The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA. The multi-material Eulerian and Lagrangian coupling algorithm was adopted. A flu-id-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground, multiple ALE element for simulating air and TNT explosive material. Numerical simulations of the blast pressure wave propagation, struc-tural dynamic responses and deformation, and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed. The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure. The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation. The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic defor-mation subjected to intensive blast waves, and columns lost carrying capacity, subsequently lead-ing to the collapse of the whole structure. The approach coupling influence between struc-tural deformation and fluid load well simulated the progressive collapse process of structures, and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load.
首先提出了定量化研究结构振动的主动质量驱动AMD(Active Mass Driver)控制系统主动控制力方向等特征的一系列指标,包括表征主动控制力与质量块相对运动速度和相对运动位移等的方向关系、主动控制力与AMD子系统惯性力峰值和均方值的比例关系等指标。其次以一个单自由度结构受AMD系统控制为分析对象,设计三组代表性工况进行数值分析,采用经典线性二次型最优LQR(Linear Quadratic Regulator)控制算法,研究了AMD系统主动控制力特征指标、结构振动控制效果与控制算法参数和系统输入荷载等的相互关系,系统地分析和总结了AMD系统主动控制力特性及其控制效果影响因素。最后基于定量和定性分析结果,得出不能采用半主动变阻尼控制装置取代AMD系统中的作动器来实现主动控制的结论。
针对传统伺服阀控液压作动主动质量驱动控制系统(Active Mass Driver,AMD)存在的能源效率低等问题提出基于无阀作动器的直驱式DAMD(Direct driving Active Mass Driver)控制系统。首先分析了直驱式容积控制作动器的组成和控制原理及其用于AMD控制系统的策略;其次基于电机学、流体动力学原理推导建立了DAMD控制系统的转速-驱动力关系模型,给出了以泵的转速(伺服电机的驱动电压)为输入量、系统主动控制力为输出量的系统转速-力关系模型,建立了受控结构-DAMD控制系统的状态方程。最后以顶部设置DAMD控制系统的两层剪切型框架结构为例,进行地震荷载输入下DAMD主动控制的数值分析,计算结果表明直驱式容积控制作动器能够满足各种结构地震响应主动控制典型工况的出力需求,能够有效地减轻结构的反应,在一定范围内可以代替传统的AMD控制系统,实现结构振动的主动控制。
