an interlocking grid structure as shown slots 26 are open to the bottom end of one set of parallel strips and open to the top end of a second set of parallel strips disposed orthogonally to the first set of strips to permit the two sets of strips to be intermeshed in an interlocking arrangement with the top and bottom ends of the two respective sets of strips lying in the same horizontal planes the small slots 34 are provided for stress reduction purposes fig5 is an enlarged vertical section view showing the attachment of a grid assembly side strip 14 to the end of an intersecting interior partition strip 12 as shown the side strip is provided with an indentation 36 which conforms with the indentations provided at the top and bottom ends of each interior partition strip slots 38 see fig2 are provided in side strip 14 to receive tabs 40 see fig3 a weld 42 is made where each tab 40 fits within a slot 38 to securely attach the side plates to each interior partition fig6 and 7 are enlarged vertical section and plan views illustrating the welds 44 used to join intersecting interior partition strips 12 at their points of intersection although the views illustrated are taken at the top of a grid assembly it should be understood that similar welds are provided.