Mechanics question (calculating reactions)

[Studious_stud]

Homework Statement

Homework Equations

Sum of forces = 0
Sum of moments = 0

The Attempt at a Solution

Hey everyone, this problem has me stumped. I'm only just starting to study solid mechanics now and I need some help with this problem.

Any help would be greatly appreciated.

Thanks

 

[Mapes]

The first step should always be to draw a free-body diagram, containing only the object (i.e., the beam), forces, and moments. One should abstract the constraints into all the possible forces and moments that they could represent. For example, a clamped constraint could apply horizontal and vertical forces and a moment, because this constraint prevents translation in both axes along with rotation. A pin on a roller, however, allows rotation and horizontal translation.

With a suitable free-body diagram, one can write and solve the equations of static equilibrium.

 

[pongo38]

This problem is statically indeterminate, and therefore needs one equation in addition to those of equilibrium. You need to think about using compatibility of displacements.

 

[Studious_stud]

Thanks so far everyone. So basically support B only provides an upward force then right? While A provides a force and a reactionary moment.

So I'll have one equation where the sum of all forces = 0

One equation taking the moment about A

And the last one will be taking the moment about B?

One thing that's kind of throwing me off is constructing the equations for the reactionary moments. The fact that it's a uniformly distributed load in addition to point loads. Could you guys help me understand these 2 moment equations and how they're constructed in this question?

Thanks again, I'm just trying to get to grips with this problem for study.

 

[pongo38]

How many unknowns do you have? And how many equations. You should have a go at the equations and submit them for further help. Try to interpret "the algebraic sum of the moments about any point must be zero", By developing the equilibrium equations, you will understand emotionally as well as technically what a statically indeterminate stucture is. You need to experience the embarassment of being unable to solve it. Incidentally, this is not a problem for beginners of mechanics. Are you sure the problem is given correctly?