Page 2 :
3.19, , (1), flange section, 150 mm, bi, 20 mm, dl, = 150x20, bi dl, al, = 3000 mm2, , bl, 2, , =, , Web section (1), 25 mm, = 100 mm, , = 25 x 100, , =, , 150 = 75, mm, , dl, , = 75 mm, , - dl 4, , 20, = 10 mm, 2, , 2, , = 2500 mm2, , 2, 20+, , 2, , Eax _ (al Xi +, , (3000 x 75 + 2500 x 75), (3000 + 2500), , Note : If XI =, , mm, , = 75 mm, , = 75 mm then X is also equal to 75 mm, , Eay _ (al + a2Y2), (3000 x 10 + 2500 x 70), (3000 + 2500), reference., , 37.27 mm, , Common centroid G is at (75, 37.27) from axes of, , 2. Find the centroid of unequal angle section 100 x 80 x 20 mm, [Oct 20071., , Solution, Flange section (1), , bi = 80 mm, dl = 20 mm, , al = bi dl, , = 80 x 20, , = 1600 mm2, , Web section (1), = 20 mm, d2 = 80 mm, , a2 = b2d2, , = 20x80, = 1600 mm2

Page 3 :
3.20, , 80 = 40 mm, , - --2 =, , = 10mm, = 20 +, , = 60 mrn, , b2=20, , Web, , 0? deep overall, , Fig .pb 2, , Lax, , (at + a2, , (1600 x 40 + 1600 x 10), (1600 + 1600), , Eay, , 25 mm, , (al + a2Y2), , (1600 x 10 + 1600 x 60), (1600 + 1600), , = 35mm, , 3. Find the centroid of a T-section withflange 120 mm x 10 mm, and web 110 mm 00 mm. [Apr. 2005, 20131

Page 6 :
3.23, x, , 100 mm, , 40 +, , 160, , x,, , 120 mm, , 100 mm, , 40+160+, = 220 mm, , X = 100 mm (Since XI =, , 1001, , [8000 x 20 + 6400 x 120 + 8000x 2201, [8000 + 6400 + 80001, = 120 mm

Page 7 :
3.25, , solution, Section (1), = 300 mm, = 50 mm, - 300%50, , -150, , = 15000 rnrn2, , b2=25, , = 150 mm, -150, , = 25 mm, Section (2), , b2 =, 2 =, =, 2 =, , 25 mrfig .pb6, 200 mm, b2d2 = 25 x 200, = 5000 mm2, 150 mm, , = 50 +, , Section (3), — 120 mm, , = 25 mm, = b3d3 = 120x25, = 3000 mm2, = 150 mm, , = 50+200+, = 262.5, , = 150 mm, , = 150 mm [Since, , =, , 150], , [15000 x 25 + 5000 x 150 + 3000 x 262.5], [15000 + 5000 + 3000], — 83.15 mm