WideFlangeA992
Structural
- Jul 21, 2023
- 1
We do piling foundations for houses that use modular manufactured sections roughly 12' wide. GC typically hires manufacturer to build and design the house/sections, and hires us to design the pile foundation. We design girders and girder to beam connections along with x-bracing to allow for wider spans or bracing configurations outside of the prescriptive code requirements in our state.
It is often a challenge to make these work in coastal areas with high wind speeds combined with how the manufactured sections are designed. The manufacturer plans often show extremely high concentrated hold-down requirements for the shear walls that appear to be designed with FTAO, say around 15 kips in some areas where the loads above stack down. This usually requires several 6-8 studs with pre-bent straps or HDUs. Then this usually requires bumping up the girders several sizes to handle the hold down load if it lands in the middle of a girder.
I generally fell like I need to design for the loads the manufacturer shows so I do not have to take responsibility for the manufacturers work. I have called these manufacturers to get more info or question their loading and they either will not talk to me as a matter of policy or are not helpful.
My question is are there other ways to handle these high hold down loads or with different analysis approach, or different detailing. The NDS does not seem to allow any other anchorage than at the ends of the wall. Things that come to mind are sheathing lapped over the girders with additional fasteners or connectors, or additional sill plate anchorage through the length of the stud wall etc. Basically I am asking if I can treat the shear wall loads as distributed loads instead of simple overturning point loads.
It is often a challenge to make these work in coastal areas with high wind speeds combined with how the manufactured sections are designed. The manufacturer plans often show extremely high concentrated hold-down requirements for the shear walls that appear to be designed with FTAO, say around 15 kips in some areas where the loads above stack down. This usually requires several 6-8 studs with pre-bent straps or HDUs. Then this usually requires bumping up the girders several sizes to handle the hold down load if it lands in the middle of a girder.
I generally fell like I need to design for the loads the manufacturer shows so I do not have to take responsibility for the manufacturers work. I have called these manufacturers to get more info or question their loading and they either will not talk to me as a matter of policy or are not helpful.
My question is are there other ways to handle these high hold down loads or with different analysis approach, or different detailing. The NDS does not seem to allow any other anchorage than at the ends of the wall. Things that come to mind are sheathing lapped over the girders with additional fasteners or connectors, or additional sill plate anchorage through the length of the stud wall etc. Basically I am asking if I can treat the shear wall loads as distributed loads instead of simple overturning point loads.
