This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
The full bending details of the bars should be made before the reinforcing steel is ordered for any rein-forced-concrete work that is to be constructed. It has been the common practice for contractors to make these details, if they are made; and they may or may not submit them to the designing architects or engineers for their approval. Very often the plans or specifications do not state how long the bars are to be, or even state what lap of the bars is required; or they may not be very definite in the number of bars to be turned up in the beams and girders. If architects and engineers would make these details and submit them with their general drawings, the contractors could then make a very definite estimate on the amount of steel required for the work, and these details should also assist the contractor in estimating the cost of the bending of the bars. With the assistance of these details being made very definite, it should not only assist the contractor in making his bid on the work, but would often result in better work being done.
The angle at which the diagonal bars are turned up, varies from about 10 degrees to 45 degrees, and sometimes to a greater angle than
45 degrees. A great deal depends upon the length and depth of the beam or girder. If the beam is very short and deep, the bars are usually turned up at an angle of about 45 degrees, or perhaps a little greater; but if the beam is long and shallow, the angle at which these bars are turned is very small. This angle, in the average practice, is about 30 degrees.
The bending of the bars is usually a simple matter, and generally can be easily and quickly done. If bends of 30 degrees or more, with short radii, are required of large bars - 1 inch to 1 1/4 inches square - it is usually necessary to heat the bars. This makes the bending more expensive, as it requires the use of forges and blacksmiths to do the work.
Fig. 173. Plan of Bending Table.