No description available.

The programme of research described in this thesis has investigated the effect of confinement of the compression regions on the behaviour of structural concrete beams up to failure under the action of static loadings. A flexure-shear interaction design model and a corresponding approach to detailing to prevent diagonal failures in beams have been developed based on the actual physical behaviour of beams. This has been achieved by confining only the compression regions in the beam structure with closed stirrups. The increase in concrete strength resulting from the presence of the confining stirrups was aimed at offsetting the reduction in the flexural capacity of beams due to the presence of shear forces. A method for the evaluation of the flexural capacity of beams in which confinement is present has also been proposed. The approach was extended to the design of over-reinforced beams to enable them to behave in a ductile manner. A test programme comprising a total of fifty three simply supported beams was used for the development (twelve beams) and for the verification (forty one beams) of the proposed design models. The results obtained confirmed both the applicability and the effectiveness of all of the design concepts and detailing approaches which have been put forward in this research programme. It is believed that the concepts which have been put forward could form a basis for the development of a rational unified approach to the design of structural concrete members.

No description available.

No description available.

No description available.

No description available.

The work described in this thesis is concerned with procedures for the identification of nonlinearity in structural dynamics. It begins with a diagnostic method which uses the Hubert transform for detecting nonlinearity and describes the neccessary conditions for obtaining a valid Hubert transform. The transform is shown to be incapable of producing a model with predictive power. A method based on the identification of nonlinear restoring forces is adopted for extracting a nonlinear model. The method is critically examined; various caveats, modifications and improvements are obtained. The method is demonstrated on time data obtained from computer simulations. It is shown that a parameter estimation approach to restoring force identification based on direct least—squares estimation theory is a fast and accurate procedure. In addition, this approach allows one to obtain the equations of motion for a multi—degree—of—freedom system even if the system is only excited at one point. The data processing methods for the restoring force identification including integration and differentiation of sampled time data are developed and discussed in some detail. A comparitive study is made of several of the most well—known least—squares estimation procedures and the direct least —squares approach is applied to data from several experiments where it is shown to correctly identify nonlinearity in both single— and multi—degree--of—freedom systems. Finally, using both simulated and experimental data, it is shown that the recursive least—squares algorithm modified by the inclusion of a data forgetting factor can be used to identify time—dependent structural parameters.

No description available.

No description available.

No description available.