Research On Impact Resistance Analysis Of Bridge Based On Composite Simulation Method

The economy of China is developing rapidly,for the convenience of the people,the country is vigorously constructing and improving the transportation infrastructure,and the construction of bridge projects is also increasing.With the ever-increasing number of bridges and the increasing demand for transportation,the frequency of bridge collision accidents has also increased.In the past,the finite element simulation analysis of bridge collision ac cidents was mainly based on a single finite element program.There were few analysis methods for different types of collision accidents,and it was difficult to reflect the characteristics of the dynamic response of different impact objects during the impact process.In addition,previous studies often ignored the shear behavior of bridge structures in impact accidents,or the methods used could not accurately simulate the shear behavior.For this reason,based on the UT-SIM composite simulation system,this article simulates and analyzes three types of collision accidents: vehicle impact into a bridge,ship impact into a bridge,and rolling stone impacting a bridge,aiming to put forward a systematic method for bridge anti impact analysis and provide new research ideas.(1)This paper introduced the background of frequent bridge impact accidents in recent years,listed the fresh cases of vehicle impact bridge,ship impact on bridge and rolling stone impact bridge,and pointed out the deficiencies in the current research on bridge impact analysis.The composite simulation method is proposed to study the impact resistance of Bridges,and the research situation of composite simulation method in recent years is listed,and the purpose and content of this paper are defined.(2)Found the vacancies of the UT-SIM composite simulation system in the refined finite element modeling of the bridge structure dynamic analysis,and proposed a method of integrating the explicit dynamic analysis software LS-DYNA into the UT-SIM system.The UT-SIM system is oriented to researchers The open source model and standard communication protocol and data exchange format provide the feasibility of this method.The secondary development interface of user-defined elements in LS-DYNA finite element software are also the necessary premise for LS-DYNA to integrate into UT-SIM system.The user-defined shell element subroutine for UT-SIM system is written in LSDYNA,which is connected to the UT-SIM composite simulation system platform,and the composite connection between LS-DYNA and Vector2 software is successfully realized.The composite simulation method is validated by two simple test examples of different types.(3)In order to further verify the correctness and applicability of the LS-DYNA-VT2 composite simulation method,the method was introduced in the analysis of vehicle impact bridge.According to the previous research experience,in the finite element model of vehicle impact bridge,the part of the cap beam and the impacted pier deserves attention.The composite modeling analysis is carried out by selecting the cap beam and the impacted pier as the substructure module of LS-DYNA-VT2 composite model.The LS-DYNA-VT2(cap beam)composite model considers two different properties of the cap beam(elasticity and nonlinearity),and the three different impact velocities(60km/h,80km/h,100km/h)under the cap beam structure dynamic response.The results show that:(1)If the cap beam is simply considered to be elastic,the damage of the structure(especially the cap beam)in the vehicle impact accident will be ignored,and the displacement and deformation of the collided pier will be underestimated.(2)With the increase of the initial impact velocity of the vehicle,the damage degree and crack development range of the cap beam increase significantly.In the research process of this paper,the LS-DYNA-VT2(Impacted pier)composite model still has unsolved obstacles,and the results are still presented,which is the author’s outlook on the research work that needs to be carried out in the future.At the same time,we look forward to the discussion and correction of researchers.(4)Based on the UT-SIM composite simulation system,according to the different characteristics of the Open Sees-MATLAB and Open Sees-Vec Tor2 connection methods,the construction of the Open Sees-MATLAB-Vec Tor2 joint simulation method has been completed.This method is used to study the structural response of a four-span continuous girder bridge under ship collision.The comparison between the composite model and the single-machine model shows that the use of Vec Tor2 to simulate the situation of the collided pier column shows that the structural damage is higher than that of the Open Sees simulation Vec Tor2 can capture the shear behavior in the structure,which reflects the advantages of Vec Tor2 in nonlinear structural analysis of reinforced concrete.(5)For rolling stone impact bridge,a typical mountain beam bridge is taken as an analysis case,and also uses Open Sees-MATLAB-Vec Tor2 method to simulate.According to the calculation results of LS-DYNA,the contact stiffness of rolling stones and piers in general is determined,and then the composite modeling calculation is carried out.The results also show that Vector2 is more obvious to simulate the damage of the impacted pier under the impact of rolling stones.