SIR,-Professor W. G. Sutton’s contribution on rivet groups in The Structural Engineer for September adds materially to the understanding of the subject.
INFLUENCE lines can be best studied and understood by first considering a simple span having a single unit load travelling across it and noting the variation of stresses in all its members. D.Y. Hill
Detailed drawings of the test panels of brickwork, together with the numerical results obtained in testing them, appeared in pages 379 to 384 of the Journal last month. These are here followed by photographs showing the appearance of the cracks in the panels, from the front and from behind, after failure; the photographs are arranged in the same order as the drawings to admit of easy cross-reference,and in each case the Blue bricks are distinguished from the Flettons by a letter B. It is to be noted that in each case the bearing of the joist was uniform over the thickness of the panel, so that the cracks are ino way the effect of edge pressure.
WHEN a beam is loaded in any manner, it is throughout its length subjected to bending and shearing stresses of varying magnitudes, and at any given section in the beam these two stresses give rise to combined stresses. In certain cases, where the bending and shearing stresses both reach their maximum values at the same section (cf., the fixed end of a cantilever), the combined stresses may attain values considerably higher than those due to pure bending and shear alone, and in a practical design an investigation should always be made to ensure that these combined stresses do not exceed the permissible values. F.H. Thomas
The tendency towards standardisation, so marked to-day in all branches of engineering, can be usefully carried out only to a certain extent in structural engineering. In small structures, cost is saved if one is able to make use of standardised framework; butbeyond that, specialised design is an essential if efficiency is to be attained; and the larger the contract, the greater the need for the individual assessment of problems, and for seeking the most satisfactory solution. A. Frost