Steel Canopy Structure

[Yasir Saleem]

Dear all , 

 

I am working on steel canopy structure , general layout is like, its a 12m long and 3.250m wide canopy. Supported by two circular columns. which are 6m apart from them leaving 3m cantilever on sides. Canopy frame is 1.925m cantilever on front side of columns and 1.25m on the back side of column. The canopy will be cladded with aluminum. I want to know that as per ASCE and IBC this will fall under which category for live load selection and deflection criteria check.

I am attaching the code live load criteria with highlighted section and also the deflection criteria. one section of the structure is also attached for understanding.

Other loads like wind seismic have been considered as per the code requirements.  

Actually the design and strength are no issues in this only the deflection under Dead +live load is the one worrying as there may be a glass walls under the canopy in future. So i am looking for correct deflection criteria and also the live load which needs to be considered. 

code 1.pdf

code 2.pdf

code 3.pdf

code 4.pdf

drwg.pdf

[EngrUzair]

As a glass wall is expected in future, I would try to make sure that the deflection is minimum. Since it is steel structure,  self weight will also be less. For that I may go for deflection limit of L/360.

 

As far as applicable live load is concerned, it depends upon whether it will be subjected to maintenance workers load or not. In case it will (or possibly may be any time in future), I will recommend a roof live load of 20 psf, reduced as per ASCE 7 Section 4.9. Otherwise, non-reduceable live load, mentioned in ASCE 7 Table 4-1 for fabric structures, should be applicable.

 

Additionally, you will certainly be checking for wind effects on the structure for the situations with and without glass wall. You may also need to check topographic wind effects, in case the structure is not located in a plain area.

 

In addition, requirements of IBC section 1604.3.5 might also be applicable in your case.     

[UmarMakhzumi]

Yasir,

The attached drawing is not clear. Do you have architectural plans that show the information about how your canopy looks like and the way structural framing supports it.

Regarding the criteria for max deflection, you may have to check multiple ones . Canopy members supporting edge of glass should be checked against L/175. Thou shall consider twice the length for cantilever members in this check.

Thanks.

[Yasir Saleem]

sir g i am attaching the architectural plan, sir have checked this for L/150 deflection considering it has a cantilever of 1925mm from column. And also checked for L/175 considering glass edge for the same cantilever side deflection . The only issue is now that which load criteria be used for live load. If i use 0.25Kpa load then deflection is different and if i use 0.58kpa load then different. Which is correct for this type of structure. Which one should govern for deflection.

 

Thanks 

[UmarMakhzumi]

Yasir,

 

You can use 0.24 kPa if your roof is non accessible or there are no maintenance and construction loads on roofs which I believe is the case.

 

Thanks.

[Yasir Saleem]

thanks sir g ... Eid MUbarik....

[UmarMakhzumi]

You're very welcome Yasir. Eid Mubarak to you and you family too!

Thanks.