Journal of Fire Protection Engineering recent issues

An Approach for Evaluating the Fire Resistance of CFHSS Columns under Design Fire Scenarios

Fike, R.S., Kodur, V.K.R. — Wed, 18 Nov 2009 06:07:53 PST

The use of concrete filling offers a practical alternative for achieving the required fire resistance in steel hollow structural section columns. However, the current prescriptive-based approach which evaluates fire resistance based on standard fire exposure does not account for realistic fire scenarios in the design of concrete-filled hollow structural section (CFHSS) columns. This article presents a methodology for evaluating the fire resistance of CFHSS columns under design fire scenarios without the need for costly computational models. The proposed approach is a derivative of the equal area concept, and evaluates the equivalent fire resistance of the column by comparing the time temperature curve of the standard fire exposure with that of the design fire exposure. The method has been validated against the results generated from finite element analysis (coupled heat transfer and strength analysis) on numerous CFHSS columns under a large number of design fires. The applicability of the approach in design situations is illustrated through a numerical example, and it is concluded that the proposed approach offers an attractive alternative for deriving equivalent fire resistance of CFHSS columns exposed to design fire scenarios.

Failure Analysis of the World Trade Center 5 Building

LaMalva, K. J., Barnett, J. R., Dusenberry, D. O. — Wed, 18 Nov 2009 06:07:53 PST

This article describes an analysis of the structural collapse that occurred in World Trade Center (WTC) building 5 due to fire exposure on 11 September 2001. It is hypothesized that the steel column-tree assembly failed during the heating phase of the fire. A failure analysis is performed to determine the response of the portion of the building frame that collapsed during the fire ignited by falling debris from the WTC towers. Results from a finite element, thermal-stress model confirm the column-tree failure hypothesis. Based on this model, the authors conclude that the catastrophic, progressive structural collapse occurred ~2 hours into the fire exposure.

The Skip-resistant Sprinkler Concept -- Theoretical Evaluation

De Ris, J. L., Ditch, B., Yu, H.-Z. — Wed, 18 Nov 2009 06:07:53 PST

This article presents a model for the response time of a sprinkler designed to reduce the skipping phenomenon experienced during large-scale fires. The model guides the design of a cylindrical shield intended to reduce drop impingement from nearby operating sprinklers. Several designs are experimentally tested and shown to reduce likely skipping when compared to the same sprinkler without a shield. The model is validated using a laboratory Plunge Tunnel apparatus to measure the effect of the shield on the thermal sensitivity of the sprinkler and its ability to intercept water drops. This work successfully demonstrates that shielding can decrease the response time of a sprinkler in drop-laden gas flow without causing a substantial increase in response time when exposed to a dry-gas flow. This is the first of two articles on the skip-resistant sprinkler concept. The following article evaluates the performance of the shield in actual fires.

The Skip-resistant Sprinkler Concept -- An Experimental Evaluation

Ditch, B., De Ris, J. L., Yu, H.-Z. — Wed, 18 Nov 2009 06:07:53 PST

A sprinkler with a shield designed to mitigate drop impingement from nearby operating sprinklers is shown experimentally to reduce skipping as compared to the same sprinkler without a shield. As described in a companion article, a model for the response time of a shielded sprinkler has been developed and validated with a Plunge Tunnel apparatus. In this article, results from intermediate-scale spray fire tests employing Froude modeling principles with a 1 : 3 scale ratio are used to evaluate sprinkler performance both with and without the shield. By comparing the operation times of adjacent shielded and unshielded sprinklers, the intermediate-scale tests can identify test arrangements where the shielded sprinkler operates while the unshielded sprinkler does not operate. The identified arrangements are then used in a full-scale environment where a series of pan fire tests serve as a proof-of-concept that proper shielding of a sprinkler can reduce skipping in terms of both the sprinkler operation pattern and total number of sprinkler operations. This study successfully demonstrates that proper shielding of a sprinkler can significantly reduce skipping.

Thanks to Reviewers

Wed, 18 Nov 2009 06:07:53 PST

A New Intermediate-scale Fire Test for Evaluating Building Material Flammability

Nam, S., Bill, R. G. — Mon, 10 Aug 2009 07:17:42 PDT

A new intermediate-scale fire test has been developed as a screening tool to evaluate wall and ceiling assemblies for material flammability. The scale of the test is large enough for the tested materials to reveal their behavior in a full-scale fire, but still small enough to provide substantial cost savings compared to 25-ft and 50-ft corner tests used for decades to evaluate wall/ceiling panels and other building materials. The test consists of parallel panels of the material assemblies being evaluated, which are each 1.07 m wide and 4.9 m high and separated by 0.53 m. A 360 kW propane sand burner is used as the ignition source. The parallel panel test is conducted under a 5-MW fire products collector to measure fire heat release rate (HRR). Materials used during development of the new test include various thicknesses of: polyvinylchloride, fire retardant plywood, fiberglass-reinforced melamine and panels with metal facings over foamed polyurethane, polystyrene, and polyisocyanurate. Comparisons with the 25-ft and 50-ft corner tests indicate that fire propagation behavior in the corner tests correlates well with the maximum HRR in the parallel panel test as follows: fire will not propagate to the end of the test array in the 25-ft corner test with combustible wall panels and a noncombustible ceiling if the HRR in the parallel panel test is <1100 kW; fire will not reach the top of the test array in the 50-ft corner test if the HRR in the parallel panel test is less than 830 kW; fire propagation will not reach the ends of the horizontal ceiling in the 25-ft corner test with both combustible wall and ceiling panels if the HRR in the parallel panel test is <830 kW.

Calibrating an FDS Simulation of Goods-vehicle Fire Growth in a Tunnel Using the Runehamar Experiment

Cheong, M.K., Spearpoint, M.J., Fleischmann, C.M. — Mon, 10 Aug 2009 07:17:42 PDT

As with any complex fuel assembly configuration, modeling a goods-vehicle fire using fire dynamics simulator (FDS) to estimate the heat release rate in a tunnel is a challenging task. The present study involves the use of heat release rate curves taken from the Runehamar tunnel fire experiment T1 to ‘calibrate’ the heat release rate curve predicted using FDS 4.0.7. The article presents a simplified geometric representation of burning wood and plastic pallets and then illustrates that an FDS simulation of this representation is able to reproduce a reasonable estimate of the fire growth characteristics in the tunnel. The effects of the assumptions made in simplifying the fuel array are considered in order to calibrate these simulations. Finally, the article shows how the fire growth might change if conditions in the tunnel were varied.

Behavior of Full-scale Frames with Slim Floor Slab Construction under Exposure in a Fire Resistance Furnace

Dong, Y., Prasad, K. — Mon, 10 Aug 2009 07:17:42 PDT

In recent years, there has been increasing interest in developing and designing slim floor systems in steel-framed buildings. This article describes the results of a furnace test conducted on two full-scale composite steel frames with slim floor slab construction to understand their performance under fire loading. In one frame, the beam-to-column connections were protected, while in the second frame, the columns as well as the beam-to-column connections were protected. During the test, the furnace temperature, the steel and concrete temperature, as well as the horizontal and vertical displacements were recorded. The complete deformation process of the test frame observed during the heating phase and the cooling phase, including failure of the frame, is described in this article. A comparison of the data obtained from the two tests indicates that the fire resistance of a composite beam is significantly better than that of a steel column. Fire resistance of composite frames with slim floor slabs is compared with data on a conventional floor slab. Results indicate that the fire resistance rating of frames constructed with slim floor slabs is at least as good as that of frames with conventional floor slab construction.

Evaluation of the Impact of Potential Fire Scenarios on Structural Elements of a Cable-Stayed Bridge

Bennetts, I., Moinuddin, K. — Mon, 18 May 2009 06:10:12 PDT

It has become necessary to consider the potential exposure of major bridges to flames from oil or liquefied petroleum gas fires as part of comprehensive risk assessments being undertaken for major infrastructure. This article identifies and characterizes potential fire scenarios relevant for bridges and considers the likely impact on elements of a bridge structure. As part of this study, simplified heat transfer models are developed for the purpose of determining the temperatures of key structural steel elements. These models, which provide an efficient method for determining heat transfer through elements such as heavy bundled steel cable, are described in this article. The Newton—Raphson method is used to solve the key equations. Calculated temperatures are presented for the various fire scenarios involving key structural steel elements and the implication of these temperatures for the structural behavior of the steel elements is considered.

Evaluation of Protection for Plastic Containers Using Sprinkler Systems with 1.0% AFFF and Plain Water

Vincent, B. G. — Mon, 18 May 2009 06:10:12 PDT

Four large-scale fire tests were conducted to compare an aqueous film forming foam (AFFF) agent against plain water for protection of an on-floor storage arrangement of a plastic container commonly used in automated and manual materials handling. The container used in these tests was a 600 mm x 400 mm x 280 mm open-top, double-wall, polypropylene box. These boxes were stored 4.5 m high under a 10.5 m ceiling. The protection design used fast-response 688C-temperature-rated K160 sprinklers discharging either 1.0% AFFF agent/water solution or plain water at a discharge density of 30 mm/minute. Initial test parameters, which included fuel and storage configuration, sprinkler system design (sprinkler type, temperature rating, actuation link sensitivity, spacing, and discharge pressure), ignition placement within the storage configuration and the relative positioning of the storage arrangement with respect to ceiling sprinklers were consistent for all tests. The testing procedure involved a format that used an initial test followed by a validation test under the same initial test conditions.

SFPE Classic Paper Review: Diffusion-Controlled Ignition of Cellulosic Materials by Intense Radiant Energy by Stanley B. Martin

Kanury, A.M. — Mon, 18 May 2009 06:10:12 PDT

An Integrated Model to Predict Fire Resistance of Wood Floor Assemblies

Takeda, H. — Mon, 18 May 2009 06:10:12 PDT

An integrated numerical model to predict the fire resistance of wood-framed floor assemblies has been developed. The assemblies considered in this article are floors constructed with nominal 2 x 8 (38 x 191 mm²), 2 x 10 (38 x 241 mm²) or 2 x 12 (38 x 292 mm²) wood joists lined with Type X gypsum board (12.7 mm or 15.9 mm thickness) as a ceiling membrane with (or without) resilient channels and 15.9 mm thick plywood as a sub-floor. The model includes a heat transfer sub-model to calculate the flow of heat in the assembly and a structural sub-model to evaluate the mechanical performance of the assembly. The heat transfer sub-model employs two-dimensional heat conduction equations to predict the temperatures in the ceiling (gypsum board), wood joists and sub-floor of the assembly when the ceiling is exposed to fire. Using the temperature distribution in the joists predicted from the heat transfer equations, the structural sub-model analyzes the mechanical strength of the joists and calculates joist deflection in the assembly. Results from the numerical model are compared to results from full-scale tests. Reasonably good agreement is observed.

Pre-evacuation Data Collected from a Mid-rise Evacuation Exercise

Gwynne, S.M.V., Boswell, D.L. — Wed, 04 Feb 2009 04:25:53 PST

This article describes the observation of an unannounced evacuation exercise from a mid-rise administrative building. The primary focus of this activity was to collect pre-evacuation data, although evacuation times were also recorded for completeness. The article includes a description of the structure, the population, the emergency procedure employed and the observations made during the evacuation (both numerical and descriptive). Data are presented in a number of formats including raw values, averages, ranges, and distributions, i.e., in as much detail as possible and in context with the evacuation scenario. This should increase/improve potential applications, and reduces the likelihood of misunderstanding. A simple graphical scheme was developed to connect the numerical and descriptive data collected and provide a comprehensive timeline of events. In addition, a detailed description of the data collection methods employed is presented, outlining their strengths and limitations. This article therefore presents a range of valuable data, a detailed description of the methods employed and a means to clearly present the data collected.

Understanding the Effectiveness of Notification Technologies in Assisting Vulnerable Populations

Gwynne, S.M.V., Boswell, D.L., Proulx, G. — Wed, 04 Feb 2009 04:25:53 PST

Different sections of the general population were examined to establish two criteria: whether they were particularly vulnerable to death in fire incidents; and whether these vulnerabilities could be reduced through developing and/or applying specific notification technologies. This study was conducted in order to establish where there were omissions in our current understanding and where this coincided with technological solutions of particular interest. An approach was developed to identify vulnerabilities and prioritize them in order to focus future research. The approach adopted was able to achieve this goal. The suggested research was then conducted and allowed guidance to be developed regarding the use of different notification technologies. This article describes the development of this analytical framework and the analysis of some of the results produced.

Thermo-mechanical Analysis of Fire Doors Subjected to a Fire Endurance Test

Tabaddor, M., Gandhi, P. D., Jones, G. — Wed, 04 Feb 2009 04:25:53 PST

Fires doors are subjected to standard fire tests as a means of evaluating fire resistance. In this study, the thermal and mechanical response of steel double fire doors exposed to high temperatures was modeled using finite element software. The model included the necessary complexity of the product and test setup along with the temperature dependency of the constituent materials. For the thermal solution, a transient analysis was carried out while for the mechanical solution, it was found that a nonlinear steady state analysis was sufficient to capture the qualitative behavior of the fire doors seen during the test. The challenges of validating a numerical model with the limited data available from the standard fire test are described.

SFPE Classic Paper Review: Fire Performance under Full-scale Test Conditions -- A State Transition Model and Coupling Deterministic and Stochastic Modeling to Unwanted Fire by Robert Brady Williamson

Zicherman, J. B. — Wed, 04 Feb 2009 04:25:53 PST