"GOOD TO KNOW"
🤜 Benjamin Baker's famous photograph illustrates the structural principle of cantilever beams used for the Forth Bridge.
👉 To explain the theory of cantilever beams (Gerber), a visual demonstration was carried out with people. The loads were symbolized by a person seated in the middle of the span, while the arms of the people seated on either side represented the pull at the joints. The wooden bars represented the compression on the lower elements, while the bricks symbolized the anchor points to the pylons. The chairs represented the piles of granite. Imagine the chairs spaced 500 meters apart and the men's heads as high as St Paul's Cross (London Church, 104 meters), with their arms represented by steel beams and their legs by 3.5 meter tubes in diameter at the base, you will have a good idea of the structure.
👉 In 1866, Heinrich Gerber developed a theory that involved subdividing the continuous beam through ball and socket joints, thereby defining a point of zero bending moment. This type of beam with intermediate joints is now known as a Gerber beam. The position of these joints influences the behavior of the beam. Therefore, although not directly used in all structures, the Gerber beam concept can be applied approximately in some projects, allowing simplified calculations.