I present a few problems
- Given a cantilever subject to three separate loadings:
(a) a concentrated load P at the free end,
(b) a moment M at the free end, and
(c) a uniform load w over the entire beam.
The span is L.
For each loading, determine the beam deflection at the free end of the span.
Answer: (a)Answer: (b)
Answer: (c)
- Given a simple beam with a P load at midspan.
The span is L.
Determine the beam rotation at the right end of the span.
Answer:See calculation of symmetric rotation
I solved this problem using the virtual work method.
- Given a simple beam with a P load at at a distance a from the left support.
The span is L; therefore,.
Determine the beam rotation at the right end of the span.
Determine also the deflection for all points x located left of the P loading.
Answer:See calculation of asymmetric rotation
I solved this problem using the conjugate beam method (*).
Note that ifthen the third equation is equal to the second equation.
- Given a beam (or plate) with uniform load, w, subjected to a 2 point symmetric lift
The center span, L, is to be determined
The value, a, is a ratio to be determined
The left overhang = the right overhang =
Determine the span and the overhang that minimizes the absolute value of the moment along the span
Answer: see calculation of lift load points
Determine the resulting deflection at the right end of the beam, at
Answer: see hand calculation of deflection given minimized moment
Answer: see calculation of deflection given minimized moment using sympy.physics.continuum_mechanics.beam.Beam (**)
Note that my calculation of a agrees with the well-known value of a.See calculation of centerspan deflection.
I determined a few interesting values of a and charted the resulting deflections.
See calculation of cantilever deflection.
- Given a pin-supported bent with uniform EI:
The beam span is L.
The column length is μL.
Determine the horizontal deflection of the frame at point B.
Answer:
Bonus Material
For the first 2 problems, I checked some algebra using Jupyter, Plotly, Python, and Sympy.
http://khoitsmahq.firstcloudit.com/images%2Fbeam_hand_calc_check.html
Additional Bonus Material
Quite a surprise — I discovered a Sympy package named sympy.physics.continuum_mechanics.beam.Beam (**) and checked some of my results using that package too. Note Sympy’s use of singularity functions in cells 4 and 5. I use singularity functions in cells 6 through 10.
http://khoitsmahq.firstcloudit.com/images%2Fshear_and_moment.html
def f_rotation(x, E, I): sf = SingularityFunction return (-10*sf(x, 0, 2)/3 + 5*sf(x, 48, 2) - 5*sf(x, 144, 2)/3 + 12800)/(E*I) def f_deflection(x, E, I): sf = SingularityFunction return (12800*x - 10*sf(x, 0, 3)/9 + 5*sf(x, 48, 3)/3 - 5*sf(x, 144, 3)/9)/(E*I)
References
(*) Conjugate Beam Method — Wiki
(**) https://docs.sympy.org/… continuum_mechanics/beam.html
(***) A bonus from Dr. Myosotis