Steel, steel/concrete composite and reinforced concrete beams and columns exposed to fire
This thesis describes the development of a numerical method for the structural analysis of beams and columns subjected to a non-linear variation of temperatures in all three directions. The numerical method allows for analysis of a wide variety of cross sections with a number of materials and members with varying cross section along the length. The member can be subjected to any combination of axial load, end moments, lateral load and bi-axial bending. Any fire temperature characteristic can be specified. The numerical method has been validated by comparing results with a number of experimental results on steel, concrete and composite beams and columns from literature and with the experiments carried out under this research programme. Experiments were carried out on seven columns with non-uniform temperature distribution along the length and across the depth. The test rig was designed and manufactured at City University. Electrical heating elements were used to heat the specimens. To obtain a comprehensive temperature profile of the test columns several thermocouples were used. Deflection measurements were made using displacement transducers placed at different positions. Using the new method of analysis a simple design method for steel columns subjected to non-uniform temperature distribution across the depth of the section has been developed. The method has been validated with a number of results on H-section columns from numerical experiments performed using the computer programs developed in this thesis. Another parametric study has been carried out to improve the inherent fire resistance capacity of Slimflor beams. It is concluded that it is possible to design a Slimflor beam with higher fire resistance capacity than the current rating of 60 minutes by introducing steel reinforcing bars at appropriate place.