Numerical Simulation And Application Of Highway Bridge Demolition Blasting

Highway Bridge Demolition Blasting is a complicated dynamical process including loading for structure, generation and development of crack, fragment and displacement of structure, impaction of structure and collapse of bridge. because of much difference in the geography condition, many type of bridge structure and many different technique requirement, the construction condition for highway bridge blasting demolish is bad and the technique designation is faultiness, which results in sporadic unsuccessful blasting accident and bring large difficulty and danger to subsequent work. If we can simulate the overall process of bridge collapse under the design scheme by computer, and optimize the design scheme basing on the simulation results, we can reduce the construction cost and promote the transformation of highway bridge blasting demolish design from coarse to fine, which is important for advancing technique innovation. The ANSYS code is employed to construct common node separate finite element model and the LS-DYNA code is employed to simulate the highway bridge collapse process. The results are used to analysis the mechanism of reinforced concrete bridge demolish blasting. The main content of paper is as follows:(1) The common node separate finite element model for bridge structure is constructed. For the bridge demolish blasting, the intention of local breakage of bottom structure is for unstable and local breakage of top structure is for disaggregation more sufficient. The object of breakage mainly is reinforced concrete structure. Because the physics character of steel bar and concrete are different, the common node separate finite element model is adopted in the paper. When some one element is invalidation, it will be deleted automatically and lose the carrying capacity.(2) Basing on the practice case of Highway Bridge demolish blasting, the real size finite elements model of Highway Bridge is constructed and their collapse process in the design scheme is simulated with LS-DYNA code, the feasibility of design scheme is verified by numerical simulation. At the same time, the practice of Highway Bridge demolish blasting verifies the validity of numerical simulation. (3) The numerical simulation method of Highway Bridge demolish blasting is implemented in many projects and proved to be successful.The total process of highway bridge from detonation to structure collapse is reappeared by numerical simulation, the collapse mechanism of middle span and aside span is analyzed detailedly and the curves of stress and strain of steel and concrete VS time are obtained. The results of numerical simulation are very approximate to practice engineering. The study results show that it is feasibility to simulate the collapse process of reinforced concrete structure as highway bridge with LS-DYNA code and common node separate finite element model. The simulation results has guidance significance for the design and practice of blasting demolish engineering.