Study On Models For Blast Loads Acting On Building Structures Under Close-in Explosions

Currently,those available blast load models established based on spherical charges of TNT show great agreement to each other under far-range explosions while significant difference under close-in explosions when blast loads acting on building structures are predicted.Little studies have been conducted on blast load models established based on cylindrical charges of TNT,the only blast model available in UFC can’t be used for predicting blast loads which in the range of scaled distance is less than 1.2 m/kg^1/3.Moreover,a lot of researches have shown that the detonation point,the shape and dimension of explosive charge as well as the orientation have significant influence on blast loads,especially for close-in explosions.Unfortunately,none of those blast models available have taken those factors into consideration when they are established for predicting blast loads acting on building structures.Therefore,primary work and achievements in this paper are presented as followings:1.Filed experiments of close-in explosionsExperiment scheme used for collecting reflected overpressure time histories acting on building structures under close-in free-air burst explosions has been designed first,then the influence rules of different detonation points on blast loads acting on building structures detonated by spherical charges of TNT under close-in explosions,and the influence rules of different detonation points,aspect ratios as well as orientations on blast loads acting on building structures detonated by cylindrical charges of TNT under close-in explosions are studied by analyzing collected experimental data.2.Simulations of close-in blast loadsAt the scaled distance of 0.2,0.3,0.4,0.5,0.6 and 0.8 m/kg^1/3,the reflected overpressure time histories acting on building structures of 1kg spherical charge of TNT detonated at different positions and the reflected overpressure time histories acting on building structures at the radial and axial directions of 1kg cylindrical charges of TNT with different aspect ratios detonated at different positions are simulated by the CFD code AUTODYN.The influence rules of different detonation points on blast loads acting on building structures detonated by spherical charges of TNT under close-in explosions,and the influence rules of different detonation points,aspect ratios as well as orientations on blast loads acting on building structures detonated by cylindrical charges of TNT under close-in explosions are studied based on the analysis of a great number of close-in blast loads simulated.3.Establishment of close-in blast load modelsIn the light of the close-in blast loads simulated,deterministic models for blast loads acting on building structures detonated by the spherical charge of TNT under close-in free-air burst explosions are established with taking detonation point this factor into consideration,and deterministic models as well as the uncertain model for blast loads acting on building structures detonated by cylindrical charges of TNT under close-in free-air burst explosions are established with taking detonation point,aspect ratio as well as orientation those factors into consideration.