Study On The Performance Of CFST Columns Under Blast Loading And Axial Compression

The local war, international terrorism and accidental explosion caused by inflammableand explosive chemicals have existed within the scope of the world for a long time, whichhave constantly threatened people’s lives and property. Then, How to improve the level of theblast prevention and protection for the structure has become an important and realistic topic.The concrete filled steel tube columns have been widely used in engineering practice becauseof its high bearing capacity and outstanding plasticity. Until now, the way to study on theperformance of concrete-filled steel tube columns under blast loading basically were givenpriority to numerical simulation, and there were also few experimental research on it. In termsof theoretical analysis, the columns were almost treated as a flexural member. But the mostmain function of the frame columns in a real structure is to bear axial compression. So thestudy on the performance of concrete-filled steel tube columns under blast loading, which wasinfluenced by axial compression ratio, would have great practical significance. In this paper,the primary work and innovations are as follows:(1) Based on three-parameter unified strength theory, the ultimate bearing capacity ofhollow round concrete-filled steel tubular stub columns was analyzed. Using uniform restraintcoefficient and lateral pressure coefficient, the performance of regular polygon cross sectionwas analyzed by converted to circular cross section. Then, a unified ultimate bearing capacitysolution for concrete-filled steel stub columns under axial compression is proposed. Verifiedthe correctness by comparison with literature test results, the influencing factors of formula isalso discussed.(2) Based on the theory of generalized single degree of freedom, the simplified analysismethod for equivalent single-degree-of-freedom was put forward by defining quality, loadand resistance coefficient, in which the influence of axial compression ratio was considered.According to the hypothetic shape function, the characteristic parameters of the equivalentsingle-degree-of-freedom system was also analysized. Finally, the results showed that thesystem stiffness and maximum resistance was weakened by the axial compression ratio.(3) Using the above equivalent single-degree-of-freedom system considering the axial compression ratio, the experimental results in reference[65] was calculated and compared inorder to verify its validity. After influencing factor analysis, increasing steel ratio, reducingthe length to diameter ratio and improving the strength of steel were found to enhance theperformance of concrete-filled steel tube columns under blast loading, which was influencedby axial compression ratio.