Study On The Characteristics Of Concrete Filled Steel Tube Under Explosive Load

Concrete filled steel tube(CFST) with high bearing capacity, good toughness and theconvenience for manufacture and construction is used widely in engineering. The research onthe characteristics of CFST under explosive load has important significance.The dynamic responses of CFST under explosive load are studied systemically in thepaper. The analyses are carried out with the dynamic characteristic of the constituent materials,the mechanical properties in CFST and the action principle of the blast. Combined with theequivalent single degree of freedom theory, the methods of numerical calculation to thedynamic response of CFST under explosive load are established; The experimental study ofsimply supported CFST with three different thickness are carried out under different explosiveload, measuring the blast pressure-time curves, the strain-time curves and the ultimatedeflections of the components. The results show that strain peak of components are decreasedand the time reached the peak is increased with the increase of the pipe thickness under thesame explosive load. The strain peak of components are increased and the time lasted of thestrain are longer with the increase of the dose in the same thickness under the differentexplosive load. Even if the shock wave overpressure value exceeds the ultimate bearingcapacity of the component, the final deflection is less than the deflection under the static loads.Because the duration of action is very short and the load has disappeared when the componentis too late deformation. The dynamic response of CFST is solved well according to equivalentsingle degree of freedom theory under explosive load by the comparison of theoreticalcalculations and experimental results. On this basis, the numerical simulation of CFST underexplosive load is achieved by LS-DYNA finite element analysis software. The dynamicprocess of components and the variation of the stress and displacement are revealed, theinfluencing factors of the anti-explosion performance of CFST are analyzed. The results showthat the main influencing factors of the anti-explosion performance of CFST are thickness ofthe steel pipe, yield strength of the steel pipe and the strength grade of concrete. Incomparison of three factors, the largest impact is the thickness of the steel pipe, followed byyield strength of the steel pipe and the strength grade of concrete. During the anti-explosiondesign, the strength grade of concrete should be higher than C30. These conclusions providethe technical guidance to use CFST in the actual work.