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The Structural Engineer, Volume 70, Issue 1, 1992
The paper summarises the results of three load tests on composite beams of 1Om span, comprising one control composite beam (i.e. without opening) and five rectangular openings of various sizes and locations. The tests were carried out under simulated uniform load and were taken to failure of the beam at each opening. The results of the tests have been compared with existing guidance in the SCI/CIRIA publication Design for openings in the webs of composite beams. The overall model factor, representing the margin between the tests and the design method (eliminating partial safety factors and using measured properties) was in the range of 1.04 to 1.47. Reasons for this apparent conservatism are given. The control composite beam was also tested to failure without the presence of openings, and the results were compared with the method of BS59.50: Part 3. This gave a model factor of 1.04. R.M. Lawson, K.F. Chung and A.M. Price
Mr A. N. Bed (M) Thomason Partnership) It is unfortunate that, in recent years, masonry design has tended to be based too closely on concrete practice, some of which is of dubious merit. This paper is a welcome return of first principles in estimating strength of slender masonry, and it is no surprise to see the results agreeing more closely than BS 5628 does with experiments. Some years
Predicted creep and shrinkage of plain and reinforced concrete have been compared with experimental values over a period of 8 months; the comparison included symmetrical and unsymmetrical arrangements of reinforcement. Although total (creep + shrinkage) deformations can be estimated fairly accurately, creep of plain concrete and shrinkage of reinforced concrete are overestimated by the established methods of prediction. Analysis of the various proposed reduction factors for deformation of reinforced concrete suggests that the role of creep of plain concrete in influencing the modular ratio is different for accurate predictions of creep and shrinkage. In the case of creep of reinforced concrete, creep of plain concrete is not important, but in the case of shrinkage of reinforced concrete it appears that tensile creep, and not compressive creep, of plain concrete could be of importance. J.J. Brooks, A.E. Gamble and M.M. Chouman