Bending Moment Lab Report

1474 words 6 pages
Applied mechanics laboratory report
“Measurement of bending moment and shear forces for structural analysis”

Azamat Omarov

1.Theory and background
1.1 Summary
That performed laboratory session on bending moments and shear forces requires good understanding and sufficient knowledge of axial forces. Bending is defined as a behavior of any structural element that undergoes the external load, which is applied perpendicularly to longitudinal axis. That experiment helps us to find the maximum load that can be applied to the beam with rectangular cross section. Moments are calculated by using statics theory, or multiplying perpendicularly directed load by the respective distance to the pivot point.
1.2 Objective
The main objective
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The diagram below was provided by teacher assistant to make comments on. We were analyzing the case with 3 weighs applied that can be seen on the picture below. Before that it would be very useful to mention 2 additional effects on the beam.
If clockwise bending moments are taken as positive, then a positive bending moment will cause sagging whereas negative bending moment will cause hogging.

Figure6. Hogging and sagging scheme

Critical values of the bending moment on the beam can be easily illustrated on the diagram. In our case negative values of bending moments are plotted above the horizontal scale and vice-versa for positive moment.
It is also clear from the diagram and equilibrium state that moments about the ends of the beam must be zero to satisfy the laws. After that moments about points R1 and R2 were measured to display bending moments on the diagram.(R1=5.26N, R2=6.51N)
With all known values of reaction forces and weighs let’s calculate the total moment about R1.
Thus, taking anticlockwise moment as a positive reference direction and calculating it on the left we get
On the bending moment diagram it is represented above the horizontal line, which