As architects and engineers continue to push forward with ever more challenging designs for steel structures, companies that supply the service of curving steel have responded well to the new demands.
Increasingly, designers are weighing the costs and benefits of various proposals. In the best case, benders and rollers (companies that specialize in curving structural steel) are consulted early in the design process to optimize the benefits of a given design while minimizing the costs.
For example, a given design may call for a reverse curve with a straight tangent between the two curves as in the picture below. One end of this W12 x 40# beam has a 46ft inside radius with 21ft of arc. The other end has a 36ft 11in inside radius with 13ft of arc. Between the bends is an 18ft intermediate tangent.
While the curved beam may be essential to the architect’s design (it is probably for a canopy), it must be recognized that there is a cost for curving a structural member even if the cost is minimal. On the other hand, a bender/roller often can offer cost-saving suggestions that mitigate any price concerns.
There are several avenues to reduce the cost of curving steel. For example, making the reverse curve from one length of steel is most likely less expensive than making it in three sections with two full-penetration welds. Such welds are expensive, perhaps $500 each.
Another area to investigate is maximizing the yield of finished sections while minimizing the use of raw material. When structural steel is curved, the process usually requires a certain amount of “pick-up,” or “trim” at the ends which goes to waste. If multiple curved sections can be produced from a single length then the amount of material required can be reduced thereby creating a near-net yield. And nesting of sections curved to the same radius but different lengths can also provide savings.
A final example is investigating getting special lengths either from steel service centers or directly from the steel mills to lower costs by maximizing material yield.
Benders and roller welcome the conversations that provide the best value for their customers when it comes to curving metal.