Research On Mechanical Configuration Of Fulcrum Diaphragm Beams Of Multi-chamber Box Girder Bridge Based On Topology Optimization

The problem of cracking of the fulcrum diaphragm beams of box-section continuous girder bridges is very common.Due to the complex force of the diaphragm beams,there is still a lack of optimization research on the fulcrum diaphragm beams of box-section bridges.This paper takes the fulcrum diaphragm beam of a single-box three-chamber box-section bridge as the research object,establishes a multi-scale spatial finite element model.Based on topology optimization,a general analysis method for the Strut-and-Tie model is proposed,and a program is programmed to realize it automatically.The main contents of this paper are as follows:(1)A multi-scale finite element model of a single-box three-chamber box-section continuous girder bridge is established.By calculating the stress distribution state of the fulcrum diaphragm beam under the action of dead load,live load,temperature,support displacement,and analyzing the force flow transmission law,the simplified equivalent load of the diaphragm beam is obtained.(2)On the basis of the topology optimization configuration of Abaqus software,the stress trace is used to modify it,and the initial mechanical configuration of the diaphragm beam is obtained;Taking the minimum strain energy of the tie rod as the goal,the specific shape and position of Strut-and-Tie model is deduced,Arranging the reinforcement and the strength of the Strut-and-Tie model is checked according to the specifications.(3)The influence of the design parameters such as the aspect ratio of the diaphragm beam,the position of the hole,the size of the support,and the spacing between the supports on the shape of the Strut-and-Tie model is studied by the finite element topology analysis method.The results shows that the most influential parameters are the bearing distance and the aspect ratio.According to the difference of the two parameters,the configuration of the Strut-and-Tie model under various working conditions can be classified into three general shapes.The exact size of the Strut-and-Tie model can be obtained by calculating the decision variables under this configuration.(4)The genetic algorithm is applied to calculate the decision variables of the Strut-and-Tie model.The Python language is used to write a general program that can automatically generate the configuration of the Strut-and-Tie model of the single-box three-chamber box-girder fulcrum diaphragm beams,which simplifies the work of design and calculation for the fulcrum diaphragm of the multi-chamber box girder bridge.With 70 figures,17 tables and 58 references.