ASCE 7-10 wind loading over canopy structure 1

[edwin321]

Hi,

I am designing the canopy structure which comes under the 1st floor balcony slab (assume that canopy is under the slab exposed to wind pressure in which canopy is not exposed to positive wind pressure from top).. the canopy is supported by the top slab (balcony slab).
my query is how do i consider the positive wind pressure acting on the canopy as it is not directly exposed to it.. ?
I am referring ASCE 7-10 for the wind load calculation and to find the cp value for canopy i am referring to NJ COOK journal on wind loads acting on canopies attached to buildings.

 

[thaidavid40]

A quick sketch of your layout would be helpful.
Dave

Thaidavid

 

[edwin321]

Thanks Dave,

I have attached the canopy section drawing as you can see the canopy is cladded by composite panel under the slab.
According to ASCE i am getting wind pressure as 1.464 kPa and Cp value (from NJ cook text book to be +0.93 & -1.3) but because of slab on top i dont think we need to use full positive pressure coefficient..

 

[thaidavid40]

Since there is no fascia enclosing the area above the canopy, it seems reasonable to me to expect at least some wind action in the inset area above the entryway. I would be led to consider this for the code-mandated positive and negative components-and-cladding loads, as the size is small relative to the remainder of the structure surrounding it, and the fact that the total loads will not be all that great. My default position is to be conservative with respect to anticipated loads if they are either difficult to properly identify, or quantify. I also suggest adding a diagonal brace to each hanger strut in the rear. It will provide lateral stability, and would hardly be visible, since it would be at the rear of the canopy.
Dave

Thaidavid

 

[Ron]

Agree with thaidavid40. This underslung or hanging canopy should be designed without regard to the concrete slab above. Agree also that you need struts in both directions to handle the lateral movement. Be tough on the overhead attachment requirements as well....don't use chemical anchors...use mechanical anchors.

 

[edwin321]

Thank you all,

I agree with you david and ron, its better to consider full Cp value neglecting the shelter factor because of top slab but is it ok if i consider the canopy in category B than in C because the building is near to the sea and its a high rise building (100 meter high which is surrounded by other high rise buildings)

 

[Ron]

I wouldn't go to Cat B because of the variability of wind effect in such environments. The categories in ASCE 7 are "blanket" categories and for such applications "one size doesn't fit all".

 

[edwin321]

Hi guys,

I would like to know is it necessary to consider the internal pressure for the lateral wind load calculation for designing this canopy...
Please help..

 

[Ron]

No.

 

[DNod8]

Hi Edwin,

May I know what is the material of the canopy? Is it steel?

If it is, how is the connection of the canopy to the balcony slab? Is the balcony slab an existing structure?

Thanks.

a trainee who wants to learn and learn