Concrete troubles and how they should be avoided

Welding has long been considered as the art of uniting pieces of similar metals by ham- mering or compression when raised to a temperature short of the fusing point; but today a broader interpretation must be accepted to include autogenous soldering in which fusion occurs, and any added metal is similar to the pieces to be joined together in firm union. Such autogenous soldering has long been practised with lead. J Caldwell

In single storey buildings of the shed type, the vertical loads on the columns are generally small, while the overturning moments clue to wind forces are relatively large. The stability moments are supplied in one of three ways:- (l) by means of a portal frame such as a knee braced truss with the bases of the columns considered as being hinged. (2) by means of a portal frame with fixed bases to the columns. (3) by means of fixed beams to the columns, the connections of tile roof trusses to the columns being considered hinged. In methods (2) and (3) the design of the steel bases and the concrete foundations is all important, and it is the purpose of this article to deal with the design of the type of symmetrical base and foundation in common use. G J Voce

THE CHAIRMAN (Mr. H. J. Deane, Past President) said he might possibly add to what Mr. Burns had said in connection with “ slump,’’ referred to on page 440. Some might wonder why the engineers carrying out this work should have made a point of having this slump taken, but Mr. Burns, quite rightly, had not mentioned the question of specification. He had been dealing solely with the difficulties and intricacies of foundations which were rather out of the ordinary. I n order, however, to obtain satisfactory results, bearing in mind the fact that the Contractors desired to use chutes for placing the concrete, one had to arrange a specification which would meet these conditions, and at the same time give the amount of strength that was necessary for the work in general.