Purlin Design LSM
Purlin Design LSM
Purlin Design LSM
925 KN/m2
Wind pressure down ward (+ve) along Y axis = 0.065 KN/m2
Sheet dead weight per square meters = 0.25 KN/m2
Live load on roof = 0.75 KN/m2
Weight of purlin per meters @ ISMC150 = 0.1672 KN/m
Angle of roof = 5 Degree
Spacing of purlins = 1.2 m
Major direction
1) 1.5 DL+ 1.5 LL = 2.043 KN/m
2) 1.2 DL+ 1.2 LL+ 1.2 WL(+ve) = 1.728 KN/m
3) 1.2 DL+ 1.2 LL+ 1.2 WL(-ve) = 0.302 KN/m
4) 0.9 DL+ 0 LL+ 1.5 WL(-ve) = -1.246 KN/m
Minor direction
1.5 DL+ 1.5 LL = 0.179 KN/m
Y
X
X
5
Y
Design Inputs
Sectional Properties
Depth of member D = 150.00 mm
Width of flange W = 75.00 mm
Thickness of Flange tf = 9.0 mm
Thickness of web tw = 5.70 mm
Area of section A = 2130 mm2
Elastic modulus Mojar axis Zea = 105000 mm3
Plastic modulus Major axis Zpa = 118310 mm3
Elastic modulus Minor axis Zeb = 19500 mm3
Plastic modulus Minor axis Zpb = 34220 mm3
Radius of gyration Major axis Ra = 61 mm
Radius of gyration Minor axis Rb = 22 mm
Moment of Inertia about mojar axis Ia = 7880000 mm4
Moment of Inertia about minor axis Ib = 1030000 mm4
Section Clasification
ϵ = SQRT(250/fy) = 1
Beam is not susceptible shear buckling Hence full capacity can be used
Major axis
Plastic and compact Section
a ) Mdva = Mda - β (Mda-Mfda) >1.2 Zea Fy / ϒm0 = 21.631 kN-m
For Semi Compact
b ) Mdva = Zea x Fy / ϒm0 = 23.864 kN-m
Minor axis
a ) Mdvb = Mdb - β (Mdb-Mfdb) >1.2 Zeb Fy / ϒm0 = 2.876 kN-m
Semi Compact
b ) Mdvb = Zeb x Fy / ϒm0 = 4.432 kN-m
δ = 5 w l ^4 /384 EI = 37.782 mm
D W Tw Tf d1 A Ixx Iyy
mm mm mm mm mm cm² cm4 cm4
ISMC75-7.14 75 40 4.8 7.5 60 9.1 78.5 12.9
ISMC100-9.56 100 50 5 7.7 65 12.2 192 26.7
ISMC125-13.1 125 65 5.3 8.2 89 16.7 425 61.1
ISMC150-16.8 150 75 5.7 9 113 21.3 788 103
ISMC175-19.6 175 75 6 10.2 135 24.9 1240 122
ISMC200-22.3 200 75 6.2 11.4 155 28.5 1830 141
ISMC225-26.1 225 80 6.5 12.4 173 33.3 2710 188
ISMC250-30.6 250 80 7.2 14.1 194 39 3880 211
ISMC300-36.3 300 90 7.8 13.6 240 46.3 6420 313
ISMC350-42.7 350 100 8.3 13.5 288 54.4 10000 434
ISMC400-50.1 400 100 8.8 15.3 335 63.8 15200 508
Torsional
moment of
Ct Ix Zx Zy Zpx Zpy inertia (St. Rxx Ryy
Venant)
1.32 1.57 25.1 9.02 23.66 7.8 1.3 11.86 29.28
1.54 2.23 45.4 14.8 42.89 12.88 1.8 14.71 39.67
1.94 3.47 78.4 25.9 75.54 22.61 2.9 18.98 50.42
2.2 5.41 122 38.3 118.31 34.22 4.6 21.88 60.82
2.19 7.44 164 44.7 158.68 39.95 6.6 22.04 70.48
2.18 9.83 213 51.1 208.01 47.28 9.2 22.08 80.13
2.31 13.3 280 63.7 275.04 58.75 12.5 23.63 90.23
2.29 18.8 359 73.9 352.63 69.64 18.5 23.64 99.2
2.35 21.7 502 91.2 492.05 91.03 20 25.92 117.74
2.44 25.9 679 111 663.52 120.75 23.2 28.11 136.19
2.42 35.9 900 129 1277.57 148.41 33.3 28.13 154.39