Rustin Fike

High-Temperature Properties of Steel for Fire Resistance Modeling of Structures

Fire is one of the most severe conditions to which structures can be subjected, and hence, the provision of appropriate fire safety measures for structural members is an important aspect of design. The recent introduction of performance-based codes has increased the use of computer-based models for fire resistance assessment. For evaluating the fire resistance of steel structures, high-temperature properties of steel are to be specified as input data. This paper reviews high-temperature constitutive relationships for steel currently available in American and European standards, and highlights the variation between these relationships through comparison with published experimental results. The effect of various constitutive models on overall fire resistance predictions is illustrated through case studies. It is also shown that high-temperature creep, which is not often included in constitutive models, has a significant influence on the fire response of steel structures. Results from the case studies are used to draw recommendations on the use of appropriate constitutive models for fire resistance assessment.

Guidelines for Improving the Standard Fire Resistance Test Specifications

The current approach of evaluating fire resistance is mainly through standard fire tests. The specifications for standard fire tests have a number of drawbacks and require only a limited amount of data to be collected during tests, and this is hindering the development of calculation methodologies for evaluating fire resistance. This paper discusses the various drawbacks in the current specifications for undertaking fire resistance tests. The improvements needed to make the standard fire resistance tests more effective and the collected test data more useful are outlined. Strategies for implementing the proposed recommendations (improvements) in test standards are illustrated with examples. Finally, the applicability of the proposed recommendations is illustrated by undertaking fire resistance tests on a midsized column and a midsized beam under improved test specifications. Data collected from these fire resistance tests is used to calibrate finite element based computer models, thus demonstrating the effectiveness of collecting additional test data.

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

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 desi...

Comparative Fire Performance of Traditional Lumber and Engineered Wood Joists

Purpose This paper aims to present an evaluation of comparative fire resistance on traditional and engineered wood joists used in the construction of floor systems in residential housing. Design/methodology/approach Fire resistance experiments were carried out on four types of wood joists, namely, traditional lumber, engineered I-joist, castellated I-joist and steel/wood hybrid joist, used in traditional and modern residential construction. The test variables included type of wood joist, support conditions and fire protection (insulation). Findings Results from these tests indicate that webs of engineered I-joists and castellated I-joists are highly susceptible to fire, and failure generally occurs through the burn-out of the web. In addition, engineered I-joists have much lower fire resistance than traditional solid joist lumber. The application of an intumescent coating on an engineered I-joist significantly enhances its fire resistance and yields a similar level of fire resistance as that of a traditional lumber joist. Originality/value The presented fire tests are unique and provide valuable insight (and information) to the behavior and response of four types of wood joists when subjected to gravity loading and fire conditions.