Metals: NASCLA Commercial General Building Practice Questions

What does the designation W14x90 tell you about a steel beam?

W is wide flange; the first number is the nominal depth in inches and the second the weight in pounds per linear foot.

Fourteen W12x26 beams are each 30 ft long. What is their total weight in tons (2,000 lb per ton)?

The second number of the designation is pounds per foot. Dividing by 1,000 instead of 2,000 gives 10.92.

Which ASTM steel grade is the usual specification for structural wide-flange (W) shapes in buildings?

A992 (50 ksi yield) is the standard for W shapes; A36 is common for plates and angles, A615 is reinforcing bar and A53 is pipe.

What is a "snug-tight" bolted joint?

Snug-tight is enough for many bearing connections; pretensioned and slip-critical joints need controlled tensioning methods.

Which method can be used to install high-strength bolts to their required pretension?

Approved methods include turn-of-the-nut, calibrated wrench, twist-off-type tension-control bolts and direct tension indicators.

Which weld is the most common in structural steel connections, joining two surfaces at roughly a right angle?

Fillet welds are triangular welds in corner, T and lap joints; groove welds fill a prepared joint and cost more.

Who should perform structural welding on a building?

AWS D1.1 requires welder qualification testing for the process, position and joint type; structural welding is also a common special inspection item.

Under OSHA's steel erection standard, at what height must most workers on a walking/working surface with an unprotected edge be protected from falls?

Subpart R sets 15 ft for most steel erection workers; connectors and workers in a controlled decking zone have special rules between 15 and 30 ft (or two stories).

Connectors working on steel erection must be protected from falls when they are more than how high?

Connectors must be protected above two stories or 30 ft, whichever is less; between 15 and 30 ft they still need fall arrest equipment available and must be trained.

Before steel erection begins, the concrete in footings, piers and walls must have reached what level, unless other verification is given?

The controlling contractor must give the erector written notice that concrete has reached 75 percent of design strength (by ASTM test methods or other approved means) before erection starts.

Under OSHA Subpart R, how many anchor rods (anchor bolts) must a column base generally have?

Four anchor rods make a column stable while it stands free during erection; posts (lightweight members) are an exception.

During the final placing of a solid web structural member, when may the load be released from the hoisting line?

Two bolts per connection (of the size and strength specified) or an equivalent the engineer approves keep the member from falling when the crane lets go.

In multistory steel erection, how much unfinished bolting or welding may there be above the foundation or the uppermost permanently secured floor?

The 4-floor or 48-ft limit keeps the frame from getting too far ahead of the permanently connected structure.

What is a controlled decking zone (CDZ) in steel erection?

A CDZ is allowed between 15 and 30 ft, limited in size (90 ft wide and 90 ft deep from the leading edge), with access restricted to trained deckers.

Why must bridging be installed on open-web steel joists before workers or loads are placed on them?

Long, slender joists can roll over or buckle laterally; OSHA 1926.757 and the joist institute's practices set when erection bridging must be in place.