Study On Damage Effects Of Reinforced Concrete T-beam Bridges Under Blast Shock Wave

As the throat of land transportation,bridges play a vital role in modern warfare.Therefore,it is of great significance to study the damage effect of bridges under blast shock wave.In this paper,reinforced concrete simply supported T-beam bridge is taken as the research object,the target characteristic of the bridge is analyzed.Based on the tactical needs,we classify the damage level of the bridge,establish the damage tree and find the key vulnerable components of the bridge.The damage effect of the T beam and bridge deck is studied through the experiments,theoretical analysis and numerical simulation.The main research contents and the main conclusions are as follows:(1)Based on the structural characteristics,material characteristics and functional characteristics of the bridge,the target characteristics of the bridge are analyzed.Combining with the damage mechanism of each component of simply supported T-beam bridge,a damage tree of the bridge structure is established,and the key components to determine the vulnerability of the bridge are T-beams,bridge deck and piers.(2)The explosion damage reduction ratio model of T-beam bridge was designed,and,the experiment of the charge with different charge diameter and different length-to-diameter ratio applied to the top of bridge deck of bridge deck was performed.We obtained the bridge deck damage laws with the length-to-diameter ratio and diameter of the charge changing.When the diameter of charge is invariant,the dimensionless perforation diameter,the dimensionless frontal damage diameter of bridge deck and the dimensionless diameter of backside collapse increase with the increase of length-to-diameter ratio of charge,whereas the increment of velocity is reduced gradually.The contact explosion test of the charge just above the T beam rib is carried out,the main failure modes of the rib on contact explosion conditions are obtained,a simplified method to calculate the residual bearing capacity of T-beam is proposed,and the damage criterion of T-beam is given.In addition,the damage experiment of bridge deck under near-field explosion was carried out,the main failure modes of bridge deck are obtained as partial collapsing and perforation.Based on the near-field explosion experiment data,an engineering calculation formula,which is about the explosive damage effect of bridge deck in near-field condition,was obtained by dimensional analysis.(3)The finite element software AUTODYN was applied to simulate the damage and destruction of the bridge deck on the contact explosive condition.The collapsing and destructive laws on the bridge deck with different diameters of charge and length-to-diameter ratios were obtained.The simulation results agree well with the experimental results.The numerical simulation results show that there exists the ultimate length-to-diameter ratio of charge and the ultimate perforation diameter of the interacting between the charge and bridge deck in the event of contact explosion and collapse.(4)Based on the damage data and the numerical simulation results of the bridge deck under the condition of contact explosion,the engineering formula of the failure diameter,the perforation diameter and the back collapsed diameter of the bridge deck was obtained by dimension analysis.The research results of this subject have certain reference value for the design of anti-bridge warhead and the damage assessment of the bridge target attacked by the warhead.