How do you interpret the bending moment and shear force diagrams in STAAD?

1 What are bending moment and shear force diagrams?

Bending moment and shear force diagrams are two types of diagrams that show the distribution of internal forces along the length of a beam or column. Bending moment is the tendency of a beam or column to bend or rotate due to the applied loads, while shear force is the tendency of a beam or column to slide or shear along its cross-section. Both bending moment and shear force depend on the magnitude, direction, and location of the external loads and the type and position of the supports.

2 How to generate bending moment and shear force diagrams in STAAD?

To generate bending moment and shear force diagrams in STAAD, you need to first create a model of your beam or column, define the material properties, assign the loads and supports, and run the analysis. Then, you can select the member you want to view, and click on the Post Processing tab. Under the Results menu, you can choose Beam Diagrams, and select the type of diagram you want to see: Bending Moment, Shear Force, Axial Force, or Torsion. You can also adjust the scale, orientation, and units of the diagrams.

3 How to read bending moment and shear force diagrams in STAAD?

To read bending moment and shear force diagrams in STAAD, you need to understand the meaning of the axes, the sign convention, and the shape of the curves. The horizontal axis represents the length of the beam or column, while the vertical axis represents the value of the bending moment or shear force at any point. The sign convention is based on the right-hand rule: positive bending moment causes clockwise rotation, while negative bending moment causes counterclockwise rotation; positive shear force causes upward shear, while negative shear force causes downward shear. The shape of the curves reflects the variation of the internal forces along the member, depending on the external loads and supports. For example, a point load causes a sudden change in shear force and a linear change in bending moment, while a distributed load causes a linear change in shear force and a parabolic change in bending moment.

4 How to interpret bending moment and shear force diagrams in STAAD?

To interpret bending moment and shear force diagrams in STAAD, you need to compare them with the design criteria and the expected behavior of your beam or column. For example, you can use the diagrams to check if your member is subjected to excessive bending or shear stress, which might cause failure or deformation. You can also use the diagrams to identify the critical sections where the maximum or minimum values of bending moment or shear force occur, and where you need to provide adequate reinforcement or cross-section. You can also use the diagrams to verify if your member behaves as a simply supported, fixed, cantilevered, or continuous beam or column, and if it follows the elastic or plastic theory of bending.