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Weekly Quiz Answers

Here are the answers to Modern Steel Construction's Weekly Quiz questions! 

Week of October 7, 2020

True or False: When a specific tolerance is not specified in the AISC Code of Standard Practice, that tolerance should not be interpreted to be zero.
Answer:
True. Section 1.10 states this specifically. The associated commentary clarifies that typical tolerances necessary for usual fabrication and erection are addressed and, where an additional tolerance is important for design, constructability, or another reason, it should be specified in the contract documents.


Week of September 30, 2020

My number may not be in your phone but you know how to connect with me. You may still fasten onto my old names even though I've got it all--and with a twist! Close your eyes tight and think. What am I?
a. ASTM F1554
b. ASTM F3125
c. ASTM A588
d. soda with a twist of lime
Answer:
d. ASTM F3125 is the ASTM specification for structural bolts. 


Week of September 23, 2020

True or False: Stress ranges that are completely in compression need to be investigated for fatigue.
Answer:
False. Fluctuations in stress that do not involve tensile stresses do not cause crack propagation and are not considered to be a fatigue condition. For a member subjected to compression only, cracks may initiate only in regions of high tensile residual stress and do not propagate because residuals stresses are relieved by the crack. Thus, stress ranges that are completely in compression do not need to be investigated for fatigue.


Week of September 16, 2020

The process by which individual plate girder flange sections are cut to the proper curvature from wider plates is referred to as:
a. heat-curving
b. cold-curving
c. cut-curving
d. cut-bending
Answer:
c. cut-curving


Week of September 9, 2020

ASTM F1554 is a common specification for which construction material?
a. turnbuckles
b. washers
c. structural bolts
d. anchor rods
Answer:
d. anchor rods


Week of September 2, 2020

Unless stated in the contract document or state specification, what level of surface preparation should be specified for a steel bridge that is using uncoated weathering steel (UWS) as the corrosion protection strategy?
a. Provide SSPC - SP10 (Near white metal blast cleaning) to all girders
b. Provide SSPC - SP6 (Commercial blast cleaning) to fascia girders only
c. Provide SSPC - SP15 (Green metal blast cleaning) to all girders
d. Provide SSPC - SP 5 (White metal blast cleaning) to all girders
Answer:
b, Provide SSPC - SP6 (Commercial blast cleaning) to fascia girders only


Week of August 26, 2020

True or False: The requirements in AISC 360 and AISC 341 are the same for buildings and nonbuilding structures similar to buildings.
Answer:
True. Although ASCE 7 may have different requirements for nonbuilding structures similar to buildings, neither AISC 360 nor AISC 341 differentiate between the two; the requirements apply equally to both.


Week of August 19, 2020

What are the three factors that must be present for constraint-induced fracture of welded details to occur?
a. Material constraint, high residual stress, presence of defect or crack-like geometry
b. Material constraint, live load stress, dead load stress
c. Overlapping welds, high residual stress, troll living under the bridge
d. Material constraint, cold temperature, presence of defect or crack-like geometry
Answer: 
a. Material constraint, high residual stress, presence of defect or crack-like geometry


Week of August 12, 2020

True or False: It is necessary to remove the ceramic insulator from a stud shear connector in composite construction.
Answer: 
True. Section 7.4.6 in AWS D1.1 states: “After welding, arc shields shall be broken free from studs to be embedded in concrete, and, where practical, from all other studs.” This is required for visual inspection of the weld.


Week of August 5, 2020

True or False: According to the RCSC Specification for Structural Joints Using High-Strength Bolts, the minimum bolt pretension for pre-installation verification is equal to 70 percent of the specified minimum tensile strength of bolts as specified in ASTM specifications for tests of full-size ASTM F3125 Grade A325 and Grade 490 bolts with UNC threads loaded in axial tension, rounded to the nearest kip.
Answer:
False. The minimum bolt pretension for Pre-Installation Verification is equal to 1.05 times the specified minimum bolt pretension required in Table 8.1, rounded to the nearest kip. (Refer to the RCSC Specification, available at aisc.org/specifications, Table 7.1)


Week of July 29, 2020

AASHTO has published a new Guide Specification for IRMs in steel bridges. What does “IRM” stand for?
a. Internationally Rumored Member
b. Internally Redundant Member
c. Internationally Renowned Member
d. Internally Revolved Member
Answer:
b. Inernally Redundan Member.


Week of July 22, 2020

True or False: Structural steel does not lose any of its metallurgical properties when it is recycled. 
True. The quality and properties of recycled steel are the same as virgin steel, making steel infinitely recyclable.


Week of July 15, 2020

In the Code of Standard Practice for Steel Buildings and Bridges (AISC 303-16), which of the following is a true statement regarding Architecturally Exposed Structural Steel (AESS)?
a. AESS level 1 is typically the most expensive.
b. AESS level 2 is recommended for a feature element viewed from further than 20 feet.
c. AESS level 4 is typically used for basic elements.
d. AESS levels refer to the finish type and do not correlate to cost.
Answer:
b. AESS level 2 is recommended for a feature element viewed from further than 20 feet.


Week of July 8, 2020

Concerning fillet welds, the more transverse the load direction:
a. the smaller the rupture surface and the lower the strength
b. the smaller the rupture surface and the higher the strength
c. the larger the rupture surface and the lower the strength
d. the larger the rupture surface and the higher the strength
Answer:
d. The transverse load orientation affords strength increase because the failure “plane” is a curved surface whose area is greater than the area defined by the effective throat extruded the length of the weld (the failure plane for longitudinally loaded fillet welds). See Design Guide 21 Section 3.5.7 for discussion.


Week of July 1, 2020

True or False: In building structures, corrosion protection is not required for steel that will be enclosed by a building finish, coated with a contact-type fireproofing or in contact with concrete.
Answer:
True. When enclosed, the steel is trapped in a controlled environment and the products required for corrosion are quickly exhausted. The surface condition of unpainted steel framing of longstanding buildings that have been demolished has been found to be unchanged from the time of its erection, except at isolated spots where leakage may have occurred. Even in the presence of leakage, the shop coat is of minor influence as indicated in Specification Commentary Section M3. A similar situation exists when steel is fireproofed or in contact with concrete. Accordingly, shop primer or paint is not required unless specified in the contract documents (refer to page 2-36 of the Manual).


Week of June 24, 2020

The intent of Specification Table J2.4 (minimum fillet weld size) is to ensure sufficient:
a. material quantity
b. heat input
c. weld visibility
d. time spent
Answer:
b. heat input. Assuming minimum weld sizes are made in a single pass (as the footnote in Table J2.4 indicates) there is a direct relationship between weld size and heat input. Sufficient heat input is required in order to achieve fusion and to slow cooling, preventing cracks that may otherwise occur. See Design Guide 21 Section 3.5.1 for more information.


Week of June 17, 2020

Cambering is clearly a better option for addressing deflection compared to shoring. However, for cases where beam shoring is required, the EOR should carefully consider the increased potential for ________. 
a. black eyes from shoring pole collisions.
b. shoring colors that clash.
c. slab cracking.
d. shoring that blocks views.
Answer:
Slab cracking. Allowing the dead load deflection to occur after the concrete has set will more likely result in slab cracks. This slab cracking may occur over the girders and can be addressed by providing negative reinforcement. This will make the cracking more distributed and less noticeable.


Week of June 10, 2020

What is the minimum length for a fillet weld without reduction of design strength?
a. The weld size
b. Twice the weld size
c. Four times the weld size
d. Eight times the weld size
Answer:
c. The strength of fillet welds not meeting this criterion may be calculated with size taken as one-quarter of the length, per AISC Specification J2.2c.


Week of June 3, 2020

When determining the amount of beam camber needed, it is common practice to specify a camber equivalent to ____ of the estimated simple-span deflections resulting from the dead load.
a. 90%
b. 80%
c. 70%
d. No reduction
Answer:
b. 80%. AISC Design Guide 3: Serviceability Design Considerations for Steel Buildings presents the 80% to account for end connection partial restraint. The magnitude of design camber will depend on several factors, including the framing condition and the method of screeding the concrete. Most engineers design for 80% and require the contractor to supply extra concrete and screed level. Some design-build contractors design for 100% and require flexible bar screeds be used to screed a uniform slab thickness.


Week of May 27, 2020

For which of the following joint types does the maximum fillet weld size apply, per AISC Specification section J2.2b? 
a. Lap
b. Butt
c. Inside corner
d. Tee
Answer:
a. The limits, based on material thickness, are intended to prevent melting away of exposed edges. Tee joints and inside corner joints do not have exposed edges. Butt joints cannot be joined with fillet welds. See Design Guide 21 Section 3.5.2 for images and further discussion.


Week of May 20, 2020

In order to avoid damage, the heat used to camber members should not exceed: 
a. 1,100 °F
b. 1,200 °F
c. 1,300 °F
d. 1,400 °F
Answer:
b. 1,200 °F .  The Specification for Structural Steel Buildings (ANSI/AISC 360, available at www.aisc.org/specifications) Section M2.1 conservatively limits the temperature of heated steels to 1,100 °F for ASTM A514 and ASTM A852 steels and 1,200 °F for other steels. The goal is to keep the steel temperature to less than the phase change temperature, which starts at approximately 1,300 °F.  The 1,200 °F limit allows for a variation of about 100 °F which is a common range achieved by experienced fabricators.  Also, note that heat camber is generally much more time consuming and labor intensive than cold cambering and therefore is rarely used.*

*We kind of goofed on this one, because the answer does depend on on type of steel and it also depends on if you are counting on the actual phase change temperature of steel of 1,300 °F. So, everyone except the 1,400 °F people get entered in this one!


Week of May 13, 2020

Tension-control bolts (ASTM F3125 Grade F1852 and Grade F2280) are limited to a maximum diameter of: 
a. 1 in.
b. 1 1⁄8 in.
c. 1¼ in.
d. 1½ in.
Answer:
c. 1¼ in. TC bolts were previously limited to a maximum diameter of 1 1⁄8 in., but this maximum has increased up to 1¼ in. per the new ASTM F3125 standard.


Week of May 6, 2020

When intermittent fillet welds are used to transfer calculated stress across a joint or faying surface, what is the minimum length of a fillet weld segment?
a. ¾ in.
b. 1 in.
c. 1¼ in.
d. 1½ in
Answer:
d. See AISC Specification J2.2b. (e).


Week of April 29, 2020

Which fillet weld geometry results in a higher strength-to-volume ratio?
a. ½-in. size × 12-in. length
b. ¼-in. size × 24-in. Length
Answer:
b. Strength, which is proportional to the product of length and size, is the same for each choice. Volume, which is proportional to the product of length and size squared, is half as much for choice b. BONUS: It should be noted that relative volume is an indirect indication of relative cost. Since labor, not material, dominates fabrication costs, the number of passes required to produce the weld can be a better indication of cost. Table 8-12 of the AISC Steel Construction Manual (www.aisc.org/manual) indicates that the ½-in. fillet weld will require four passes, whereas a ¼-in. fillet weld only requires one pass. The relative cost can be estimated as the product of the number of passes and their lengths.


Week of April 22, 2020

True or False: Per the new ASTM F3125 standard, ASTM A325 high-strength bolts are now specified and ordered as ASTM F3125 Grade A325 high-strength bolts.
Answer:
True. Since the new ASTM F3125 standard replaced six standards (ASTM A325, ASTM A325M, ASTM A490, ASTM A490M, ASTM F1852 and ASTM F2280), the term “grade” is used to help identify which specific product is required. It should be noted that the new grade names are the same as the names for the previous standards. This should facilitate a smooth transition. In order to help engineers in specifying bolts, Chapter J Section J3.1 of the 2016 AISC Specification for Structural Steel Buildings (ANSI/AISC 360, available at www.aisc.org/standards) establishes Bolt Groups as follows:

  • Group A—ASTM F3125/F3125M Grades A325, A325M, F1852 and ASTM A354 Grade BC
  • Group B—ASTM F3125/F3125M Grades A490, A490M, F2280 and ASTM A354 Grade BD
  • Group C—ASTM F3043 and F3111

So, rather than specifying a bolt as F3125 Grade A325 or F3125 Grade F1852 in your design documents, you would only need to specify a Group A bolt to encompass all bolt styles of the same strength level.


Week of April 15, 2020

Which of the following are not well suited for camber? 
a. Crane beams 
b. Spandrel beams 
c. Cantilevered beams 
d. All of the above
Answer:
d. All of the above. Camber is generally not recommended for these situations and should be carefully considered. It would be a good idea to consult with the contractor before doing so.


Week of April 8, 2020

True or False: Shear flow can be used to design the weld attaching the reinforcing to the existing steel member.
Answer:
True.


Week of April 1, 2020

True or False: Temperature crayons can be used to monitor the temperature of the base metal near the weld.
Answer:
True.


Week of March 25, 2020

When welding to loaded members, it is recommended to set the maximum interpass temperature to:
a. 300 °F
b. 600 °F
c. 800 °F
d. 1,100 °F
Answer:
a. 300 °F. Where appropriate, it’s recommended to set the maximum interpass temperature to 300 °F.


Week of March 18, 2020

True or False: The term “type” is used to differentiate between heavy-hex bolts and tension-control (TC) bolts.
Answer:
False. The term “style” is used to differentiate between heavy-hex bolts and TC bolts. “Type” refers to different steel compositions.


Week of March 11, 2020

Using intermittent welds to attach member reinforcement will:
a. Potentially lower welding costs
b. Decrease corrosion potential in exposed structures
c. Less weld shrinkage distortion
d. Both a and c
Answer:
d. Use of intermittent welds will potentially lower welding costs (should be confirmed with the fabricator performing the work) and should result in less weld shrinkage distortion.


Week of March 4, 2020

True or False: The 15th Ed. Manual includes both LRFD and ASD approaches for the design of structural steel members and connections.
Answer:
True. As indicated on page 2-9 of the Manual, the “two approaches are equally valid for any structure for which the 2016 AISC Specification is applicable” and there is “no preference stated or implied in the Specification.” Refer to page 2-9 of the Manual for additional information.


Week of February 26, 2020

Which end-loaded fillet weld geometry results in a higher strength-to-volume ratio?   
a. ¼-in. size × 24-in. length.
b. ¼-in. size × 48-in. length.
Answer:
a. Strength-to-volume ratios would be equal, were it not for the penalty on end-loaded fillet welds longer than 100 times their size per the 2016 AISC Specification J2.2d. Increases in length result in less uniformity in stress distribution, owing to complex effects of relative stiffnesses in addition to shear lag. The condition does not frequently occur in practice.


Week of February 19, 2020

Camber is typically induced in members: 
a. after bolt holes for member connections have been made to the member.
b. before bolt holes for member connections have been made to the member.
Answer:
a. After bolt holes for member connections have been made to the member. It is more difficult to run a cambered beam through a fabricator's automated process for creating bolt holes.


Week of February 12, 2020

True or False: All column base plates must be designed and fabricated with a minimum of four anchor rods, per the 2016 AISC Specification.
Answer:
False. This is required per OSHA regulations. See Section 1926.755(a)(1) of the 29 CFR Standards for Steel Erection. Note that posts (which weigh less than 300 lb.) are excluded from the four-anchor-rod requirement. OSHA requirements are summarized on page 2-6 of the 15th ed. Manual.


Week of February 5, 2020

For a fillet welded T-joint, what is the maximum gap allowed between pieces before the weld size must be increased by the gap size? 
a. 1/32 in.
b. 1/16 in.
c. 1/8 in.
d. 1/4 in.
Answer:
b. 1∕16 in., the same as the increment between weld sizes. See Clause 5.21.1 in AWS D1.1 and Design Guide 21 Section 3.5.11 for more information.


Week of January 29, 2020

True or False: The inelastic deformations required in common cold bending operations, such as for beam cambering, normally fall well short of the strain-hardening range
Answer:
True. Refer to the section on cold bending on page 2-35 of the Manual.


Week of January 22, 2020

Over-cambering a beam could result in:
a. Vibration issues 
b. Exposed studs 
c. Reduction in beam strength 
d. All of the above
Answer:
b. Exposed studs


Week of January 15, 2020

True or False: When two cut sections are welded back together to form the castellated section, a fillet weld is used to connect the two webs together.
Answer:
False. A full- or partial-penetration butt weld is used and is typically made from one side of the web, without prior beveling of the edges if the web thickness is relatively small.


Week of January 8, 2020

The line where the bolts are placed in angles is called:
a. Centroid line
b. Bolt line
c. Gage line
d. All of the above are correct
Answer:
c. Gage line.


Week of January 1, 2020

Which of the following terms does not belong with the others?
a. Weld backing
b. Backing strips
c. Weld tabs
d. Backing bars
Answer:
c. Weld tabs. A weld tab is not a backing bar but rather a piece of material that extends beyond the ends of a joint, on which the weld can be initiated or terminated. They are sometimes referred to a “runoff tabs.” 


Week of December 25

True or False: The web thickness in an HP shape is equal to the flange thickness
Answer:
True. HP shapes are commonly used as pilings in foundations. Their heavy webs are made to resist the impact of the piledriving hammers.


Week of December 18

True or False: The critical stress in a fillet weld is considered to be a shear stress.
Answer:
True. Tension, compression and moments acting upon a fillet-welded joint are always resolved as shear in the weld throat—i.e., the least diagonal dimension.


Week of December 11

When calling out steel bars, it is a preferred practice to call out these members in what width increments?
a. 1/8-in. increments
b. 1/4-in. increments
c. 1/2-in. increments
d. 1-in. Increments
Answer:
b. This is stated in Part 1 of the 15th Edition Manual.


Week of December 4

True or False: Provisions for determining the lateral-torsional buckling strength of solid wideflange beams can be used for castellated and cellular beams if the cross-sectional properties are calculated at the gross section of the beam.
Answer:
True. Failure of castellated beams by lateral-torsional buckling is similar to that of solid wide-flange beams, with the holes having little influence.


Week of November 27

When detailing a steel beam, the drawings do not have to be drawn to scale in which dimension?
a. Longitudinal or length
b. Depth or height
c. Width
Answer:
a. Longitudinal or length.


Week of November 20

A single-sided CJP groove weld without a backing bar:
a. is impossible
b. should be avoided
c. is possible due to recent advances in robotic welding technology
Answer:
b. This situation should be avoided. These joints are seldom justifiable economically or structurally. They are expensive for several reasons: welder qualifications are appreciably more demanding, the resulting joints are not prequalified and preparation and fit-up are more exacting. Inspection of such welds can be difficult and potentially controversial when attempts are made to confirm acceptable complete penetration. Weld repairs are intricate and may damage other portions of the joint unless care is used.


Week of November 13

Surface finish quality of steel castings typically has the appearance of a(n):
a. Eggshell
b. Popcorn ceiling
c. Orange peel
d. Hot-rolled steel member
Answer:
c. Orange peel. Surface quality needs to be addressed for architecturally exposed structural steel (AESS) castings. Appropriateness of the surface finish will depend on many factors, including the casting process, coating system used, viewing distance and AESS category.


Week of November 6

ASTM A307 bolts are commonly referred to as:
a. Common bolts
b. Plain bolts
c. Soft bolts
d. Machine bolts
e. All of the above
Answer:
e. All of the above. These fasteners are not typically used in primary framing member connections.


Week of October 30

Which of the following is true regarding weathering steel?
a. Not all shapes will age/color the same
b. Standard electrodes will not weather the same as adjacent materials
c. A low corrosion rate can achieve a 120-year design life with nominal maintenance
d. All of the above
e. None of the above
Answer:
d. All of the above. Find out more about the benefits and challenges associated with weathering in the NASCC presentation “Building with Weathering Steel.”