| Reticulated shells as a typical long-span spatial structure, once destroyed by the explosion, the collapse will bring great loss of life and property. Therefore, it i s necessary to carry out anti-knock properties and defense design of the reticulated shell structures to ensure the structural safety and minimize disaster losses. In addition, setting explosion-protection wall around the building can effectively reduce structural damage caused by the impact of the explosion, which is one of the important protective measures for reticulated shell under terrorist bombing attacks. In this paper, theory and numerical simulation on properties and defense methods for kiewitt8 single-layer reticulated shell were studied using finite element(FE) analysis software LS-DYNA, details as follows:(1) Based on the blast experiment of Luoyang Institute of Hydraulic Engineering and Technology, propagation of blast shock waves around explosionprotection wall was simulated. The overpressure-time curve of FE modal had good agreement with the experiment and the maximum error of reflection and diffraction overpressure is less than 20%. Therefore, the ALE(Arbitrary-Lagrange-Euler) algorithm, material model, state equation and parameter setting were feasible to analyze the influence of explosion-protection wall on blast shock wave.(2) To study the performance of reticulated shell with explosion-protection wall under blast loading and grasp the influence of explosion-protection wall parameters on structural dynamic response, Kiewitt-8 single-layer reticulated shell with span of 40 m was established to simulate. The dynamic responses of structure with explosion-protection wall subjected to external blast loading and the response rules of the structure in varied height, position, length of explosion-proof wall and span ratio of reticulated shell are obtained using ALE algorithm. The effect of circulating action of blast shock wave and reflecting action between the structure and explosion-protection wall on the structure were analyzed. Adverse height of explosion-protection wall including specific values was proposed and four damage types of reticulated shell with the explosion-protection wall were defined by summarizing all the structural response of FE numerical models under different TNT explosion weights, which could provide reference for reasonable defense design of reticulated shell structure.(3) A theory analysis model is introduced to establish the Lagrange equilibrium equations according to Hamilton’s principle, and MATLAB is used to solve the numerical solution of differential equations to obtain the structural dynamic response under blast load, including the maxmium node displacement and velocity, kinetic energy and internal energy within the system. To verify feasibility and applicability of the simplified calculation method when using it study structural dynamic response under blast load, the method is applied to a simply supported beam firstly, results showed that: the vibration law and peak displacements correspond well with results of FE analysis. Then, the simplified calculation method is extended to calculate dynamic response of K8 single-layer reticulated shell under triangle blast load. Influence rules of the parameter numbers in deformation function and the peak load on results were analyzed. Finally, based on the error analysis of results of theory analysis model with LS-DYNA FE analysis, the simplified calculation method is improved. The applicability of this simplified calculation method when using in calculating dynamic response of reticulated shell under blast load is summarized. |
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