A structural analysis procedure using shock spectra loading has.been used as a design tool for truck and trailer mounted refrigeration unit frames. The units experience shock and vibration from highway, rail and ship transportation. The loading information has been obtained from a thorough investigation by NASA of transportation loading in cargo areas. The procedure consists of computing stresses in the frames with a finite element model. Both the static equivalent load method and the response spectrum method have been used. The static equivalent load method consists of using the peak acceleration value multiplied by 1.5 to account for dynamic amplification. The response spectrum method selects the acceleration load according to the frequency domain and combines stresses based on the square root of the sum of the squares (SRSS) rule for modes and directional components.