Structural, Snow & Wind Loading Appraisal Report

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1 Company Name Or Logo Here Structural, Snow & Wind Loading Appraisal Report In accordance with Guide to the Installation of Photovoltaic Systems nd Edition Reference number 001 Company Name Solar Company Date 26/11/2014 Address of property Post Code Software Tedds 2014 Page 1 of 12

2 Table of Contents 1. APPLIED LOADINGS 2. JUSTIFICATION OF PANELS FOR GRAVITY LOADS 3. JUSTIFICATION OF PANELS FOR UPLIFT LOADS 4. CONCLUSIONS Disclaimer: The Desk Top Appraisal Report has been produced from information supplied by the client. Solar Roof Surveys cannot be held responsible for any damage caused from the supply of limited information or damage caused due to inaccuracies within the information supplied or non-compliance with Guide to the Installation of Photovoltaic Systems nd Edition Page 2 of 12

3 1. APPLIED LOADINGS. In considering the applied loading we have designed as noted below: Dead loads are based on the actual specified make up for the existing roof. Imposed loads are based on the loadings within (BS EN ). Wind loadings are calculated on a site specific basis. Applied loads are as follows: EXISTING ROOF MAKE UP: DEAD LOADS Existing Tiles = 0.55kN/m2 Existing Felt = 0.02kN/m2 Existing Trusses = 0.15kN/m2 Total DL = 0.72kN/m BS EN states: On roofs which are not accessible except for normal maintenance and repair, imposed loads need not be applied in combination with either snow loads and /or wind action. EXISTING ROOF WIND LOADINGS: Calculated using TEDDS design software for both positive and negative internal pressure and for wind acting both perpendicular and parallel to the front elevation of the building. EXISTING ROOF SNOW LOADINGS: Calculated using TEDDS design software for both basic and where appropriate complex snow loadings. Page 3 of 12

4 WIND LOADING (EN ) TEDDS calculation version Plan 7600 Elevation Building data Type of roof; Length of building; Width of building; Height to eaves; Pitch of roof; Total height; Duopitch L = mm W = 7600 mm H = 4900 mm α 0 = 32.0 deg h = 7275 mm Basic values Location; Bournemouth Wind speed velocity (FigureNA.1); v b,map = 21.9 m/s Distance to shore; L shore = km Altitude above sea level; A alt = 22.0m Altitude factor; c alt = A alt 0.001m = Fundamental basic wind velocity; v b,0 = v b,map c alt = 22.4 m/s Direction factor; c dir = 1.00 Season factor; c season = 1.00 Shape parameter K; K = 0.2 Exponent n; n = 0.5 Probability factor; c prob = [(1 - K ln(-ln(1-p)))/(1 - K ln(-ln(0.98)))] n = 1.00 Basic wind velocity (Exp. 4.1); v b = c dir c season v b,0 c prob = 22.4 m/s Reference mean velocity pressure; q b = 0.5 ρ v 2 b = kn/m 2 Orography Orography factor not significant; c o = 1.0 Terrain category; Sea Displacement height (sheltering effect excluded); h dis = 0mm The velocity pressure for the windward face of the building with a 0 degree wind is to be considered as 1 part as the height h is less than b (cl.7.2.2) The velocity pressure for the windward face of the building with a 90 degree wind is to be considered as 1 part as the height h is less than b (cl.7.2.2) Peak velocity pressure - windward wall - Wind 0 deg and roof Reference height (at which q is sought); z = 4900mm Displacement height (sheltering effects excluded); h dis = 0 mm Exposure factor (Figure NA.7); c e = 2.02 Peak velocity pressure; q p = c e q b = 0.62 kn/m 2 Page 4 of 12

5 Structural factor Structural damping; δ s = Height of element; h part = 4900 mm Size factor (Table NA.3); c s = 0.92 Dynamic factor (Figure NA.9); c d = 1.02 Structural factor; c scd = c s c d = Peak velocity pressure - windward wall - Wind 90 deg and roof Reference height (at which q is sought); z = 7275mm Displacement height (sheltering effects excluded); h dis = 0 mm Exposure factor (Figure NA.7); c e = 2.27 Peak velocity pressure; q p = c e q b = 0.70 kn/m 2 Structural factor Structural damping; δ s = Height of element; h part = 7275 mm Size factor (Table NA.3); c s = 0.93 Dynamic factor (Figure NA.9); c d = 1.03 Structural factor; c scd = c s c d = Structural factor - roof 0 deg Structural damping; δ s = Height of element; h part = 7275 mm Size factor (Table NA.3); c s = 0.92 Dynamic factor (Figure NA.9); c d = 1.02 Structural factor; c scd = c s c d = Peak velocity pressure for internal pressure Peak velocity pressure internal (as roof press.); q p,i = 0.70 kn/m 2 Pressures and forces Net pressure; Net force; p = c scd q p c pe - q p,i c pi; F w = p w A ref; Roof load case 1 - Wind 0, c pi -0.3, +c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) F (+ve) G (+ve) H (+ve) I (+ve) J (+ve) Total vertical net force; F w,v = kn Total horizontal net force; F w,h = kn Walls load case 1 - Wind 0, c pi -0.3, +c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) A B D Page 5 of 12

6 E Overall loading Equiv leeward net force for overall section; F l = F w,we = -4.3 kn Net windward force for overall section; F w = F w,wd = 38.2 kn Lack of correlation (cl.7.2.2(3) Note); f corr = 0.85; as h/w is Overall loading overall section; F w,d = f corr (F w - F l + F w,h) = 53.2 kn Roof load case 2 - Wind 90, c pi 0.20, -c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) F (-ve) G (-ve) H (-ve) I (-ve) Total vertical net force; F w,v = kn Total horizontal net force; F w,h = 0.00 kn Walls load case 2 - Wind 90, c pi 0.20, -c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) A B C D E Overall loading Equiv leeward net force for overall section; F l = F w,we = kn Net windward force for overall section; F w = F w,wd = 16.8 kn Lack of correlation (cl.7.2.2(3) Note); f corr = 0.85; as h/l is Overall loading overall section; F w,d = f corr (F w - F l + F w,h) = 30.3 kn Roof load case 3 - Wind 90, c pi -0.3, +c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) F (+ve) G (+ve) H (+ve) I (+ve) Total vertical net force; F w,v = kn Total horizontal net force; F w,h = 0.00 kn Page 6 of 12

7 Walls load case 3 - Wind 90, c pi -0.3, +c pe Zone Ext pressure coefficient c pe Peak velocity pressure q p, (kn/m 2 ) Net pressure p (kn/m 2 ) Area A ref (m 2 ) Net force F w (kn) A B C D E Overall loading Equiv leeward net force for overall section; F l = F w,we = -2.7 kn Net windward force for overall section; F w = F w,wd = 32.9 kn Lack of correlation (cl.7.2.2(3) Note); f corr = 0.85; as h/l is Overall loading overall section; F w,d = f corr (F w - F l + F w,h) = 30.3 kn Page 7 of 12

8 D Windward face A B E 7600 Side face Leeward face Wind - 90 o Plan view - Duopitch roof Page 8 of 12

9 D 7600 Windward face A B C E Side face 7600 Leeward face Page 9 of 12

10 2. JUSTIFICATION OF PANELS FOR GRAVITY LOADS From the calculated loads we see that each panel weighs 17.25kg and is 1639mm by 982mm. Therefore the weight per m2 = 10.72kg/m2. The support frame weighs 2kg/m2 Total dead load = kg/m2 = kn/n2 Once the panel is in situ this area of roof will not be trafficked and so there is no need to consider the actual weight of the panel as being an additional imposed load on the roof. Should anyone stand on the panel it will destroyed, the owner of the property will therefore take strict steps to ensure that no one at any time stands on the panel. Therefore this area of roof can be considered as carrying less than the design imposed load indicated in EN Therefore there is no requirement for strengthening as a result of combined imposed load and panel load. With regards snow loading we see that the snow load is 0.28kN/m2. This load will be cumulative to the weight of the panel. Ref to Guide to the Installation of Photovoltaic Systems nd Edition. Dead Load = 0.72 kn/m2 less Snow Load = 0.28kN/m2 = 0.44 kn/m = kn/m2 which is within the design load of 0.75kN/m2 Page 10 of 12

11 SNOW LOADING (EN ) In accordance with EN :2003 incorporating corrigenda dated December 2004 and March 2009 and the UK national annex incorporating Corrigendum No.1 TEDDS calculation version Characteristic ground snow load Location; Bournemouth Site altitude above sea level (user modified value); A = 22 m Zone number; Z = 2.0 Density of snow; γ = 2.00 kn/m 3 Characteristic ground snow load; s k = (( (0.1 Z )) + ((A - 100m) / 525m)) 1kN/m 2 = 0.25 kn/m 2 Exposure coefficient (Normal); C e = 1.0 Thermal coefficient; C t = 1.0 Building details Roof type; Width of roof (left on elevation); Width of roof (right on elevation); Slope of roof (left on elevation); Slope of roof (right on elevation); Duopitch b 1 = 4.48 m b 2 = 4.48 m α 1 = deg α 2 = deg Shape coefficients Shape coefficient roof (Table 5.2); µ 1_α1_T52 = 0.75 Shape coefficient roof (Table 5.2); µ 1_α2_T52 = 0.75 Shape coefficient roof (Table UK NA.1); µ 1_α1_NA1 = 1.12 Shape coefficient roof (Table UK NA.1); µ 1_α2_NA1 = 1.12 Loadcase 1 Table 5.2 Loading to roof 1 (LHS); s 1_1 = µ 1_α1_T52 C e C t s k = 0.19 kn/m 2 Loading to roof 2 (RHS); s 2_1 = µ 1_α2_T52 C e C t s k = 0.19 kn/m 2 Loadcase2 UK NA1 Loading to roof 1 (LHS); s 1_2 = 0 C e C t s k = 0.00 kn/m 2 Loading to roof 2 (RHS); s 2_2 = µ 1_α2_NA1 C e C t s k = 0.28 kn/m 2 Loadcase3 UK NA.1 Loading to roof 1 (LHS); s 1_3 = µ 1_α1_NA1 C e C t s k = 0.28 kn/m 2 Loading to roof 2 (RHS); s 2_3 = 0 C e C t s k = 0.00 kn/m 2 Page 11 of 12

12 3. JUSTIFICATION OF PANELS FOR UPLIFT LOADINGS From the TEDDS calcs we see that the panels should ideally be placed within Zone H Given that the panel fixings will transfer the load into the existing roof and the roof was originally designed for this wind load, no strengthening works will be required to the roof structure. To calculate the actual wind uplift on the solar array we refer to BRE Digest 489 revised & EN From our calculations above we know that q (Peak Velocity Pressure) = 0.70kN/m2 see page 5 and where a module is less than 0.3m from the roof surface the Wind Uplift Net Pressure Coefficients for the panels in the centre of the roof is -1.3 With a safety Factor of x (-1.3) x 1.35 = kn/m2 all roof fixings must be able to withstand this uplift 4. CONCLUSIONS From the TEDDS calcs and the fixing calculations we see that the proposed solar panels can safely be fixed to the existing roof structure with no strengthening works being required. The roof fixings should follow the manufacturer s guidelines. Page 12 of 12

Load combinations will be created according to the below option.

Load combinations will be created according to the below option. Eurocode Wizards The Eurocode Wizard option shows a dialogue box where various pre-defined beams, frames, rafters and trusses can be stated easily and roof, snow, wind and imposed loads as well as load