ASCE 7-16 Anchorage of Structural Walls 2

[StructuralAddict]

Clause 1.4.4 of ASCE 7-16 states that "The connections must be capable of resisting a horizontal force at the strength level, perpendicular to the plane of the wall, equal to 0.2 times the weight of the wall tributary to the connection, but not less than 5 psf".

I would appreciate some numerical examples demonstrating how to apply these forces. For instance, in the case of a building with two floors and a roof, how would the 0.2 times the weight factor be applied? Additionally, where exactly should the 5 psf load be applied?

Thank you for your assistance.

 

[phamENG]

In both cases, it's applied to the surface of the wall. So if you have a wood stud wall that is 8 feet tall and weights 10psf (studs + insulation + gyp + whatever else), then you'd have to design the connection of each stud to the sole and top plates for 8ft*1.333ft*5psf/2 = 27lbs OR 8ft*1.333ft*(10psf*0.2)/2 = 11lbs, whichever is greater. The plates would then need to be anchored to the diaphragms above and below for 27lbs/1.333ft = 20plf. (This all assumes the studs are at 16" on center.)

This is a basic stability check, ensuring walls that are supporting loads have some minimum capacity to resist out of plane loads.

Of course, there are other loads to consider, this is just looking at that one section you quoted.

 

[StructuralAddict]

Thank you for your clarification, that's very helpful.

I have follow-up questions if you don't mind:

1- my understanding is that Clauses 1.4.1 (Load Path Connections), 1.4.2 (Lateral Forces), 1.4.3 (Connection to Supports), and 1.4.4 (Anchorage of Structural Walls) are all general stability checks to be considered where applicable. These are also called "notional loads" as described in Section 1.4 and to be combined with unique load combinations in Section 2.6 (not with the standard combinations). Is this correct statement?

2- In Section 1.4.1, what does the term "portion of the structure" mean? The 5% is a percentage of the portion's self weight? Or a percentage of the load the portion is carrying?

3- What is the difference between Section 1.4.1 and 1.4.3? Is Section 1.4.3 an additional requirement for beams, girders and trusses only?

4- Section 1.4 states that "Seismic Design Categories B, C, D, E, or F shall be deemed to comply with the requirements of Sections 1.4.2, 1.4.3, and 1.4.4". So, my understanding is that clause1.4.1 should be considered for structures in all seismic design categories (A, B, C, D, E, or F); whereas, the remaining clauses (1.4.2, 1.4.3 and 1.4.4) are only applicable to seismic design category A. Is this correct statement?

I appreciate your feedback. Much appreciated!

 

[Luceid]

1. Correct - Section 2.6 references 1.4 as the definition of notional loads that must be combined using the combos in 2.6.

2. Portions self-weight and SDL of the portion as well.

3. Not sure what the specific difference is - may need to check the commentary. It seems like the difference is that 1.4.3 includes live load.

4. Correct - the assumption is that the seismic provisions and detailing requirements elsewhere will always govern over, or satisfy the 1.4.2/1.4.3/1.4.4 requirements, they will always be more stringent. If you are in SDC A - you have to do the due diligence to make sure you satisfy these provisions because there may be no other specific code provision forcing these basic lateral load path checks.

 

[StructuralAddict]

Thank you so much for the clarification!