The figure shows a rigid bar A B C D pinned at A and supported by vertical bars at B and C. The vertical bar at B is labeled 1 and pinned at its top end and the vertical bar at C is labeled 2 and pinned at its bottom end. The separation between A and B is 760 millimeters. The separation between B and C is 760 millimeters and the separation between C and D is 120 millimeters. A load P directed vertically downwards is applied at D.

The equilibrium equation

MA=F1(760 mm)          -F2(1,520 mm)            (35 kN)(1,640 mm)=0  

and the compatibility equation:

1760 mmF1L1A1E1=-11,520 mmF2L2A2E2

can be solved simultaneously to determine F1 and F2.

F1=+19.466 kN     F2=-28.030 kN

To compute the normal stress in each member, divide the internal axial force by the cross-sectional area A1=A2=160 mm2:

σ1=121.7 MPa (T)        σ2=175.2 MPa (C)