50
Fixing silo steel formwork
waterfront. This structure was de- signed to carry a full live load plus wind load at different angles of in- clination.
The Janssen's formula for deep bins was used in estimating the pres- sure on the silo walls, the physical properties of wheat, used in the cal- culations were that of the angle of internal friction
25°. the coeffi- cient of friction between wheat and concrete, m 0.444 and the density D 50 lb cu. ft.
The concrete mix for the 71⁄2 in. thick silo walls was 1:2:4 'A' and the
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reinforcement was high tensile steel bars of 8 in. and 1⁄2 in. Ø.
Special studies have been made on the problems of the twisting of the corner silos when the interspace is full of wheat and the surrounding silos are empty. The results of these studies have been incorporated in the reinforced concrete design.
The decision of using supporting walls instead of columns to support the silos was made after studying the economics of the foundation cost. By doing so the thickness of the pile raft was reduced by two feet. The tor-
sional rigidity along the longway direction of the raft was increased due to the effect of supporting walls joining the raft and the bottom slab of the silos forming a box section 20 ft. high. The saving in the foun- dation costs amounted to HK$200,000.
The silo block is supported on 260 231⁄2 in. diameter Franki piles. More than 7 cases of loading conditions were analysed by the consulting engineers in the pile and pile cap design.
The mill and storage blocks are ordinary reinforced concrete framed structures. The flour and bran
Slipform ready for receiving concrete
Far East Architect & Builder January, 1967