculation is mainly carried out in combination with the content in chapter 3.The results prove that the force transmission calculation method proposed in this dissertation is relatively accurate.The joint force calculation and angle calculation are carried out according to the force transmission ratio curve,and the collision inspection of the bridge deck is analyzed in combination with the position of the rotation center of the temporary hinge.Finally,a fullbridge model considering the rotational stiffness of the temporary hinge is established to analyze the stress of the temporary hinge.Through the analysis and research in this dissertation,it is shown that the essence of the stress behavior of bolt temporary hinge is the rigid body movement and component deformation of two adjacent eccentric shear bolt groups with initial fit clearance under external load.The shear force of bolt group with initial fit clearance is not Uniform distribution under the action of axial force,shear force or bending moment only,and the corresponding calculation formula is proposed.The influence of three factors on the force transmission and deformation mode of bolt temporary hinges is very obvious.The evaluation standard for the reasonable arrangement of temporary hinges is that the bearing capacity limit value of members is high and the stiffness is small.Propose the design process of temporary hinge and related formulas;Hangrui Dongting Lake Bridge can adopt bolt temporary hinges except for two positions.For the Oujiang Beikou Bridge,it is advisable to install large freerotation hinges at some temporary hinges. |
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