FERRO=CONCRETE WORK IN NEW ZEALAND.

Progress, Volume II, Issue I, 1 November 1906, Page 11

FERRO=CONCRETE WORK IN NEW ZEALAND.

Mr. Samuel Brown, of Wellington, read an interesting paper before the Wellington Industrial Association recently explaining to members what is being done in Auckland and other places with regard to re-inforced concrete. There is no difficulty in driving the piles for the new wharves at Auckland. The piles are made long enough to come to about low-water mark. A frame is then made, and the pile made up with steel and concrete to the height required in the same manner as the pile itself Temporary staging is then made and the whole boarded over. The longitudinal girders have framing of deep boxes. In these boxes are placed mild steel frames, about three in each box. These frames, where they rest upon the pile, are about 6ft. deep at each end, and taper off to about 2ft., the middle of the girder being about 2ft. deep and somewhat the same as the ordinary beam with brackets underneath at each end. The bottom chord, which gives the shape to the beam, is i-J-m. round mild steel. The top one is small section, and between the top and bottom chords are upright rods of steel, about £in. thick and about 6m. apart. The whole is wired together with steel wire. Wherever a cross girder meets a longitudinal girder there are three steel bars 1 Jin. bent over so as to tie both together, that is to say, the cross girders to the longitudinal girders. These boxes are filled with concrete rammed in a similar manner to the piles

Mr. Brown also minutely described the deckwork being carried out on the contract. In Auckland they have built a very large wharf, and are spending altogether about In addition there is a wharf and foundation for a crane at the Calliope Dock, costing about The first process is making the piles. Four rods of i£m. round mild steel are formed into a square 2m. smaller than the pile, so that there is 2in. concrete outside ; that is to say, if the pile was 14m. square when finished, the square of steel rods would be 12111. These rods are made into a square by having light cast frames fixed at certain distances apart. They are bound together by steel wire every few inches right round, also diagonally. The ends of the four steel rods are bent at the end in the same shape as a pile when it is pointed. This frame is placed in a box, which is 2m. larger every way, so that when it is filled there is 2in. of concrete outside of the steel frame. There is also the ordinary pile shoe placed m the box and the whole filled with concrete. This concrete is well rammed with iron rammers, the concrete being made pretty fine — no stones larger than a walnut. The result of careful ramming is that when the frame^is taken off, the pile is as smooth as if it had been plastered over. Extra long piles, say 40ft., have hollow pieces of wood placed in the centre ; these are about 6in. diameter and are placed about lit apart. This is to lighten the pile, and is claimed by the engineer to be equally as strong. " It would seem," said Mr. Brown, " that in San Francisco steel frame buildings stood the

earthquake well. These, as far as can be gathered, were frame structures with the panels filled in with brick, stone, or marble. Although the frames stood well, it would seem that the panels in cases came out. The difference between this and the system that I have been trying to describe is that in one a whole panel may be shaken out, but the other is a complete network of steel interwoven in the concrete and which adheres to the steel so closely that it never rusts. It is said that reinforced beams for floors are now made for spans of iooft. In addition to being the best style of construction to resist earthquakes, it is said to be also equally valuable as a fire-proof construction. The personal opinion I have formed of it is that in Wellington it would be as safe as a wooden building for earthquakes and more fire-proof than any other mode of construction."