The ultimate strength of reinforced concrete beams of
both rectangular and tee section under the combined effect of
bending and shear forms the topic of this investigation. The
published results of tests on over 1000 rectangular and tee beams
have been collected and the ultimate strength of each of them
predicted from an empirical formula. The overall coefficient of
variation of the ratio of predicted to observed strengths is found
to be about 18%. By simulating the anticipated variations in the
parameters of the empirical formula it has been shown that the
overall variation in the results is not excessive.
Over 200 new tests on beams of reinforced plaster both
rectangular and tee sections, and also the previously published
test results on plaster beams support the general form of the
Fourteen new tests on reinforced concrete tee beams with
short shear spans indicate that the behaviour of such tee beams can
be predicted as confidently as that of rectangular beams.
The proposed empirical formula will successfully predict
the strength of beams tested in the restrained condition and also
under uniform load. This is supported by further tests on reinforced
The mechanism of shear in reinforced concrete beams is
explained by quoting the test results of other investigators and
also by the present tests on plaster beams. It will be shown that
bond between the reinforcement and concrete is a fundamental factor
which influences shear failures.
The load factors of the simply supported beams implied
by the shear clauses in the current British Code, the current
American Code and also by the proposed British Code are compared.
The reliability of such predictions is examined.
The economic design of reinforced concrete beams is
examined by different approaches and the cost is compared. It
is suggested that the cost of shear reinforcement is a very small
part of the total cost of such beams.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.