【正文】 by a very modest gas explosion on the 18th floor led to new provisions in the UK Building Regulations, outlawing for many years of so called system built schemes, demolition of several pleted buildings, temporary removal of gas in high rise construction and the formation of the Standing Committee on Structural Safety. Eventually, the benefits of properly engineered prefabrication were recognised, safe methods for the installation of gas were devised and the industry moved on. However, the structural design guidance produced at that time that still underpins much present day provision was essentially prescriptive in nature with no real link to actual performance. Subsequent incidences of progressive collapse such as the Murragh Building and the World Trade Centre brought increased attention to the actual phenomenon and issues of how it might reasonably be taken into account for those structural designs where it was considered appropriate. In doing this it is, of course, essential to include both the risk of a triggering incident and the consequences of a failure so that the resulting more onerous structural demands are used appropriately. Arguably, a disproportionate response in terms of requiring costly additional provisions in cases where the risks/consequences are very low/very minor may be as harmful as failing to address those cases where the risks/consequences are high/severe. This paper will review current approaches to design to resist progressive collapse and contrast these with work undertaken over the past seven years at Imperial College London, where the goal has been the provision of a realistically based method suitable for use in routine design. The essential features of the method will be presented, its use on several examples described and results presented to illustrate how it is leading to a better understanding of both the mechanics of progressive collapse and the ways in which structural engineers can best configure their structures so as to provide enhanced resistance to resist progressive collapse The two most frequently used design approaches intended to address the issue of progressive collapse are:*c Providing tying capacity *c Checking alternate load pathsFigure 1: Tie Forces in a Frame Structure The first is essentially prescriptive and consists of ensuring that beams, columns, connections and floor (or roof) can act together to provide a specified minimum level of horizontal tying resistance?？惯B續(xù)倒塌，或者，更特別的是，了解力學的現(xiàn)象和發(fā)展適當?shù)姆绞?，以適應我們正常的框架內(nèi)審議的結(jié)構(gòu)設計，可以這么認為。取締了多年來所謂的系統(tǒng)構(gòu)建方案，拆除了幾個完整的建筑物，排除高層建筑物里的臨時瓦斯和建立建構(gòu)安全方面的常務委員會。該方法可以在分析方面的高度化的不同程度被實現(xiàn)；比如，在美國最近的研究為線性靜力分析，非線性靜態(tài)或非線性動態(tài)分析制定規(guī)定和為各自的使用提供一些指導。 圖3：單梁的非線性靜力反應*a) 首先拉力組件的產(chǎn)生（支撐連接的頂級螺栓排）*b) 其中的一個連接（支撐）的光束翼緣的總功率*c) 系統(tǒng)的總功率（底部中跨連接的螺栓行的破壞）*d) 軸向載荷變成零（在軸向載荷從抗壓到抗拉變化的地方的梁的撓度）*e) 一個連接的翼緣力在軸向荷載變相等的地方的梁的撓度參考文獻[1] Gudmundsson GV and Izzuddin BA. The Sudden Column Loss Idealisation for Disproportionate Collapse Assessment. The Structural Engineer。 2010 [12] Vlassis AG. Progressive Collapse Assessment of Tall Buildings。*c 該方法可以實現(xiàn)在結(jié)構(gòu)，亞結(jié)構(gòu)，地板格柵或單梁的標準（見圖2）.*c 一個現(xiàn)實的破壞標準被采用，對應于在連接中到達延性限制。無論如何，近代研究（Nethercot et al 2010a。但是,近年來,發(fā)展成為一個復雜的消防工程學科，關(guān)心火災荷載，提供防護系統(tǒng),如灑水裝置，在發(fā)生火災情況下的反應的計算,能夠使定量對比結(jié)構(gòu)安排之間選擇。 for example, recent thinking in the United States (SEI 2010) makes provision for any of: linear static, nonlinear static