The Failure Mechanisms Of Curved Composite Walls Under Concentrated Loads And Their Blast Resistant Performance

With the explosion/shock terrorist attacks and accidents in recent years,the safety of building structures has become a hot topic of research.The explosion-proof walls formed by steel-concrete composite structures have received special attention from the engineering community.For this reason,this paper tests and finite element numerical simulation analysis of the local failure mechanism of curved steelconcrete-steel composite walls under static local load and its anti-explosion performance under blast loading.The specific research contents are as follows:(1)Three curved steel-concrete-steel composite walls structures with different thicknesses of steel plates were designed and fabricated,and steel plates were connected by steel bars.The hemispherical hammerhead was used to test the curved steel-concrete-steel composite walls under the concentrated load at the top.The loading deformation process,failure mode,bearing capacity and full-process forcedisplacement curve of the specimen under static load were obtained.The test results show that the test piece undergoes four stages under concentrated load: near elastic stage,yield stage,strengthening stage and failure stage;the deformation of the test piece is mainly local deformation,and the failure mode is that the joint between the connecting piece and the lower steel plate of the test piece is disengaged,the concrete is broken and the upper steel plate near the hammer head is cracked;the connecting piece is pulled before the specimen reaches the yield bearing capacity,and some connecting parts are withdrawn during the strengthening stage.(2)Based on the finite element analysis platform LS-DYNA,the detailed modeling of the curved steel-concrete-steel composite walls was carried out.The applicability and accuracy of the finite element model are verified by comparing the force-displacement whole process curve and failure mode with the static test results.The effects of different concrete thickness,steel plate thickness and rise-span ratio on the mechanical behavior of composite walls were analyzed.The effects of the above factors on the yield bearing capacity,ultimate bearing capacity,failure characteristics and stress distribution of concrete and steel plates of curved steel-concrete-steel composite walls are obtained.(3)Combined with the deformation characteristics,failure process and characteristics of the specimens obtained by finite element numerical simulation,the failure mechanism of the sandwish shell structure under local load is obtained.The failure of the specimen in the yield stage is mainly reflected by the bending failure of the positive section.When the stage reaches the ultimate bearing capacity,the upper steel plate is cracked.Based on the force method equation and the flat section assumption,the calculation method of the yield bearing capacity of the curved steel-concrete-steel composite wall structure applied in a given range is proposed,and the calculation results were verified by test and finite element simulation results.(4)The finite element model of the curved steel-concrete-steel composite wall under blast loading is established.The accuracy of the finite element model under blast loading is verified by comparing with the results of the double-steel concrete composite wall panel explosion test.The different failure modes of the specimen under close-range ground explosion,close-range center point explosion and longdistance explosion are compared and analyzed.The rationality and effectiveness of the curved steel-concrete-steel composite wall as a protective structure are verified.The concrete layer is worked as the main energy-consuming part.The steel plates on both sides and joints play the role of restraining the concrete and reducing the overall deformation of the composite wall.The parameter analysis under the blast load was carried out,and the influence of the explosion position,explosive equivalent,concrete layer thickness,steel plate thickness and rise-span ratio on the anti-blast performance of the composite wall was obtained.