Internal forces in a three-hinged frame for a line load

Last modified on 29.04.2014

Category: Beams and Frames

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The internal forces in a three-hinged frame for a line load can be determined graphically. The reaction forces are used to construct the N and V Diagrams. The Moment Mx at any point in the structure can be found by multiplying the vertical intercept yx between the ideal thrust line and the system line at any point of the structure with the horizontal pole distance H: Mx = H * yx. The Moment Diagram can be determined using the parabola construction once the moment in the corners has been determined since Mmax for this load case is known. 
Move the hinge and observe the implications for the distribution of internal forces in the frame. What is the optimal position of the hinge for this loading?