Wind Load on Bridge Mounted Signs
Wind Load on Bridge Mounted Signs
(OP)
I am trying to calculate the shear and tension forces caused by the dead load and wind load acting on a bridge mounted sign.
I already calculated the wind force acting into the face of the sign, where tributary area is the total area of the face, and point of application located middle point of the sign height.
Now, when I calculate the wind force acting behind the sign, I'm not sure what tributary area to use. Only part of the sign area is exposed above the bridge deck, and the traffic barrier railing on the bridge edge is blocking some of the wind load too. Also, the bottom part is being shielded from the wind by the exterior beam adjacent to the sign.
Please let me know how to calculate the wind load behind the sign, and where should I apply that load in order to get the greatest tension and shear forces.
Thanks.
I already calculated the wind force acting into the face of the sign, where tributary area is the total area of the face, and point of application located middle point of the sign height.
Now, when I calculate the wind force acting behind the sign, I'm not sure what tributary area to use. Only part of the sign area is exposed above the bridge deck, and the traffic barrier railing on the bridge edge is blocking some of the wind load too. Also, the bottom part is being shielded from the wind by the exterior beam adjacent to the sign.
Please let me know how to calculate the wind load behind the sign, and where should I apply that load in order to get the greatest tension and shear forces.
Thanks.






RE: Wind Load on Bridge Mounted Signs
Apply the load at the centroid of the exposed area (as seen in elevation).
Use your judgement. Chances are that the full wind load applied to the fully exposed face will control the design of the connections and members. How much money can you save the client if you can eliminate 5 or 10 bolts, or a couple of feet of weld?
"when in doubt - make it stout." (Unless you're design is for 100 signs)
good luck.
RE: Wind Load on Bridge Mounted Signs
I had been doing basically what you explained, but I wasn't sure if there was a more accurate way to design the signs.
When you solve for the reactions at the supports of the sign beams, the wind pressure behind the sign case governs over the other one. That's why I am so concern about it. Also, I am designing a large number of signs.
RE: Wind Load on Bridge Mounted Signs
I just hang here (occasionally)