Concept: Deflection of beam: ● The deformation of a beam is usually expressed in terms of its deflection from its original unloaded position. ● The deflection is measured from the original neutral surface of the beam to the neutral surface of the deformed beam. ● The configuration assumed by the deformed neutral surface is known as the elastic curve of the beam.
Methods of Determining Beam Deflections:
Method
Details
Double-integration method
This method is best when there is continuity in the applied loading.
Moment-Area Method
The method is especially suitable when the deflection or angle of rotation at only one point of the beam is desired.
Strain-energy method (Castigliano's Theorem)
Castigliano's Theorem lets us use strain energies at the locations of forces to determine the deflections. The Theorem also allows for the determining of deflections for objects with changing cross-sectional areas.
Conjugate-beam method
This method is based on the construction of a conjugate beam, defined as an imaginary beam of length equal to that of the original beam and loaded with an elastic weight M/EI, where M is the BM of the actual beam. This method is especially useful for simply supported and cantilever beams with varying flexural rigidities.
Method of Superposition
The slope and deflection of the beam caused by several different loads acting simultaneously can be found by superimposing the slopes and deflections caused by the loads acting separately.
Explanation: The moment distribution method is a structural analysis method for statically indeterminate beams and frames developed by Hardy Cross.