Elevator shaft pressurization for smoke control in tall buildings: The Seattle approach

CONTAM simulations of both commercial and residential tall building models are conducted in order to study recently adopted Seattle code requirements for elevator shaft pressurization systems. In contrast to the International Building Code (IBC) requirements, the Seattle approach specifies across elevator door pressure minimums and maximums on only four “fire floors” (including one above, and two below, the fire floor). This is accomplished using a minimal pressurization of the entire elevator shaft in conjunction with venting of the four fire floors. The present study adresses the feasibility of calibrating such a system to meet the design objectives in tall buildings (system performance during an actual fire event is not considered). The two building models correspond to 37 story buildings with dual elevator and dual stairwell shafts extending the entire height of the building. Each model is calibrated to experimental data. Simulations are conducted for a variety of ambient temperatures and exterior building door positions. Coupled pressurization of the stairwells is also considered. The system requirements are found to be achievable for both elevator only and coupled elevator and stairwell pressurization systems. However, the observed pressure differences do change with changes in the ambient temperature as well as changes in the ground floor exterior door position. It is therefore recommended that such systems should be calibrated for pressure differences intermediate to the prescribed minimum and maximum values to compensate for changes to the system performance. Providing a relief vent to ambient on any recall floor may also be advisable.     

关于高层民用建筑加压送风防烟系统设计

针对高层民用建筑防烟楼梯间及其前室、消防电梯间前室和合用前室的加压送风防烟系统设计中的一些常见问题 ,结合对高规的理解 ,提出了在设计中的一些常用方法和应引起注意的一些问题。     

高层建筑加压送风防烟系统软、硬件部分可靠性分析

为了分析系统可靠性,将《高层民用建筑设计防火规范》（GB50045—95）表8.3.2-1～4的4种加压送风防烟方案进行了简化。分析硬件部分的可靠性时,根据该规范规定的防烟技术条件,运用概率理论和可靠性原理推导并建立了加压送风防烟系统的可靠度计算数学模型,经过简化、推理分析,对不同方案的可靠度进行了比较。软件部分是防烟系统致命失效的重要原因,涉及加压送风防烟的许多原则问题,如加压送风量的计算方法、加压送风的最佳部位、加压送风口的形式及开启方式,以及笔者从实际工程调查中发现的加压送风系统保障体系等,对这些软件元素故障机理和对系统可靠性的影响等分别进行了分析。对系统硬件部分和软件部分可靠性分析的结论,可为加压送风防烟系统的优化和防烟规范条文的修订提供理论依据,供高层建筑防烟设计和研究人员参考。     

高层建筑加压送风系统影响因素的实验研究

通过现场实验研究，讨论风机设置于建筑上部的多点加压送风系统的设计，通过数值拟合的方法得出送风管道中的风速分布，风速与加压风机的流量、送风管道的截面积以厦管道的高度有关。在实际情况下，研究影响高层建筑加压送风系统的各种因素有着较为重要的意义。     

Stack effect of smoke for an old-style apartment in Taiwan

Many existing apartments in Taiwan allow parking of motorcycles on the 1st floor along the arcade. For the purposes of lighting and ventilation, there is an opening in upper of the gates. Taking motorcycle arson as a fire scenario, this study proved that smoke would move into the building quickly via the opening and flow upward through the staircases, posing a serious risk whenever motorcycle arson was committed. The simulation results from FDS demonstrated that the visibility decline is very fast inside staircase. When the opening was moved to the bottom of the gate, the decline became slow because the stack effect phenomenon was effectively diminished. Image-recording and laser smoke layer measurement equipment was used to measure smoke diffusion, referring to the Australian Standard, AS 4391-1999 “Smoke management systems-Hot smoke test”. The experiments were executed in a five-story building by recording visibility at a height of 1.8 m on each floor. The results indicated the same conclusions when the opening was moved to the bottom of the gate. The results also verified that the door in the attic staircase was open; the stack effect was very significant.     

关于高层建筑地下室通风排烟系统设计规范的解读

结合规范,阐述高层建筑地下室通风排烟系统设计常见的几种形式,并分析各种形式的优缺点。     

高层建筑防烟楼梯间机械加压送风问题的探讨

本文分析了对高层建筑防烟楼梯间及其前室、消防电梯前室或二者合用前室进行机械加压送风的必要性，并在大量实际工程调研和资料分析的基础上，对不同的系统负担层数和送风部位给出了加压送风量；通过对不同计算公式的比较和对主要影响因素的分析，提出了加压送风量计算公式的选择，公式参数的确定及其他设计考虑要点。     

The effect of the wind speed velocity on the stack pressure in medium-rise buildings in cold region of China

This paper presents the numerical simulation results of the stack effect in medium-rise buildings in Harbin, a typical city in the severe cold region of China. The simulation was carried out using the multizone ventilation model COMIS. The effect of the wind speed velocity and the temperature of the stairwell on the pressure difference curves shape have been investigated. The pressure difference between the stairwell and the outside shows a linear variation with the height. However, the wind speed velocity may have a strong effect on the pressure difference. The results of the simulation show that at high wind speed velocity the curve of the pressure difference is not linear in shape. It has been also shown that the air total change cannot be provided by only infiltration due to leakage particularly for such air-tight residential building in windy cold climate. Therefore, mechanical ventilation is required to compensate for the lack of it. A quantitative evaluation of IAQ based on the total volatile organic compounds (TVOCs) concentration has been done. The effect of the wind speed velocity and the temperature of the stairwell on the VOTCs concentration at each floor have been also presented.     

Study of FDS simulations of buoyant fire-induced smoke movement in a high-rise building stairwell

Numerical simulations of fire-induced smoke movement in the stairwell of a high-rise building are conducted using FDS, version 6.0.1, with default settings. Twelve scenarios are considered. The required fineness of the grid has been determined in earlier work by considering both the fire source and the vent flow, and by assessing the velocity profile at the bottom opening and the vertical distribution of temperature in the stairwell. In the present study, the results including the airflow velocity at the bottom opening, vertical distribution of temperature, the temperature at the middle opening, pressure distribution, and neutral plane height in the stairwell, are compared to experimental data. For the average velocity through the bottom opening, a maximum deviation of 16.23% is obtained. Good agreement is achieved for the vertical temperature inside the stairwell (maximum relative deviation of 12.3%). By analyzing the temperature at the middle opening, it is found that the smoke moves faster than in the experiment. The influence of the staircase on the pressure distribution is demonstrated by comparing two cases: one with and one without staircase. The difference between the pressure inside the stairwell and the pressure outside increases with height, due to fire-induced buoyancy. However, the pressure difference evolution is non-monotonic when there are staircases inside the stairwell. The neutral plane height value, as obtained by post-processing the simulation results, is too high in the simulations, compared to experimental data and the corresponding analytical expression. Finally, the influence of the turbulence model is shown to be negligible.     

Smoke movement in elevator shafts during a high-rise structural fire

In high-rise fires, smoke is often the leading cause of fatalities. Therefore, in the event of a fire, the ability to predict the movement of smoke throughout a tall structure is of vital importance. Smoke moves depending on a number of interacting and complex factors including weather conditions, building construction, operation of HVAC equipment, as well as the location and intensity of the fire. Smoke often travels long distances from the fire floor, and in the particular case of a high-rise fire, smoke frequently moves to upper floors via open passages such as elevator shafts and stairwells.     

A new model for determining neutral-plane position in shaft space of a building under fire situation

In this study, a new model is proposed for predicting the location of the neutral plane inside the shaft space of a building under fire situation. The shaft space of the building is divided into two zones, i.e., fire zone and inner space, in the model. The temperature is assumed uniform in each zone. To validate the proposed model, a parametric numerical study is also carried out by using a computational fluid dynamics (CFD) code, i.e., FDS code. The comparisons between the proposed model and the CFD model are processed and the agreements between the two approaches are satisfied. It is found that the location of the neutral plane is above the mid-height of the building and the simulation results are consistent with the proposed model approximately. The ratio of the neutral plane height to ceiling height depends on the ventilation condition of the fire room greatly, which is found varying between 0.50 and 0.62.     

高层建筑加压送风系统试验研究

介绍了哈尔滨市一座高层建筑楼梯间及其前室、合用前室的加压送风系统的试验情况。分析了几种不同试验工况下,楼梯间与前室、合用前宣的正压值、门洞风速、加压送风量等问题,并对机械加压送风的若干问题作了探讨。试验结果表明,目前国内在加压送风系统设计、验收、防排烟产品质量方面存在不少问题,必须认真对待。《高规》中有关加压送风的某些条文有待进一步充实和完善。     

对防烟楼梯间及其合用前室分别加压送风防烟方案的流体网络分析

应用流体网络分析法,对现行高层建筑防火规范第8章第8.3.2条表8.3.2-2中的风量控制数据进行了校验性计算,揭示了分别加压送风的流动特性。计算结果表明,向防烟楼梯间加压是徒劳的,因为加压送风会直接从防烟楼梯间的疏散外门流失。     

竖井自然排烟在高层民用居住建筑中的应用

概要地介绍了自然排烟竖井在高层民用居住建筑中应用的可行性及竖井断面的确定原则，并通过所做的某一实例，对该做法的优点进行了总结，以推广该排烟方案，从而达到有效、方便、经济的目的。     

高层建筑加压送风设计若干问题的探讨

分析了讨论了门的开启层数与数量，加压送风防烟系统的正压度，加压送风口的型式等问题，提出了它们的确定方案及加压送风量的计算步骤与方法。     

高层民用建筑防排烟设计常见问题分析

提出和分析了防排烟设计审查中发现的一些问题,包括加压送风(排烟)量的确定、加压送风系统余压阀和止回阀的设置、加压送风机房新风进风通路的设置、地上地下共用(防烟)楼梯间时加压送风系统的设置、宜设机械排烟设施的几种特殊情况、采用自然排烟建筑高度及开窗型式和面积的限制、排烟防火阀的设置及加压送风口和排烟口风速的控制等,给出了相应的解决建议。     

高层民用建筑防排烟设计中排烟口设置的探讨

针对排烟口在高层民用建筑防排烟设计中的重要地位,阐述了自然排烟系统中可开启外窗面积的要求、自然排烟的设置位置的要求以及需注意的问题,论述了需要机械排烟系统的设置部位及设置排烟口的一般规定,以供防排烟的设计人员参考。     

高层建筑防烟楼梯间及前室机械加压送风常见问题的探析

本文通过分析防烟楼梯间及前室机械加压送风所要求的余压值难以达到规范要求的原因,探析了高层建筑防烟楼梯间及前室机械加压送风系统设计及施工中存在的问题,分析了对策,并提出相应的解决方法。     

A computer technique for predicting smoke movement in tall buildings

An approach to the analysis of stack effect has been developed which allows the prediction of internal air flow quantities and associated pressure differentials for specific buildings prior to construction. An example of the application of this analysis is presented for a hypothetical 75-story office building. Note: The authors presented this paper at a symposium on “The Control of Smoke Movement on Escape Routes in Buildings,” sponsored by the Joint Fire Research Organization and held on April 9 and 10, 1969 in Hertfordshire, England.     

高层建筑新风竖井设计问题

针对设计人员对高层建筑新风竖井大小要求不严的情况，结合具体例子证明新风竖井风速过大的不利性，并提出对风速较大的新风竖井进行加压送风的建议。