| Explosion is a kind of dangerous disasters.However,the outbreak of the modern war in the some area,especially the deliberate destruction on public facilities by some terrorists,may cause explosions in some areas.These may have a great impact on society.In recent years,accidents and terrorist attacks around the world have aroused public concern about the safety and protection of the national infrastructure.Up to now there are few researches on the damage of the explosion,especially to the bridge or other infrastructure.The bridge structure plays an important role in national development and people’s daily life.Once the bridge was destroyed by an explosion,this will have a great impact on the country’s economic construction and people’s daily lives.Therefore,it is necessary to study the dynamic response and damage of the bridge under blast loading,which provides the basis for the design of the structure.According to the actual flying swallow type arch bridge,the dynamic response and damage situation under explosion load are analyzed by using finite element simulation method on in this paper.The following research works have been carried out:(1)The production and propagation of explosion,the characteristics of blast shock wave and its effect on structure are introduced in this paper.The basic principle and application of the explosion analysis software AUTODYN and transient dynamics analysis method of ANSYS are described.(2)The model about relationship of bridge structure,air and explosive are established by AUTODYN.Then analysis explosion of the side span box girder and the main span bridge deck.By this way,the propagation of blast shock wave,the dynamic response and damage situation.of bridge structure under blast loading are studied.(3)According to curve of the explosion pressure and time,then considering the characteristics of explosion shock loading and the existing explosion load simplified theory,a simplified method of explosive load under the action of close range explosion is established according to the principle of keeping the impulse consistent.In this way,the explosive load is simplified to a triangular load.(4)According to the actual arch bridge project,a simplified model is established by using ANSYS.Then apply simplified blast load to the arch bridge by transient dynamic analysis method.The positive load and partial load are set along the bridge.Eccentric and non eccentric loads are loaded along the transverse of bridge.In the case of eccentric eccentric loads,different explosive equivalent is used.Based on the above analysis,the effect of the explosive position and the equivalent of explosive on the overall response of the arch bridge is analyzed.Then the possibility of failure of main arch is studied.These studies shows: The damage of reinforced concrete box girder and bridge deck is not large in the case of Eccentric or non eccentric loads explosion.Both shows a small range of local damage,and The damage mainly occurred near the explosives.When the explosion occurs in the box girder,the damage is much larger than external explosion,and because of the reflection of the shock wave in the box girder,the top plate,bottom plate and web plate of the box girder are seriously damaged.The influence of the explosion above the bridge deck is the destruction of the bridge deck system,the effect on the arch is relatively small,the deformation of the bridge deck is much larger than that of the arch.When the quality of the TNT is less than 1000 kg,the deformation of the main arch is small and there is no failure risk.When the mass of TNT increases to 1000 kg,the maximum displacement of the main arch May increase to over 0.21 m,which has the risk of failure.The above research results can be used to predict the degree of damage and explosion resistance of bridge structure to a certain extent.It can also be used as a theoretical basis for the explosion-resistant design of bridge.This has important practical significance. |
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