We are a professional manufacture and exporter for steel prodcuts. The main products are pre galvanized steel pipe, hot dip galvanized pipe,welded steel pipe, square&rectangular tube and scaffolding products. Our manufacturing equipment include 4 pre galvanized product lines, 8 ERW steel pipe product lines, 3 hot-dipped galvanized process lines. According to the standard of GB,ASTM,DIN,JIS. The products are under the ISO9001 quality certification manage mode. Annual output of various pipe is more than 300 thousands tons, covering the range of 21.3-457mm round pipe,15*15-500*500mm square tube,15*20-500*100mm rectangular tube, , with thickness of 0.8-30mm.
The rings are made of 8mm steel bars. For first two feet keep the distance 6 inches between rings and then carry 9 inch upto the two feets before at the end it means from top and bottom side up to the two feets the distance between the rings should be 6 inches and for rest length you can carry upto the 9 inch. On the other hand you can keep all rings at 6 inches if the building height is more than two stories. The main important point in column formation is distance between the rings. In general 4 of 16mm steel bars with two 10 or 12 mm size steel bars are sufficient but again I tell you it depends on the load calculation.
Here you can see this formation for the house construction.