Basic diagrams of internal forces

In this part of the guide I will present 7 basic diagrams that you have to know! Why is it so important? Because with these 7 diagrams for straight beams, you can create graphs without calculations for large frames or beams with many elements.

Let’s start with diagrams with fixed beams, these are 3 out of 7 examples. If the support is just a confirmation, we have a simplified work, because we do not have to know the value of support reactions. We need to know the reaction value for complex schemes in beams with articulated supports, but let’s leave it for now. We will deal with these issues in the next guide.

Basic graphs for fixed beams.

The beam is fixed with force P. The force is on the edge of the beam.

The beam is fixed with a rectangular force. The force works over the entire length of the beam.

The last graph with the support is the beam with the applied bending moment.

Now it’s time for beams with articulated supports.   

Beam with concentrated force in the middle.

Beam with concentrated force P applied anywhere.

Beam with a rectangular force acting along the entire length.

The last graph will be the articulated beam with the applied bending moment.

These are all basic graphs of beams with restraints and articulated supports. Once again, I repeat that you must memorize them! It is really a mandatory knowledge to draw more complex charts. In the next step, there will be a guide on how to draw graphs for complex structures from memory.

Finally, I would like to add that training makes perfect. Just because you learn these charts by heart does not mean that you will draw them easily. You have to convert at least a few dozen different examples, change the place of applying forces, dimensions of the structure, etc. This is all the way to pass the exam. Good luck!