Dynamic Response And Damage Assessment Of Duplex Hollow CFST Column Subjected To Blast Loading

With the continuous development of the national economy, accidental explosions mightalso occur because of the aging of the gas container or the electric machine and improperstorage of tinder and explosive in chemical plants. At the same time, explosion is a growingthreat to the building structure because more and more explosive terror attacks and explosiveaccidents have happened around the world. In order to keep structure having excellentexplosion resisting performance, the explosion resisting performance of column itself plays avery important role. Duplex hollow CFST (Concrete Filled Steel Tube) column has manymerits such as higher bearing capacity, better plasticity, and higher bending stiffness. Theevaluation for the explosion resisting performance of duplex hollow CFST column hasimportant theoretical significance and practical value. Experiment analysis and numericalsimulation method are integrated to study dynamic response and damage assessment ofduplex hollow CFST column subjected to blast loading in this dissertation, and the primarywork and achievements are as follows:(1) Simulation of blast wave prorogation and its interaction with duplex hollow CFSTcolumn are studied. Using a explicit dynamic finite element analysis program,ANSYS/LS-DYNA, and with ALE fluid-solid coupling method, a finite element model ofCFST column is developed for simulating dynamic response and damage assessment.Furthermore, the influence of the mesh size effect on the numerical results is also analyzed.The results show that the mesh size has greater impact on the waveform and the propagationtime. The peak pressure decreases according to the mesh size increases. The simulating resultscorrespond with the experiment results well when the mesh density increases.(2) The explosion experiments in connection with CFST columns have performed. Theexplosion experiments have been executed for the popular CFST column and the duplexhollow CFST column respectively. By analysis about column macroscopic deformation andthe pressure values of measurement points at the scale distance of1.1m/kg1/3, the results showthat the popular CFST column still has a good carrying capacity and its deformation belongsto elastic stage. And by analysis about column deformation at the scale distance of 0.14m/kg1/3, the results show that the plastic bending deformation occurs on the surface facingthe explosive of the duplex hollow CFST column and there is a minor crack on the upside ofrib plate. So, it is important to strengthen the joint of column in order to keep the explosionresisting performance of duplex hollow CFST column.(3) Parametric studies are adopted to investigate the effects of column parameters ondynamic response and damage of duplex hollow CFST column. The results show that thehollow rate increases according to the decrease of pressure in the inner concrete. The resultsalso show that explosion resisting performance of the circular section is superior to the squaresection for the former has lower pressure value under the same explosive shock wave. And,the adjustment to the concrete strength grade has little effect on explosion resistingperformance. However, the adjustment to the scale distance has great effect on explosionresisting performance of duplex hollow CFST column. The peak displacement increasesquickly according to the decrease of the scale distance. The pressure on the surface facing theexplosive changes more sensitively according to the lower value of the scale distance.(4) Damage assessment criterion for duplex hollow CFST column are discussed andestablished. A pressure-impulse damage criterion for duplex hollow CFST column is definedbased on the deflection of the surface facing the explosive of the duplex hollow CFST column,and a numerical method to generate pressure-impulse diagram (P-I curve) is established. Andfinally, Damage assessment criterion is established to evaluate the damage situation for theduplex hollow CFST column under the condition of bending deformation.