Tension force on banners under wind load. 1

[Mina Bekhit]

Hi

I am new to this forum.

I am assigned to design a structural support for a mesh vinyl banner with dimensions of 40'x120'. The banner will be one way span in the 40 ft direction. This banner will be located in New Jersey where the wind speed can reach 99 mph. Based on that the banner will be subject to 45 psf wind load.

I am trying to calculate the tension force in the banner under wind load and transfer this load to my structure. I am using this formula
T = WL2/8xS
W = 45 psf wind load. L = 40 feet. S = banner sag (missing information)
Based on banner sag of 3", the Tension force will be 36kip/ft
Based on banner sag of 24", the Tension force will be 4.5kip/ft
I am also missing the banner modules of elasticity and strain. I tried to obtain this information from the banner company with no luck of getting it.

Can any one help on the above calculation and what is a reasonable modules of elasticity and strain to be used? Is there any other way of calculating the tension in the banner? What is a reasonable sag range for a 40 ft banner span?

Thanks in advance.

 

[rb1957]

ok, but without the data sought (and the manufacturer is not forth-coming) there's not much to be done, analytically.

Does it, a banner, need to resist a 99mph wind ?

Blow-out panels seem a good way to limit the load.

Can the garage structure carry the banner loads ??

another day in paradise, or is paradise one day closer ?

 

[BridgeSmith]

We do alot of span wire traffic signal structures, which have gravity loads and horizontal wind loads. We use the same incremental analysis for catenary spans in both directions.

 

[Agent666]

Similar to blowout panels, I assume it would also be possible to design the connection point to break a through bolt or something at some level of load that was lower/predictable, in effect provide a secondary mechanism that the banner can break away and release the load under higher design loads so as not to damage any support structures or attachment points to buildings and the like.

People don't think twice when these things blow away or fail during hurricanes (though it might get taken down if one is known to be coming)?

 

[Mina Bekhit]

I believe the banner grommets itself will not resist the warp/weft and will fail very early. I am pushing to get more data from the manufacture and make the client aware of the current condition.

 

[BUGGAR]

I would question the blow out panels if this is going up on the G.W. Bridge (traffic hazards and all). But a blow out would be a good way to restrict traffic flow if that be the goal.