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Sloped Roofs: Joists Designs

Sloped Roofs: Joists Designs

Sloped Roofs: Joists Designs

I'm modeling a sloped roof and I'm trying to account for the negative wind pressures that are applied to the roof. I applied a negative Live Load to the roof (to act like the wind).

I checked out the steel joists designs on the roof and the UTL load became negative (meaning the negative wind pressure overcame the Dead Load).

Risa Floor still provided a design for the Joists. I'm just wondering...

1) Can joists can be designed with negative moments or negative loads?

2) If so, is Risa floor currently designing the joists assuming the absolute value of the distributed load?

RE: Sloped Roofs: Joists Designs

RISAFloor will not design open web steel joists for negative bending. The design / bridging for this type of loading would have to be done by hand.

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