12 METHOD OF CONSTRUCTION OF CONCRETE SHIPS. 



PLACING OF REINFORCING STEEL. 



The exact method of placing the steel varied, depending partly upon the 

 method employed in supporting the steel. Following is a description of the method 

 employed at San Diego for placing the shell steel. 



On the inside of the outside forms the location of the outboard longitudinal 

 bars was marked off, starting at the keel. On these lines nails were partly driven 

 into the forms in transverse rows about 8-foot centers, indicating the location of 

 the bars. The outboard steel is then placed directly in position on these nails as it 

 is carried from the car. 



It was more convenient for the workman walking back and forth if all the side 

 shell steel is placed before placing the bottom steel. After placing the side, hori- 

 zontal, outboard steel, the vertical side shell bars are placed, followed by the diago- 

 nal spacing bars and the horizontal inboard shell steel. The side shell steel is held 

 away from the forms by means of small cement blocks wired to an occasional bar of 

 the outboard layer of steel. The floor or bottom steel is then placed in a manner 

 similar to the side shell steel, except that cylindrical cement blocks about 2 inches in 

 diameter and of varying heights are used to support the steel off of the forms. A 

 cement block, 2 inches high, carrying the second or transverse layer of reinforcing 

 steel, was found to be preferable to a i-inch block carrying the outboard steel, as 

 the latter would occasionally crush. Where the higher block was used the outboard 

 layer of longitudinal shell steel was suspended to the transverse bars with No. 16 

 gage annealed wire ties attached to every alternate transverse bar. 



Staging was erected on the inside of outside forms for the use of workmen in 

 handling the side shell and frame steel. Three different methods were employed 

 by the several contractors. The method of hanging the staging from the top is pref- 

 erable in that it keeps a clear space for handling the steel at all elevations along the 

 sides of the forms and requires no holes through the sheathing. 



San Francisco used ^ by i%-inch wood strips placed transversely at each 

 frame, lightly nailed to the inside of the outside forms for supporting the shell steel 

 off the forms. Jacksonville used ^-inch round bars in the same manner as the 

 wood strips above, but only across the bottom forms. The wood strips were re- 

 moved after the concrete was placed and the surface was pointed up. The round 

 rods were not removed, however. For supporting the side shell steel, cubes of con- 

 crete were made with a groove in the top. These cubes have a hole through the 

 center perpendicular to the groove for bolting to the inside of the outside forms, and 

 the groove is so placed that the horizontal rod will be supported ^ inch from the 

 forms. The nut of the bolt is placed on the inside so that after casting the con- 

 crete the bolt can be removed and the hole filled with cement. The cubes were 

 spaced about 6 feet longitudinally and 3 feet vertically. The horizontal rods between 

 the cubes were hung to the rods on the cubes by S-shaped wire hangers. As the 

 vertical shell steel was placed the horizontal bars were wired to it and thus securely 

 held in position. At Mobile, small cement or ceramic tile blocks were used to 

 support the steel from the forms, and a special prekinked wire was used to space 



