im assuming u have earn school credits in strenght of material and engineering mechanics. if that is the case, best source is the AISC and the Smith and Van Laan Pping and Pipe Support System. You'll need also to check the weld and stiffness so include the Blodgett Welding Hndbook and the Klienlogel Simplifed Book on structural analysis (its plug and chug type of cookbook) - mostly the confugration apply to pipesuport such as the knee frame, portal frame, cabtliver, etc.