中文摘要：

在爆炸冲击荷载下,地下框架结构的动态响应是一个复杂的非线性过程。本文首先介绍了模拟连续倒塌的3种方法（即替代传力路径法、直接模拟法和三阶段模拟法）和本文所采用的数值模型;其次,本文运用LS-DYNA显式动力分析软件相关功能,建立钢筋混凝土的三维分离式模型（钢筋和混凝土的连接采用共节点方式）,将本文采用的三阶段模拟法与直接模拟法、替代传力路径法对比分析,验证了本文方法的合理性及有效性;再次,具体阐述未做防护的地下结构在爆炸荷载作用下的倒塌机理,并为防护提供一定的理论指导;最后提出了两种防护措施（改变梁的箍筋间距）,并对比两种防护措施的防护效果,通过对比可以为抗爆设计提供一定的设计依据。计算结果表明：在爆炸荷载下,未做防护的结构破坏十分严重,并最终连续倒塌,做防护的结构整体性完好,没有发生连续倒塌。

英文摘要：

The dynamic response of underground frame structure subjected to blast load is a complicated nonlinear process. First, three methods simulating progressive collapse （alternative load path method, direct simulation method and three-stage simulation method） and numerical model used in this paper are introduced. Secondly, the related functions of the LS-DYNA explicit dynamic analysis software are used to build a three-dimensional discrete model of reinforced concrete （connections of steel bars and concrete are treated as node sharing method） , and the reasonableness and validity of the present method are verified by the way of comparing three-stage simulation method （TSSM） used in the article with direct simulation method （DSM） and alternative load path method （ALPM）. Furthermore, the collapse mechanism of unprotected underground structure under blast load is presented, and the certain theoretical guidance for protection is provided. Finally, two protective measures （ changing the spacing of the beam stirrup） are proposed and the protective effect of the two protective measures are contrasted, and it can provide certain basis for explosion resistance design. The analytical result shows that under blast load the unprotected strueture damages seriously and collapses finally, while the protected structure doesn＇ t collapse due to its intact integrity.