NEW YORK — Nucor Corp. has raised its raw materials surcharge on steel reinforcing concrete bar (rebar), merchant bars and structural products by $35 per ton ($1.75 per hundredweight) and lowered its base price for the products by $10 per ton (50 cents per cwt), resulting in a $25-per-ton ($1.25-per-cwt) net increase in transaction prices effective with April 1 shipments, the steelmaker said in a March 12 letter to customers.