Unstable Analysis And Collapse Simulation Of Frame Construction By Blasting Demolition

As a special way of demolition, blasting demolition has been widely used in city's construction demolition. For more and more constructions need to be demolished in city's transformation, and it becomes harder to demolish high constructions, which has been confirmed by several unsuccessful blasting examples in the world in recent years, mostly because that fixing blasting parameters is based on empirical formulas, and the research on demolition which relies on the constructions'structure is not deep enough. Its theory has obviously fallen behind the practice. So it is necessary to research on the construction blasting demolition. Combined with the collapse mode, this paper majors in the dynamics analysis of instability collapsing of the frame structure construction's blasting demolition. Using finite element and ANSYS/LS-DYNA simulate the course of collapse occurring during blasting demolition by computer.(1) Introduce the type of frame-structured construction and the stress system of bearing structure. The structure's transverse direction and long direction system bracing for each other, improving both rigidity and load bearing ability greatly. According to the different features of blasting demolition, combining with detailed cases, reclassify the collapse mode of frame-structured construction, and research on the condition of instability collapse, building the mechanical model of the frame construction's blasting demolition.(2) Combine with the usual mode of blasting demolition, kinetic equations are applied in analyzing the course of the construction collapse. Separately researches on the single-span frame construction's collapsing multi-span frame construction's level collapsing part by part and frame construction's directional collapsing, and figure out the approximate analytic solution to the collapse.(3) Introduce the ways and steps when apply ANSYS/LS-DYNA in simulating the collapsing of frame construction's blasting demolition. Entity unit (SOLID164) was first used to build frame construction model. According to the structure features of frame construction, beam and column nodes are dealt with previously to build finite element model. Keywords *LOAD_BODY_GENERALIZED are used to simulate exerting gravity, and keywords like *MAT_ADD_EROSION are used to define the material invalidation to simulate the formation of blasting incision. Also, it explains the key files which need to be added or modified during simulating.(4) Concrete examples are applied in simulating the collapsing of frame structure with the finite element software ANSYS/LS-DYNA. Compared with actual engineering data, result of the simulation analysis has come to an expected effect. Comparative analysis among different blasting projects about collapse's form and the factors which affect the simulation has shown that when other parameters are not changed while the altitude of blasting incisions and the intervals are different, then it will have some effects on blast altitude, the apogee's distance and the time it takes to collapse.