Structures Exam I

e

1.5"-deep corrugated steel roof decking is to span, in one-span mode, between support trusses that are spaced 6'-0" O.C. apart: Dead Load = 20#/ft2 Live Load = 20#/ft2 What is the thinnest gage of decking, and the associated weight per square foot of galvanized decking, that is required to meet the Maximum SDI Construction Span? Select one: a. 16 gage weighing 3.54#/ft2 b. 20 gage weighing 2.14#/ft2 c. 21 gage weighing 1.46#/ft2 d. 18 gage weighing 2.82#/ft2 e. 21 gage weighing 1.97#/ft2

b

1.5"-deep corrugated steel roof decking is to span, in one-span mode, between support trusses that are spaced 6'-0" O.C. apart: Dead Load = 20#/ft2 Live Load = 20#/ft2 What is the thinnest gage of decking, and the associated weight per square foot of galvanized decking, that is required to meet the Maximum SDI Construction Span? Select one: a. 18 gage weighing 2.82#/ft2 b. 21 gage weighing 1.97#/ft2 c. 16 gage weighing 3.54#/ft2 d. 20 gage weighing 2.14#/ft2 e. 21 gage weighing 1.46#/ft2

d, e

According to the analysis of beams with rectangular cross sections, the fractional deflection varies in proportion to: Select one or more: a. b b. L3/bh c. (L/b)3 d. 1/b e. (L/h)3

a, e

According to the analysis of beams with rectangular cross sections, the fractional deflection varies in proportion to: Select one or more: a. (L/h)^3 b. L^3/bh c. b d. (L/b)^3 e. 1/b

e

A beam is supported by a moment connection as shown. The moment at the support end of the beam would be: Select one: a. M = + 192 Kft b. M = - 128 Kft c. M = + 16 Kft d. M = - 16 Kft e. M = - 256 Kft

a

A beam is supported by a moment connection as shown. The reaction forces at the support end of the beam would be: Select one: a. Ax=-12K, Ay=16K b. Ax=12K, Ay=16K c. Ax=-6K, Ay=8K d. Ax=6K, Ay=8K e. Ax=8K, Ay=-16K

d

A beam is supported by a pin connection and a roller connection as shown. Which of the following answers most accurately shows the convention adopted in this course for replacing the support symbols with their equivalent reaction forces?

b, e

A pure force couple: Select one or more: a. Tends to create rotation about the x-axis and y-axis and translation in the z direction b. Tends to create rotation, but no translation c. Tends to create translation, but no rotation d. Tends to create both rotation and translation e. Creates the same moment about every point in the universe

a, b, c, e, f

Concrete: Select one or more: a. Is rot-resistant b. Is corrosion-resistant c. Is a good material for blocking sound transmittance, thereby providing sound privacy and protection from noise d. Is impermeable to water e. Molds to irregularities in the soil under the foundations f. Is fire-resistant

b

Consider the following floor construction: 6'-0" decking span between supporting trusses One-span mode for the decking 1.5"-deep corrugated steel floor decking Lightweight concrete in composite action with the corrugated steel 5.0" overall decking thickness 80#/ft2 Live Load What is the gauge of decking that is required to meet the SDI Maximum Unshored Clear Span to support the concrete during the concrete curing process? Select one: a. 16 gauge weighing 3.54#/ft2 b. 19 gauge weighing 2.49#/ft2 c. 19 gauge weighing 1.78#/ft2 d. 20 gauge weighing 2.14#/ft2

a

Corrugated steel decking is made to work in composite action with concrete cast on top of it by: Select one: a. Embossing the corrugated steel decking to engage the concrete and assure that the concrete and the steel do not slide past each other b. Driving high-strength nails up through the decking into the concrete c. Putting glue on the surface of corrugated steel decking d. Lacing the concrete with steel fibers e. Tempering the steel so that it becomes stiffer

d

Flimsy, thin sheet steel can be made into a structural decking material by: Select one: a. Lacing it with carbon fiber b. Laminating it with zinc coating on each side c. Laminating it with plastic coating on each side d. Corrugating the sheet material e. Tempering the steel so that it becomes stiffer

c

For #2 Douglas Fir-Larch, what is the design (allowed) bending stress? Select one: a. 625 #/in2 b. 775 #/in2 c. 900 #/in2 d. 575 #/in2 e. 850 #/in2

e

For #2 Douglas Fir-Larch, what is the design (allowed) shear stress? Select one: a. 135 #/in2 b. 150 #/in2 c. 200 #/in2 d. 160 #/in2 e. 180 #/in2

b, c, e

For a beam having a single cantilever at one end, being subjected to a uniform load w along its entire length, the moment diagram: Select one or more: a. Is a straight line on the cantilever and a parabola between the supports. b. Is negative over the entire length of the cantilever. c. Is parabolic for the cantilever portion and parabolic between the supports. d. Has a discontinuity at the interior support. e. Has no discontinuities.

d

For a beam of rectangular cross section with a depth h and a width b, the formula for the cross-sectional stiffness is:

b

For a beam of rectangular cross section with a depth h and a width b, the formula for the cross-sectional strength in resisting moment is: Select one:

e

For a beam of rectangular cross section with a depth h and a width b, the formula for the cross-sectional strength in resisting shear is: Select one:

a, c, d

For a simple-span beam subjected to a uniform load w along its entire length, the moment diagram is: Select one or more: a. A maximum at mid-span of the beam b. A straight line ascending from left to right c. Zero at each end of the beam d. A parabola e. A straight line descending from left to right

d

For a simple-span, steel, wide-flange beam, where can we safely remove a substantial part of the flanges? Select one: a. Anywhere b. Near the quarter points c. Near the center span d. At the ends e. Near center span, but just the top flange

b

For a simple-span, steel, wide-flange beam, where can we safely remove a substantial part of the web? Select one: a. Near center span just below the top flange b. Near center span near the neutral axis c. Anywhere d. Near the quarter points e. Near the ends

a, b, c

For planar forces in the x-y-plane, the equation ΣM=0 can be used to solve for: Select one or more: a. Py forces b. Px forces c. Moments about the z-axis d. Only Pz forces e. Only Moments about the z-axis

a

For this force system: The moment about point Q is: Select one: a. +800 Kip·feet b. +600 Kip·feet c. +600 Pound·feet d. Zero Kip·feet e. -200 Kip·feet

e

In Wood-Frame ROOF construction, we typically use the following decking: Select one: a. 3/4"-thick tongue-and-groove plywood spanning 36" b. 1 1/2"-thick corrugated steel decking spanning 6' c. 5/8"-thick plywood spanning 24" d. 3/8"-thick plywood decking spanning 24" e. 1/2"-thick plywood decking spanning 24"

d or e

In answering this question, use the I-Joist Design Tables provided on Moodle, rather than the tables in the book. The most current tables provided by the industry are provided on Moodle. For residential applications for which pDead = 10#/ft2 pLive = 40#/ ft2 The longest span achievable with Boise Cascade I-Joists spaced at 16" O.C. is: Select one: a. 28'-7" b. 30'-4" c. 36'-10" d. 33'-7" e. 33'-2"

c

In answering this question, use the I-Joist Design Tables provided on Moodle, rather than the tables in the book. The most current tables provided by the industry are provided on Moodle. For residential applications for which pDead = 10#/ft2 pLive = 40#/ ft2 Span = 20ft At a spacing of 16" O.C., the shallowest I-Joist that will safely support the load and satisfy the deflection criterion of L/480 is: Select one: a. 11 7/8" 90 2.0 b. 9 1/2" 6500s 1.8 c. 11 7/8" 6500s 1.8 d. 14" 6500s 1.8 e. 16" 6500s 1.8

c

In applications of the principles of equilibrium, we are going to focus our attention on planar forces in the x-y-plane. The equations that apply to such force systems are: Select one: a. ΣPx=0, ΣPy=0, ΣPz=0, ΣMx=0, ΣMy=0 b. ΣPz=0, ΣPx=0, ΣMx=0 c. ΣPx=0, ΣPy=0, ΣM=0 d. ΣPx=0, ΣPy=0, ΣPz=0, ΣMx=0, ΣMy=0, ΣMz=0 e. ΣPx=0, ΣPy=0, ΣPz=0, ΣM=0

a

In beams, the web is primarily responsible for handling Select one: a. Shear force b. Buckling c. Moment d. Torsion e. Tension

a

In beams, the web is primarily responsible for handling Select one: a. Shear force b. Moment c. Buckling d. Torsion e. Tension

a, b, c, e

In changing the cross sectional shape from the section on the left to the section on the right, the total cross sectional area, and hence the amount of material, does not change. In making the change shown above: Select one or more: a. Web buckling becomes a possible factor b. The cross-sectional moment strength of the beam increases c. The cross-sectional stiffness of the beam increases d. The cross sectional shear capacity of the beam increases e. The lateral stability of the beam increases

e

In the following floor framing plan, wood I-joists are supported by LVL girders which are supported at each end by columns. The columns are spaced 20ft O.C. The floor loads are: pDead = 10#/ft2 pLive = 40#/ ft2 For one of the perimeter girders, the design moment would be: Select one: a. 12000 #ft Incorrect b. 26700 #ft c. 80000 #ft d. 44400 #ft e. 25000 #ft

c

In the following floor framing plan, wood I-joists are supported by LVL girders which are supported at each end by columns. The columns are spaced 20ft O.C. The floor loads are: pDead = 10#/ft2 pLive = 40#/ ft2 For one of the perimeter girders, the design shear force would be: Select one: a. 1200 # b. 8000 # c. 5000 # d. 2670 # e. 4440 #

d

LVL is made from: Select one: a. Alternating layers of wood veneer in which adjacent layers of veneer have the grain running perpendicular. b. Thin, alternating layers with grain running parallel to the length of the board and grain running perpendicular to the board, butcher-block style. c. Wood wafers glued up with the grain oriented in random directions. d. Layers of wood veneer having the grain running generally parallel to the length of the board. e. Exotic hardwoods that grow in abundance in the forests of Vietnam and Brazil.

a.

LVL is made from: Select one: a. Layers of wood veneer having the grain running generally parallel to the length of the board. b. Alternating layers of wood veneer in which adjacent layers of veneer have the grain running perpendicular. c. Wood wafers glued up with the grain oriented in random directions. d. Thin, alternating layers with grain running parallel to the length of the board and grain running perpendicular to the board, butcher-block style. e. Exotic hardwoods that grow in abundance in the forests of Vietnam and Brazil.

e

The following truss is simply supported at the ends and consists of 13 square bays of width and height 6': Apply the chord forces in the freebody above, aggregate the applied forces and reactions, and take moments to determine the compressive force C in the top chord member. In doing this operation, note that the aggregated force from the six 1P forces is a 6P force centered between the two center 1P forces. The compression force C in the top chord is: Select one: a. +24P b. -12.5P c. +18.33P d. -18P e. +21P

d

The forces and moments provided by supports to keep a structure in equilibrium are referred to as: Select one: a. Arrows b. Balancers c. Foundations d. Reactions e. Connections

b, e

The Webs of Wood I-Joists: Select one or more: a. Are the residual material left after material is removed from a sawn beam b. Can be made of oriented strand board c. Are often made of specially tempered aluminum sheet d. Can be made from high-shear-strength sawn lumber e. Can be made of plywood

a

The beam on the left is a simple-span beam supported by the same kind of plate connection at each end. In the context of the overall structure, this would be regarded as what kind of connection? Select one: a. Pin connection b. An unsatisfactory connection, since it does not engage the full cross section of the beam. c. Roller connection d. Moment connection e. Should have used a single larger bolt, instead of four smaller bolts, to facilitate free rotation of the end of the beam.

c

The connection identified by the red circle would be regarded as a: Select one: a. one-force connection b. two-force connection c. moment connection d. roller connection e. pin connection

e

The connection outlined by the red ellipse would be regarded as a: Select one: a. threaded connection b. moment connection c. welded connection d. roller connection e. pin connection

d

The connection outlined by the yellow ellipse would be regarded as a: Select one: a. pin connection b. moment connection c. welded connection d. roller connection e. threaded connection

d

The equation ΣP=0 is equivalent to: Select one: a. ΣPx=0, ΣPy=0, ΣPz=0, ΣM=0 b. ΣPx=0, ΣPy=0, ΣPz=0, ΣMx=0, ΣMy=0, ΣMz=0 c. ΣPz=0, ΣPx=0, ΣMx=0 d. ΣPx=0, ΣPy=0, ΣPz=0 e. ΣPx=0, ΣPy=0, ΣPz=0, ΣMx=0, ΣMy=0

e

The following structure consists of square bays of dimension s by s. Use a moment equation to solve for the reaction RA (in terms of P): The reaction RA at the left end is: Select one: a. + 6.67 P b. - 10 P c. + 16.67 P d. + 10 P e. - 6.67 P

b

The following truss is simply supported at the ends and consists of 11 square bays of width and height 6': Apply the chord forces in the freebody above, aggregate the applied forces and reactions, and take moments to determine the compressive force C in the top chord member, which is: Select one: a. -18.33P b. +15P c. +24P d. -12.5P e. +18.33P

c

The image at the top shows a truss with square bays of depth 6 ft. The image below that shows the same truss scaled in the vertical dimension down to a depth of 4 ft. If the maximum chord force in the top truss has a magnitude of 15P, what is the magnitude of the maximum chord force in the bottom truss? In thinking about this, keep in mind that the depth of the truss is the lever arm for the chord forces in generating the internal resisting moment. Since the required internal resisting moment does not change, changing the lever arm requires a compensating adjustment in the chord forces. Select one: a. 20P b. 25K c. 22.5P d. 10K e. 30P

d

The moment about point R is: Select one: a. -200 Kip·feet b. -600 Kip·feet c. -500 Kip·feet d. +500 Kip·feet e. +600 Pound·feet

b

The moment capacity of this connection is predominantly provided by: Select one: a. The horizontal plate outlined by the blue ellipse, which serves as a seat for the end of the beam b. The combined action of the two horizontal bolted connections (outlined by the red and blue ellipses) c. The bolted connection outlined by the red ellipse d. The combined action of the bolted connections outlined in yellow and red ellipses e. The shear connection provided by the vertical plate that penetrates through the column and is bolted to the webs at the ends of both the beams meeting at the connection (outlined by the yellow ellipse)

c

The overall length of the beam is 40ft. What would be the optimal length of the cantilevers to produce the minimum moment along the length of the beam under the uniform live load shown? Select one: a. 12.5 feet b. 7.67 feet c. 8.28 feet d. 10.00 feet e. 5.67 feet

a

The procedure presented in the videos for the sizing of sawn wood beams was based on which of the following design methods: Select one: a. ASD b. Resistance factors but not Load Factors c. LRFD d. LRFD with amplified Resistance Factors to account for the uncertainty in the performance of wood e. Load factors but not Resistance Factors

e

The reaction at A is: Select one: a. 0 P b. 8 P c. 10 P d. 7 P e. 12 P

c

The resistance to vertical gravity forces is predominantly provided by: Select one: a. The horizontal plate outlined by the blue ellipse, which serves as a seat for the end of the beam b. The bolted connection outlined by the red ellipse c. The shear connection provided by the vertical plate that penetrates through the column and is bolted to the ends of the webs of both the beams meeting at the connection (outlined by the yellow ellipse) d. The combined action of the bolted connections outlined in yellow and red ellipses e. The combined action of the two horizontal bolted connections (outlined by the red and blue ellipses)

a, c, d

The steel plate girder is continuous over the central support. Select one or more: a. The bolted connections are field connections, which are occurring where the moment is a minimum under full distributed vehicular load. b. The moment is a maximum at the bolted connections, but it does not make any difference, because the beam has been made much deeper and stronger than it needs to be. c. The vertical plate over the central support that is welded to the web with its plane perpendicular to the beam web is to stiffen the beam web against buckling under the large localized force exerted on the bottom of the beam by the central support. d. The thick bottom flange over the central support is to handle the large negative moment that is creating a high compressive force in the bottom flange at that location. e. The welding of this structure is all done in the field.

a, b, e

This corrugated steel decking: Select one or more: a. Is smooth everywhere because there is no intention of having concrete in composite action. b. Is typically welded or nailed to its supporting beams or trusses. c. Is made in sheets 20ft wide by 50ft long. d. Is for use in composite action with concrete for floor decking. e. Nests compactly to make transport very efficient.

d

This failure is caused by: Select one: a. Residual Stress b. Thermal stress c. Friction over the supports d. Moment stress e. Shear stress

b

Three-ply laminated wood decking (3" nominal, actual thickness approximately 2 ¼ in) in Random Length Continuous configuration made of Douglas-Fir, Larch, or Southern Pine subjected to a roof live load of 20#/ft2 Can span up to: Select one: a. 11 ft b. 13 ft c. 7 ft d. 9 ft e. 15 ft

b

What is the critical cross sectional property for avoiding excessive deflection of a sawn wood beam? Select one: a. Area b. Moment of Inertia c. h d. Section Modulus e. b

d

What is the critical cross sectional property for preventing moment stress failure of a sawn wood beam? Select one: a. Moment of Inertia b. h c. b d. Section Modulus e. Area

a

What is the critical cross sectional property for preventing shear stress failure of a sawn wood beam? Select one: a. Area b. Section Modulus c. b d. Moment-of-Inertial e. h

b

What is the critical cross sectional property for preventing shear stress failure of a sawn wood beam? Select one: a. Moment-of-Inertial b. Area c. Section Modulus d. b e. h

b

When object A exerts a force on object B, object B exerts a(n) ________ and _________ force on object A. Select one: a. proportional, opposite b. equal, opposite c. equal, reinforcing d. equal, perpendicular e. greater, parallel

c, e

Which of the following formulas are parabolas? Select one or more: a. y = - kx^3 + kx2 - c b. y= kx3 c. y = kx2 d. y= kx4 e. y = - kx2 + c

b, e

Which of the following formulas are parabolas? Select one or more: a. y= kx^4 b. y = kx^2 c. y = - kx^3 + kx^2 - c d. y= kx^3 e. y = - kx^2 + c

b

Which support configuration above is optimal in terms of reducing the required internal resisting moment? Select one: a. H b. C c. E d. F e. A f. B g. G h. D

a, b, c, d

Wood I-Joists: Select one or more: a. Can have flanges made of finger-jointed sawn wood b. Can have flanges made of Laminated Veneer Lumber (micro-lam) wood c. Can have webs made of OSB d. Can have webs made of plywood e. Are made by gluing and nailing together three sawn boards

a, b, d, e

Wood I-Joists: Select one or more: a. Can have flanges made of Laminated Veneer Lumber (micro-lam) wood b. Can have webs made of plywood c. Are made by gluing and nailing together three sawn boards d. Can have webs made of OSB e. Can have flanges made of finger-jointed sawn wood

c

x1.5"-deep corrugated steel roof decking is to span, in three-span mode, between support trusses that are spaced 6'-0" O.C. apart: Dead Load = 20#/ft2 Live Load = 20#/ft2 What is the thinnest gage of decking, and associated weight per square foot of galvanized decking, that is required to meet the Maximum SDI Construction Span? Select one: a. 16 gage weighing 3.54#/ft2 b. 24 gage weighing 1.46#/ft2 c. 22 gage weighing 1.78#/ft2 d. 22 gage weighing 2.14#/ft2 e. 18 gage weighing 2.82#/ft2