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ExAC Cards - Section 3 - Final Project Questions and Answers
with 100% Complete Solutions UPDATED!!!
What is: Design wind pressure? - ANSWER Design wind
pressure:
Minimum design value for the equivalent static pressure on the
exterior surfaces resulting from critical wind velocity (equal to a
reference wind wind pressure measured at 33', 10m). The # is
modified by a bunch of coefficients to account for: exposure
conditions, building height, wind gusts, geometry/orientation.
Why are horizontal forces more critical than vertical ones in
seismic design? - ANSWER Because structures usually have
considerable reserve for dealing with additional vertical loads.
Define Base Shear. - ANSWER Base shear:
Minimum design value for the total lateral seismic force
(assumed to act in any horizontal direction)
Define the following: Collinear Forces, Concurrent Forces,
Nonconcurrent Forces. - ANSWER Collinear Forces:
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Occur along straight line. Vector sum= sum of magnitude of
forces acting along same line of action.
Concurrent Forces:
Lines of action intersecting at common point. Vector
sum=equivalent to, and produces same effect on rigid body as
the application of the vectors of the several forces.
Nonconcurrent Forces:
Lines of action that do not intersect at common point. Vector
sum=single force that would cause the same translation and
rotation of a body as the set of original forces.
What is a moment (structural forces)? - ANSWER Moment:
The tendency of a force to produce rotation of a body about a
point or line
What is a Couple (structural forces)? - ANSWER Couple:
Force system of 2 equal parallel forces acting in opposite
directions tending to produce rotation but not translation
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What are beams designed to do? - ANSWER Designed to carry
and transfer transverse loads across to supporting elements.
Define Deflection - ANSWER Deflection:
perp distance a spanning member deviates from true course
under transverse loading
What is the difference between a simple beam and a Fixed-End
Beam? - ANSWER Simple Beam:
Rests on supports at both ends - no moment resistance (ends
free to rotate)
Fixed-end beam:
Both ends fixed against translation and rotation (reduced max
deflection, transferred bending stresses, increased rigidity)
Distinguish between the following three frame types:
-Fixed Frame
-Hinged Frame
-Three Hinged Frame - ANSWER Fixed Frame
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rigid frame connected to its supports with fixed joints (more
resistant to deflection than hinged from but also more sensitive
to settlements and thermal expansion/contraction)
Hinged Frame -
Rigid frame connected to its joints with pinned connections
(pinned connections prevent high bending stresses by allowing
rotation)
Three-hinged Frame - structural assembly of 2 rigid sections
connected to each other and to its supports with pin joints
(more sensitive to deflection than fixed or hinged, 3-hinged
system is least affected by support settlements and thermal
stresses - can also be analyzed as a statically determinate
structure
Name 1 kind of beam for each wood, steel, and concrete, that
can span >60' (18m). - ANSWER Wood:
Laminated Beams (Timber)
Trusses (Timber)
Steel:
OWSJ
ExAC Cards - Section 3 - Final Project Questions and Answers
with 100% Complete Solutions UPDATED!!!
What is: Design wind pressure? - ANSWER Design wind
pressure:
Minimum design value for the equivalent static pressure on the
exterior surfaces resulting from critical wind velocity (equal to a
reference wind wind pressure measured at 33', 10m). The # is
modified by a bunch of coefficients to account for: exposure
conditions, building height, wind gusts, geometry/orientation.
Why are horizontal forces more critical than vertical ones in
seismic design? - ANSWER Because structures usually have
considerable reserve for dealing with additional vertical loads.
Define Base Shear. - ANSWER Base shear:
Minimum design value for the total lateral seismic force
(assumed to act in any horizontal direction)
Define the following: Collinear Forces, Concurrent Forces,
Nonconcurrent Forces. - ANSWER Collinear Forces:
,2|Page
Occur along straight line. Vector sum= sum of magnitude of
forces acting along same line of action.
Concurrent Forces:
Lines of action intersecting at common point. Vector
sum=equivalent to, and produces same effect on rigid body as
the application of the vectors of the several forces.
Nonconcurrent Forces:
Lines of action that do not intersect at common point. Vector
sum=single force that would cause the same translation and
rotation of a body as the set of original forces.
What is a moment (structural forces)? - ANSWER Moment:
The tendency of a force to produce rotation of a body about a
point or line
What is a Couple (structural forces)? - ANSWER Couple:
Force system of 2 equal parallel forces acting in opposite
directions tending to produce rotation but not translation
,3|Page
What are beams designed to do? - ANSWER Designed to carry
and transfer transverse loads across to supporting elements.
Define Deflection - ANSWER Deflection:
perp distance a spanning member deviates from true course
under transverse loading
What is the difference between a simple beam and a Fixed-End
Beam? - ANSWER Simple Beam:
Rests on supports at both ends - no moment resistance (ends
free to rotate)
Fixed-end beam:
Both ends fixed against translation and rotation (reduced max
deflection, transferred bending stresses, increased rigidity)
Distinguish between the following three frame types:
-Fixed Frame
-Hinged Frame
-Three Hinged Frame - ANSWER Fixed Frame
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rigid frame connected to its supports with fixed joints (more
resistant to deflection than hinged from but also more sensitive
to settlements and thermal expansion/contraction)
Hinged Frame -
Rigid frame connected to its joints with pinned connections
(pinned connections prevent high bending stresses by allowing
rotation)
Three-hinged Frame - structural assembly of 2 rigid sections
connected to each other and to its supports with pin joints
(more sensitive to deflection than fixed or hinged, 3-hinged
system is least affected by support settlements and thermal
stresses - can also be analyzed as a statically determinate
structure
Name 1 kind of beam for each wood, steel, and concrete, that
can span >60' (18m). - ANSWER Wood:
Laminated Beams (Timber)
Trusses (Timber)
Steel:
OWSJ
