Thesis (M. App. Sc.)--Carleton University, 2005. / Includes bibliographical references (p. 322-325). Also available in electronic format on the Internet.

The mechanical and material properties of structural steel at elevated temperatures play an important role in structural fire design. The South African 350W and S355 structural steels are common in building structures with S355 slowly replacing the older 350W. The cost and feasibility of full scale fire tests are some of the causes for the lack of experimental data on the behaviour of steel structures when exposed to fire. Therefore excessively conservative design codes based on isolated laboratory experiments are used in practice which leads to increased material costs. Another area of concern with respect to building safety is the reusability of structural steels post fire exposure, which is not effectively addressed within these codes. This study aims to establish greater insight into structural fire design and simulation on which further research can be built. Experimental programs on the temperature dependent behaviour of these steel members loaded axially are conducted and compared with theory and the Eurocode 3 standard [1]. The reusability of steel exposed to fire and after being cooled down is investigated and compared to the findings by Outinen [2]. Further testing on material to determine the relationship between remaining life and hardness degradation after cooling down was conducted. Experimental data from various external studies are used to develop novel computer models using the finite element analysis software, SimXpert [3]. These are verified against the original data and compared to existing design codes. A parametric approach is used with these models to demonstrate the advantages of computer simulations in structural fire design. Different cross sections and slenderness ratios are evaluated for their susceptibility to buckling at elevated temperatures. The results of this study show that as temperature and exposure time increase the integrity of steel members decrease. The current design codes accurately predict the behaviour of isolated specimens but lack data on real situations where the specimen is part of a complex structure. It was found that steel members can be reused if their exposure temperature does not exceed 700°C, after which their strength can reduce to 90%. This temperature dependant behaviour was successfully modelled using basic computer simulations and then demonstrated the ease in which they can be used in place of experimental regimes. The parametric advantages of these simulations were demonstrated by predicting the effects of slenderness ratios and geometry cross sections on the buckling behaviour. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2012.

This study is a presentation of an instantaneous and simultaneous velocity and concentration measurement technique and its applications on car park fire scenarios. <p>In this actual chapter 1 general introduction is given to each chapter. Chapter 2 is dedicated to a detailed description of the instantaneous and simultaneous velocity and concentration measurement technique and its associated error assessment methodology. The name of the new technique is derived from the names of the acquired parameters (VELocity and COncentration) and shall be hereafter referred to as VELCO. After having validated and performed an error assessment of this technique, it is applied to an investigation of full-scale car park (30 m x 30 m x 2.6 m – Gent / WFRGENT) fire cases in chapter 3. The measurements were carried out with the financial support of IWT-SBO program. In the full-scale measurements only the velocity part is applied of VELCO, yet it can be considered as its application since the special data treating was developed and implemented in the Rabon (see: §2.1.2) program, which is the software of the new technique along with Tucsok (see: §2.1.1) and they will be both discussed in the related chapter. Here it is enough to mention that the concentration and velocity information can be obtained independently as well. During the full-scale measurements, beyond of VELCO the smoke back-layering distances (SBL) are also derived from the temperature values, which were measured by thermocouples under the ceiling in the midline of the car park. The critical velocity, which is an important measure of fire safety, can be obtained from the SBL results. In chapter 4, isothermal fire modeling is surveyed in order to present how full-scale fires are modeled in small-scale. In this part of the study the theory of fire related formulae and an isothermal model are described. Here it is important to stress the fact that the fire modeling is not directly related to the VELCO technique. However it connects the full-scale to the small-scale measurements, which the technique is applied on. Chapter 5 discusses small-scale measurements (1:25 – Rhode Saint Genese / VKI) on the car park introduced in chapter 3 and their validation. After the validation, more complex car parks scenarios are also investigated due to the easy to change layout in the small-scale model with respect to the full-scale car park. In this chapter the smoke back-layering distances are obtained by VELCO. Finally, in chapter 6 important conclusions are drawn with the objective of increasing fire safety. <p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished