砌体结构长脉宽爆炸荷载损伤等级评估方法

A damage assessment method for masonry structures subjected to long duration blast loading

随着百千吨级当量爆炸工业事故的频繁发生,建筑结构的损伤评估和抗爆安全性更受到关注。目前,构件级的评估方法相对成熟,而大当量冲击波作用下的建筑结构整体毁伤评估依旧是个开放性问题。本文中,面向结构级的毁伤评估,提出了一种新的评估方法−构件损伤加权。该方法以承重构件损伤程度为基础,通过基于应变能的构件权系数加权,进而评估结构级损伤破坏程度。为了验证评估方法的有效性,以典型砌体结构为例,利用自主研发的冲击波结构毁伤模拟有限元程序,开展了百毫秒脉宽爆炸冲击波荷载下结构动力学响应数值模拟。根据数值模拟结果,结合构件损伤加权的评估方法,获取砌体结构损伤等级与冲击波超压的关系。预测的超压值的相对误差为−16.9%~26.2%,验证了评估方法的有效性。该评估方法为获取砌体结构的超压-冲量曲线提供了可行的途径,可为结构的抗爆安全设计提供参考。

With frequent blast accidents of hundreds of tons equivalent explosion, increasing attention has been paid to the damage assessment and anti-explosion safety of building structures. Some evaluation methods give procedures to obtain the pressure-impulse diagrams on the structural components. However, to the best knowledge of authors, how to evaluate the damage degree of building structures as a whole still remains open. In this paper, a weighted component damage method is proposed to evaluate the damage of structures subjected to long duration blast loading. The method, as its name suggests, is to define a damage degree of the whole structure by adding the damage degrees of all components in a weighted manner. The weight of a component, which represents its contribution to the anti-explosion safety, is defined by a strain energy based method. In order to verify the effectiveness of the proposed method, a high-resolution numerical simulation has been performed on a two-story masonry structure subjected to blast loading with a positive phase duration of 100 ms using a selfdeveloped parallel finite element program for shock wave structure destruction simulation. A support rotation criterion based on the flexural deformation model of components is adopted to determine the damage degree of load-bearing components such as brick walls, columns and floors. The damage degree of the whole structure is then obtained using the proposed weighted component damage method. Upon the overpressure-damage curve is obtained, interpolations was carried out to obtain the threshold values of the overpressure corresponding to the six predefined damage levels. The numerical predicted overpressure values were compared with those from literature data. It was shown that the relative error of the overpressure is between-16.9% and 26.2%,and the effectiveness of the proposed method was verified. The proposed assessment approach can be used to obtain the pressure-impulse diagrams of masonry structures and provide effective measures in protecting structures against blast loads.