Experimental Study on Flame Wander of Fire Whirl

In this paper, the flame wander of fire whirl is investigated by experimental means. Small-scale fire whirls were produced by two split cylinders, and the data of vertical velocity measured by stereo particle image velocimetry are analyzed to track the flame displacement along the horizontal direction. Medium-scale fire whirls were produced by a fixed wall facility, in which a video camera was used to monitor the flame position along the horizontal direction, thereby the flame displacements are determined by image analyses. It is found that during each test the flame displacements at different heights vary synchronously, suggesting that the flame is wandering as a whole. The flame displacements at different heights involve different variation ranges. By using the flame displacement data, the appearance probabilities of flame along the horizontal direction are calculated for small- and medium-scale fire whirls. The results show that the probabilities follow the Gaussian distribution, suggesting that a fire whirl almost always wanders at the very vicinity of the pool center. Finally, it is verified that the frequency of flame wander linearly depends on the circulation of fire whirl, while the correlation formulations differ between small-scale and medium-scale fire whirls.     

Innovative Design of Fire Doors: Computational Modeling and Experimental Validation

Usually the design of fire doors is carried out to fulfil thermal requirements only, whereas also thermal distortion could significantly affect the safety behavior of the door. Indeed, the door tends to bend away from its supporting frame due to a non-uniform temperature distribution, which could lead to flame and smoke propagation. In this work an innovative design scheme is proposed, where the mechanical response of the door is enhanced without affecting its insulating properties. This improvement is achieved by changing the disposition of the constitutive elements (insulating material and structural plates). The behavior of a conventional and of an innovative door during a fire test was simulated with three-dimensional (3D) finite element models. A non-linear thermo-mechanical transient analysis was performed as well. The numerical results were validated with an experimental campaign made on true scale specimens, where the doors were heated by a furnace reaching a maximum temperature of 950°C. The temperature distribution was measured with several thermocouples and an infrared camera, whereas displacements were monitored with a laser sensor. It was observed that, while temperatures on the unexposed surface were around 120°C in both cases, the maximum out-of-plane displacement measured in the innovative door was 3 times smaller than that of the conventional configuration.     

钢筋混凝土剪力墙耐火性能及抗火设计

钢筋混凝土剪力墙是高层建筑结构中的重要构件,深入研究其耐火性能并进行合理科学的抗火设计至关重要。为此,简要回顾了钢筋混凝土剪力墙火灾下力学性能的研究现状,介绍了Eurocode 2、BS 8110-2、ACI 216R-89、AS 3600-2001、NS 3473E-1992、NZS 3101、GB 50045—95和GB 50016—2006规范的有关设计要求,探讨了钢筋混凝土剪力墙耐火性能及抗火设计的若干问题。     

Behaviour of Reinforced Concrete Walls Under Fire: A Review

Fire Technology - Fire has been a scourge of society for a very long time due to its impact on the human and economic aspects. Fire resistance is a characteristic of concrete buildings, and...     

吸取TVCC失火教训 加强外墙的防火是当务之急

分析了TVCC失火原因,幕墙屋面保温材料和面板材料防火性能不好是TVCC火灾技术内因.阐述了外墙、屋面节能必须与防火安全并举,中国建筑节能不能照搬外国模式,必须建立中国式建筑防火节能体系.提出应积极吸取TVCC及近年频繁的幕墙屋面火灾的惨痛教训,切实加强外墙及屋面的防火是当务之急.     

Applications of the Equivalent Gap Fraction Criterion Method for Fire Whirl Risk Evaluation and Prevention in a Real Fire Disaster

In this paper, a method is proposed for spontaneous fire whirl analysis and prediction due to non-regularly or randomly distributed flame sources, by defining an equivalent gap fraction and providing an adapted criterion. The topological structure of the flame source configuration, the eccentric direction of each equivalent gap and the integrated effect of all the gaps are considered. By the application of the equivalent gap fraction criterion, predictions can be made in a real fire disaster for the likelihood, the rotating direction and the rough intensity of the swirl and then suggestions can be provided for configuration design to prevent fire whirls or to reduce the damage.     

深基坑支护结构设计与施工

某项目基坑深度在13.6m～18m,开挖面积达3万m^2,深基坑修建在距钱塘江38m处的粉砂土层中,且周围10m左右已在使用的建筑物,由于设计方案、监测方案、施工方案的合理和可行,深基坑设计和施工取得了成功,可为同行参考借鉴。     

预应力锚定梁挡土墙设计

通过某工程挡土墙设计的多种方案技术经济比较,最后采用了预应力锚定梁挡土墙设计方案.该方案具有结构轻、圬工省、施工快、造价低等优点,在大型挡土墙中的应用优势十分明显.同时简要介绍了预应力锚定梁挡土墙的设计要点、构造措施及施工要求.     

加劲与不加劲钢板剪力墙的试验研究和理论分析

带或不带加劲肋的钢板剪力墙系统主要用于抵抗水平荷载,尤其是地震作用。现有文献对不带加劲肋的钢板剪力墙进行了大量的理论分析和试验研究,并提出了多种适用于超薄钢板剪力墙的分析方法,但对带加劲肋的钢板剪力墙研究较少。对2个带和不带加劲肋的单肢钢板剪力墙和其中的1榀外框架进行试验。结果表明,加劲肋提高了钢板剪力墙的性能,使钢板的能量耗散能力增加26%、剪切刚度增加51.1%,而对钢板的剪切强度影响甚微。此外,利用试验结果验证剪力墙-框架相互作用理论(PFI)的可行性。试验结果表明,该理论能够用于预测带或不带加劲钢板剪力墙剪切时的荷载-位移曲线。     

碳纤维布加固低强度空斗墙试验研究

进行了2片未加固和4片碳纤维布加固的低强度空斗墙的水平低周反复荷载试验,研究了空斗墙加固前后的破坏形态、承载能力和极限变形能力等抗震性能.试验结果表明,三斗一眠空斗墙的抗震性能优于全空斗墙体;采用X交叉形式对空斗墙进行抗震加固能取得较好加固效果.建议实际工程中采用X交叉形式对空斗墙进行抗震加固,两端粘贴竖向碳纤维布加固空斗墙的效果有待进一步研究.     

新型装配式围挡结构设计及工程应用

目前市政工程的施工围挡一般为砖砌围挡和传统简易围挡,不仅功能形式单一,而且耗材量较大,循环利用率低,施工噪声大。因此,提出了用新型装配式围挡作为施工场地围挡,并通过数值模拟验证了该围挡结构的安全性和抗风稳定性,对比了有钢支撑和无钢支撑时的结构稳定性。该新型装配式围挡的成功应用,充分体现出了安全隔离作用,同时具有美观、轻便、成本低、迁移快及可重复使用的特点。     

装配式榫卯预制混凝土景观围蔽设计与施工技术

装配式榫卯预制混凝土景观围蔽是一种新型的围蔽施工方法,其具有快速装拆,全程干作业、可回收、美观度高等优势。本文通过结构计算验证了装配式榫卯预制混凝土景观围蔽结构的整体强度及抗倾覆性满足设计,利用有限元数值模拟验证了在最大风荷载作用下结构连接处的强度及稳定性满足设计要求。在此基础上,详述了装配式榫卯预制混凝土景观围蔽施工流程及关键施工要点,为类似工程提供借鉴和参考。     

火灾下钢筋混凝土墙计算模型及影响因素分析

采用有限元软件ABAQUS对火灾下钢筋混凝土墙的变形全过程进行了计算,计算结果与以往实验结果吻合较好.在此基础上,系统分析了轴压比、侧向荷载比、高厚比、墙厚度、混凝土抗压强度、钢筋屈服强度、配筋率和混凝土保护层厚度对钢筋混凝土墙变形和耐火极限的影响规律.研究结果表明,受火过程中,钢筋混凝土墙在无侧向荷载且轴压比或墙厚度...     

Fire Resistance and Post-fire Seismic Behavior of High Strength Concrete Shear Walls

In this study, both fire tests and low-frequency cyclic loading tests after fire were conducted on three conventional high strength concrete (HSC) shear walls and a superimposed HSC shear wall with precast recycled aggregate concrete (RAC) panels. The RAC in this paper was made with recycled concrete aggregate. When specimens suffered the fire exposure on one side for 45 min, 90 min, and 135 min separately, spalling of concrete, temperature distribution and deformation of specimens were investigated as indicators of fire response. When specimens were subjected to cyclic load after fire, hysteresis curves were obtained, based on which the secant stiffness degradation and energy dissipation capacity of walls were analyzed. The results indicated that HSC would suffer severe spalling during the fire and that fire response of the superimposed wall including spalling was smaller than that of conventional walls. Using RAC panel as a thermal barrier was found to be effective to alleviate spalling, as it reduced more than 60% of spalling of HSC compared with bare walls. Based on the seismic tests results, the fire exposure deteriorated the load bearing capacity, lateral stiffness and energy dissipation capacity of walls, whereas the application of RAC panels improved the load bearing capacity by about 10% even when the superimposed wall was exposed to the fire for a long time.     

附加粘弹性阻尼墙结构设计应用

利用结构设计软件Etabs对某部委全钢结构的办公大楼进行分析。原结构采用框架偏心支撑体系,有控结构则以粘弹性阻尼墙取代部分支撑,对2种结构体系在各种地震加速度峰值作用下的各项性能指标进行分析比较,得出结论：粘弹性阻尼墙可以有效减小结构的地震反应,提高了结构的抗震性能,且满足规范的各项要求。     

一种新的消防设计方法--性能化消防设计

国内的建筑师在进行建筑消防设计时,通常是严格依据相关的消防规范条文进行的,这种方法被称为"指令性"的设计方法.目前,国际上正在兴起一种从指令性消防设计向性能化消防设计转变的趋势.本文从基本概念、政府规定、分析方法、运作方式、工程实例等方面介绍了这种可以针对某一工程"量身定做"的性能化消防设计方法.     

钢框架内填预制钢筋混凝土剪力墙试验研究

为改进钢框架内填预制钢筋混凝土剪力墙的抗震性能,将耳板装置引入钢框架与内填墙的连接中.通过2个2层单跨钢框架内填预制钢筋混凝土剪力墙1/3模型试件的循环荷载试验,考察耳板连接装置的可靠性和内填墙裂缝的开展与结构变形能力,分析结构的破坏机理、滞回性能、刚度退化、变形及延性等,并对钢框架内填预制混凝土剪力墙体系与现浇混凝土剪力墙体系和带竖缝混凝土剪力墙体系进行对比.研究结果表明:抗剪连接件(U形筋)在梁柱节点上下耳板的帮助下未发生破坏,耳板连接装置具有可靠的工作性能;合理设计的钢框架内填预制钢筋混凝土剪力墙结构具有良好的延性.     

探析建筑消防设施的维修保养问题

本文分析了建筑消防设施中存在的问题和影响建筑消防设施作用发挥的原因,阐述了加强建筑消防设施的监督及管理对策。     

无粘结预应力混凝土板火灾试验构件设计

首先对试验构件的截面参数、无粘结预应力筋的型号及混凝土标号进行了设计,然后分别 用荷载平衡法和规范中的公式对试验简支板构件和连续板构件中的无粘结预应力筋数量进行了 估算,接着对构件中的非预应力筋的用量也进行了估算,最后对设计的构件进行部分项目的验算, 并对两种方法进行了比较,指出了引起两者差别的原因.