The document summarizes proposed design changes to a carport canopy structure based on wind tunnel testing results. It recommends adding a deflector to the photovoltaic structure to reduce wind loads and lighter structural members. Analyzing configurations in RISA 3D, it suggests reducing beam dimensions to a lighter W14x34 profile and using thinner 16-gauge purlins instead of all 14-gauge to minimize weight and costs while still passing code checks. Specifically, it proposes using stronger 14-gauge purlins for the two end bays and lighter 16-gauge purlins for the middle bays. Bracing may also need adjustment to accommodate moment distribution. Analysis shows this design achieves required D/C ratios and

1. Structural Designon CarportCanopy Considering
Wind Tunnel Testing
Givenwindtunnel analysisconducted byCPP,we canconsiderthe additionof a deflectoruponthe PV
structure inorder to reduce the windloaduponthe structural systemandreduce the weightof purlins,
columns,andbeamsthemselves.
Usinga providedRISA 3Dfile,we cananalyze outvariousconfigurationsof the structure inordertofind
the optimal membersthatisbothstructurallysoundandeconomicallybeneficial.
GENERAL CONFIGURATION
The configurationthatthe newdesignwill implementisasfollows inFigure 1(pisfor panels):
The opencircles( ) representthe endpointsof individualpurlins. Variationsof thispatterncanbe used
dependingonspecial availabilityandnumber of baysneeded.
Columns
The original columndimensions(HSS12x8x8) we have usedwithinthe DSA plansare sufficientforthe
newdesign. These shouldnotbe changedasthisis a commonspec forthissteel type andwill keepthe
material purchasingeasyand efficient.
Beams
Givena more accurate testmodel fromthe windtunnel report,we can reduce the dimensionsof a
beamto W14x34. This will be slightlylighterandcheaperthanthe original W
3p 10p 2p 8p 2p 8p 2p 8p 2p 7p 3p
Fig. 1 – Sample configuration of purlin and beam
supports for canopy (p is for panels)

2. Purlins
To minimize weightandtomaximize savings,we wanttochoose cold-formedpurlinswiththinnercross-
section.The model will workwithall 14gamemberpurlins(12CS4x070);however,tofurtherdecreaseto
cost and weight,we canutilize a16ga memberonselectmembersof the structure.The structure does
not passthe code checkif all purlinswere ata 16ga thickness.
Giventhe windtunnel testmodel,we cansee thatmost of the greaterloadswill be concentratedon
eitherendsof structure.Thisisindicated belowwithwindloadcase A inbothup and downdirections.
We can change the leftmostandrightmostpurlinsinto a stronger14ga purlins,while the middle purlins
not supportingthe critical loadscanhave a 16ga thickness. Specifically,the twoleftmostandthe two
rightmostpurlinswillbe the only4purlinlineswitha14ga thickness.
Fig. 2 – Side view of wind load case A
Fig. 3 – Purlin set-up

3. Bracing
If purlinsdonot satisfythe D/Cratio, bracingscan be adjustedtoaccommodate the momentdistributed
across the member. For example, one of the bracing on the top left was moved towards the middle to
account fora large momentconcentratedtowardsthe middle.
MEMBER SPECS
Purlins
Type Thickness Strength Weight
12CS4x070 14ga (0.070in) 55 ksi 5.002 lb/ft
12CS4x056 16ga (0.056in) 65 ksi 3.934 lb/ft
Beams
Type Thickness Strength Weight
W14x37 F: 0.455 in , W: 0.285 in 50 ksi 344.028 lb/ft
Columns
Type Thickness Strength Weight
HSS12x8x8 0.465 in 56 ksi 58.528 lb/ft
SAVINGS PER BAY
Each bay stretchestoabout 34.75 feetperbay.There are 12 total purlins.
Cases Weightperbay
Case 1: All purlins 14ga 2805.83lb
Case 2: 4 purlins14ga, 8 purlins16ga 1788.93 lb
Thisresultsina difference of 296.904 lbof savedforthe new purlindimensions
Fig. 4 – Adjustment of bracing

4. RESULTS
Afterusingthe membersizesandadjustmentsfromabove,we can achieve the followingD/Cresultsfor
the structure:
Fig. 5 – D/C for beams and columns
Fig. 6 – D/C for beams and columns