DESIGN OF PURLIN : DEAD LOAD CALCULATION : Self weight of Purlin = 22.3 Kg/m 14 Spacing of Purlin = 1.35 m Span of Purlin = 4.15 m UDL of CGI sheet roofing = 14 x 1.35 18.9 Kg/m Total UDL due to DL on Purlin = 22.3 + 41.2 Kg/m 0.042 T/m SNOW LOAD CALCULATION : ( CLAUSE 3 OF IS : 875 ( PART 4 ) - 1987 Depth of Snow Blanket on ground = 0.61 m ( Max ht is allowe 5463 0.75 4097.6 UDL of Snow Blanket on Purl 1.35 x 417. 563.9 Kg/m 0.564 T/m LIVE LOAD CALCULATION : ( CLAUSE 4.5.1 OF IS : 875 ( PART 2 ) - 1987 Live Laod on roof = 75 18.18 0 Live Load Reduction = 40.00 UDL of Live Load on Purlin 1.35 x 40 = 54.00 Kg/m 0.054 T/m Combination: Total Udl of DL+LL = 0.096 T/m Total Udl of DL+Snow load = 0.606 T/m FOR WIND LOAD : Coefficient for this case = -1.400 Uplift Wind Load Uplift Force = -0.102 T/m Net Uplift Force = 0.103 - 0.638 x Cos 0.011 T/m Uplift 0.606 T/m ( ISMC-200 ASSUMED ) CGI sheet roofing = Kg/m 2 Ground Snow load =( 0.61x 913 x 9.81) = N/m 2 ( Density of Ice = Shape Coefficient = m = Snow Load on plan area of roof = S = m N/m 2 Kg/m 2 Roof Angle = a = Kg/m 2 WIND PARALLEL TO RIDGE ( q = 90 0 ) + INTERNAL PRESSURE CASE GOVERNS
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PURLINDESIGN OF PURLIN :DEAD LOAD CALCULATION :Self weight of Purlin =22.3Kg/m( ISMC-200 ASSUMED )CGI sheet roofing =14Kg/m2Spacing of Purlin =1.35mSpan of Purlin =4.15mUDL of CGI sheet roofing = 14 x 1.35 =18.9Kg/mTotal UDL due to DL on Purlin = 22.3 + 18.9 =41.2Kg/m0.042T/mSNOW LOAD CALCULATION : ( CLAUSE 3 OF IS : 875 ( PART 4 ) - 1987Depth of Snow Blanket on ground =0.61m( Max ht is allowed 2ft )Ground Snow load =( 0.61x 913 x 9.81) = s0 =5463N/m2( Density of Ice = 913 Kg/m3 )Shape Coefficient = m =0.75Snow Load on plan area of roof = S = m x s0 =4097.6N/m2UDL of Snow Blanket on Purlin =1.35 x 417.6975 =563.9Kg/m0.564T/mLIVE LOAD CALCULATION : ( CLAUSE 4.5.1 OF IS : 875 ( PART 2 ) - 1987Live Laod on roof =75Kg/m2Roof Angle = a =18.180Live Load Reduction =40.00Kg/m2UDL of Live Load on Purlin =1.35 x 40 =54.00Kg/m0.054T/mCombination:Total Udl of DL+LL =0.096T/mTotal Udl of DL+Snow load =0.606T/mFOR WIND LOAD :WIND PARALLEL TO RIDGE ( q = 90 0 ) + INTERNAL PRESSURE CASE GOVERNSCoefficient for this case =-1.400UpliftWind Load Uplift Force =-0.102T/mNet Uplift Force =0.103 - 0.638 x Cos18.19 =0.011T/mUplift0.606T/mAnalysis Of Truss :Span of Truss = l =4.15mTotal UDL on truss = w =0.61T/mDesign B.M. at center on span = wl2 / 8 =1.30TmDesign Shear Force at support = w l / 2 =1.26TDesign Of Truss :Considering Depth of Truss at center =0.50mForce in Top Chord of Truss =2.61TUse ISMC 100A =12.20cm2D =100mmA =157.60cm2D =400mmZxx =33.5cm3Tf =7.7mmZxx =1598cm3Tf =15.3mmIxx =192cm4Rmin =1.48cmIxx =31962cm4Rmin =10.51cml =1700mml/Rmin =114.86l =1625mml/Rmin =15.46Local bending in Top chord membersLoad = w =0.61T/mSpan = l =1.700mLocal BM = wl2 / 10 =0.18TmLocal bending stress in Top chord = Fb =522.70Kg/cm2
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