A flatbed trailer design that uses clamps, or a clamp and an L-bracket, to secure aluminum main beams to their respective suspension hangers without penetrating the lower flange portion of the main beams. Where the main beams are I-shaped, a clamp secures a part of the lower flange portion on each side of the main beam web to a support plate that is welded to the suspension hanger. Where the main beams are L-shaped, a clamp secures a part of the lower flange portion to the support plate that is welded to the suspension hanger; an L-bracket is then used on the other side of the L-shaped main beam to secure the main beam web to the support plate.