roof/ceiling I-beam spans and load capacity
Are you the contractor or the owner? If the contractor, you certainly can afford to hire a structural engineer to design the job, you pass the cost along to the owner. If you are the owner, I am guessing you have some channel left over from a previous job, and want to reuse it. Reuse is good, we like to save the planet. However, as previously noted, you need professional help, a hands on visit, and careful evaluation of the options. A channel is normally not used individually as a bending element because of asymmetrical bending issues, generally they are used back to back in this type of application, or else an I beam or H beam is used. But your engineer will discuss these issues with you, and will no doubt make the right recommendation.