Shear, flexure and axial tension in reinforced concrete members (1970)
Type of ContentTheses / Dissertations
Thesis DisciplineCivil Engineering
Degree NameDoctor of Philosophy
PublisherUniversity of Canterbury
AuthorsO'Leary, Arthur Josephshow all
In this project the strength and behaviour of reinforced concrete beams subjected to flexure, shear and axial tension are examined. This combination of actions may be induced by lateral loading in the external column of a multibay frame or in the lower columns of a coupled shear wall. Although the flexural behaviour of such members is well understood little is known about their deformation characteristics and resistance to shear.
Ten beams subjected to eccentric axial tension have been tested. The load was so applied that the axial force to shear force ratio remained approximately constant throughout each tests. The major variables examined have been content of web reinforcement and variation in axial load to shear force ratio.
A theoretical method of determining the deformations of flexurally and diagonally cracked beams subjected to axial tension is developed. It is shown that allowance for stirrup anchorage slip must be incorporated in such a theory if it is to predict beam behaviour successfully.
To enable the contribution of dowel action to be evaluated in the test beams concrete cantilever dowel test specimens have been tested, and also dowel shear tests on yielded reinforcement bars, are reported. In this way the dowel shear resistance throughout the loading of the test beams is examined.
It has been found that current code recommendations for the shear resisted by stirrups in members subjected to axial tension are conservative. Diagonal cracks form in similar patterns to those in normal flexural members, and the critical separation diagonal crack forms at an angle of less than 45° to the axis. The presence of diagonal cracks reduces the stiffness of the members in the elastic range of loading. The members are ductile if adequate shear reinforcement is present.