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61.
Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion
Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation , is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations , a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. The final conclusions based on the numerical results will provide some guidance in engineering practice. 相似文献
62.
Based on phase-plane orbit analysis, the mathematical model of piecewise-smooth systems of multidegree-of-freedom under the mode coordinate is established. Approximate analytical solution under the physical coordinate of multi-degree-of-freedom self-excited vibration induced by dry friction of piecewise-smooth nonlinear systems is derived by means of average method, the results of which agree with those of the numerical solution. An effective and reliable analytical method investigating piecewise-smooth nonlinear systems of multi-degree-of-freedom has been given. Furthermore, this paper qualitatively analyses the curves about stationary amplitude versus rubbing velocity of hands and versus natural frequency of hands, and about angular frequency versus rubbing velocity of hands. The results provide a theoretical basis for identifying parameters of the system and the analysis of steady region. 相似文献
63.
64.
65.
An adaptive terminal sliding mode control (SMC) technique is proposed to deal with the tracking problem for a class of high-order
nonlinear dynamic systems. It is shown that a function augmented sliding hyperplane can be used to develop a new terminal
sliding mode for high-order nonlinear systems. A terminal SMC controller based on Lyapunov theory is designed to force the
state variables of the closed-loop system to reach and remain on the terminal sliding mode, so that the output tracking error
then converges to zero in finite time which can be set arbitrarily. An adaptive mechanism is introduced to estimate the unknown
parameters of the upper bounds of system uncertainties. The estimates are then used as controller parameters so that the effects
of uncertain dynamics can be eliminated. It is also shown that the stability of the closed-loop system can be guaranteed with
the proposed control strategy. The simulation of a numerical example is provided to show the effectiveness of the new method.
Project supported by the National Outstanding Youth Science Foundation of China (NSFC:69725005) and the Zhejiang, Provincial
Natural Science Key Foundation of China (ZD9905) 相似文献
66.
采用测斜技术,观测和分析天荒坪大溪滑坡体的位移发展规律,并与稳定性计算相结合,揭示滑动后残余边坡体的工作状态,为滑坡体研究和治理提供依据。 相似文献
67.
陈松清 《长江工程职业技术学院学报》1999,(4)
论述了负摩阻力产生的条件及负摩阻力随桩基类型不同对桩基承载力和沉降的影响有所区别; 指出关于负摩阻力标准值计算的有关方法, 同时对负摩阻力在群桩效应下基桩的下拉荷载标准值的计算方法进行了探讨。 相似文献
68.
吴泽庆 《南京晓庄学院学报》1999,(4)
运动的汽车,受着地面给它的摩擦力作用,并在摩擦力作用下沿摩擦力的方向运动了一段位移。摩擦力对运动的汽车是否作功?本文从体动力角度和功的定义这一基本概念出发,分析了摩擦力对运动的汽车并不作功,但摩擦力却起到将汽车发动机中的内能转化为运动汽车的动能的作用。 相似文献
69.
通过运动学分析的方法,对我国参加2008年北京奥运会的三名优秀女子铅球运动员的滑步技术进行研究,发现巩立姣在滑步阶段右腿的蹬伸方式不合理,蹬摆配合不好,右腿收拉不积极,滑步距离小、用时多.李玲右腿蹬伸充分,滑步距离较长.李梅菊滑步阶段身体重心上下起伏的程度小,滑步技术好. 相似文献
70.
现阶段,加工贸易在我国国民经济中发挥着积极的作用,这是其它的贸易方式不可替代的。同时,我国加工贸易也面临诸如双刃剑效应、监管方式不适应、加工贸易内销问题及对加工贸易企业分类管理的争议等一系列情况。另外,由于我国的社会主义市场经济体制仍处在完善之中,现阶段还存在一些制约因素。认清我国加工贸易面临的挑战,并努力克服,才能使加工贸易健康稳定地发展。 相似文献