panels 14 are normally made of light weight metal material making them durable inexpensive and easy to install additionally the storage bin 10 has a cylindrical wall enclosure 18 which in the embodiment shown is formed from light corrugated metal panels and has an access door 20 and attached ladder 22 in keeping with the principal objects of the present invention and as more clearly shown in fig2 and 3 the roof structure 12 is raised and held at a distance y above the wall enclosure 18 by a plurality of brackets or brace members 24 spaced therealong as a result a series of air vents 26 equal in number to a number of brace members 24 are opened between the roof structure 12 and an upper edge 28 of the wall enclosure 18 upon inspection of fig4 it will be seen that each individual brace member 24 used to elevate the roof panels 14 comprises a main body portion 30 ears 32 a tongue 34 and support bars 35 preferably the main body 30 is contoured to follow the arc of cylindrical wall enclosure 18 and the ears 32 are disposed at an angle a to align with roof panels 14 as more fully discussed below additionally the tongue 34 projects upwardly above the ears 32 to install the vent structure one brace member 24 for each roof rib 16 is fastened to the cylindrical wall 18 along upper edge 28 utilizing bolts 36 and holes 38 roof panels 14 are then placed on top of brace ears 32 such that.