Shear Effect on the Elastic Stability of Frames

The effects are investigated of the inclusion of pulverised-fuel ash on the elastic modulus and strains up to and beyond maximum stress, creep, creep recovery and post-creep-recovery strength and elastic modulus, drying shrinkage, and thermal expansion, using a wide variety of ashes in a range of concrete mixes designed for the same workability and 28-day strength as a series of control OPC concretes. R.K. Dhir, J.G.L. Munday and L.T. Ong

Bridge decks consisting of precast, prestressed concrete U-beams acting compositely with an in situ concrete top slab are a popular form of construction, sometimes requiring half joints at the ends of the beams. In the past, this has been achieved by using complicated timber formwork attached to the ends of a standard U-beam mould. An alternative method has been proposed which results in a composite half joint, and full-size tests on four such half joints are described in this paper. It is shown that consideration has to be given to behaviour under both service and ultimate loads, and, on the basis of an analysis of the test results, a design procedure is proposed. B.S. Gill, L.A. Clark and J.P.J. Taylor

Mr E. Booth (M) (Ove Arup & Partners): This paper presents test evidence on the failure loads of rc wall beams under various load conditions, which are then compared with the design recommendations of the CIRIA guide (ref. 11 in the paper) and ACI 318 (ref. 16). As the first systematic test of these recommendations since the publication of the CIRIA guide that the writer is aware of, this is an important paper. The authors are also to be congratulated on the clarity of presentation.