Unified Solutions On Bearing Capacity And Blast-Resistant Of Concrete-Filled Double Skin Steel Stub Column With Equal-Angle Octagon Section

Recent years,explosions have occurred from time to time,threatening people’s lives,building structure safety and social stability.To protect the objects under the explosion,one of the current research directions of scholars is the anti-blast performance of building structures.CFST has good blast resistance,and one of its forms is octagonal concrete-filled double skin steel tube column,developed from the square section,which can reduce stress concentration by adding bevel edge,and it has the advantages of easy connection,higher load-carrying capacity,high rigidity,etc.However,a lot of current research focuses on its static performance,and the research on its dynamic performance is relatively vacant.This article takes the concrete-filled double skin steel tube column with octagon section column as the research object,studying on the calculation method of its axial load bearing capacity and the dynamic response under the action of explosion by theoretical methods.The main work and conclusions of this paper is as follows:(1)For the force mechanism of the octagonal concrete-filled double skin steel tube,the column is divided into two parts.Based on the UST,octagonal concrete-filled double skin steel tube is equivalent to concrete-filled double-skin tube column with circle hollow section outer and circle hollow section inner tube according to the principle of area equivalence.The compressive strength of each component is then deduced.Finally,the calculation formula for the axial compression bearing capacity of the concrete-filled double skin steel tube short column with octagon section is obtained by superposition.Based on the above,the influence of some factors on the bearing capacity is analyzed,and the expansion formula is derived.At last,the influencing parameters are analyzed(2)According to the unified theory,the calculation formulas for the combined strength and combined elastic modulus of the concrete-filled double skin steel tube column with octagon section are given.The plastic limit bending moment is derived based on the characteristics of the section.Finally,the characteristics of explosion load are considered and simplified into a linear function of monotonic decline and the SDOF is used to obtain the theoretical solution of the maximum dynamic displacement of the concrete-filled double skin steel tube column with octagon section under blast.(3)Using Hyper Mesh and LS-DYNA software,the dynamic response of octagonal hollow sandwich concrete-filled steel tubular column under blast load is simulated by using the method of fluid-structure coupling.The effective stress,strain and mid-span displacement of a column fixed at both ends under explosion load are analyzed.By changing factors of the model and taking the maximum displacement in the column as the standard,the influence of these parameters on the anti-blast performance of the octagonal concrete-filled double skin steel tube was studied.