Classification of Atria and Measures for Their Fire Protection

Due to imperfection of the present architecture fireproofing technique criterion for the fire protection of atrium, it can't satisfy the needs of practical project. On the basis of practical experience, by the way of analysis and synthesis, the forms of atrium are classified and the suitable measures of fire protection and smoke management system for atrium are suggested. The aim of this paper is to provide a scientific and perfect method for their design and auditing.     

Thermal Radiation Effects on Smoke-flow in Atrium Fires

The field models for smoke flow in atrium, takings into account strong buoyancy, turbulence, radiation exchange and wall heat losses are developed according to the characteristics of the atrium fire. Realistic combustion processes in the burning fuel have not been included. A six-flux radiation model is included in a general mathematical model for fires, which are taking as a volumetric heat source, It is applied to the predictions of fire smoke development in a small-scale atrium. In order to avoid complicated radiation exchange models, radiation heat loss effects are combined to the wall heat loss. A General-purpose compute program PHOENICS has been developed to meet this need. Results of numerical calculations based on the field model are compared with test data for a fire in the small-scale atrium test facility. The resullts indicate that radiation transfer has the minor effects, due to the relatively low temperatures encountered. The method that the effect of radiation is included in the calculation of wall heat transfer losses by using maximum heat transfer coefficient is feasible. The field model used in the present study is not good enough, which a turbulent combustion sub-model must be included.     

Smoke Control Method in Atrium Building

This paper presents several regular smoke control methods in atrium buildings and analyses the factors that determine the smoke production rate of fire in atrium and balcony.As a result,eight designs of smoke control system are developed.     

Analysis of Heat Transfer during the Response Time of Temperature Sensor Fire Detector

This paper analyzes the heat transfer principle of temperature sensor fire detector, establishes mathematical model of heat transfer with considering the effect of radiation heat transfer and presents a new calculation method for the response time. The results of calculation show that when the environment temperature is rather low and the response temperature is set higher, the effect of radiation heat transfer on response time shouldn't be neglected. This paper may be helpful in appraising fire safety and designing alarm system.     

Smoke Management Systems for Large Volume Space

Atria and other large volume space do not have the compartmentation that has traditionally been a major contributor of fire protection.The effectiveness of sprinklers in these large volume spaces is limited. For these reasons, smoke management systems for large volume spaces is of particular importance. Their primary goal is to maintain an enviroment in which the impact of smoke and heat on occupants is not life threatening. This involves keeping the height of the smoke layer above the highest level of occupancy for a defined period of time, longer than the expected time to evacuate the building. Three approaches to these systems are smoke filling , gravity smoke venting ,and smoke exhaust .This paper describes the design approaches to smoke management to achieve fire safety in atrium.     

The Research of Using BP Neural Network in Prediction of Woods Fire Insurance Grade

The relation between circumfluence index and woods fire.index is described. BP neural network is trained by the known circumfluence index and woods fire index. The restricted feedback and stimulant feed forwardcalculation are to realize self-organizational learningof BP Network.Thereby the nonlinear mapping between circumfluence index and woods fire.index isperformed. With this network, characteristic choice can be carriedout and the accurate prediction of woods fire insurance grade can be given. Its accurate prediction rate is 89%in spring and 82%in summer. The correctnessand feasibilityare illustratedwith the simulate results.     

Analysis and Strategic Decision of Extinguishments System at the Initial Stage of Fire in Commercial Buildings

The best chance to extinguish the fire in commercial buildings is at the initial stage of a fire.For the problems during extinguishments at the initial stage of fire,a fire extinguishment system model at initial stage of fire in commercial buildings is designed.The fire data come from the fire cases in Chinese commercial buildings.The expected value and Variance of probability of basic events are calculated by using Bayesian statistical analysis method,which has overcome the difficulty from inefficient fire datum and obtaining repeated fire experience.Then the failure probability of extinguishments system at initial stage of fire is concluded from fault tree analysis and the error propagation analysis of fault tree is made.A systematic strategic decision has been made finally.     

Fire Resistance Analysis of High Strength Q460 Steel Beams-Part II：Theory Validation

In the previous companion paper, the fire resistance of high strength steel beams made from Q460 was theoretically studied. The methods to obtain temperature distribution, critical moment, critical temperature and stability coefficient were presented. The temperature distribution and load bearing capacity was analyzed by finite element method, and the validation was evaluated by comparison of results between theoretical computation and finite element analysis as well as experimental results. The comparison was made between Q460 steel beam and mild Q235 steel beam and the difference on fire resistance was obtained. A simplified approach for fire resistance of high strength Q460 steel beams was proposed and an example was given to show the application and reference of the approach.     

高温下钢管约束型钢混凝土柱的受力性能

火灾下无防火保护的结构构件温度会迅速上升,从而造成钢材和混凝土的强度明显下降。为了研究火灾下钢管约束型钢混凝土柱的受力性能,考虑火灾下钢管约束型钢混凝土柱的不均匀温度分布及温度对材料力学性能的影响,提出了火灾下受轴心荷载作用的钢管约束型钢混凝土柱承载力的计算方法。利用有限元软件ABAQUS对提出的计算方法进行了验证,结果吻合较好。进而采用该计算方法对影响高温下承载力的参数进行了分析,研究表明：随着构件截面尺寸的增加以及混凝土强度和钢材强度的提高,构件的承载力逐渐增加,而钢管壁厚的改变对承载力并无太大影响。利用有限元软件ABAQUS分析了荷载比、构件尺寸、钢管壁厚等因素对构件耐火极限的影响,发现耐火极限随着荷载比和钢管壁厚的增加而减小,随着构件尺寸的增加而增大。     

Calculation of Constant Pressure Values for Relief Valves in the Fire Suppression Systems of High-Rise Buildings

The calculation of constant pressure values for relief valves in the fire suppression systems of high-rise buildings usually is based on the working pressure of pipe systems by experience.However,this method only is applied in the condition that the relief valves are installed on the effluent pipes of pumps.In order to confirm the proper constant pressure values of relief valves in fire suppression systems,a formula is deduced using hydraulics theory.The applications of the formula in fire suppression systems are also discussed.The constant pressure values for relief valves are directly related to three factors,namely,the flux and pressure of the fire pump,the located height of the relief valves,and the head loss of flux from the pump exit to the inlets of the relief valves.It is necessary to analyze the working condition of fire suppression systems and to be certain of the permissive pressure range for overpressure.     

Automatic Measuring Method of Eyeglass Lens Power

A method of measuring eyeglass lens power is proposed. A position detector and 3 beams of ray are used to measure the prismatic, spherical and astigmatic powers. Based on the method, an automatic focimeter with simple structure can be developed. The measure errors of prismatic and spherical powers are analyzed, from which it is concluded that the precision of the position detector is the key to the method.     

RS和GIS技术在沈阳市火灾监测中的应用研究

卫星遥感技术在火情监测中具有监测面积大、速度快、成本低,且可长期动态监测等优势。笔者将RS和GIS技术有机结合,进行沈阳地区火情卫星遥感监测技术研究。基于火点像元背景亮温差异进行计算机自动判识,综合火点发生特点和下垫面情况进行人机交互修正火点判识阈值,利用地理信息数据进行火点精确定位,获取火点所在乡镇乃至村信息、像元个数以及土地利用情况。通过与实际火点资料对比分析,火点判识结果较理想。在2014年秋季和2015年春季火情遥感监测期间成效较好,为政府相关部门防火、救火等决策提供相应参考依据。     

On the Analysis of Reliability Taking Precautions against Fire Calamities for the Systems of City Lifeline Engineering

This paper expounds the important meaning to guarantee and raise the reliability taking precautions against fire calamities for the system of city lifeline engineering.It quotes a large number of fire and fail cases to explain that it is a complex system engineering to evaluate the abiity of the fire systems in the city lifeline cngineering.It epresents some methods to evaluate the reliability of complex systems, these methods are being used in the different trades at the present. After comparing these evaluation methods, this paper presents the advantages and defects of analy tical method of the fail tree.It also shows clearly that this method can completely be competent at the job to analyze the reliability taking precautions against fire calamities for the city lifeline engi neering.     

Analysis of Yangtze River Water as a Potential Source for Developing a Water Source Heat Pump in Chongqing

Characteristics of smoke flow and fire spread in a patio space of a high-rise building were studied to investigate their influences on fire compartment and safety evacuation. Fire development model was established and fire scenarios were designed to simulate fire and smoke spread by CFD software numerically based on concepts of fire performance-based design in a high-rise building with double patio space, whose height are 74. 65 m and 55. 95 m, respectively. Simulation results show that in all fire scenarios, performance targets for safety evacuation for people in each floor was satisfied, if smoke was extracted naturally using the patio space. Hang walls mounted in corridors around the patio space prevent smoke flowing out smoothly, shorten the coming of the risk time and increase fire danger. Using chimney effect, it is preferred to adopt natural smoke exhaust method in a high rise building with patio space.     

Numerical Simulation for Fire Smoke Flow in a High-rise Building with Patio Space

Characteristics of smoke flow and fire spread in a patio space of a high-rise building were studied to investigate their influences on fire compartment and safety evacuation.Fire development model was established and fire scenarios were designed to simulate fire and smoke spread by CFD software numerically based on concepts of fire performance-based design in a high-rise building with double patio space,whose height are 74.65 m and 55.95 m,respectively.Simulation results show that in all fire scenarios,performance targets for safety evacuation for people in each floor was satisfied,if smoke was extracted naturally using the patio space.Hang walls mounted in corridors around the patio space prevent smoke flowing out smoothly,shorten the coming of the risk time and increase fire danger.Using chimney effect,it is preferred to adopt natural smoke exhaust method in a high-rise building with patio space.     

Current Situation and Prospects of Atrium Smoke Management Research

This paper surveys the current situation of atrium smoke management research at home and abroad. Recent research such as the types and configurations of atrium buildings, atrium smoke management system, smoke exhaust system modes and smoke exhaust effectiveness, atrium smoke filling process and its time constant, pre_stratification and detection, air flow for smoke control between the atrium and adjoining space, sprinkler effect are discussed. Regulations of atrium design and some problems in current national code (Code for Fire Protection Design of Tall Buildings GB50045-95) are also discussed and areas of further research are specified.     

A Preliminary Survey on Analysis Method of Building Structures Under Post-Earthquake Fire

Considering the impact of post-earthquake fire on building structures in structure design, an analysis method is proposed to analyze and simulate the response of building structures under post-earthquake fire. Based on the seismic response and thermal stress analysis, this method considers the structure seismic damage through a simplified seismic damage model, and the simulation of the response of building structures under post-earthquake fire was reached by linking the heat transfer analysis and thermal stress analysis to the results of seismic damage. A single-storey concrete frame and a multi-story concrete frame were analyzed with this method and compared with experimental results of the same concrete frame under fire without seismic damage. It is shown that the collapse mode may change for seismic damaged structures and the fire resistance decreases with the increasing of seismic damage degree.     

REALIZATION OF PRE-ALERT AND UP-ALEAT IN FIRE DETECTION AND CONTROL

From a viewpoint of the sectirity and the exactness for a fire system,this paperexplicates the function and the element of two-degree alert(TD),pre-alert and up-alert applied tothe detection and the control in the fire system. An example in the paper deduces the logical expres-sion designing TDA and the hardware logic circuit is given. The paper also presents the software pro-gram realizing TDA utilizing the single chip microcomptiter(87C48),     

基于RS与GIS技术的安徽省林火监测研究

森林火灾是当今世界发生面广、危害性大、时效性强、处置救助困难的自然灾害之一。安徽省森林资源丰富,由于自然或人为原因导致的火灾经常发生。本文基于RS和GIS技术对安徽省林火监测进行研究,设计和开发相应的安徽省林火监测系统进行分析、处理并结合基础地理信息数据确定火点及其周边环境信息,根据土地利用数据判定火点中心点所在的土地利用类型,利用GIS空间分析功能快速定位,通过互联网或其它通讯设施实时发布林火信息给相关部门,从而可以较少的人力、物力和可行的成本,实现安徽省林火的监测。集成的监测系统对安徽省2008和2009年监测到的火点信息建立数据库,根据土地利用数据判定火点中心点所在的土地利用类型,结合时间分析着火的原因。研究成果已为安徽省林火监测业务服务。     

A Thermal Simulation of the Enclosure in Physical Model of Atria under Fire

This article elaborates the significance of the thermal simulation of the enclosure in physical model of atria under fire and presents an idea to conduct the thermal simulation. A series of one-dimensional thermal transfer equations of the enclosure are found for the atria with a round section under fire. The series of equations can be solved by the method of numerical analysis and based on the result, the analysis and comparison are carried out.