Research On Optimal Design Of Rope-fixing System Of Pontoon Bridge Based On Hydrodynamic Performance

With its rapid mobility and strong support and support capability,pontoon bridge structure not only plays an important role in the military field,but also can be used as an emergency means to protect people’s life and property safety in the event of natural disasters.Therefore,the safety,speed and mobility of pontoon bridge system has become an urgent problem to be solved and guaranteed.At present,the main research contents of the pontoon bridge system in China mainly focus on ensuring the safety and traffic performance of the part of the river,and there is a lack of relevant research on the riverbank straining and fixing system.When the anchorage conditions in the river is poor and the flow velocity in the river is high,it is necessary to establish the riverbank straining system to ensure the safety and normal passage of the pontoon bridge system.Therefore,it is of great practical significance to study and optimize the straining system.This thesis takes the preliminary design scheme of the rope-fixing system of a heavy-duty pontoon bridge as the research object,and carries out the research on the hydrodynamic optimization design of the fixed system.The main contents are as follows:(1)Using ICEM CFD,the three-dimensional structured grids of the single boat model without considering the fluid interference effect and the multi-boat model considering the fluid interference effect were established respectively,and the simulation simulation of the two models under the gas-liquid two-phase flow was carried out through Fluent.Obtain the change curve of the fluid resistance with the flow velocity of the two models,comprehensively consider the calculation results and calculation efficiency,select the single boat model to carry out the subsequent simulation analysis;(2)Based on the gas-liquid two-phase flow theory,Fluent was used to analyze the variation of fluid resistance with depth in the single float model at a determined flow velocity(the maximum flow velocity in Hanoi was 3.5m/s),and the time-varying curves of fluid resistance in each float model were obtained.Based on the principle of leverage,the maximum draft depth of a certain type of tank was calculated.The fluid resistance calculation model under different draft depths was established with 0.1m as the step length,and the resistance scatter diagram was calculated.The relationship equation between fluid resistance and draft depth was obtained by fitting.The fluid resistance values of different floats at different times and their time-varying curves were obtained,and the calculation results of fluid resistance were modified by considering wave load;(3)Based on the catenary and cable slip theory,the form-finding and slip cable element analysis program is compiled by ANSYS APDL language,and verified by example analysis.The results show that considering the cable slippage effect will make the tension distribution across the continuous cable more uniform and reasonable,and the geometric nonlinearity of the cable can be fully considered.The comparison of the calculation results proves that the slippage cable element in this thesis has good working performance and is simple and practical;(4)Based on ANSYS APDL language,the rope-fixing system nonlinear transient analysis program is compiled,the study shows that the rope-fixing system of the pontoon bridge preliminary design scheme of horizontal steel breaking security hidden danger,tower columns,beams,brace and stable cable material waste,need for preliminary design of the state of the pontoon bridge system Banks of the river section optimization design research;(5)Based on the ANSYS optimization analysis theory,the rope-fixing system optimization analysis program was compiled using ANSYS APDL language,and the optimization analysis and exploration of different schemes of the rope-fixing fixed system were carried out.By evaluating the internal force response of various components in each scheme,the deviation of the tower top,and the amount of materials and whether it is beneficial to improve the mobility of the system,select the optimal layout plan.Studies have shown that the optimal design and layout of the rope-fixing system is: horizontal projection angle of the anchorage of the horizontal line is 20°,the stable cable structure is cancelled,the diameter of the horizontal line is 50 mm,the column section adopts Φ76×10mm,the cross section adopts Φ108×10mm,and the diagonal brace section adopts Φ12×4mm.