Design of Steel Structures online quiz on “Behaviour and Ultimate Strength of Plates and Possible Failure Modes”.
1. What is the fundamental path in graph?
a) line along load axis up to P > Pcr
b) line along load axis up to P < Pcr
c) line along load axis up to P = Pcr
d) line along load axis up to P ≥ Pcr
Answer: c
Clarification: If axial load verses lateral displacement is plotted, we get a line along the load axis up to P=Pcr, this is called fundamental path.
2. Which of the following is true about secondary path?
a) lateral displacement increases indefinitely at constant load
b) lateral displacement decreases indefinitely at constant load
c) lateral displacement remains same at constant load
d) lateral displacement increases indefinitely and decreases at constant load
Answer: a
Clarification: When the axial load reaches the Euler bucking load, the lateral displacement increases indefinitely at constant load. This is called secondary path, which bifurcates from fundamental path at the buckling load.
3. Which of the following statement is true?
a) plate cannot carry loads higher than elastic critical load
b) plate cannot carry loads lesser than elastic critical load
c) secondary path for a plate is unstable
d) secondary path for a plate is stable
Answer: d
Clarification: The secondary path shows that plate can carry loads higher than elastic critical load. The secondary path for a plate is stable.
4. What is apparent modulus of elasticity?
a) ratio of average strain carried by plate to average stress
b) ratio of average stress carried by plate to average strain
c) product of average strain carried by plate to average stress
d) product of average stress carried by plate to average strain
Answer: b
Clarification: Elastic post-buckling stiffness is measured in terms of apparent modulus of elasticity, E*. It is the ratio of average stress carried by plate to average strain. In most of the cases, the value of E* is in the range 0.408 – 0.5 E and may be approximately taken as 0.5E.
5. The effective width of hot-rolled and welded plates is given by
a) be/b = α √(fy/fcr)
b) be/b = α √(fcr x fy)
c) be/b = α √(fcr +fy)
d) be/b = α √(fcr/fy)
Answer: d
Clarification: The effective width of hot-rolled and welded plates is given by be/b = α √(fcr/fy), where α is the parameter that indicates the inclusions of influence of initial curvatures and residual stress. Generally α=0.65.
6. The effective width of cold-formed steel sections is given by
a) be/b = (fcr/fy)[1-0.22√(fcr/fy)].
b) be/b = (fcr/fy)[1+0.22√(fcr/fy)].
c) be/b = (fy/fcr)[1-0.22√(fcr/fy)].
d) be/b = (fcr/fy)[1+0.22√(fy/fcr)].
Answer: a
Clarification: The effective width based on tests on cold-formed steel sections is given by be/b = (fcr/fy)[1-0.22√(fcr/fy)]. This formula was first adopted in AISC specification for light gauge cold-formed sections.
7. Which of the following is true about local buckling?
a) failure occurs by twisting of one or more individual elements of member
b) failure occurs by buckling of one or more individual elements of member
c) failure occurs by both buckling and twisting of one or more individual elements of member
d) cannot be prevented by selecting suitable width-to-thickness ratio of elements