- #26

- 88

- 0

OK,

I take the "contact forces" to mean you have a single horizontal reaction at the ridge and a single vertical reaction at the connection to the wall. I would not think any joints to be moment resisting in this problem.

The snow should be modeled as a single concentrated load at the midpoint of the rafter acting vertically only. The problem should be easily solved by isolating a free body of one of the rafters. You find the point where the wall vertical force and the horizontal force at the ridge would intersect (somewhere in the right corner of the picture). Now, sum moments about this point and you will find the force required in the cross-tie.

Most wood framed houses are basically this same setup. There are pinned connections at the ridge, cross-tie, and at the rafter to wall intersection. The roof diaphram keeps the building laterally stable by distributing the lateral loads to the shearwalls at the ends of the house.

I take the "contact forces" to mean you have a single horizontal reaction at the ridge and a single vertical reaction at the connection to the wall. I would not think any joints to be moment resisting in this problem.

The snow should be modeled as a single concentrated load at the midpoint of the rafter acting vertically only. The problem should be easily solved by isolating a free body of one of the rafters. You find the point where the wall vertical force and the horizontal force at the ridge would intersect (somewhere in the right corner of the picture). Now, sum moments about this point and you will find the force required in the cross-tie.

Most wood framed houses are basically this same setup. There are pinned connections at the ridge, cross-tie, and at the rafter to wall intersection. The roof diaphram keeps the building laterally stable by distributing the lateral loads to the shearwalls at the ends of the house.

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