I have no problem determining the wind loads on the roof. I was looking for guidance in how other engineers detailed the condition and/or guidance how the wind load is applied to roof.
ASCE7-05 is the applicable design standard, The wind force is P=Qh(GCp-GCpi). I am in a 110 psf, exposure...
Bagman
I am not talking about a deck over open space but rather a placing decking on sleepers over a flat roof to an enclosed space. I do not believe that roof overhang uplifts forces would not apply to this situation.
But what is the uplift force? Any internal uplift force will be resisted by the roof joists below but how do you calculate the uplift suction force on the deck from the wind blowing accross the roof? You need this info to be able to design the fastners which are not that simple to flash and...
I design many oceanfront homes in hurricane areas. Architects often specify wood roof decks placed on sleepers over the flat roof areas (1/4"/ft pitch to drain). In the past the wood decking and sleepers would be installed like pallets so that they could be removed to allow for cleaning and...
Yummm cake, I admit that I do eat my cake when I have it. Yes I I do make rationalizations but I do not change them to suite me. The connection is assumed pinned but with enough stiffnes to transfer the shear accross a 3" plate. Is this an absolute truth? Of course not but it is close...
Dave once again you get it and others just get perturbed. To look at a connection as a cantilever is just not correct. There is a beam attached to the connection that is not free to rotate, it is supported at its other end and there for the joint rotation is limited by the beam stiffness. The...
Unless you have rigid stucture on one side (such as a reinforced concrete wall) then I would not count on coming up with a connection that will allow the end of the truss to move 4 inches without the top of column or spandrel beam moving and taking a large lateral force. That is why i said good...
Assuming it is a slab on grade and has the potential to get damp then I would not allow the joists to be glued to the slab and all lumber should be pressure treated. While not the easiest way to skin a cat there is nothing wrong with your detail. The detail can be simplified by using...
For the condition that you describe, I do not design the column for any moment as the beam on the opposite side will resist any induced moment that may occur. Any moment in the column would be negligable. I will use a 3" eccentricity from the face of the column when a beam is framed into only...
Thanks for your replies. How do you calculate the shear transfer force to the chord remains my question. Is it (2 x chord force/length of the chord) or would VQ/It apply? The building was recently erected and when I went out to look at it, the transfer of the shear force to the chord accross...
I have a one story 50' X 86' building with 22 ga type roof deck on steel bar joists at 5'-6" o/c and spanning 50 feet. I designed the metal deck roof deck diaphragm and it can tranfer the lateral loads to the shear walls on each end. My chord force for the diaphragm is 4.2 kips. I am using...
If you use a scissor truss on a 250 ft span you are going to have a large horizontal deflection or lateral outward force to deal with and only a cantilevered wall or column to hold it back. Good luck with that. Also, while South Florida does not have earthquake loads, you may find yourself...
2x10 roof joists spanning 17 feet will have little or no additonal capacity above the flat roof snow load. I would strengthen any portion of the roof that has additional load being added. A common bending value for lumber of that time would be 1250psi for Doug Fir. You can increase that by...
