1P2 Structures

Question 1

How do you determine whether a structure is statically determinate?

Answer 1

Dj = b + r

Where D is the dimensions, j is the joints, b is the bars, and r is the restraints.

If Dj> b + r it is a mechanism

If Dj < b + r it is statically indeterminate

Question 1

What is method of sections and methods of joints?

Answer 1

Sections = draw a cut on the body and use external force considerations to find bar forces through the cut.

Joints = consider the equilibrium of forces at all the joints

Question 2

What conditions are required to apply superposition to trusses?

Answer 2

Must be a linear system, so the material must remain in the linear elastic range and the gemoetry changes due to deformation must be small.
Usually true for metal structures.

Question 3

What assumptions are made for segmented arches?

Answer 3

Blocked are infinitely strong under compression.
Bloacks unable to carry bending momnets
Block interfaces have infinite friction.
Therefore can use a line of thrust analysis.

Question 4

How do you find the shape and length of a cable under a uniform loading?

Answer 4

Take a element of cable of witdth dx and do an arguement based on the equilibrium of forces. Use the formula in the databook for the lenght of a parobla

Question 5

What is true for beams under exclusively point forces?

Answer 5

Shear force is constant, bending moment varies linearly.