GLFEA Breakfast Meeting
Designing for Savings on Steel Structures

Detroit, Nov. 1, 2002 - Designers can save money on steel structures if they understand construction costs and what can cause delays on steel projects. That was the topic of "Holding the Line on Project Costs: Designing Lower Cost Steel Structures," discussed at the Great Lakes Fabricators and Erectors Association breakfast meeting, Nov.1 at the Westin Hotel in the Town Center in Southfield.

GLFEA hosts the periodic breakfast meetings as a service to the construction and, particularly, to the design communities. The programs, which are free, are geared toward architects, engineers, detailers, specifiers, and other construction/design/engineering professionals. GLFEA Executive Director Jim Walker introduced the Nov. 1 program and speakers: engineers Don Makins, president of MBM Fabricators and Erectors, Romulus, and current

'There's just no standard job.' William Treharne, P.E., GLFEA Past President & Current Board Member, and Director of Administration & Engineering, Midwest Steel Inc., Detroit

GLFEA president, and William Treharne, P.E., GLFEA Past President and current board member, and director of administration and engineering at Midwest Steel Inc., Detroit.

Makins began the program by announcing that the association's membership had increased to 62. Members include fabricators, erectors, designers, galvanizers, joist manufacturers, industrial maintenance contractors, equipment suppliers, engineering consultants, steel suppliers, industrial machinery movers, painters, transportation, metal deck suppliers and riggers. "We represent a lot of people and we'd like to be more active with you people in helping you make designs that are economical for us and for the owner," he told the audience of mostly architects, engineers, detailers and contractors. The GLFEA (www.glfea.org) is expert in all facets of steel construction and its role within the broader construction industry. The association promotes the efficient use of steel and negotiates contracts with Iron Workers Local 25 and Operators Local 324.

"Architects and engineers are being required to provide more value added for less fees," Treharne said. "We are also experiencing construction delays. Delays all cost money and one of the things that we want to do is be able to avoid them." It's easy to say, he admitted, but working together as a team is essential. "That's what we're all here for: to save the owner costs."

Makins and Treharne clearly stated they did not intend to tell designers how to design but, rather, they wanted to provide information on how to save costs on structural steel design by pointing out the things that cost the most for fabricators and erectors.

As an example, Makins outlined the cost of shear studs in steel construction. Although the average cost is about $2, the minimum cost of bringing out a stud installer is $1600. Unless 800 or more are required, designing the steel heavier and eliminating the use of field-installed shear studs on the project can generate significant savings, Makins said.

Checking the AISC manuals and specifying standard materials can also reduce costs. "Right now, the major mills charge extra for wide flanges of (grade) A36," Treharne explained. "That used to be the standard in the industry. That's not the standard anymore for wide flanges. (Now) It's grade ASTM-A992."

Makins provided a broader overview of costs, allowing that detailing costs $400 to $500 per sheet. Steel material costs are between $450 and $550 per ton, he said, and fabrication costs can vary significantly from

'If you need answers, we'll get you answers.' GLFEA President Donald Makins, President, MBM Fabricators & Erectors Inc., Romulus

$400 to $2,500 per ton, as can erection costs, from $400 to $3,000 per ton. The rule of thumb is material represents 25% of the total cost of the job and labor 60%. Increasing the weight of steel used on a job in some situations can, therefore, actually save money if it reduces labor requirements.

Standardizing geometry and member sizes in the design of trusses often saves money, both engineers agreed. Treharne described a job he saw recently where two roof trusses of the same geometry, 7 ft.-11-5/8 in. out-to-out by 50 ft. long, required different load-bearing capacity. The total load for Truss A was 166K and for Truss B it was 120K. The difference in weight between the two trusses was 137 lbs, yielding a savings of $31 for the lighter-weight Truss B. However, the two extra detailing sheets required for the lighter-weight Truss B cost $800, and additional costs also were incurred with drawing reproductions, approvals, and shop-time for cutting different angles and extra layout. Making two of the heavier Truss A would have saved all of those extra charges, Treharne observed.

The type of bolt specified also affects the cost of the project, Makins noted, considering not only the cost of the bolt itself, but also the number of bolts required and the other installation and inspection costs involved. The AISC's Research Council on Structural Connections' Specification for Structural Joints Using ASTM A325 or A490 Bolts, revised June 23, 2000, is available on the Internet. "The new code is really based on the latest research," he said. "I encourage you all to read it." Also available on the Internet are portions of the Structural Bolting Handbook, published by Steel Structures Technology Center Inc. in Novi. It's a book Treharne said he really likes and gives to his foremen. "If you want to understand bolts this is a clear concise way to understanding bolts," he declared.

The least expensive bolt specification is a "snug-tight" bolt, Trehanre said, noting its installed cost is around $7 per bolt in the Detroit area. If you need pretensioned bolts, the X-Type bolt with no threads in the shear plane costs around $7.70 each. The N-Type bolt has threads in the shear plane and also costs around $7.70, but more of them are required. Slip-critical bolts cost around $8.40 each, not including extra costs for masking to avoid painting around the bolts, field touch-up painting, and inspection. Masking is necessary on painted structures, since even over-spray must kept away from the slip-critical connection. The procedure costs an additional $2-$3 per bolt. The highest-cost bolts are those using Direct Tension Indicator (DTI) washers. Erection costs are around $9.80 per bolt, plus the cost of the DTI washers.

In most specifications he reads, Makins said the minimum requirements are 5/16-in. thick connection material and bolts that have threads included in the shear plane. "I wish that you would say make all connection material 3/8 (in.) minimum and make sure that there's at least 1/8 (in.) stick-through on the bolt past the nut, and that way we would always exclude the threads from the shear plane," he said. "That works for 7/8 (in.) and 3/4 (in.) bolts. That little change in your specification would probably cut down the number of bolts and save money, and the cost of the material I can guarantee you would almost be negligible."

Reducing field connectors and standardizing shop connections typically realizes savings, Makins advised.

"As a fabricator and erector, one of the most expensive costs is making connections at the point of the column and making sure our clearances are available," he offered. Using larger columns may be more economical, by reducing shop and field labor because flanges of beams framing into the web of larger columns may not need to be coped, room inside the columns makes bolting-up easier, holes don't need to be staggered, and eccentricities don't need to be created. "Probably the cost of a…difficult connection in the field is $200-$300 more than a very basic connection where you don't have any interference problems," Makins said. Treharne added that connections designed using the actual design loads are generally more economical than those designed using tables because actual loads can be grouped together for standardization.

The March 7, 2000, edition of the AISC's Code of Standard Practice for Steel Buildings and Bridges was rewritten by engineers, fabricators, and erectors and represents the best collective experience in the steel industry, Treharne said, recommending that this book be used.

When the fabricator is allowed to select or complete the connection details, he said, design drawings need to include: information on any restrictions on the type of connections; data concerning loads including shears, moments, and axial forces; transfer forces to be resisted by individual members or connections, and which loads are service loads and which are factored loads.

Section 3.2 of the Code of Standard Practice, says all requirements for the quantities and locations of structural steel are to be shown or noted on the structural design drawings. The information can also be on other drawings, but all the information needs to be on the structural drawings at least, since they are used for detailing and estimating steel structures.

Sometimes the engineer of record will reject the fabricator's design calculations, Treharne explained, when poor organization of calculations prevents them from being understood, or because of differences in theory or poor communication. The detailer can be slowed down or stopped when this happens, and the project put on hold until the issues are resolved. Good teamwork and good communication, including a pre-detailing meeting with the detailer, the connection design engineer, and the engineer of record can prevent these problems.

If it is not needed, camber should not be specified, Makins advised. If beams must be purchased with natural camber built in, the additional costs will be about $30 per beam. But, if camber needs to be put in later with heat additional, costs can be up to $200 per beam.

Erection tolerances need to be kept in mind, as well as the difference between structural tolerances and architectural tolerances, Treharne advised. Situations that call for the designer to consider tolerance differences include high-rise drift where stair openings at the top may be different than at the bottom, temperature differences during erection, column shortening, and dead load deflection.

Regarding weld size and type, Makins noted: "In the manufacturing facility where we use gas-metal arc welding - we use wire-feed semi-automatic machines - the biggest weld we can put down is 1/4 in., so I'd rather see 1/4 in. than 5/16 (in.). That's the best size for a fillet weld. The fillet weld is obviously very easy to fit up, (and it) creates very low distortion."

The 1/4-inch fillet weld is especially good for shop applications, he observed. In the field, a 5/16-in. weld can be attained by a stick electrode but a semi-automatic process is faster, he said. Dynamic loading restricts the use of partial joint preparations, but where there is a choice, partial joint preparation is preferable to complete joint preparation, or a full penetration weld, because it's easier to fit up and distortion is reduced. Full penetration welds are the most expensive welds on the job because most need to be inspected, Makins advised. They also create greater distortion, which requires costly straightening.

Other cost-sensitive issues that need to be addressed, he said, include:

• Galvanized surfaces cannot be welded. The galvanized portion needs to be ground away before welding and that can create a health hazard, additional costs, and require touching up. Another problem: the "touch up" usually does not equal the quality of the original coating.
• If painting is not necessary, it is better not to paint. Where some surfaces are to be painted and some are not, painted sections should be clearly specified. Primer is only a base for the complete paint system and can only protect structural steel from corrosion for a limited time. How long the primer will last depends on dry film thickness, surface preparation, percentage of pigment in primer, and type and length of exposure. For a short exposure a red or brown iron oxide can be used. For a long exposure zinc-rich paints or epoxies are recommended.