A review on research of fire dynamics in high-rise buildings

Since serious fire occurred frequently in recent years, fire safety of high-rise building hasattracted extensive attention. A National Basic Research Program (973 program) of China has been setup by Ministry of Science and Technology (MOST) of China in 2012 to meet the research requirementsof fire safety in high-rise buildings. This paper reviews the current state of art of research onfire dynamics of high-rise buildings, including the up-to-date progress of this project. Thefollowing three subjects on fire dynamics of high-rise buildings are addressed in this review: theejected flame and fire plumebehavior over facade out ofthe compartment window, the flame spread behavior over facade thermal insulation materials, and the buoyancy-driven smoke transportationcharacteristicsalong long vertical channels in high-rise buildings. Prospective future works are discussed andsummarized.     

Stack effects on smoke propagation in subway stations

In fires of subway stations, the most immediate threat to passengers' life is not the direct exposure to fire, but the smoke inhalation because it contains hot air and toxic gases. To understand the mechanisms driving the motion of smoke is therefore an important issue of fire safety, and the stack effect is found to be an important mechanism having significant influence. In this paper, we compute the three-dimensional smoke flow fields under various fires happened in a representative subway station of Taipei Rapid Transit System. To clarify the mechanisms corresponding to the stack effect, a simplified three-dimensional configuration is also considered. Results indicate that, without mechanical smoke control, the stack effect plays a decisive role and is virtually the sole factor influencing the smoke movement. Because of the stack effect, most or sometimes all of the smoke will choose a vertical shaft (usually a stairwell) to evacuate, and the cross sectional area of the shaft and the location of fire determine which shaft is chosen. Present computational results show the evidences of the importance of the stack effect and provide both valuable information to the design of the passenger evacuation routes in fires as well as criteria to the design of smoke control systems of subway stations.Received: 16 January 2003, Accepted: 10 March 2003, Published online: 12 September 2003     

建筑物内火灾烟羽流和顶蓬射流诱发的空气运动盐水模拟实验研究

盐水在清水中的扩散与火灾烟气在空气中的蔓延相似，因而可用盐水的扩散来模拟火灾烟气的蔓延；同样地，由于盐水的扩散而导致的环境清水的运动也可用来模拟烟气蔓延诱发的空气运动。基于这一原理，本文用实验的方法，研究了建筑物内初起火灾产生的烟羽流和顶蓬射流所诱发的空气运动，并对走廊空气层生长规律和运动特性进行了初步的测量和分析。所得结果基本合理，对建筑物通风排烟及疏散通道设计有帮助，从而为建筑火灾环境空气的运动的实验研究开辟了新的思路，也为火灾区域模拟提供了实验依据     

Smoke Control of Fires in Subway Stations

We investigate the effectiveness of the smoke control scheme of the Gong-Guan subway station (GGSS), a typical subway station of the Taipei Rapid Transit System and whose mechanical control systems are also standard in modern subway station design. Three-dimensional smoke flow fields under various kinds of fires are computed by computational fluid dynamics techniques and the results are illustrated on various cross-sectional planes. Results indicate that the stack effect plays a deterministic role in smoke control when a fire occurs near the stairwell; under such circumstances, no mechanical smoke control is necessary. When a fire occurs in other places, such as at the end or the center of the platform, the current mechanical control schemes of GGSS are effective; namely, the smoke can be well controlled, either it is confined to a small region or is evacuated from the station, leaving the four exits free of smoke so that the passengers can escape through them. The effect of the platform edge door (PED) on smoke control is also investigated. With the PED, the effectiveness of the present smoke control system for fires occurring on the chassis of a train, a serious fire in the subway station, increases. We also propose an innovative smoke control scheme with a PED, which turns out to be much more efficient in evacuating smoke than that currently used. This study provides both valuable information for the design of passenger evacuation routes in fires as well as criteria for the design of a smoke control system for subway stations. Received 12 August 2002 and accepted 22 October 2002 Published online 14 February 2003 RID="*" ID="*" The financial supports for this research from both the SinoTech Engineering Consultant Inc. and the National Science Council under Grant NSC 89-2212-E-002-61 are gratefully appreciated. Communicated by H.J.S. Fernando     

基于ABAQUS的超高层建筑动力弹塑性抗震分析Dynamic elasto-plastic seismic analysis for a super high-rise building based on ABAQUS

某国际金融中心超高层建筑共113层,结构高度423 m。首先,利用S A P2000软件建立结构的有限元模型,通过基于C＃语言开发的导航式接口程序TJU ．SAP2ABAQUS将SAP2000模型转换为 ABAQUS模型。然后,依据规范进行7°多遇、基本和罕遇地震作用下的弹塑性时程分析。最后,模拟了超大震作用下该超高层结构的破坏过程。结果表明,（1）不同强度地震作用下结构的层间位移角均能满足规范限值要求。（2）罕遇地震作用下,结构满足大震不倒的抗震设防要求且有较高的安全储备。（3）超大震作用下,结构竖向刚度变化位置是结构潜在的薄弱部位,在抗震设计时应给予重点关注。     

高层建筑物荷载与地下水开采叠加作用下的地面沉降特征

在地下水开采和高层建筑荷载叠加作用下,城市地面沉降分布愈加复杂。以天津塘沽地区为例,考虑到土体在固结沉降中的平衡条件、弹性本构条件、变形协调条件和水流连续条件,以比奥固结理论为基础,建立了高层建筑荷载和地下水开采叠加作用下三维地面沉降模型,采用有限元方法进行了数值计算。结果表明,高层建筑物的附加荷载作用在其建成后的3~4a内将产生可观的地面沉降量; 抽水和高层建筑荷载叠加作用下的地面沉降存在耦合效应,叠加作用下的地面沉降值小于可比条件下单独抽水和单独荷载作用下地面沉降值之和。     

考虑风-结构-土耦合作用时高层建筑顺风向风振响应分析

本文综合考虑了风-结构-土的耦合作用对高层建筑顺风向风振响应的影响，研究了在各种参数下高层建筑风振响应的特性。由于在风-结构-土耦合作用问题的整个体系的控制方程中，既有时域中的耦合关系，又有频域中的耦合关系，本文提出采用傅立叶变换-时频迭代法来进行求解，较好地解决了用普通的方法难以解决的问题。最后采用数值计算的方法比较了考虑风-结构-土的耦合作用和仅考虑土-结构相互作用以及刚性基础的结构位移响应及加速度响应。     

分段吸气高层建筑减阻性能的数值研究

为减小高层建筑的风致阻力, 采用CFD方法研究了主动吸气控制下高层建筑模型的风载荷减阻性能, 分析了竖向开孔位置、吸气孔高度和吸气速度等参数对减阻性能的影响, 并详细展示流场,讨论吸气控制机理. 结果表明: 保持流量系数不变, 增加吸气孔高度(或减小吸气速度)使得模型各表面的风压折减效 率$\eta_{\rm{PR}}$, 阻 力折减效率$\eta_{\rm{DR}}$和基底弯矩折减效率$\eta_{\rm{MR}}$增大, 且只有$\eta_{\rm{MR}}$在较大吸气孔高度时超过1.0. 拟合了$\eta_{\rm{DR}}$ 和$\eta_{\rm{MR}}$关于吸气孔中心高度、吸气孔高度和吸气速度的经验公式, 为分段吸气控制的应用提供参考. 基于最大风压折减效率和最小吸气功率,比较了 各分段吸气模型和全高吸气模型的减阻性能, 发现全高吸气模型的减阻性能优于分段吸气模型. 可在高层建筑中上部设置吸气装置来减小基底弯矩或改善其局部风压特性.     

基于光声气体滤波的早期火灾烟气测量方法

火灾烟气中气体和烟雾浓度测量对火灾研究有着重要意义。本文提出一种利用光声技术同时在线测量CO浓度和烟雾消光的非接触式方法。根据气体滤波和粒子散射原理,采用两个光声腔分别作为CO测量腔和烟雾参比腔,在其与光源之间的开放路径中进行火灾产物的测量,通过测量两个光声腔信号,依据信号变化量计算CO浓度和烟雾消光。基于标准火的实验证明该方法可以实现烟雾颗粒和CO气体的复合测量。     

超高层建筑受大型高速飞行物撞击所致非连续性坍塌模拟与研究

为了解大型高速飞行物撞击超高层建筑后,建筑物塌落过程及其特征,使用基于颗粒流的PFC3D作为平台对坍塌过程进行模拟。所构建的超高层建筑为核心筒-框架结构,飞行物由较大的三个颗粒组成,其撞击速度为720km/h,撞击高度为建筑侧面250m和100m。研究了撞击物进入层间运动的特征,及在两种高度撞击后的坍塌过程。模拟结果表明,飞行物非直接撞击核心筒时建筑不会发生整体破坏,核心筒的受撞破坏是建筑坍塌破坏的关键。建筑高处受撞击后坍塌可分为两个阶段,其现象和原因各不相同。指出了建筑高处和低处受撞坍塌过程的三点不同。最后分析了撞击塌落后的地面影响范围及特征。     

上海中心大厦脉动风荷载模拟研究

风荷载是超高层建筑设计的主要荷载之一,对超高层建筑进行风振时程分析能更准确和直观地了解结构风振响应的特性.为了进行风振响应时程分析,必须较为准确地模拟作用在结构上的脉动风荷载.首先,本文采用基于自回归(AR)模型的线性滤波法对上海中心大厦场地的脉动风速时程进行了数值模拟,通过检验模拟脉动风速的功率谱和相干函数平方根与目标值的吻合程度,验证了基于AR模型模拟超高层建筑脉动风速时程的可行性.然后,本文考虑了上海中心大厦外形向上扭转收缩的特点,由模拟的脉动风速时程计算生成作用在结构上的脉动风荷载.     

OPTIMAL DISTRIBUTION OF EIMD FOR IRREGULAR HIGH-RISE BUILDING STRUCTURE VIA GENETIC ALGORITHM 1)

为了解决应用新型电磁惯性质量阻尼器于偏心高层结构控震工程中的优化布置问题,提出一种基于遗传算法的优化配置策略。首先建立地震动作用下新型电磁惯性质量阻尼器(electromagnetic inertial mass dampers,EIMD)偏心高层结构的动力学方程,其次选取合适的适应度函数并基于遗传算法得到EIMD最优配置数量及集成位置信息,最后提出一种可行的半主动控制策略对优化的结构进行控震分析。以一个24层实体不规则高层结构为例,仿真分析结果表明优化配置后的EIMD 对结构的控震效果明显优于随机布置。     

黏滞阻尼器在超高层结构体系中的效率研究

250m以上的超高层结构主要有框架-核心筒、框筒-核心筒和巨型框架-核心筒等三种结构体系．由于超高层结构的高宽比通常较大（5以上）,结构的侧向变形往往成为控制因素．随着消能减震技术的不断成熟,黏滞阻尼器越来越多的应用于建筑结构领域．本文分别将黏滞阻尼器均匀布置在上述三种超高层结构体系中,对比其消能减震效果并分析原因,最后建议了黏滞阻尼器在这些结构中的较优布置．     

An experimental study on wind loads acting on a high-rise building model induced by microburst-like winds

In the present study, an experimental investigation is conducted to quantify the characteristics of the microburst-induced wind loads (i.e., both static and dynamic wind loads) acting on a high-rise building model, compared to those with the test model placed in conventional atmospheric boundary layer (ABL) winds. The experimental study is performed by using an impinging-jet-based microburst simulator available at Iowa State University. In additional to conducting flow field measurements to quantify the flow characteristics of the microburst-like wind, both mean and dynamic wind loads acting on the test model induced by the microburst-like wind are assessed in detail based on the quantitative measurements of the surface pressure distributions around the test model and the resultant aerodynamic forces. It is found that the microburst-induced wind loads acting on high-rise buildings would be significantly different from their counterparts in conventional ABL winds. Both the static and dynamic wind loads acting on the high-rise building model were found to change significantly depending on the radial locations and the orientation angles of the test model in respect to the oncoming microburst-like wind. The dynamic wind loads acting on the test model were found to be mainly influenced by the periodical shedding of the primary vortices and the high turbulence levels in the microburst-like wind. The findings derived from the present study are believed to be useful to gain further insight into the underlying physics of the flow–structure interactions of high-rise buildings in violent microburst winds for a better understanding of the damage potential of microburst winds to high-rise buildings.     

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采用经典的火羽流模型,预测了2008奥运国家主体育场典型火灾场景下火源上方不同高度处 的烟气温度;结合钢结构在不同温度条件下的强度、弹性模量参数,选取了保守的钢结构极 限环境温度值;综合上述两个方面的结果,确定了2008奥运国家主体育场钢结构中需要开展 消防保护的区域为：观众席座椅区距离座椅的垂直距离小于10.2 m的区域.     

高层建筑动态风干扰的瞬态风压积分法研究

提出通过在风洞试验中多通道测量刚性模型表面瞬态风压并进行积分的方法研究高层建筑的动态风干扰。模型表面的瞬态风压利用多通道同步压力测量而得到。为提高数值积分精度,测压孔位置按高斯求积节点布置。设计了表面布置有测压孔的受扰高层建筑刚性模型和三种不同高度的干扰建筑模型,研究了相同高度以及不同高度的两个高层建筑之间的顺风向和横风向动态风干扰。借助干扰因子讨论了近邻建筑的位置、距离以及楼高对受扰建筑基础动态倾覆力矩的影响规律,并与传统方法所得结果作了比较。     

Analysis of building structures by replacement sandwich beams

In this paper replacement beams of building structures are developed, and the stiffnesses of the replacement beams are derived. The analysis is robust and can be used for slender and wide structures consisting of frames, trusses, shear walls, or coupled shear walls. The utility of the derived replacement beam is demonstrated through the examples of the in plane and flexural–torsional buckling and vibration analyses of high-rise buildings.     

An experimental study of a high-rise building model in tornado-like winds

An experimental study was conducted to quantify the characteristics of wake vortex and flow structures around a high-rise building model as well as the resultant wind loads (both forces and moments) acting on the test model in tornado-like winds. In addition to measuring wind loads acting on the tested high-rise building model using a high-sensitivity load cell, a digital Particle Image Velocimetry (PIV) system was used to conduct detailed flow field measurements to quantify the evolution of the unsteady vortex and turbulent flow structures around the test model in tornado-like winds. The measurement results revealed clearly that the evolution of the wake vortex and turbulent flow structures around the test model as well as the resultant wind loads induced by tornado-like winds were significantly different from those in conventional straight-line winds. The detailed flow field measurements were correlated with the wind load measurement data to elucidate the underlying physics to gain further insight into the flow-structure interactions between the tested high-rise building model and tornado-like vortex. The new findings derived from the present study could be used to provide more accurate prediction of wind damage potential to built environment with the ultimate goal of reducing life loss, injury casualty, and economic loss that results from tornados.     

Predicting air pressure in drainage stack of high-rise building

It is necessary to understand the features of air pressure in a drainage stack of a high-rise building for properly designing and operating a drainage system. This paper presents a mathematical model for predicting the stack performance. A step function is used to describe the effect of the air entrainment caused by the water discharged from branch pipes. An additional source term is introduced to reflect the gas-liquid interphase interaction (GLII) and stack base effect. The drainage stack is divided into upper and base parts. The air pressure in the upper part is predicted by a total variation diminishing (TVD) scheme, while in the base part, it is predicted by a characteristic line method (CLM). The predicted results are compared with the data measured in a real-scale high-rise test building. It is found that the additional source term in the present model is effective. It intensively influences the air pressure distribution in the stack. The air pressure is also sensitive to the velocity-adjusting parameter (VAP), the branch pipe air entrainment, and the conditions on the stack bottom.