Numerical Simulation Of Masonry Wall Under Combined Action Of Blast And Fragments

Masonry wall is widely used in various construction projects in China due to its good function and economy,whether it is used as the main force-bearing component of the masonry structure or as the filling member of the frame structure and the frameshear structure.With the growing frequency of explosion accidents in production and terrorist attacks,the masonry wall,as one of the commonly seen main protective structures,remains a critical challenge.The researches on damage,destruction and antiexplosion reinforcement of the masonry wall under the effect of explosion also has great practical and theoretical significance.In recent years,although the domestic and international researches on masonry walls under the effect of explosion have made great progress,most of them only considered the damage of explosion shock waves to the wall,and ignored the threat of high-speed fragments generated during the explosion.The researches on the masonry wall under the combined action of the explosion shock wave and the fragment is very scarce.Based on the above background,this paper uses the display finite element analysis software ANSYS/LS-DYNA to conduct a large number of numerical simulations on the damage and destruction processes of the masonry wall under the action of the explosion shock wave and the high-speed fragment group respectively and the combined action to study the damage mechanism,failure mode,dynamic response and anti-explosion reinforcement.The main research work and results of this paper are as follows:(1)The numerical simulation of the explosion of TNT explosive in air is carried out in this paper.By comparing the numerical simulation results and the calculation results of empirical formulas,the reliability and applicability of the numerical model material parameters,explosive impact load,fluid-structure coupling algorithm,etc.are verified;the numerical simulation of the shock wave-driven prefabricated fragments group is to verify the reliability of the prefabricated fragments driven by explosive shock waves by comparing the design trajectory velocity of general fragments.(2)In this paper,the numerical model of air-explosive-fragment-masonry wallrigid ground is established,and the damage of masonry wall under different working conditions such as single action of shock wave,single action of fragment group,combined action of shock wave and fragment are analyzed respectively and comparisons are made among these actions.The research shows that the peak overpressure,projectile velocity,and projectile displacement of the masonry wall under the blast shock wave alone will gradually decrease with the increase of the proportional distance;when the prefabricated fragment group acts alone on the masonry wall,part of it will cause penetration,and the overlap between the pressure wave and the reflected stress wave generated by the fragments impacting the masonry wall will bring relatively large local damage to the masonry wall;under the joint action,the masonry wall will change due to the penetration damage of the high-speed fragment group.The overall performance of the wall makes the damage more serious than the single-acting condition and the linear stacking of the two.Not only the area erosion and spalling in the shock wave action area has greatly increased,but the high-speed fragment impact area has also formed a more serious local penetration,which makes the damage mechanism more complicated.(3)In this paper,different FRP materials are coupled into the joint action model,and the anti-explosion strengthening ability of different FRP materials to the masonry wall under the joint action is studied.Studies have shown that CFRP,AFRP,and GFRP materials can noticeably improve the anti-explosion performance of masonry walls,and significantly reduce the overall damage of the masonry walls and the block ejection phenomenon of the explosion shock wave.However,the protection of pit damage and penetration caused by the impact of high-speed fragment groups driven by explosive shock waves is limited,of which CFRP has the best anti-explosion reinforcement capacity,followed by AFRP,and GFRP is the worst.