Mahatma,
Welcome to the Forum. Your question is one that could be likened to going to a forum of Surgeons and asking them how to perform brain surgery. [Edit]Those surgeons would be hesitant to provide information if such a question were asked since the nature of the question would cast doubt upon the abilities or knowledge of the person asking the question.[End of Edit] Many of the individual tasks are very simple yet how they are performed, why they are performed etc are based upon years of training and experience. What you ask is highly involved and includes questions that would be answered by Engineers, Designers, Specification writers, INspectors, NDE technicians etc.
It is possible that due to the manner in which you worded your question I may not be understanding what you ask.
What is your current experience in welding related fields? This may help us to better understand what you may need to know. Consulting with a local designer near y ou may alos help.
The American Welding Society publishes a great many publications that may be of help as does the American Institute of Steel Construction. A local library may also be of use to you.
Please do not take offense at the post. You may very well find some help here.
Have a good day.
Gerald Austin
You might try the steel joist institute. (SJI?) They might have some standards published for roof structures. In fact, some of the joist suppliers may have design guidelines in their sales lit, but usually they do the design and sell the roof system. Last time I checked, D1.1 did not cover bar joists per se, but they can be qualified to D1.1. X-ray and UT is not typically used on bar joist groove welds - they are qualified by macro and visual inspections. For the rest, you could refer to D1.1, but I would defer to a designer. Things like roof loads from snow or rain are important considerations if you design a flat roof building (must have reverse camber etc..) I no longer work with structural stuff, so I may be off base as to how they do it now...