PURPOSE: To provide sufficient stability, light-weight characteristic, workability and strength or the like and further to enable a spacing of mounting stages of shelf plates to be optionally set and changed by a method wherein a spacer and a receiving seat are provided with a hollow part of which diameter is approximately the same as an outer diameter of a central shaft and the hollow part is passed through the central shaft to constitute a supporting column.

CONSTITUTION: Each of a spacer 4 and a receiving seat 6 has hollow parts 4a, 6a of which diameters are substantially the same as an outer diameter of a central shaft 2 in such a manner that the central shaft 2 may pass therethrough, they are alternatively passed through the central shaft 2 to constitute a supporting column 1. The number of spacer 4 and receiving seat 6 passed through the central shaft 2 is determed in reference to the number of mounting stages of the shelf plates to be required. The supporting columns 1 are arranged at four corners in a 4-rows × 3-rows, for example, on a furnace boggie, the lower end of the central column 2 of each of the supporting columns 1 is fixed on the furnace boggie by a supporting column receiver having holding portions to which they are fitted together with the lower end of a long spacer 4 passed at the lower-most part. In addition, the upper end of the central shaft 2 is connected to and fixed by a connecting plate having a plurality of holes formed in compliance with an arranging space of the columns for every vertical and lateral rows against the central shaft 2 of the other supporting column 1.