Currently, the chassis assembly contributes about 73 percent of the overall weight of a 14.63 m long haul trailer. This paper presents alternative design concepts for the structural floor of a van trailer utilizing sandwich panels with various material and geometric characteristics of the core layer in order to reduce its weight significantly below that of the current design configuration. The main objective of the new designs is to achieve optimal tradeoffs between the overall structural weight and the flexural stiffness of the floor. Various preliminary design concepts of the core designs were compared on the basis of a single section of the core structure. Six different designs were analyzed by weight, maximum displacement and maximum stress under bending and torsion loads. Each concept was kept uniform by length, thickness, loading and boundary conditions. Each design concept was examined through testing of scaled model for floor assemblies. Finite element analysis was used to compare the performance of various design configurations. Scaled models were also developed and prototyped, instrumented, and tested in the laboratory environment, in order to validate the predictions of the theoretical models. These models were developed as a means to predict and understand the actual performance of the various floor design configurations, either in the form of cross member panels or sandwich composite panels.