Steel Design- Final Exam
Identify stiffened and unstiffened plate elements in compression. - Answer-Stiffened - a projecting piece
of steel whose two edges parallel to the direction of a compression force are supported
Unstiffened - a projecting piece of steel having one free edge parallel to the direction of a compression
force, with the other edge in that direction unsupported
Describe local buckling and compactness within the context of columns. - Answer-Local buckling -
localized plate instability
One element (web, flange, leg, stem) buckles before global buckling occurs
Compactness - if λ ≤ λr for all elements no local buckling
Explain the effect of local buckling on design strength. - Answer-May reduce design strength
Describe the behavior of a built-up compression member. - Answer-Double angle buckles flexural about
the x-axis
Double angle buckles flex-tors about the y-axis
Single angle buckles between connectors about the z-axis
Sufficient connectors prevent buckling about the z-axis
Explain why a column base plate is required to transmit axial force from a steel column to a concrete
footing. - Answer-It distributes loads from the column to concrete footing; it is necessary for the column
load to be spread over a sufficient area to keep the footing from being overstressed. Loads for the steel
column are transferred through a steel base plate to a fairly large area of the footing below.
, Explain structural difference between beams and girders with respect to load and bracing. - Answer--
Beams
Continuous bracing, includes the dead loads, live loads, and self weight
-Girders
Discrete bracing, includes the reactions of the beams and self weight
Describe various stages in flexural response leading up to the ultimate beam capacity, the fully plastic
moment - Answer--When beam is resisting moment at each point
-Load increases 🡪 outer fiber of flanges begin to yield 🡪 yielding moves through flanges into first fibers
of the web 🡪 yielding occurs across entire cross section
Define and determine the fully plastic moment, Mp - Answer-The moment that will produce full
plasticity in a member cross section and create a plastic hinge
Mp=FyZx
Determine if member is compact - Answer-If no local buckling occurs
Classify type of flexural failure based on unbraced length. - Answer--Continuous bracing
Steel decking w puddle welds
Steel decking w concrete slabs and shear studs
-Discrete bracing
Other members restraining compression flange
Account for effect of residual stress on flexural strength. - Answer-They cause forces (tension &
compression) with in the member before loads are applied which need to be accounted for when finding
flexural strength.
Define the moment gradient coefficient. - Answer--Cb - Lateral torsional buckling modification factor
Identify stiffened and unstiffened plate elements in compression. - Answer-Stiffened - a projecting piece
of steel whose two edges parallel to the direction of a compression force are supported
Unstiffened - a projecting piece of steel having one free edge parallel to the direction of a compression
force, with the other edge in that direction unsupported
Describe local buckling and compactness within the context of columns. - Answer-Local buckling -
localized plate instability
One element (web, flange, leg, stem) buckles before global buckling occurs
Compactness - if λ ≤ λr for all elements no local buckling
Explain the effect of local buckling on design strength. - Answer-May reduce design strength
Describe the behavior of a built-up compression member. - Answer-Double angle buckles flexural about
the x-axis
Double angle buckles flex-tors about the y-axis
Single angle buckles between connectors about the z-axis
Sufficient connectors prevent buckling about the z-axis
Explain why a column base plate is required to transmit axial force from a steel column to a concrete
footing. - Answer-It distributes loads from the column to concrete footing; it is necessary for the column
load to be spread over a sufficient area to keep the footing from being overstressed. Loads for the steel
column are transferred through a steel base plate to a fairly large area of the footing below.
, Explain structural difference between beams and girders with respect to load and bracing. - Answer--
Beams
Continuous bracing, includes the dead loads, live loads, and self weight
-Girders
Discrete bracing, includes the reactions of the beams and self weight
Describe various stages in flexural response leading up to the ultimate beam capacity, the fully plastic
moment - Answer--When beam is resisting moment at each point
-Load increases 🡪 outer fiber of flanges begin to yield 🡪 yielding moves through flanges into first fibers
of the web 🡪 yielding occurs across entire cross section
Define and determine the fully plastic moment, Mp - Answer-The moment that will produce full
plasticity in a member cross section and create a plastic hinge
Mp=FyZx
Determine if member is compact - Answer-If no local buckling occurs
Classify type of flexural failure based on unbraced length. - Answer--Continuous bracing
Steel decking w puddle welds
Steel decking w concrete slabs and shear studs
-Discrete bracing
Other members restraining compression flange
Account for effect of residual stress on flexural strength. - Answer-They cause forces (tension &
compression) with in the member before loads are applied which need to be accounted for when finding
flexural strength.
Define the moment gradient coefficient. - Answer--Cb - Lateral torsional buckling modification factor
