Revisions to ASCE 7-10. For example, dead loads which can be established with high con˜dence have a strength. How ASCE 7-10 a˜ects wind loads for components and cladding. In all cases a mean roof height of 30 feet, component area of 15 ft2 and corner zone (Zone 5) was assumed.
I'm currently working on a project that consists of a PEMB as MFRS with our firm designing a brick and metal stud curtainwall system 17.33' tall. These studs are bypassing the PEMB system, being connected to a wind beam @ EL 15.17'.
My question is in regards to both the design of the stud as well as the design of the connection. I'm contending that for design of the stud; parapet C&C pressure along with wall C&C pressure should be based on an effective area of the entire stud (17.33.17.33/3=100ft2) instead of the individual areas for individual pressures. This makes a significant difference in the deflection calculation and our office is in disagreement as to which way to move forward with this.
Does anyone have any literature or insight addressing this situation?Thanks for the help,Brett RE: ASCE 7-05 Effective Area for Parapet (Structural) 3 Jul 12 16:27. I would tend to agree with your application but don't really have anything to back it up. The application of ASCE 7 wind loads, especially components and cladding, isn't well-defined.The reason for the different pressures at different effective wind areas is due to the statistical likelihood of a member seeing localized high pressures due to a small effective wind area. It's more likely that a small fastener will see 50+ psf wind loads over its whole area, for example, than for a roof joist to see 50+ psf wind loads over its whole area. Crossing between boundaries should not change your effective wind area for the entire member you are designing. RE: ASCE 7-05 Effective Area for Parapet (Structural). Ref - Text book: Loads and Load Paths in Buildings by Narendra Taly and published by ICC.The width of the effective wind area used to determine (G.Cp) need not be taken as less thanone-third the length of the area.Some of the solved examples from the book:Example 5.5 - Wall 17 feet high, 6' thick, R/W #4 @ 12'.Ae = 17 x 1 = 17 sftAe = 17 x 17/3 = 96 sft (controls)Example 5.6 - Roof panel 2' x 4'Ae = 2.
4 = 8 sft (controls)Ae = 4. 4/3 = 5.33 sft RE: ASCE 7-05 Effective Area for Parapet (Civil/Environmental) 4 Jul 12 12:21. Have you looked at the definition of 'Effective Wind Area' in ASCE 7?From ASCE 7-05 (7-10 is similar):'EFFECTIVE WIND AREA, A: The area used to determine GCp.
For component and cladding elements, the effective wind area in Figs. 6-11 through 6-17 and Fig. 6-19 is the span length multiplied by an effective width that need not be less than onethird the span length. For cladding fasteners, the effective wind area shall not be greater than the area that is tributary to an individual fastener.' RE: ASCE 7-05 Effective Area for Parapet (Structural).