Structures Week 1

Question 1

A neutral surface is

Answer 1

where longitudinal fibres of the material will not undergo a change in length

Question 2

For a positive bending moment, does a contraction occur in fibres located above or below the neutral axis?

Answer 2

Above

Question 3

The curvature of a beam is given by

Answer 3

(Bending moment at point)/(Material’s modulus of elasticity)(Beam’s second moment of area about neutral axis)

Question 4

Shear stress in a bent beam is given by

Answer 4

VQ/It where V is the shear force, Q is the first moment of area of the area situated further from the neutral axis than the line shear stress is being found at, I is the second moment of area for the entire cross-section, and t is the width

Question 5

The normal stress at height y in a bent beam is given by

Answer 5

-(bending moment)*y/(second moment of area)

Question 6

What is the equation for the elastic deformation of an axially loaded member?

Answer 6

PL/AE where P is the internal axial force, L is the distance between two points, A is the cross-sectional area and E is the modulus of elasticity of the material

Question 7

What is the equation for thermal deformation of a member?

Answer 7

alphadeltaTL where alpha is the linear coefficient of thermal expansion, deltaT is the algebraic change in temperature and L is the original length

Question 8

Boundary conditions for internal pin or hinge:

Answer 8

M=0

Question 9

Boundary conditions for free end:

Answer 9

M=0

V=0

Question 10

Boundary condition for fixed end:

Answer 10

theta=0

delta=0

Question 11

Boundary conditions for pin:

Answer 11

delta=0

Question 12

Boundary conditions for roller:

Answer 12

delta=0