THE STORAGE OF GAS
685
Fig. 425.—Bonket’s Tank with Bulging Sides.
the columns, and by a horizontal outward radial thrust in the top ring curb.
The principle of the method is undoubtedly inter-esting, but it has made little headway in practice. The most interesting example of a tank constructed on these lines is that at Simmering, in connection with. a holder ha ving a capacity of nearly 5J, million cubic feet.
F. S. Cripps has designed a tank for attaining the same object in which the sheets, instead of being bulged, are fluted. The sides are split up into a series of circular ares of mueh
smaller radius than. that of the tank, with vertical posts at the intersections, the whole being united by a ring girder at the top. As pointed. out by Cripps, however, the greatest objection to this type of construction is the enor-mous stress on the top girder (see Fig. 427).
Reinforced Concrete Tanks
Reinforced concrete as a material of construction for gasholder tanks is now beginning to make some headway. The inherent principle of reinforced structures
is that whilst the compressive stresses may be apportioned to the concrete the tensional forces must be provided for by the insertion of steel. In the gasholder tank the stresses are almost wholly tensional, with the result that the amount of steel required for reinforcement is no less than that required for the construction of a complete steel tank. This statement must be qualifled by the faet that the efficiency of the riveted joint must be taken into account, but in large steel tanks the heavier plates may have a joint efficiency of 90 per cent. It is agreed that even though this be the case the steel work
is merely inserted. in place in the concrete and, pIG. 427.—Cripps’ Fluted Tank. consequently, there is no riveting to be done.
It is clear, however, that the cost of the concrete itself might be greater th.an the
expense ineurred for riveting.
When under construction there is 110 little difliculty in getting the rcinforcing