This $10 total does not include the cost of the concrete nor of the steel.
CHAPTER XX.
METHOD AND COST OF BUILDING CONSTRUCTION OF SEPARATELY MOLDED MEMBERS.
This chapter deals exclusively with the methods and cost of molding and erecting separately molded wall blocks, girders, columns and slabs. The structural advantages and disadvantages of this type of construction as compared with monolithic construction will not be considered. The data given in succeeding paragraphs show how separate piece work has been done and what it has actually cost to do it in a number of instances.
COLUMN, GIRDER AND SLAB CONSTRUCTION.—European engineers have developed several styles of open web or hollow girder and column shapes, but in America solid columns and girders have been used except in the comparatively few cases where one of the European constructions has been introduced by its American agents.
Warehouses, Brooklyn, N. Y.—In constructing a series of warehouses in Brooklyn, N. Y., the columns and girders were molded in forms on the ground. For molding the columns, forms consisting of two side pieces and one bottom piece, were used, saving 25 per cent. in the amount of lumber required for a column form, and doing away with yokes and bolts, since only simple braces were required to hold the side forms in place. It was found that the side forms could readily be removed in 24 to 48 hours, thus considerably reducing the time that a considerable portion of the form lumber was tied up. It was figured by Mr. E. P. Goodrich, the engineer in charge of this work, that this possible re-use of form lumber reduced the amount required another 50 per cent. as compared with molding in place. Girders were molded like columns in three-sided forms; the saving in form work was somewhat less than in the case of columns, but it was material. In general, Mr. Goodrich states, the cost of hoisting and placing molded concrete members is higher per yard than when the concrete is placed wet. That is in mass before it is hardened.
Fig. 239.—Sketch Showing Forms and Reinforcement for Visintini Girder.