Canopy for Carpark

[drago8]

Greeting to All

I need help on how to design the covered carpark for this one. Please find attached the plan for the car park and the options for the sections member.

The cantilever canopy will be about 6m length with 7degrees slope. I intend to use hollow sections as per Architect's desire and instead of truss, will be using rafter only. However I wonder if that will help with the uplift and the deflection? At this moment, I only tie the rafter to my post using 100x75 SHS.

The architect proposed to put steel framing on the roof. Will it help in the stability of the frame?

May I ask if there is any program which can help to double check my design for this?

Thank you for your help.

#LoveWins

 

[KootK]

However I wonder if that will help with the uplift and the deflection?

The trussing would make your frame stiffer and stronger. It's more expensive to fabricate however. As a first pass, I think that I'd try to make it work without the trussing to keep things clean and simple. Another option might me to include only the trussing on the back side. That would improve your rafter/column moment connection while still keeping things clean on the front side. You'd also avoid the shallow angle connections that trussing the front side would create.

Will it help in the stability of the frame?

No more so than a roof in another material such as would. With HSS members, you should be in pretty good shape for stability.

May I ask if there is any program which can help to double check my design for this?

Risa, Ram, SAP2000, Scia Engineer, Visual Analyis, STAAD... many options.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Ron]

I'm not sure where you are located and under which code you must work; however, there are several manufacturers in the US who provide such canopies and will provide appropriate engineering for them.

I've designed hundreds of canopies for different applications including almost exactly what you have descibed. Most of the ones I have done are aluminum structures so there are some quirks of design that are different than steel, but the basics are the same.

Agree with KootK's comments.

Also, I currently use RISA 3D, but have used a variety of FEA programs in the past 30 years.

 

[drago8]

Thank you for your comments.

I have tried design the canopy just for one span using Prokon, but I ended up having a deflection. Right at the moment, I am using 300x300 HS for the vertical post and 200x200 HS for the other members. At first I am using a DL of 0.75, LL = 0.5 and WL = 1.0; but I reduced it to DL = 0.5 LL=0.25 (i.e. no access to the roof) but my deflection still big. If I further increase the section sizes, then it would be uneconomical.

Other existing canopies with same design as mine, can stand still and even their sizes are smaller than mine. But why my design got a large deflection there I am confused.

I haven't tried the one with trussing at the back as suggested by Kootk. Will try that one later.

I see. I am using Prokon to check now. Will check the other softwares out.


#LoveWins

 

[KootK]

I would expect large deflections. Are you sure that's actually a problem here? Part of the reason we tilt these things upwards is to mask sag.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[drago8]

Hello KootK,

Actually what I am trying to say is yes, that's true. I got large deflection as expected and ended up having a large member size. And when I look at a real life i.e. existing canopy that we have here, having sama physical design as mine, their member sizes are a lot smaller compared to mine. So yeah, just questioning.


#LoveWins