水平及抗弯约束对梁抗爆动力响应的影响分析

Analysis of Dynamic Responses of a Beam Under Explosion Loadings with Horizontal Supports and Rotational Restraints

边界约束的差异会直接影响结构的抗爆动力响应及承载能力,建立了水平弹性约束和抗弯约束条件下抗爆梁在弹性阶段的数值差分计算方法和塑性阶段的理论解析方法,并计算分析了水平约束刚度、荷载形式以及屈服弯矩动力强化系数对动力响应的影响。计算结果表明,在塑性阶段,水平约束和抗弯约束影响结构的动态响应显著,水平约束使梁截面在变形过程中产生横向压力,抗弯约束直接限制刚体转动,均有效降低了梁位移动力系数,相对提高结构的承载力。相同约束刚度和荷载峰值条件下,平台荷载下结构的位移动力函数均高于三角形荷载下位移动力函数,说明动力荷载的作用时间越长,对结构承载越不利。另外考虑屈服弯矩的动力增强系数时,可提高结构的抗爆潜力。

The differences of boundary restraints do directly affect the dynamic antiknock responses and bearing capacity. The different method of a beam with horizontal flexible supports and rotational restraints in elastic stage and the analytical method in plastic stage of the one under explosion loadings, the effects of horizontal supporting stiffness, load shape and the dynamically intensifying coefficient of yielding bending moment on responses are analyzed. The results show that Horizontal supports and rotational restraints have great effects on dynamic responses, horizontal supports exert transverse pressure on section in deformation process, rotational restraints confine the rotation of rigid body directly, they both reduce the dynamic coefficient of displacement, so the resistances of the beam can be relatively increased. Under the condition of the same constraint stiffness and the same peak load, the dynamic coefficient of displacement of a beam under rectangular loads is always higher than the one under triangle loads, so the longer actuation duration the more negative for bearing capacity. In addition, antiknock potential can he improved by taking intensifying coefficient of yielding bending moment into account.