Reinforced Concrete.

Hokitika Guardian, 31 August 1922, Page 1

Reinforced Concrete.

TALLEST BUILDING IN AMERfCA According to “Concrete,” there has just been completed in New York an eighteen-storey building in reinforced concrete, and known as the “Hide and .Leather Building.” This constitutes the tallest building of its type in the United States of America, and provides a notable example of concrete both as a structural and architectural building material. From basement door to roof the : total height is 223 ft. The building is square in plan of 75ft side, and is divided into bays each way of about 18ft square. The whole structure, which includes the. W),000 gallon water tank on the roof, embodies no structural steel or brick .Situated on what is known as “The Swamp,” its foundations are of especial interest. These are of the ‘Protest” type, selected as tli only .possible, in view of the fact that the bearing strata consisted of 100 ft of sand of,varying qualities underlying stmta of muck and pent. In the system sectional precast concrete pile* nru driven by hydraulic, pressure ns the building progresses. The piles are driven in in stages as theweight upon them increases, and only attain their final position when the frame of the building is complete. Their efficiency depends upon the “bulb of pressure,” that is. the portion of the strata which actually carried the load. It is found that if points of equal pressure are joined, the shape is that of a hull), the cohesion of the particles of the material of which sustains the load. It is known that piles which have successfully withstood certain test loads often settle when much smaller loads are later applied. Success depends upon the maintenance- 'of the hull) once it is formed. To carry out the system, shallow pits aro excavated at the locations of walls and columns. Cylinders of steel 1 easing 3ft long and 20in in diameter aro grouped as may he required by tho final load, and filled with con-' Crete. They are surmounted by wood blocks to the height of the under-side of the future concrete cap or column footing. Thcne caps are then placed in position, and the erection of the building proceeded with, thus saving time while the foundations are being finshed. The cylinders are then jacked down by hydraulic rams in successive stages as the building proceeds, further sections of casting and concr(?t« being added to maintain the continuity of the pile. When tho,pile has reached its linal position the pressure which is already upon it through a hydraulic ram is,then transmitted through an I beam cut to length and wedged in between the pile and the concrete cap. This method appears to he the only one-which could have been adopted, and- the building, the first all-concrete skyscraper, will probably lie the forerunner of many more of tin same type.