Study On Blast Resistance And Optimized Design Of Precast Concrete Facade Panel Frame Structure

In recent years,terrorist attacks and accidental explosions have occurred frequently in the world.External explosions of building structures often cause damage to the enclosure members and load-bearing members,and even resulting in continuous collapse of the structure.The traditional masonry infill wall of the frame structure is poorly integrated,and a large amount of debris will generate under the blast load,causing serious casualties.At present,prefabricated buildings are popularized and applied for their high construction efficiency,good quality and energy saving.Prefabricated reinforced concrete panels have good integrity and ductility,and are gradually applied to the facade system of building structures such as reinforced concrete frames.In this paper,the frame structure with assembled facade panels is taken as the main object,and the numerical simulation method is used to compare effect for blast damage mitigation of the panel at different positions of the frame structure under blast loading.Then analyze the key factors of effect for blast damage mitigation of facade panel and propose optimized design measures for the inadequacies of prefabricated facade panel,the main research work and results are as follows:(1)Compare the blast damage mitigation and protection effect of the prefabricated facade panel and the embedded panel on the frame structure,and prove the superiority of the facade panel in dissipating the explosive wave energy by self-destroying and providing protection for the load bearing members of frame structure.Different damage distribution and dynamic response of the facade panel under near and far-distance blast loads are also observed.(2)The key factors affecting the blast mitigation effect of the prefabricated facade panel are studied.Under the near-explosion condition,increasing the reinforcement ratio of the facade panel from 0.57% to 2.26% can reduce the damage of the column,but has little effect on the deformation of the middle pillar.Under the far-explosive condition,improving the reinforcement ratio can simultaneously reduce the damage and up to 51% the deformation of the column in the frame.Under the near-explosion condition,improving the concrete strength grade of the facade panel from C40 to C50 can reduce the damage of the panel itself,but the influence on the deformation of the middle column is little.Under the far-explosion conditions,improving the strength grade of the facade panel concrete can simultaneously reduce its own damage degree and up to 56.6% the deformation of the middle column.Under the near-explosion condition,the greater the spacing between the facade panel and the frame structure,the smaller damage and deformation of the column in the frame.However,in the case of far-explosive conditions,excessive spacing will cause the panel to deform too much,thereby increasing deformation of the column in the frame.(3)Optimized design of facade panels.The pre-stressing of the facade panel can improve the stiffness of the panel near the column in the frame and reduce the damage degree of the panel and deformation of the center pillar.The wall panel at the position of the frame column is designed to be a variable section form,which reduces the impact on the frame column when the wall panel is deformed,and enables the beam and the floor layer to provide support for the facade panel,thereby avoiding excessive deformation of the wall panel under far-explosive conditions.Install an independent facade vertical panel at the column in the frame.Damage is mainly concentrated on the facade vertical panel,it can facilitate the repair and replacement of the panel after the explosion events without affecting its blast mitigation performance.