Numerical Simulation Study On Blast Induced Collapse Of Thin Wall Tubular Structures Using Ls-dyna

The cooling tower is a special kind of structure,its wall thickness far smaller than the radius of its bottom section,the height-width ratio very limited,the wall along height not a straight line but a curve,demolition of such buildings is also no uniform theory.A numerical simulation study of this kind of structure based on an actual cooling tower blasting demolition will be discussed in this paper.As most plans used in cooling tower blasting demolition are derived from the successful experience of traditional high-rise structure at present,reviewing the traditional structure of the collapse of the principle is necessary,on this basis,by comparing two different structures of the structural characteristics,combining characteristics of the collapse acquired from the video of actual cooling tower blasting demolition,made specific collapse theory for this kind thin wall tubular structure:(1) The structure obviously makes sports of sitting wholly,the tower wall is easy to be destroyed then deformed and turned back;(2) when the blasting kerfs closed and touched the ground,because the tower wall is the curve type,can't form rational receiving the strength state,will accelerate the destruction of the tower wall;(3) The structure whole and huge,affected by inertia theory,will cause the tower wall stretching and squeezing damage;(4) the collapse of movement similar to the traditional rotation collapse in the early stage, but more of a free collapse.in the final time.Blasting projects can not be repetitive,which caused a lot of inconvenience for our study. The introduction of numerical simulation technology well solved this puzzle.The FEM (finite element method) software ANSYS/LS-DYNA is suitable for the numerical simulation study of blasting demolition since its powerful large deformation dynamic analysis.This paper focused on the main factor of the problem,established a reasonable numerical model, and better simulated the entire process of the structure collapse with the help of restart analysis technique.Combining with realistic projects,the simulation result verified the collapse theory of thin wall tubular structure talked above and provided a large number of data concerning the diversification of stress and strain.The collapse of thin wall tubular structure is a very complicated process,traditional research methods there are many limitations,and the research with the help of numerical simulation technology is a positive attempt.Along with the development and improvement of technology,numerical simulation study will play an increasingly important role in the field of blasting demolition.