+3 votes
in Mathematics by kratos

Fig, shows vertical forces 20KN, 40KN and UDL of 20KN/m in 3m lengths. Find the resultant force of the system and draw the shear force and B.M. diagram.

1 Answer

+2 votes
by kratos
 
Best answer

Total force acting are 20KN, 40KN and 60KN (UDL),

Hence resultant of the system = √(∑H)2 + ∑H)2

∑H = 0 and ∑V = 20 + 40 + 60 = 120KN

R = 120KN

Here total two-section line, which cut AB, AC

Distance of section 1-1 from point A is X1

Distance of section 2-2 from point A is X2

Consider left portion of the beam

*.F. Calculations:

*.F.1-1 = – 20 – 20.X1 (Equation of inclined line)

At X1 = 0

SFA = –20KN

At X1 = 1

SFB = –40KN

*.F.2-2 = –20 – 40 – 20X2

At X2 = 1

SFB = –80KN

At X2 = 3

SFC = –120KN

Plot the SFD with the help of above value

B.M. Calculations:

B.M.1–1 = –20X1 – 20.X1(X1/2) (Equation of Parabola)

At X1 = 0

BMA = 0

At X1 = 1

BMB = –30KN-m

BM2-2 = –20X2 – 40(X2-1) – 20X2(X2/2)

At X2 = 1

BMB = –30KN-m

At X2 = 3

SFC = –230KN-m

Plot the BMD with the help of above value.

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