Recent Lessons Learned in Structural Fire Engineering for Composite Steel Structures

The knowledge in the field of structural fire engineering has been greatly advanced through assessment of a number of real fires (WTC, Torre Windsor, Broadgate, etc.) and, especially, by the Cardington series of full scale structural fire tests. This knowledge has been used to validate and verify the use of computational finite element models that have expanded the range of structures that can be investigated under severe fire exposure. This paper presents a selection of key lessons learned by the authors through the assessment of structures in fire for real commercial building projects. The key areas of sensitivity that have been encountered are described and a discussion of each point presented. The paper is aimed at describing potential weaknesses that have been observed in the commercial work of the authors, often driven by the requirements for efficient ambient structural design. The paper concludes with some suggested advice for structural engineers aimed at increasing the general robustness of building structures. This is based on designing out as far as possible in the ambient design of a structure the potential weaknesses identified in past project work.     

建筑消防设计审核及相关问题研究

伴随着改革开放的日益发展,社会经济进行着飞速地增长,建筑工程消防设计越来越重要,但从目前来看其问题已日益突出。文章从建筑工程消防设计审核的必要性出发,浅析建筑工程消防设计需要审核的内容及若干在审核过程中易忽视的问题,提出一些个人总结的经验。以便能够引起大家的注意,避免在审核工作中出现类似的错误。     

Analysis of heated structures: Nature and modelling benchmarks

The move from using the standard fire test for structural fire design towards more rational design methods has led to an increased requirement for numerical modelling of structures in fire conditions. Such modelling is demanding and requires the inclusion of a number of phenomena that can usually be disregarded at ambient temperature. This paper identifies the key phenomena needed for accurate high temperature structural modelling and highlights their importance by reference to a conceptually simply but structurally complex problem. Consideration of this problem also highlights areas where relying on the standard fire test for structural fire design may lead to unconservative designs. The paper then proposes and defines two benchmark problems that will allow analysts to show that their modelling approach is valid and that the software they use is capturing all the required phenomena.     

Finite Element Modelling of Post-tensioned Timber Beams at Ambient and Fire Conditions

An increased environmental conscientiousness in society and the abundance of timber in Canada has inevitably led to the desire for more timber construction. In order to increase the opportunity for timber products in construction, novel building systems such as post-tensioned (PT) timber have been developed. Limited development on numerical modelling has been done on PT timber systems for the optimization of design for fire performance. In industry, there is need for a modelling software capable of approximating complex timber system behaviours that is accessible to practitioners. This research program serves to evaluate the current capabilities or shortcomings of modelling PT timber in both ambient and fire conditions, and to develop a methodology for analyzing the performance of the system. Several numerical models of PT timber beam tests are developed and validated using general purpose FEM software ABAQUS. This software is a good research tool and the lessons learned may be used to refine an accessible model for practitioners. Various material definitions are compared including isotropic and orthotropic models. The numerical models show highly promising results for demonstrating the loading and failure behaviour of PT timber beams. Material property directionality is paramount, captured best with the use of Hill’s Potential Function for non-elastic behaviour. Ambient beam tests are modelled with accurately demonstrated load–deflection behaviour and peak loads are computed to within 5% of experimentally recorded values. For PT timber beam standard fire furnace tests, beam failure times are modelled within 3 min of experimental beam failure times for various fire exposure durations (about 5%), and load–deflection behaviour and failure mechanisms are accurately demonstrated. Thermal gradients align with the recorded thermocouple readings and char depths are computed within 4 mm of the observed layers.     

钢结构抗火设计在“上海水立方”中的应用

随着性能化结构抗火设计的发展,结构的抗火能力和相应的结构防火保护措施可以通过对结构在真实火灾温度场下的实际性能分析来确定。对于大空间结构,根据其内部的可燃物、通风条件和空间大小等特性,采用性能化结构抗火设计往往可以不影响结构抗火安全水平的前提下降低对结构进行防火保护的要求,实现安全、美观且经济的建筑设计。本文将介绍工程设计实践中行之有效的性能化结构抗火设计方法,并以上海东方体育中心的大空间结构抗火设计为例,证明该钢结构抗火方法的切实有效性。     

Recent developments and applications in structural fire engineering design—A review

This review outlines some of the major developments that have occurred in structural fire engineering design during recent years.

The general principles used in fire engineering are discussed together with the various approaches that can be adopted by an architect or engineer to design a structure capable of withstanding the attack of fire without collapsing, using scientific concepts as a basis for determining the fire resistance and protection requirements. Details are provided of recent full-scale tests and research work either completed or in hand with the aim of producing design concepts and information which the fire engineer may use. Examples are discussed to show how structural fire engineering has been utilised in both large and small buildings to precisely define the fire resistance and protection requirements of steel frameworks. In some instances, estimates of the financial savings realised in following this type of approach are also given.     

北京天文馆营建史探赜

现代天文馆是1920 年代诞生于德国的一种新建筑类型,是光学、电气、机械制造、结构设计等多个工程学科合 作的成果,不但利用新技术创造出新的建筑新形象,星空剧场的演示方式也成为人们的新娱乐方式,在科学和社会等 方面产生了重要变革。本文追溯德国天文馆建筑设计的缘起及其在世界各国的传播和改进,在此基础上论述1954— 1957年间北京天文馆筹备建设的策划和建设过程,讨论最早使用喷射混凝土技术的这一新中国著名建筑的设计和 施工特点及其经验得失。     

Performance-based analysis of large steel truss roof structure in fire

Due to the fast developments of large-space multi-functional architectures, large-span steel structures have been widely used in recent years. Therefore, the fire-resistance design of this kind of structures has attracted more attentions. Since traditional ISO834 standard fire curve is not suitable for large space structures, performance-based fire resistance design method is required. This paper presents the comprehensive case studies on the fire performance of a large space exhibition centre in Shanxi province, China under real fire scenarios including heating and cooling phases. The non-uniform fire temperature fields of the large space exhibition centre for the designed fire scenarios have been generated by using Fire Dynamic Simulator (FDS). A finite element (FE) model has been developed using FE software ANSYS for modelling the structural behaviour of the exhibition centre under different fire scenarios. Based on the results generated in this research some recommendations for the fire resistance design of large space steel truss structures have been proposed.     

Deformation-reversal in component-based connection elements for analysis of steel frames in fire

A previous paper covered the principles of practical modelling of common steel beam-to-column connections in frameworks at elevated temperatures, using a component-based approach to represent the main structural actions generally grouped at bolt rows. This is needed for the structural modelling which is a necessary part of performance-based structural fire engineering design based on analysis of a range of natural fire scenarios. This paper extends the treatment of components to the effects of change of temperature during an analysis. This includes the treatment of reversal of displacement, which is essential in order to allow components within the whole model to change their temperatures, even when temperatures are increasing monotonically. Reversal curves, and their Intersection Points with the zero-force axis, are used to link the states of deformation of any component on adjacent force–displacement curves at different temperatures. A desirable feature of this treatment is that it encompasses the effects of cooling after heating, which has been observed in full-scale tests to cause failure of connections as beams contract. A simple sub-frame model including beams, columns and endplate connections, has been analysed using the component-based model, in order to illustrate how the connection and its components behave, and how failure develops when the members and connections are subjected to a heating–cooling sequence.     

Hospital learning from extreme weather events: using causal loop diagrams

Extreme weather events (EWEs) represent an important opportunity for hospital facilities managers to learn lessons to improve future hospital resilience. However, little is known about the process by which this occurs and how effectively this happens. These questions are addressed by an exploration of how individual hospital stakeholders learn about the performance of their facilities and share these lessons in the adaptation of future hospital disaster management plans. More specifically, the evidence of behavioural and social/collective learning is investigated amongst hospital stakeholders during EWEs. The data gathered from a case study of a major hospital network of four hospitals were qualitatively analysed within a constructionist ontology and interpretivist epistemology using causal loop diagrams (CLDs). This revealed how lessons were learned in the hospital network from collective stakeholder EWEs’ experiences. The findings highlight the need to develop appropriate processes and structures to capture, share and use facilities-related knowledge and embed new lessons learnt into future hospital disaster planning processes. Using Nonaka and Takeuchi's model of organizational knowledge creation, this paper presents new theoretical and practical insights for hospital facilities managers to build hospital resilience by better capturing the facilities-related lessons learnt in responding to an EWE.     

Representing Design Knowledge with Neural Networks

Neural networks have been used in a number of civil engineering applications because of their ability to implicitly learn an input–output relationship. Typically, the applications involve deriving an input–output relationship for problems that may be too complex to model mathematically, computationally expensive, or difficult to solve using the traditional procedural computing approach. Heuristic design knowledge used by structural engineers when performing structural design often falls in the latter category of being difficult to represent procedurally. Neural networks have been investigated for the representation of heuristic design knowledge, and the results of this investigation and the lessons learned regarding neural network training are presented.     

浅析社区会所火灾应急照明强起的设计

结合一社区会所案例,阐述火灾应急照明强起设计存在的误区及正确实施的必要性,对如何可靠及时的实现火灾应急照明的设计与投入运用提出一些需要注意的问题,以飨读者。     

钢-混凝土组合结构抗火性能研究与应用

钢-混凝土组合结构抗火性能研究是当前的研究热点之一,国内外学者对此展开大量试验研究和理论分析。通过介绍国内外研究者在组合板、组合梁、组合柱等构件以及结构节点和结构体系抗火性能方面研究概况,分析了我国现有防火设计规范的特点以及工程应用情况,指出现有研究的不足,对组合结构抗火研究领域在高温材料热-力耦合本构关系、计算理论、数值火灾试验和设计方法等方面需进一步研究的工作进行了展望。文中指出,建立考虑升降温、多轴应力状态、不同加卸载路径的钢材和混凝土热-力耦合本构关系,建立基于整体性能、考虑升降温全过程的结构抗火分析理论,建立整体结构数值火灾试验方法,提出“三水准”结构抗火设计与灾后结构损伤评估原则以及基于时变可靠度和结构整体性能的组合结构抗火设计方法是钢-混凝土组合结构抗火性能研究的关键科学问题。表2参119     

Three‐dimensional computer‐aided finite element method retrofitting modeling and non‐destructive testing techniques for the assessment of actual existing high‐rise fire‐damaged reinforced concrete building

Concrete is generally fire resistant. A fire in a concrete structure rarely results in a serious damage as to require substantial demolition. But, loss of the utility of a building could result in serious financial consequences for the owner, which calls for immediate reinstatement. To work out proper and efficient repair strategy, however, would require a thorough investigation of the effect of fire on the structural properties of the concrete and steel; the significance which any permanent change in material characteristics may have on the future structural performance of the member; the feasibility of repairs to compensate of any unacceptable reduction in structural performance, durability, and so on; and the influence which fire exposure of individual member may have on the performance of the entire structure. These all said tasks are dependent on the complete analysis of the fire‐damaged building. Without it, no repair works estimation, extent of repair and kind of repair can be carried out for the fire‐damaged buildings. Therefore, the impeccable analysis and design is of utmost importance for repair of such buildings after preliminary investigation of the extent of fire damages to the concrete structural members. This forms the basis of this research study, which aims at detailed analysis and design of the actual existing high‐rise fire‐damaged buildings for fire retrofitting and assessment of fire damages by non‐destructive techniques. Fire damages in buildings due to explosion, accidents or by some other reasons cause severe structural damages. The structural integrity of existing buildings is now a burning issue. Analytical, theoretical and design‐cum‐construction techniques are constantly being reviewed by government agencies and engineering consultants. Therefore, researchers are delving into this matter to find the best retrofitting techniques for fire‐damaged buildings. This paper is an outcome of such detailed research studies. It covers the actual case study of existing buildings, review of existing knowledge for fire damages and their mitigation and protective design technologies, and analytical and computational techniques, which have limited research data. In this study, Extended 3D Analysis of Building Systems (ETABS) is used as software for fire retrofitting analysis, and UBC‐97 is used as a code for the fire analysis and design. The ETABS building model is verified by manual calculations as well. Copyright © 2011 John Wiley & Sons, Ltd.     

Das Sandwich‐Platten‐System (SPS)

Sandwich Plate System (SPS). SPS was initially developed to provide impact resistant plating for offshore structures, ice islands, working in the Canadian Beaufort Sea. Research and development over the last thirteen years has focused on basic research into structural behaviour and performance, material characterization, fire resistance and fire engineering analyses, as well as development of design rules and energy absorption design philosophies. In addition connection details specific to sandwich plate structures and methods for in‐situ installations (SPS Overlay), repair, prefabrication and inspection have been developed. This work summarized in this paper, clearly demonstrates that not only SPS plates can be designed to be structurally equivalent to stiffened steel plates, but that the implied economical use of SPS plates provides a number of further advantages with respect to performance and safety.     

钢屋盖结构防火的性能化消防工程分析

因为建筑学上和构造上的原因,越来越多的建筑设计采用了钢结构。为了保证建筑结构构件的完整性,建筑规范提出了结构耐火性能的要求。但是,已规定的要求没有促进具有良好经济效益的设计,并且假定遵照规范是达到安全等级的唯一途径。本论文提出采用以性能设计为基础的消防工程理论方法来证明火灾中钢构件的性能。消防工程准则已发展至符合规范的要求,并能保证结构在火灾中的安全性能。本文采用一个游泳/跳水馆作为例子来讨论对钢屋顶结构进行耐火保护。本例的研究表明,游泳/跳水馆的钢屋顶结构可以不用耐火涂料,并且不会降低整个建筑的防火安全等级。     

A critical review of “travelling fire” scenarios for performance-based structural engineering

Many studies of the thermal and structural behaviour for large compartments in fire carried out over the past two decades show that fires in such compartments have a great deal of non-uniformity (e.g. Stern-Gottfried et al. [1]), unlike the homogeneous compartment temperature assumption in the current fire safety engineering practice. Furthermore, some large compartment fires may burn locally and tend to move across entire floor plates over a period of time. This kind of fire scenario is beginning to be idealized as travelling fires in the context of performance-based structural and fire safety engineering.This paper presents a literature review of the travelling fire research topic and its state of the art, including both the experimental and theoretical work for the past twenty years. It is found that the main obstacle of developing the travelling fire knowledge is the lack of understanding of the physical mechanisms behind this kind of fire scenario, which requires more reasonable large scale travelling fire experiments to be set up and carried out. The demonstration of the development of a new travelling fire framework is also presented in this paper, to show how current available experimental data hinder the analytical model development, and the urgent need that the new travelling fire experiments should be conducted.     

钢结构抗火安全研究现状与发展趋势

火灾引起的高温严重降低建筑钢材的强度和刚度,从而造成钢结构损伤、严重破坏甚至倒塌。20世纪90年代人们开始重视钢结构抗火理论研究,2001年美国“9·11”事件引起了世界各国对钢结构抗火问题的高度关注。结构抗火学科经过几十年的发展,已形成系统的抗火理论和设计方法,文章介绍火灾引起钢结构破坏的原因,论述结构抗火设计原则的发展过程,归纳近年来钢结构抗火研究的重大进展,指出钢结构抗火的重要发展趋势,供有关研究者参考。