For interesting reading, go to:
The Michigan Tech Notes was just updated Sept 13, 2006 so this is very current.
I've been on both sides of the issue - I've been the one sending plans out to component manufacturers and I've been the one designing the component. Both sides think they don't have the responsibility for calculating loads on a truss or joist. Here's the answer...
The WTCA has published Tech Notes for each state and a National version specifying the Design Responsibilities for Commercial Construction Projects. The WTCA represents the structural building components industry. This version specifically mentions trusses, but I bet you'll find a steel joist version out there somewhere too.
Here is what the Michigan version says:
"WTCA has developed this Technical Note to clearly outline a component manufacturer's role and responsibility for commercial construction in the context of the building code and professional engineering law applicable in the State of Michigan. This Technical Note is based on conversations with and questions from various Michigan local building officials and registered design professionals. The analysis is based on the current engineering laws of the state Michigan and the 2003 Michigan Building Code (MBC), which is based on the nationally recognized model building code the 2003 International Building Code (IBC)."
Skip to Page 4 -
"In preparing the Construction Documents, the Building Designer needs to provide the Truss Designer with the information necessary to properly design the Structural Building Components for the Building. According to ANSI/TPI 1-2002 (TPI 1) Chapter 2 (see Appendix C for complete text), which is adopted by reference in the MBC Sections 102.4 and 2303.4, and Chapter 35 "Reference Standards" provisions (see appendix B), the following information should be provided:
........skip to... 2.5.2.4 The location, direction, and magnitude of all dead and live loads applicable to each Structural Element and Truss...
2.5.2.5 All Structural Element and Truss anchorage designs required to resist uplift, gravity, and lateral loads;
2.5.2.6 Allowable vertical and horizontal deflection criteria and any specific criteria...
2.5.2.7 Proper transfer of design loads affecting the Structural Elements and Trusses;
2.5.2.8 Adequate connection between Trusses and between Structural Elements...but not Truss to Truss girder connections...
2.5.2.9 Permanent bracing design for the Building...and permanent bracing for all Structural Elements and Trusses...
I think this is pretty clear. It is the Building Designer, not the component designer who had better specify the loads to be applied. I read that as the EOR, if a structural engineer is involved, or the Architect if no SE is involved.
Right below that section reads:
"The Truss Manufacturer and Truss Designer must rely on the Building Designer to take the information provided by the Truss Design Drawing, the Building Component Safety Information (BCSI 1), and the Building Designer's analysis of the flow of loads through the Building to design a Permanent Building Stability Bracing system that takes the reisted truss member buckling loads (if any) and tie these loadsas off tto the Building's load path system... The Building Designer is the professional who is most intimately familiar with the flow of loads through the entire Building and is the one who can use this knowledge to ensure bracing load transfer and overall Building performance success..."
It is recommended that a copy of this be included with contract documents. I think that is a great idea.
And to any structural engineers out there who don't think they should have to take responsibility for figuring the loads on a truss (me included...), this should help explain why truss designers make $15/hour and engineers make $30+, don't you think?