Efficient allocation of fire department resources — Part I

The author discusses computer oriented mathematical models for the simultaneous selection of the number and location of fire engines and stations. The discussion also considers multiple engine response and distance and budget constraints as well as operational problems, such as closing or relocating existing stations. Note: This research supported in part by grants from the American Risk and Insurance Association and Gage-Babcock, Inc.     

CFD simulations of a tunnel fire—Part I

This paper concerns sensitivity studies of computational fluid dynamics (CFD) simulations of a fire in a tunnel. The simulations were of an experimental fire in a tunnel carried out by the Fire and Thermofluids Section of the Health and Safety Executive, Buxton, UK. The fuel used in the experiment was kerosine, the heat output rate was 2.7 MW and the tunnel was longitudinally ventilated. During the period of the experiment studied in the simulations, there was an upstream layer of approximate length 11 m. Simulations were carried out for two areas of the tunnel: the area around the fire and the area downstream of the fire. This paper describes the simulations of the area around the fire, whilst the accompanying Part II paper describes the area downstream of the fire. In the fire area simulations, the upstream propagating smoke layer length was found to be sensitive to the ventilation velocity, the ventilation velocity profile, the turbulence model used and the heat input rate. This case, in which the fire did not extend over the width of the tunnel, gave an upstream layer at higher ventilation velocities than those found in the literature. While reduction of the heat input rate to allow for radiative heat transfer from the flame caused a significant change in results, neither radiative heating of the tunnel ceiling nor the distribution of the fuel across the fuel pan had a significant effect on the results.     

CFD simulations of a tunnel fire—Part II

The sensitivity of results of simulations of the area downstream of a fire in a tunnel to several factors was quantified. The factors were natural convective heat transfer, radiative heat transfer, wall roughness, downstream boundary position, slope and turbulence model. The results were most sensitive to natural convection, radiation and wall roughness. The results were not sensitive to which of the two turbulence models were used, nor to the position of the downstream boundary position. Overall uncertainties between the simulations were up to 60%, and temperatures were overpredicted in the base case by up to 75 K. The simulation carried out using a combination of factors gave maximum temperatures at the downstream end of the tunnel within 25 K of the experiments.     

Wind and Fire Coupled Modelling—Part I: Literature Review

Wind and fire phenomena can together be a devastating force, whether in the case of a building fire, release of smoke in an urban area or forest fire near an urban habitat. Most of the fire phenomena are influenced by the wind, usually for the worse. If we want to understand fires, we have to understand wind as well, and model it appropriately. This modelling is described by the discipline of Computational Wind Engineering, from which we are able to transfer invaluable knowledge to coupled wind-fire analyses. This two-part review is dedicated to such a transfer. In Part I, the authors describe the historical and most current instances of wind and fire coupled modelling, referred to as simple models, in situ measurements, wind tunnel experiments or numerical studies with CFD. The review is subdivided into six categories, namely flame behaviour in wind conditions, indoor flows, natural smoke ventilators, tunnel ventilation, wildfires and firebrand transport, and urban dispersion of smoke. Besides flame behaviour, all remaining topics are covered, to the best of the authors’ knowledge, with multiple references to valuable experimental and numerical studies. In Part II of the review, the authors describe the best practices of Computational Wind Engineering, that may be transferred to fire-oriented numerical studies. This part provides good practice guidelines, reference studies and a proposal for the optimisation of the simulation procedure for coupled wind and fire models.     

Continental Roofs: Some New Clues—Part I

Abstract

From the point of view of vernacular architecture France is still the terra incognita of Western Europe, and from ignorance of the French evidence several misconceived theories have developed among scholars in northern Europe. The poinçon (hung king-post) which is probably the most typical feature of French roofs is not a true post but a vertical brace in the dominant family of principal rafter roofs. The most common types of relation between posts, wall-plates and tie-beams are 'reversed assembly' and the 'anchor beam', common in most parts of France as in other Western European countries. The origins of these current vernacular patterns may be found in medieval aisled buildings (barns or market-halls) at a time when the French rafter roof was only found in buildings of high economic and artistic status. In vernacular architecture the French rafter roof has a mainly southern distribution and comprises only three basic types.

The roof of the medieval peasant house before 1400 was seemingly of ridge-post type, but in Romance countries ridge-post roofs are associated with principal rafters. Still widespread in France, they are very common in many parts of northern Spain. Except in Galicia, the vernacular names of the ridge-post (or at least of its elementary forms) come from the Latin 'furca.'     

Load capacity of cold-formed column members of lipped channel cross-section with perforations subjected to compression loading – Part I: FE simulation and test results

An investigation was carried out into the influence of perforations of various shapes on the buckling behaviour of cold-formed column members of lipped channel cross-section. A finite element analysis using ANSYS, an experimental investigation, and design code predictions using the AISI Specification, British Standards (BS) and EU Standards, are employed to determine the buckling load capacity. An experimental investigation of the buckling behaviour of flat and fixed ended columns is presented, and the findings from this are used to validate finite element results, and compare with design code predictions. The numerical results of load vs. displacement behaviour are shown to be in good agreement with those reported from the tests. It is shown that the ultimate failure load of the lipped channels under compression varies greatly with the presence of perforations.     

A comprehensive study of externally venting flames—Part I: Experimental plume characteristics for through-draft and no-through-draft ventilation conditions and repeatability

Externally venting flames have been examined during a series of eight full-scale flashover tests. Furniture was used in a burn room larger than a standard one. The purpose of the work has been to investigate the likelihood of external fire spread from a burn room window with standard glass when the external facade is non-combustible. The effects on externally venting flames of internal ventilation conditions and wind have been studied in detail. Secondary fires and glass breakage have been examined. Repeatable experimental data and reliable information on externally venting flames have been generated for numerical model validation and performance-based design code development. In Part I of this two-part paper, the emphasis is on the repeatability of the experimental data on externally venting flames. A new averaging method introduced previously has been used for this purpose. In Part II, extensive comparisons are given with available experimental data and empirical approximations from the literature. Surface fits to the experimental data are also presented for communication purposes.     

Building frames—Effect on fire resistance of floor and ceiling assemblies

In many cases, fire endurance tests of seemingly comparable floor and roof assemblies have yielded different results. The author reports on a current study which, thus far, has involved analyzing thermal moments developed in floor assemblies due to fire exposure, evaluating the distribution of thermal forces to the adjacent building frame, and deriving the resultant reaction of the structure. He discusses techniques for determining the onset of structural collapse mechanisms, using mathematical expressions for the change in modulus of elasticity and yield stress as a function of temperature. Note: This paper was presented by the author at a symposium on methods and application of testing building materials for fire resistance held at the Armstrong Cork Company's Technical Center, Lancaster, Pa., June 24 and 25, 1965.     

The Äspö pillar stability experiment: Part I—Experiment design

The Äspö pillar stability experiment was carried out to examine the failure process in a heterogeneous and fractured rock mass when subjected to coupled excavation-induced and thermal-induced stresses. The rock pillar was created by the excavation of two adjacent large-diameter boreholes. The pillar was loaded by a combination of excavation-induced stresses and heating of the surrounding rock by a rectangular heater pattern. The experiment was designed using the observation design method. The characterzation of the experiment volume showed that the experiment was located in a fractured water-bearing rock mass that was considered typical for the Äspö Hard Rock Laboratory (Äspö HRL) and for the Fenno-Scandinavian shield. Scoping calculations using two- and three-dimensional elastic stress analyses were carried out to reduce the uncertainty for the far-field in-situ stresses, establish the geometry for the access tunnel that would provide a elevated uniform stresses in the floor of the tunnel, and determine the optimum width of the pillar. It was concluded, based on the rock mass characteristics, that a 1 m-wide pillar formed by two 1.75 m diameter boreholes would meet the design objectives. Thermal modelling showed that thermally induced stresses in the pillar were adequate to elevate the pillar stresses above the stress magnitude required to initiate failure.Acoustic emission, displacement, and thermal monitoring systems were installed according to the experiment design without problems. No sensors were lost over the three month duration. After the experiment was completed, a laser scan of the pillar revealed the extent of the damaged pillar. The experiment commenced in January 2002 and was successfully completed in 2006.     

A study on the spread of fire caused by the stack effects of patio—A computer modeling and a reconstruction of a fire scenario

This study reported an actual building fire incidence for a ten-story building that occurred in Taiwan in 2008. Due to the stack effects the fire occurred on the third floor spread through the patio in a short time to the upper floors and caused three deaths in a tenth floor apartment. This study also attempted to reconstruct the actual fire scenario using computer simulation. The spread of the fire to the combustibles due to hot smoke was accounted for in the simulation. Variation of the fire scenario and the factors causing the fire spread were studied. It was found that an initial fire size below 1.0 MW would not generate sufficient hot smoke to cause fire spread despite the stack effects. However, any obstructions in the patio such as window shading has been found to cause heat accumulation that would aggravate the fire spread problem. The presence of a canopy at the top of the patio can cause higher concentration of smoke for the upper floors. The simulation results are found to be in good agreement with the actual incidence. Moreover the simulation results also show that when the fire spread through the patio the initial fire size of 1.0 MW at the fire site can grow to a building fire of 300 MW.     

Challenges of forest landscape modeling—Simulating large landscapes and validating results

Over the last 20 years, we have seen a rapid development in the field of forest landscape modeling, fueled by both technological and theoretical advances. Two fundamental challenges have persisted since the inception of FLMs: (1) balancing realistic simulation of ecological processes at broad spatial and temporal scales with computing capacity, and (2) validating modeled results using independent, spatially explicit time series data. The paper discusses the current status and future directions regarding these two challenges.     

Wind and Fire Coupled Modelling—Part II: Good Practice Guidelines

The requirement to model wind is inherently connected with the modelling of many fire-related phenomena. With its defining influence on fire behaviour, spread and smoke transport, the solution of a problem with and without wind exposure will lead to substantially different results. As wind and fire are phenomena that often require different scales of analysis and approaches to modelling, their coupling is not a trivial task. This paper is the second part of a two-paper review of the coupling between fire safety engineering and computational wind engineering (CWE). Part I contained a review of historical interactions between these disciplines, sorted into six distinct areas: flames, indoor flows, natural ventilators, tunnels, wildfires and urban smoke dispersion. This part of the review contains practical information related to wind modelling in fire analysis, based on various available CWE best practice guidelines. As the authors conclude, the most relevant of these are guidelines related to urban physics and natural ventilation; however, many more are discussed and presented, together with the results of other essential wind engineering experiments and computations. Introduction of wind as a boundary condition is explained in details, both based on wind statistics, or meso/micro scale coupled modelling. The guidelines for wind/fire coupled analyses are subdivided into recommendations for: building the digital domain, spatial and temporal discretisation, the consequences of the choice of a turbulent flow model, and the procedure for optimising CFD analysis of both wind and fire phenomena.     

Occupant Tenability in Single Family Homes: Part I—Impact of Structure Type,Fire Location and Interior Doors Prior to Fire Department Arrival

This paper describes an experimental investigation of the impact of structure geometry, fire location, and closed interior doors on occupant tenability in typical single family house geometries using common fuels from twenty-first century fires. Two houses were constructed inside a large fire facility; a one-story, 112 m², 3-bedroom, 1-bathroom house with 8 total rooms, and a two-story 297 m², 4-bedroom, 2.5-bathroom house with 12 total rooms. Seventeen experiments were conducted with varying fire locations. In all scenarios, two bedrooms had doors remaining open while the door remained closed in a third bedroom immediately adjacent to the open door bedrooms. Temperature and gas measurement at the approximate location of a crawling or crouching trapped occupant (0.9 m from the floor) were utilized with the ISO 13571 fractional effective dose (FED) methodology to characterize occupant tenability up to the point of firefighter intervention. The FED values for the fire room were higher for heat exposure than for toxic gases, while target rooms reached highest FED due to CO/CO₂ exposure. The closed interior door decreased FED significantly, with the worst case scenario resulting in a 2% probability of receiving an incapacitating dose compared to the worst case scenario for an open bedroom of 93% probability of receiving an incapacitating dose. In fact, in 7 of the 17 experiments, the closed interior door resulted in a less than 0.1% chance of an occupant receiving an incapacitating dose prior to firefighter ‘intervention.’     

Improved assessment of mass concrete dams using acoustic travel time tomography. Part I — theory

This is the first part of an investigation on improved assessment of mass concrete dams using Acoustic Travel Time Tomography (ATTT). It presents the concept and basic science for ATTT. ATTT combines aspects of ultrasonic measurements previously used for material characterization, ultrasonic methods applied to test concrete and features of methods used in shallow seismic surveys. This science/technology is integrated into a system that records travel time data and applies tomography software. The resulting tomographs have the potential to provide cross-sectional images of the structure that can be used to locate cracks, identify regions of structural damage, and other anomalies deep inside a massive concrete structure. Results from initial laboratory and field studies obtained with a system that embodies the approach presented in this paper and which provides proof-of-concept data, are presented in a companion paper (Kepler WF, Bond LJ, Frangopol DM. Improved assessment of mass concrete dams using acoustic travel time tomography. Part II — applications. Constr Build Mater, 2000; vol. 14, No. 3, pp. 147–156).     

Environmentalism and the multinational corporation: a viewpoint — part I

In this essay, we attempt to apply lateral pressure theory to conceptual thinking on MNC. “Power as capability” is implicit in the rationales firms engage in international production, viz., ownership advantage, location advantage, and internalization advantage. It is argued that issues of control (an internalization advantage) are crucial for the MNC, and the development of a complex mechanism for integrating information flow represents one important aspect of its capability. Part Two of this essay will explore in detail “power as influence” perspective of MNC bargaining power, relocation of production, and the impact of environmentalism in its value chains.     

Social Aspects of Beijing''''s Old and Dilapidated Housing Renewal——Beijing''''s Old and Dilapidated Housing Renewal(Part Ⅵ)

Ⅰ.Introduction Since the start of the program in 1990,Beijing＇s Oldand Dilapidated Housing Renewal has received considera-ble attention from all areas of society-from government of-ficials and professionals as well as ordinary citizens.The re-newal program has not only exerted a major impact on theold city areas of Beijing like the demolition of the old CityWall and the Pai Lou(Memorial Archways),but has alsobeen a sensitive issue related to housing problems whichmay affect hundreds of thousands of residents both in theold city and in other parts of Beijing.Furthermore,the pres-ervation of architectural relics and the historic core of Beij-ing Old City is now receiving more and more attention.Asa result,research on Beijing＇s housing renewal program in-volves a broad range of issues covering city development,housing construction and Old City preservation. The work of our group has involved lookingcomprehensively at all aspects of residential area renewal inold city areas-the economic,social and enviro     

Beach protection and restoration Part II: a perspective of “soft” methods

In Part I (Vide previous issue) the authors underscored the world‐wide character of coastal erosion and particularly the shrinking of beaches. If nature is the causal agent, man clearly enhances the process. To counter the steady encroachment of the sea upon the land, several protective devices have been placed along the shores. Some of these were even conceived as means to bring about sand accretion in specific sites.

The results have been overall disappointing, or of local value only. In this paper beach protection and beach restoration methods that call upon the natural processes are examined. The “soft” approach to the problem includes implanting artificial reefs, placing vegetation, or fences, on dune or beach, and especially artificial beach nourishment.     

Coagulation and precipitation of a mechanical pulping effluent—I. Removal of carbon,colour and turbidity

This study examined the effects of metal coagulant concentration, effluent dilution and pH on the removal of total carbon, colour and turbidity from a combined bleached chemithermomechanical/thermomechanical (BCTMP/TMP) effluent. Both chloride and sulphate salts of iron and aluminum were effective in treating the mechanical pulping effluent in batch jar screening tests. pH had a pronounced affect on precipitation. In terms of minimizing the total carbon (TC), colour and turbidity levels, the optimum adjusted pH ranges were: 4.0–6.5 for ferric chloride, above 7.4 for ferrous sulphate, 5.0–6.0 for aluminum chloride and 5.8 to 6.8 for aluminum sulphate. Removal of TC, colour and turbidity of up to 88, 90 and 98%, respectively, were observed. The precipitation yielded a supernatant which was virtually clear and colourless.