Abstract
This thesis describes a theoretical and experimental study of the behaviour of the compression chords for through-bridges. The behaviour of the compression chords has been studied theoretically for the case when the chords have cross-sections with two axes of symmetry and negligible torsional and warping rigidities. The stability of the chords has been investigated for the cases when they remain straight up to the point of buckling , and for the cases when the live load is applied on to the flexible cross-girders and the chords consequently deflect before the buckling loads are reached. The same problems as those mentioned above have been studied for the more general case when the chords have cross-sections with only one axis of symmetry and when both the torsional and warping rigidities are taken into account. Experimental work has been carried out on a xylonite and on an aluminium model through-bridge in order to provide experimental verification for the theoretical analyses. Generally a very close agreement was obtained between the theoretical and experimental results. All the theoretical results nave been obtained using Fourier series, and they are given in the general form. Provided an infinite number of terms are used in the formulae they will give the exact answers for the problems considered. In order to estimate the practical values of these results, the convergencies of the Fourier series have been studied. It was found that for most practical cases the theoretical formulae will provide the required design data without too elaborate computations being involved.