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HomeMy WebLinkAboutLA208904 - APPROVED - Krishnaswamy Lakeville MN Engineering Letter Stamped___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com To: BlueRavenSolar 1403NorthResearchWay,BuildingJ Orem,UT.84097 Subject: CertificationLetter KrishnaswamyResidence 18365GleedRd Lakeville,MN.55044 ToWhomItMayConcern, DesignCriteria: භ ApplicableCodes=2018IBC/IRC,ASCE7Ͳ16 භ RoofDeadLoad=7psf(MP1&2) භ RoofLiveLoad=20psf භ WindSpeed=115mph(Vult),ExposureC භ භ Sincerely, JohnCalvert,P.E. ProjectEngineer December15,2022 Theroofstructuresof(MP1&2)consistofcompositionshingleonroofplywoodthatissupportedbypreͲmanufacturedtrusses thatarespacedat@24"o.c..Thetopchords,slopedat33degrees,are2x4sections,thebottomchordsare2x4sectionsandthe webmembersare2x4sections.Thetrussmembersareconnectedbysteelgussetplates.Themaxunsupportedprojected horizontaltopchordspanisapproximately6'Ͳ8''. Theexistingroofframingsystemsof(MP1&2)arejudgedtobeadequatetowithstandtheloadingimposedbytheinstallationof thesolarpanels.Noreinforcementisnecessary. GroundSnowLoad=50psfͲRoofSnowLoad=35psf Thespacingofthesolarstandoffsshouldbekeptat48"o.c.forlandscapeand24"o.c.forportraitorientation,withastaggered patterntoensureproperdistributionofloads. AjobsiteobservationoftheconditionoftheexistingframingsystemwasperformedbyanauditteamofBlueRavenSolarasa requestfromDomusStructuralEngineering.Allreviewisbasedontheseobservationsandthedesigncriterialistedbelowand onlydeemedvalidifprovidedinformationistrueandaccurate. Ontheabovereferencedproject,theroofstructuralframinghasbeenreviewedforadditionalloadingduetotheinstallationof thesolarPVadditiontotheroof.Thestructuralreviewonlyappliestothesectionoftheroofthatisdirectlysupportingthesolar PVsystemanditssupportingelements.Theobservedroofframingisdescribedbelow.Iffieldconditionsdiffer,contractorto notifyengineerpriortostartingconstruction. Thescopeofthisreportisstrictlylimitedtoanevaluationofthefastenerattachment,underlyingframingandsupporting structureonly.Theattachment'stotheexistingstructurearerequiredtobeinastaggeredpatterntoensureproperdistribution ofloading.Allpanels,rackingandhardwareshallbeinstalledpermanufacturerspecificationsandwithinspecifieddesign limitations.Allwaterproofingshallbeprovidedbythemanufacturer.DomusStructuralEngineeringassumesnoresponsibility formisuseorimproperinstallationofthesolarPVpanelsorracking. Pleasecontactmewithanyfurtherquestionsorconcernsregardingthisproject. Note:SeismiccheckisnotrequiredsinceSs<.4gandSeismicDesignCategory(SDC)<B Attachment:1Ͳ5/16dia.lagscrewwith2.5inchmin.embedment depth,atspacingshownabove. Krishnaswamy Lakeville MN.xlsm 1 I hereby certify that this plan, specification or report wasprepared by me or under my direct supervision and that I am aduly Licensed Professional Engineer under the laws of the Stateof Minnesota.John A. Calvert, License No. 52823 ExpirationDate: 30-June-2024 Digitally signed by John A. Calvert Date: 2022.12.15 15:02:40 -07'00' Concept Approval ONLY Subject to Field Inspection Inspector Date 2020 MN Bldg Code 12/14/2022dpfannenstein Please provide a copy of the City Approved plans on site at final inspection. ____________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com 50 psf (ASCE7 - Eq 7-1) 1 (ASCE7 - Table 7-2) 1 (ASCE7 - Table 7-3) 1 35.0 psf (ASCE7 - Eq 7-2) 1 35.0 psf 3.58 psf 3.0 psf 2.00 ft 6.08 ft 12.17 sft 37 lb 4.00 2.00 0.73 0.00 (Ceiling Not Vaulted) 0.27 7.0 psf 8.3 psf Gravity Loading PV System Weight Weight of PV System (Per Blue Raven Solar) X Standoff Spacing = Y Standoff Spacing = Note: PV standoffs are staggered to ensure proper distribution of loading 2x4 Top Chords @ 24"o.c. I = Importance Factor = Cs = Slope Factor = Standoff Tributary Area = ps = Cspf ps = Sloped Roof Snow Load = pf = Flat Roof Snow Load = DL Adjusted to 33 Degree Slope Roof Snow Load Calculations pg = Ground Snow Load = Ce = Exposure Factor = pf = 0.7 Ce Ct I pg Ct = Thermal Factor = Roof Live Load = 20 psf Roof Plywood Roof Dead Load (MP1&2) Composition Shingle Note: Roof live load is removed in area's covered by PV array. DL Adjusted to 33 Degree Slope Point Loads of Standoffs Miscellaneous Vaulted Ceiling Total Roof DL (MP1&2) PV Dead Load = 3 psf (Per Blue Raven Solar) Krishnaswamy Lakeville MN.xlsm 2 ___________________________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com 115 mph C Gable Roof 33 degrees 20 ft 21.3 ft 0 ft (Eq. 26.10-1) 0.90 (Table 30.3-1) 1.00 (Fig. 26.8-1) 0.85 (Table 26.6-1) 1.00 115 mph (Fig. 26.5-1A) II (Table 1.5-1) qh = 25.95 Zone 1 Zone 2 Zone 3 Positive ya =0.77 0.80 0.80 0.77 GCp =-1.71 -2.00 -2.89 0.87 (Fig. 30.3) Uplift Pressure =-34.3 psf -41.5 psf -60.0 psf 17.3 psf (Eq. 29.4-7) ASD Uplift Pressure =-20.6 psf -24.9 psf -36.0 psf 10.4 psf X Standoff Spacing = 2.00 2.00 1.33 Y Standoff Spacing = 6.08 3.04166667 3.04166667 Tributary Area = 12.17 6.08 4.06 Dead Load on attachment = 37 lb 18 lb 12 lb Footing Uplift (0.6D+0.6W) = -229 lb -141 lb -139 lb Zone 1 Zone 2 Zone 3 Positive ya =0.75 0.80 0.80 0.75 GCp =-1.65 -2.00 -2.83 0.84 (Fig. 30.3) Uplift Pressure =-32.2 psf -41.5 psf -58.7 psf 16.4 psf (Eq. 29.4-7) ASD Uplift Pressure (0.6W)=-19.3 psf -24.9 psf -35.2 psf 9.8 psf X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 3.50 1.75 1.75 Tributary Area = 14.00 7.00 4.67 Dead Load on attachment = 42.00 21.00 14.00 Footing Uplift (0.6D+0.6W) = -246 lb -162 lb -156 lb -246 lb 450 lb Therefore, OK Fastener =1 - 5/16" dia. lag Number of Fasteners = 1 Embedment Depth = 2.5 Pullout Capacity Per Inch = 250 lb Fastener Capacity = 625 lb w/ F.S. of 1.5 & DOL of 1.6= 667 lb Therefore, OK Fastener Capacity Check Mean Roof Height Ground Elevation Kd (Wind Directionality Factor) = 667.2 lb capacity > 246 lb demand Ke (Ground Elevation Factor) = V (Design Wind Speed) = Risk Category = Standoff Uplift Calculations-Portrait Standoff Uplift Calculations-Landscape Standoff Uplift Check Standoff Uplift Capacity = 450 lb capacity > 246 lb demand Wind Calculations Maximum Design Uplift = Design Wind Pressure Calculations qh = 0.00256 * Kz * Kzt * Kd * Ke * V^2 Kz (Exposure Coefficient) = Kzt (topographic factor) = Wind Speed Exposure Category Roof Shape Roof Slope Effective Wind Area PerASCE7Ͳ16ComponentsandCladding Input Variables Krishnaswamy Lakeville MN.xlsm 3 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com (MP1&2)PASS Dead Load 8.3 psf PV Load 3.6 psf Snow Load 35.0 psf Governing Load Combo = DL + SL Total Load 46.9 psf Fb (psi) = f'b x Cd x Cf x Cr (NDS Table 4.3.1) 1650 x 1.15 x 1 x 1.15 Allowed Bending Stress = 2182.1 psi (wL^2) / 8 = 521.3737 ft# = 6256.484 in# Actual Bending Stress = (Maximum Moment) / S = 2043 psi L/180 (E = 1500000 psi Per NDS) = 0.444 in Deflection Criteria Based on = (w*L^4) / (185*E*I) = = L/371 > L/180 Therefore OK Allowed Deflection (Live Load) =L/240 0.333 in (w*L^4) / (185*E*I) L/497 > L/240 Therefore OK Member Area = Fv (psi) = 135 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 313 lb Framing Check 5.3 in^2 Check Shear w = 94 plf 2x4 Top Chords @ 24"o.c. Member Span = 6' - 8" 709 lb Allowed > Actual -- 44.2% Stressed -- Therefore, OK 1650Fb/1.5E Member Spacing @ 24"o.c. Maximum Moment = Check Deflection I (in^4) 5.36 Lumber Sp/Gr Actual Deflection (Live Load) = Allowed Deflection (Total Load) = Actual Deflection (Total Load) = Allowed > Actual -- 93.7% Stressed -- Therefore, OK Member Properties Member Size 2x4 S (in^3) 3.06 0.161 in Continuous Span 0.216 in Check Bending Stress (True Dimensions) Krishnaswamy Lakeville MN.xlsm 4