q P B C A D Figure F.1 (a) Loaded Portal Frame 1
BC BC M M B C BC BC T T B C BC V BC V C B CD AB T T C B CD CD V M C AB C V B AB M B F.1 (b) AB CD V V A D AB CD M M A D AB CD T T 2 A D
The positive sign convention consistent with beam theory is shown in F.1(b). As seen from F.1 (b), the positive sign convention is (a) tension axial force, (b) shear forces that produce clockwise moments and (c) bending moments that result in tension stresses in the interior frame fibers. The sign convention of F.1(b) can be seen to be equivalent to the beam sign convention rotating columns AB and CD to line up with beam BC. 3
Example Deflection Calculation – Mechanically Loaded Truss Structure EA = constant Rocker Calculate the vertical displace- ment at A. 4
Example Problem Shear and Moment Diagrams Calculate bending moment equations and the rotation at D. 5
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