A generic segmental analysis of all types of RC members.

Abstract

This thesis contains a series of journal papers in which a new segmental moment-rotation (M/θ) approach is developed for both instantaneous and long term loading. The analysis technique is based on the starting position of moment-rotation rather than moment-curvature and the assumption that plane sections remain plane, but not on the often applied corollary of a linear strain profile. Using the well-established mechanics of partial-interaction theory, the M/θ approach simulates the formation and gradual widening of cracks as well as tension stiffening, as the reinforcement slips relative to the concrete which encases it, and, using the mechanics of shear-friction theory, the approach simulates the formation and failure of concrete softening wedges. Moreover, being mechanics based, the M/θ approach can in theory be applied to any type of member, that is any cross section, with any concrete properties, and any reinforcement type with any bond characteristic. Hence using partial-interaction and shear friction theories, the M/θ approach obviates the need for both empirically derived effective flexural rigidities and hinge lengths. This leads to the establishment of a new equivalent flexural rigidity that accounts for both concrete cracking and concrete softening and can be applied to both instantaneous and long term loading. Having established the equivalent flexural rigidity from segments of a member, it can then be used to predict the effective flexural rigidity of an entire member, and hence the load deflection behaviour through the application of a numerical segmental analysis procedure. It is further shown that with simplifying assumptions closed form solutions to describe the equivalent flexural rigidity of a segment can be obtained and member deflections described using standard analysis techniques. Having established that the M/θ technique can be applied using both numerical and closed form solutions, it is used to predict a broad range of reinforced concrete behaviours. These behaviours include: the instantaneous deflection of beams reinforced with both ductile steel and brittle fiber reinforced polymer bars and the instantaneous deflection of laterally and eccentrically loaded columns, including those in which second order effects are considerable and the long term deflection of simply supported beams. Through these broad applications, it is shown that the M/θ approach represents a mechanics based solution to reinforced concrete analysis, capable of accurately predicting both instantaneous and long term deflections from serviceability through to peak loading and collapse, where the only empirically derived requirements are material properties. Hence, the M/θ approach can be considered an extension of traditional analysis techniques in that it removes the need to empirically define effective flexural rigidities and hinge lengths to determine member behaviour.