Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I
Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I
复制标题
由于结构设计中圆柱体上的衍射和/或冲击波的多重反射而产生的峰值超压和脉冲 - 第 I 部分
DOI：
--
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Rutner
中科院分区：
文献类型：
--
作者：
A. Hahn;Martin Mensinger;M. Rutner
柱子等结构部件的设计和规划以抵御爆炸荷载是一项复杂的任务。通常使用设计规范或其他文献中规定的标准自由场爆炸载荷来分析目标。然后，根据周围几何体的拓扑(Mach-Stem)、受影响对象本身的形状和冲击波反射，进一步增加或减少这些载荷。然而，这些研究工作大多纯粹专注于对结构构件本身的评估，而忽略了复杂的流体力学现象，如绕射，当圆柱子挨着站立或放置在立面之前时，这是特别有趣的。这篇文章涉及三个主要主题。首先，文章回答了柱后区域是否受到保护的问题，即构成阴影区域。我们提出的发现是，柱子后面的封闭区域会受到更高的压力和脉冲值的影响，就像没有柱子时一样。因此，由于绕射，入射压力有很大的积聚。这种压力积累是用压力增加系数来量化的，并与伴随的冲量一起表示。其次，这种压力积累与柱后立面的现实设计相关，而目前的设计规范根本没有涉及这一点。对设计过程中的相关参数进行了讨论。第三，与对柱后因绕射而产生的压力的评估直接相关的是对柱后区域由于立面处的多波反射而产生的压力和脉冲的评估，这可能会对柱和/或立面的设计产生重大的压力和脉冲放大。本文找出了在结构设计框架内对爆炸波的绕射和随后的多次反射的理解方面的差距，并就如何建立考虑这些影响的安全设计提供了见解。
The design and planning of structural components, such as columns, to resist blast loads is a complex task. Often standard free-field blast loads, specified in design codes or other literature, are used for the analysis of the object. These loads are then further increased or decreased depending on the topology of the surrounding geometry (Mach-Stem), the shape of the impacted object itself, and blast wave reflection. However, most of these research works focus purely on the assessment of the structural components itself, ignoring a complex fluid mechanics phenomenon such as diffraction, which is of particular interest when circular columns are standing next to each other or placed in front of a façade. The article addresses three main topics. First, the article answers the question whether the area behind the column is protected, meaning constituting a shadowed area. We present findings that the close area behind a column is subjected to higher pressure and impulse values as there would be without the column. Hence, the incident pressure sees significant pressure buildup due to diffraction. This pressure buildup is quantified using pressure increase factors and presented together with the accompanying impulse. Second, this pressure buildup is of relevance for realistic design of a façade behind the column, which is not covered in current design codes at all. We discuss relevant parameters in the design process. Third, directly coupled with the assessment of the pressure buildup behind the column due to diffraction is the assessment of pressure and impulse in the area behind the column due to multi-wave reflection at a façade, leading to a significant pressure and impulse scale-up, which might be relevant for design of a column and/or a façade. This article identifies gaps in understanding diffraction and subsequent multi-reflection of blast wave within a structural design framework and provides insights on how to establish safe design accounting for these effects.