1. A rectangular steel plate is subjected to an axial dead
load of 133 kN and a live load of 213 kN. The yield
strength of the steel is 250 MPa.
a) LRFD Method: Determine the required plate
cross - sectional area based on yielding of the
gross section, using the LRFD method. Use a
resistance factor of θ = 0.90 and load factors of
1.20 and 1.60 for the dead and live loads,
respectively.
b) ASD Method: If a factor of safety of 1.50 with
respect to yielding is required, determine the
required plate cross- sectional area according to
the ASD method.
2. A column (compression member) in the upper story of
a building is subject to the following loads:
Dead load:
109 kips compression
Floor live load: 46 kips compression
Roof live load:
19 kips compression
Snow:
20 kips compression
a) Determine the controlling load combination for
LRFD and the corresponding factored load.
b) If the resistance factor f is 0.90, what is the
required nominal strength?
c) Determine the controlling load combination for
ASD and the corresponding required service
load strength.
d) If the safety factor Ω is 1.67, what is the required
nominal strength based on the required service
load strength?
2-1 A column in the upper story of a building is subjected
to a compressive load from the following sources: dead
load = 30.8 kips, occupancy live load = 1.7 kips, roof live
load = 18.7 kips, and snow load = 19.7 kips
a) If load and resistance factor design is used,
determine the factored load (required strength)
to be used in the design of the column. Which
AISC load combination controls?
b) What is the required design strength of the
column?
c) What is the required nominal strength of the
column for a resistance factor f of 0.90?
d) If allowable strength design is used, determine
the required load capacity (required strength) to
be used in the design of the column. Which AISC
load combination controls?
e) What is the required nominal strength of the
column for a safety factor Ω of 1.67?
2-2 A column is subjected to the following loads: dead
load = 26 kips, occupancy live load = 15 kips, roof live
load = 5 kips, snow load = 8 kips, rain load = 5 kips, and
wind load = 8 kips. All loads are compression except for
the wind load, which can be either tension or
compression.
a) If load and resistance factor design is used,
determine the factored load (required strength)
to be used in the design of the column. Which
AISC load combination controls?
b) What is the required design strength of the
column?
c) What is the required nominal strength of the
column for a resistance factor f of 0.90?
d) If allowable strength design is used, determine
the required load capacity (required strength) to
be used in the design of the column. Which AISC
load combination controls?
e) What is the required nominal strength of the
column for a safety factor Ω of 1.67?
2-3 The loads on a roof beam consist of a dead load of
0.2 kips/ft, a roof live load of 0.13 kips/ft, and a snow load
of 0.14 kips/ft.
a) If load and resistance factor design is used,
determine the factored load (required strength)
to be used in the design of this beam. Which
AISC load combination controls?
b) If allowable strength design is used, determine
the required load capacity (required strength) to
be used in the design of the column. Which AISC
load combination controls?
2-4 Beams will be designed for the roof and floor
systems of an office building. The loads for these
systems are as follows: Roof: dead load = 30 psf, roof
live load = 20 psf, snow load = 21 psf, and a rain load
consisting of 4 inches of water. Floor: dead load = 62 psf
and occupancy live load = 80 psf.
a) For each of these systems, determine the
required factored load capacity for LRFD. Which
load combination controls?
b) For each of these systems, determine the
required ASD load capacity. Which load
combination controls?
2-5 Structural steel buildings frequently are designed
with diagonal bracing systems to resist lateral loads
(horizontal forces resulting from wind or earthquake
loadings). A certain bracing system is subjected to the
following loads: dead load = 13.3 kips, occupancy live
load = 6.9 kips, roof live load = 1.3 kips, snow load = 1.3
kips, wind load = 150.6 kips, and earthquake load =
161.1 kips.
a. Determine the required factored load capacity
for LRFD. Which load combinationcontrols?
b. Determine the required ASD load capacity.
Which load combination controls?
2-1.A column in a building is subjected to the following
load effects:
• 9 kips compression from dead load
• 5 kips compression from roof live load
• 6 kips compression from snow
• 7 kips compression from 3 inches of rain
accumulated on the roof
• 8 kips compression from wind
a) If load and resistance factor design is used,
determine the factored load (required strength)
to be used in the design of the column. Which
AISC load combination controls?
b) What is the required design strength of the
column?
c) What is the required nominal strength of the
column for a resistance factor f of 0.90?
d) If allowable strength design is used, determine
the required load capacity (required strength) to
be used in the design of the column. Which AISC
load combination controls?
e) What is the required nominal strength of the
column for a safety factor V of 1.67?
2-2 Repeat Problem 2-1 without the possibility of rain
accumulation on the roof.
2-3 A beam is part of the framing system for the floor of
an office building. The floor is subjected to both dead
loads and live loads. The maximum moment caused by
the service dead load is 45 ft-kips, and the maximum
moment for the service live load is 63 ft-kips (these
moments occur at the same location on the beam and
can therefore be combined).
a. If load and resistance factor design is used,
determine the maximum factored bending
moment (required moment strength). What is the
controlling AISC load combination?
b. What is the required nominal moment strength
for a resistance factor f of 0.90?
c. If allowable strength design is used, determine
the required moment strength. What is the
controlling AISC load combination?
d. What is the required nominal moment strength
for a safety factor V of 1.67?
2-4 A tension member must be designed for a service
dead load of 18 kips and a service live load of 2 kips.
a. If load and resistance factor design is used,
determine the maximum factored load (required
strength) and the controlling AISC load
combination.
b. If allowable strength design is used, determine
the maximum load (required strength) and the
controlling AISC load combination.
2-5 A flat roof is subject to the following uniformly
distributed loads: a deadload of 21 psf (pounds per
square foot of roof surface), a roof live load of12 psf, a
snow load of 13.5 psf, and a wind load of 22 psf upward.
(Althoughthe wind itself is in a horizontal direction, the
force that it exerts on this roof is upward. It will be upward
regardless of wind direction. The dead, live, and snow
loads are gravity loads and act downward.)
a. If load and resistance factor design is used,
compute the factored load (required strength)
in pounds per square foot. Which AISC load
combination controls?
b. If allowable strength design is used, compute
the required load capacity (required strength) in
pounds per square foot. Which AISC load
combination controls?