Wind load criteria for delegated design

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Author Message Susan McClendon Senior Member Username: susan_mcclendon Post Number: 56 Registered: 01-2005 Posted on Tuesday, December 19, 2006 - 11:45 am:    Does anyone specify all wind load criteria in Division 1 (or another single location) and reference that location in each section that requires contractor- or manufacturer-design of products? (e.g. curtainwall, windows) If so, where do you locate such a section? If not, have you thought about doing so and rejected that idea? If so, why? John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 624 Registered: 03-2002 Posted on Tuesday, December 19, 2006 - 11:54 am:    Usually we have the wind load criteria on the structural drawings. Wayne Yancey Senior Member Username: wyancey Post Number: 244 Registered: 05-2005 Posted on Tuesday, December 19, 2006 - 11:56 am:    Susan, I have done all of the above. It is a subjective question. One project placed all of the performance criteria for all building envelope cladding systems (Curtain wall, precast) in a standalone section at the beginning of Division 08, with reference to this section in each technical section. In my region, the SE also specifies performance criteria in the Structural General Notes. Spec sections also reference this location. If you send me your e-mail address to wyancey@weberthompson.com I will send you some examples of several sections. Wayne Ronald L. Geren, RA, CSI, CCS, CCCA, MAI Senior Member Username: specman Post Number: 378 Registered: 03-2003 Posted on Tuesday, December 19, 2006 - 12:04 pm:    Like John, I almost always reference the General Structural Notes on the drawings since most of the structural engineers in this region place that type of information on the drawings. Otherwise, I place the information in the specific section if only one or two sections require it. If multiple sections require the information, then I think this information could be provided in Section 01 80 00 "Performance Requirements." J. Peter Jordan Senior Member Username: jpjordan Post Number: 212 Registered: 05-2004 Posted on Tuesday, December 19, 2006 - 05:54 pm:    More and more, I have been relying on the Structural Engineer's general notes for this information. Even on simple projects, I may have wind load requirements in 3 to 4 Sections. More complex projects may find wind load requirements in as many as 10 sections. In referencing to the structural general notes I am relying on the "Say it once" (or "If there is one thing I hate, it's two things") part of "Say it once and say it in the right place." The general notes may not be the correct place for this information, but it is where the permit reviewer people of the AHJ will make us put it. On a related note, I have put standard color information (corporate identity type stuff) in the "Products" Division 01 section. I cross referenced it from each section where we were requiring its use, and that seemed to work fairly well. Wayne Yancey Senior Member Username: wyancey Post Number: 246 Registered: 05-2005 Posted on Tuesday, December 19, 2006 - 06:22 pm:    I agree with Peter's last paragraph. His technique is popular among contractors because they only have to copy one section encompassing all colors for finish products. AHJ's prefer performance requirement information on drawings and in my region demand it for certain projects. Seattle requires specs on drawings for those products that form part of the waterproofing of the exterior building envelope for assessment and rehab projects (water-resistive barrier, sealants, windows and doors, rough carpentry used in rehab, pedestriaon traffic coatings, shingles, siding, etc). The AHJ does not require Parts 1 or 3 of the section. Just give me the materials. Mark Gilligan SE, CSI Senior Member Username: markgilligan Post Number: 120 Registered: 05-2005 Posted on Wednesday, December 20, 2006 - 03:43 am:    I favor placing wind loading and seismic criteria criteria on the drawings. This is especially appropriate when wind tunnel study has been performed and a drawing is used to indicate different loading on different portions of the cladding, This is one of those legitimate uses of General Notes and I do not see it conflicting with the basic division between specifications and drawings. Richard Howard, AIA CSI CCS Senior Member Username: rick_howard Post Number: 103 Registered: 07-2003 Posted on Friday, December 22, 2006 - 12:06 am:    The structural engineer calculates design pressures using the design wind speed and other factors taken from the building code, and maps these forces on a simple isometric drawing. This information is on a drawing sheet that is sealed by the engineer responsible for its preparation. We use these forces to specify roof uplift and positive and negative wind loading on curtainwall, windows, and other portions of the building. Each material uses the resulting information in different ways, employing various design factors, some determined from the code and others chosen by us or the owner's loss prevention officer for performance above and beyond the minimum. The approach to roofing design is different than the way we determine performance of windows. When we design the component, we decide how to use the data and state the required performance. If we are delegating the design, as we usually do for cold-formed metal framing, we specify the design criteria, including the factors we want included in the calculations. The fabricator's engineer then uses that information to determine the properties of each of the members. We don't believe it is sufficient for a spec section to give some of the design criteria and then point to the structural drawings for loads. What is the point of giving them A, B, and C in the spec and then telling them to go someplace else to find D and E? I hate to repeat information, but once we run the calculations for a project the numbers don't change. If you are not comfortable calling out all of the required design criteria, ask the structural engineer to review it. We don't want anyone assuming anything. We once had a curtainwall fabricator's engineer assume L/1600 for structural framing deflection instead of the actual L/360 used in our design, and as a result accommodated only about 50 percent of the anticipated movement in his slip connections. We now provide that information in our curtainwall spec.