Fig. 237.—Details of Cantilever Girders for Mezzanine Floor for Four-Story Garage.
FLOOR AND ROOF CONSTRUCTION FOR FOUR-STORY GARAGE.—The building was 53×200 ft., and 4 stories high, with provision for 2 additional stories in the design of footings and columns. Two rows of wall columns connected by transverse girders carrying the floor and roof slabs made a comparatively simple construction, except for a mezzanine floor carried on cantilever beams and except for the use of cantilever footings; these two special details are shown by Figs. 236 and 237. The amount of concrete in the building was 1,910 cu. yds., distributed as follows:
| Cu. yds. | |
| Footings, reinforced | 190 |
| Columns, reinforced | 450 |
| Floors and roof, reinforced | 1,100 |
| Floor on ground, not reinforced | 170 |
| —— | |
| Total | 1,910 |
The amount of reinforcing metal used was 237 tons, distributed as follows:
| Item. | Tons. | Lbs. per cu. yd. |
| Footings | 42 | 442 |
| Columns | 20 | 90 |
| Floors and roof | 175 | 318 |
| — | — | |
| Total and average | 237 | 272 |
This is equivalent to 2 per cent. of steel in 1,910 - 170 = 1,740 cu. yds.
Forms.—The total area of concrete covered by forms (1,740 cu. yds.) was 94,000 sq. ft., distributed as follows:
| Footings, sq. ft. | 4,000 |
| Columns, sq. ft. | 20,000 |
| Floors and girders, sq. ft. | 70,000 |
| ——— | |
| Total, sq. ft. | 94,000 |
For the work 50,000 ft. B. M. of old lumber was used and 170,000 ft. B. M. of new lumber was bought, the cost being as follows: