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consider 12MPA as max stress in concrete column diameter as 340mm Exercise 14: The reinforced concrete column shown has to support load P. Neglecting the weight of the column, determine the safe load P if the stress in the steel is not to exceed 124 MPa and the stress in the concrete is not to exceed 6.5 MPa. Also calculate decrease in height of column E = 24000 MPa and Ex=200000 MPa The length of the column is 4.80 metres and its diameter 400 mm 6 reinforcement steel bars each 24 mm o Rigid cap 6 bars Reinforcing bars

Answer 1

Exercise 14 Diameter of column =D = 340 mm No of reinforcing berts = 6 Diameter of barrs = d = 24 mm. Maximum stress in steel & Os max = 124 Mpar Maximum stress in concrete - Or may = 12 MPa. E = 24000 MPa E = 200000 MPa Total area of the circularm column - = * 3409 = 90792 mmar Area of steet = A = 6*7 d = 6 + 7 x 240 = 27 14.34 min Area of concrete = = 90792 - Dlle. - 88077 - 66 mm 10 = A= 90792-2714.34 We know, if = ( ) O = 124 MPa - 24000 x 124 = 14.88 . MPa. °C 2000to > Cermax = 12 MPa This is not accepted.

e max = 12 MP a - 8 = 4 + 2 x de 200000 x 12 24000 = 100 MPG C Cman = 124 MPa. de = 12 MP and 6 = 100 MPa. c. Safe load = P = 0, Ac & Op As = P & Ps = (2x 88047.66 + 100% 2714.34)8103 = 1328.87 KN. Decrease of height of column. contraction of column. Deformation per wmit length is equal A = A = decrease in column length PCL PL AE A PL = PL - 12 X 4.8 x 103 A Ą B = 2.4 mm PLL ico x 4.88 10 3 Ah Ę 200000 = 2.4mm. - Deerease in height of column=2.4 cm & 24000