how to build a loft in iron homemade

[forgiaro]

we would like to build a loft for a throw-dimensions: height 10 feet, width 11 feet load 500 kg am / q what we can recommend? for the columns we want to use box-tube 100x 100 x 4 mm for a cross beam ipe from 180 mm in the longitudinal box-80x 80 x 3 mm welding will use a single-phase inverter welder 160 amps, could you give us advice mathematical formulas drawings or photos to use as a reference thanks to those who will want to help the next