Abstract: This straight frame semi-trailer platform is adapted to receive a floor for supporting a body of a transport vehicle. The platform comprises an assembly of cross members and longitudinal members, the longitudinal members including intermediate members and side members. The side members consist of channel sections having a lower flange. The cross-sectional contour of the cross members (3) comprises a bottom area (21) adapted to bear flat on, and to be secured to, the lower flange (8) of the side members (6).