StrEng007
Structural
- Aug 22, 2014
- 545
From the textbook, "Wind Loads, Guide to the Wind Load Provisions of ASCE 7-10" by Mehta/Coulbourne, page 94 makes the following statement in regards to C&C roof zones:
"...the high pressures in corner or eave areas do not occur simultaneously at both ends."
Is this written in ASCE 7-10 for components and cladding wind loads? I'm used to applying the maximum wind loads per each roof zone. In this textbook, the author checks each joist with a combination of zone 1, 2, and 3 pressures. As an example, one joist is checked for Zone 2/3 pressure and Zone 2H at the overhang. The SAME joist is then checked for Zone 2 pressure and 2H/3H at the overhang. I've searched ASCE 7-10 and I'm not sure how those particular combinations are determined. If you're familiar with this text and example, you can see how they are combining Figures 30.4-2A and 30.4-5B for a scenario that doesn't make sense.
Also, does ASCE 7-10 mention where the "a" zone is measured in regards to a roof? The Figures show it being measured from the corner in plan. I've always understood the "a" dimensions to be the plan of the building envelope. Should "a" at overhangs been measured from the exterior edge of the overhang, regardless of the building's envelopes plan dimension? This would contradict the measurement of "a" for wall zones 4 and 5. The Standard should be more clear about this.
"...the high pressures in corner or eave areas do not occur simultaneously at both ends."
Is this written in ASCE 7-10 for components and cladding wind loads? I'm used to applying the maximum wind loads per each roof zone. In this textbook, the author checks each joist with a combination of zone 1, 2, and 3 pressures. As an example, one joist is checked for Zone 2/3 pressure and Zone 2H at the overhang. The SAME joist is then checked for Zone 2 pressure and 2H/3H at the overhang. I've searched ASCE 7-10 and I'm not sure how those particular combinations are determined. If you're familiar with this text and example, you can see how they are combining Figures 30.4-2A and 30.4-5B for a scenario that doesn't make sense.
Also, does ASCE 7-10 mention where the "a" zone is measured in regards to a roof? The Figures show it being measured from the corner in plan. I've always understood the "a" dimensions to be the plan of the building envelope. Should "a" at overhangs been measured from the exterior edge of the overhang, regardless of the building's envelopes plan dimension? This would contradict the measurement of "a" for wall zones 4 and 5. The Standard should be more clear about this.
