| Explosive blast resulting from explosion shares an high initial value,fast decay and short duration,but large destruction to constructions,so that studying structure' s plastic limit under explosive blast has an important application value.This article conducted extensive literature research for domestic and foreign anti-explosive design methods,with aiming at the characteristics of blast loads,we bring forward a explosion-resistance analysis method for multistory multispan frame structure by using the plastic limit theory --- the plastic limit method.Its' aim is to find the multistory multispan frame structure's plastic limit load (using stiffness increment variation method),and the plastic limit state of stress(or internal force) distribution and the formation of collapse mechanism.In this study,the main part of the contents of the following:(1) In accordance with explosive blast basic theory,identified the calculation formula of the explosion shock wave overpressurevalue(â–³P_m ).(2) Carried out numerical simulation to dynamic characteristics of the blast,got the equivalent shock overpressure(â–³P_m ) into node loads(P_m ),then got the equivalent dead load (P)of dynamic load(P_m )by using dynamic equivalence theory and spreaded to multistory multispan frame structure.(3) Analyzed the multistory multispan frame structure's plastic limits by using plastic limit theory,through using stiffness increment variation method,got ultimate load of plastic and the stress(or or internal force)and the final collapse mechanism.(4)Compiled the calculation procedures of the above-mentioned method by using Fortran 95 languages,done an analysis of simulated examples,then done comparison and analysis to the calculated results and the calculated results of sap2000.(5)Established the relationship between structures'ultimate collapse mechanism and explosive usage and explosive distance,then indentified the shelter distance of structure. In the end,the content of this paper has been summarized and some problems,which need further study,have been proposed. |
