I. Purlin Design Purlins are beams designed to carry roof loads. The roof purlins are usually...

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I. Purlin Design Purlins are beams designed to carry roof loads. The roof purlins are usually inclined and carry vertical loads due to dead load and live load and normal loads due to wind. Hence the purlin sections are subjected to unsymmetrical bending. Assume that the purlins are simply supported with span length, L= 4.0 m, equally spaced at 1.2 m and carry uniform vertical dead loads (250 N/m) and wind load (200 N/M) acting normal to the purlin. The slope is 30 degrees. A steel section with given dimensions is already chosen. You are required to compare the maximum bending stresses (T&C) for the two positions((Regular Z/C or inverted Z/C). Which position has the least maximum bending stress. State any assumptions made in your analysis. Assume the following dimensions of the regular sections. "Odd Group" (a) Fig 1A-ODD-Numbered Groups (Z-shape) (b) Fig 1B-EVEN-Numbered Groups (C-shape) 12 mm 180 mm 12 mm Fig. IA A E 12 mm 150 mm 12 mm 150 mm WL RAUF DL FLANGE BRACE Fig. 1B 12 mm. 180 mm 12 mm 0 EAVE STRIT I. Purlin Design Purlins are beams designed to carry roof loads. The roof purlins are usually inclined and carry vertical loads due to dead load and live load and normal loads due to wind. Hence the purlin sections are subjected to unsymmetrical bending. Assume that the purlins are simply supported with span length, L= 4.0 m, equally spaced at 1.2 m and carry uniform vertical dead loads (250 N/m) and wind load (200 N/M) acting normal to the purlin. The slope is 30 degrees. A steel section with given dimensions is already chosen. You are required to compare the maximum bending stresses (T&C) for the two positions((Regular Z/C or inverted Z/C). Which position has the least maximum bending stress. State any assumptions made in your analysis. Assume the following dimensions of the regular sections. "Odd Group" (a) Fig 1A-ODD-Numbered Groups (Z-shape) (b) Fig 1B-EVEN-Numbered Groups (C-shape) 12 mm 180 mm 12 mm Fig. IA A E 12 mm 150 mm 12 mm 150 mm WL RAUF DL FLANGE BRACE Fig. 1B 12 mm. 180 mm 12 mm 0 EAVE STRIT