Response of Steel Beam-to-Column Connections to Dynamic Loading

2001年9月11日事件的后果仍在世界各地产生反响。世界贸易中心（WTC）的建筑物倒塌使结构工程领域成为焦点，专业人士和公众都提高了对建筑物倒塌所造成的危险的认识。后世界贸易委员会的审议强调，并带来了尖锐的焦点，以前有限的辩论，在我们的知识的缺陷，框架建筑物的反应，意外或恶意损害。即使在9月11日袭击之前，美国政府的一个工作组就表示，渐进式结构倒塌是建筑物故障中受伤和死亡的主要原因，如果不是主要原因的话，无论荷载来源如何。因此，预测和设计以防止建筑物在特定攻击场景下的连续倒塌是（也应该是）一个主要目标。同一份报告指出...关于建筑物倒塌和建筑规范要求的指导将是有价值的。尽管人们普遍认识到大多数建筑物的破坏都包括建筑物的倒塌，但对连续倒塌的现象还没有很好的理解。虽然建筑规范告诫设计师要确保不发生倒塌，但它们并没有提供如何或应该如何实现这一目标的指导。他们的建议之一是，连续倒塌的性质和机制是一个值得学术界进一步研究的课题。这一专题在将近四分之一世纪的时间里没有得到有意义的讨论，但在减轻许多灾害的风险方面可能有好处。联合王国的情况与此类似。9·11事件前的一份报告承认，虽然对结构的要求是坚固的，以防止意外损坏是没有争议的，但目前还没有确定的基础来确定需要多少冗余，以提供一个可接受的安全水平，在发生损坏的情况下，或估计如何在受损的结构中重新分配的力量。同一份报告指出，建筑物固有的坚固性可能因结构分析和设计的进步而受到损害，这使设计师能够更准确地模拟结构。这一点，它认为，减少了通常的过度设计的结构框架，在追求经济的建设，并可能导致建筑物的鲁棒性降低。虽然目前英国的设计指南强调悬链线作用的重要性，以提供坚固性，防止损坏的框架建筑物，并随之要求的拉伸能力的成员和连接，在实践中，它可能是两个力矩阻力（在Virendeel桥接作用）和剪切阻力（碎片加载）的连接将同样重要。最近在英国和美国的权威出版物都强调了目前缺乏对螺栓钢连接的动力响应的知识，迫切需要关于不同类型框架结构对损伤的响应的权威数据（提议者已经在调查这一主题，而且这是先前研究提议的主题），本项目的总体目标是进行钢连接对动态荷载响应的试验研究，并将结果与现有设计建议进行比较。一系列典型的英国建筑中使用的连接将被检查，包括网络夹板，翅片板，部分深度，齐平和扩展端板。

The after-effects of the events of 11 September 2001 are still reverberating around the world. The collapse of buildings at the World Trade Centre (WTC) has thrown the field of structural engineering into the spotlight and professionals and the public alike have a heightened awareness of the dangers posed by the collapse of buildings. The post-WTC deliberations have highlighted and brought into sharp focus a previously limited debate on the shortcomings in our knowledge of the response of framed buildings to accidental or malicious damage. Even before the September 11 attacks, an American government working party stated that Progressive structural collapse is a primary, if not the leading, cause of injury and death in building failures, regardless of the source of loading...For this reason, predicting and designing to prevent progressive collapse of a building under a specified attack scenario is (and should be) a primary objective... The same report noted that ...guidance on building collapse and building code requirements would be valuable. The phenomenon of progressive collapse is not well understood, despite the widespread recognition that most building failures include building collapse. Although building codes admonish designers to ensure that collapse does not occur, they do not provide guidance on how this can or should be accomplished. Among their recommendations is The nature and mechanism of progressive collapse is a subject that merits further study by the academic community. This topic, which has not been addressed at a meaningful level for almost a quarter of a century, could have benefits in mitigating risks from many hazards. The situation in the United Kingdom is similar. A pre-September 11 report acknowledged that, whilst the requirement for structures to be robust against accidental damage is not disputed, there is presently no established basis for determining how much redundancy is required in order to provide an acceptable level of safety in the event of damage, or to estimate how the forces in a damaged structure are redistributed. The same report pointed out that, inherent robustness of buildings may have been compromised by advances in structural analysis and design, which have enabled the designer to model a structure more accurately. This, it argued, has reduced the usual over-design of structural frames in the pursuit of economy of construction, and may have resulted in buildings with reduced robustness. Although current UK design guidelines emphasise the importance of catenary action in providing robustness against damage in framed buildings, and the consequent requirement for tensile capacity of members and connections, in practice, it is likely that both moment resistance (in Virendeel bridging action) and shear resistance (to debris loading) of connections will be equally important. Recent authoritative publications in both the UK and USA have highlighted the current lack of knowledge of the dynamic response of bolted steel connections and there is a pressing need for authoritative data on both the response of different types of framed structures to damage (a topic already under investigation by the proposers and the subject of an earlier research proposal), and the dynamic behaviour of steel connections.The overall aim of this project is to conduct an experimental study of the response of steel connections to dynamic loading and compare the results with existing design recommendations. A range of connections typical of those used in UK construction will be examined, including web cleats, fin plates, partial depth- , flush- and extended endplates.