Ask the Experts in AISC's Modern Steel Construction Magazine. Written by George F. Wendt

Ask the Experts

Early involvement by subcontractors can yield the same benefits as early involvement by fabricators.

By George F. Wendt, Chicago Metal Rolled Products
In Modern Steel Construction magazine, May, 2006

AISC research has demonstrated that early involvement of a steel fabricator on a construction team can reduce construction costs and construction time. (“It doesn’t have to be that way!,” Modern Steel Construction/January, February, March 2003). Working with general contractors, engineers, architects and developers, a fabricator can contribute expertise otherwise lost without early participation. The benefits to the fabricator include the goodwill earned, the inside information derived from participation, and the increased likelihood of winning the contract. Similarly, subcontractors at times have the opportunity for early involvement. Because of the potential mutual benefit to all parties, developers, architects, general contractors, engineers, fabricators and subcontractors should consider collaborating early in a life of a project. In most cases the subcontractor will be sought out for his special services, but the subcontractor can benefit by indicating a willingness to get involved early and often with each of the parties.

As a specialty subcontractor, AISC member, Chicago Metal Rolled Products, has made its own contributions through early involvement in several high-profile projects. The company roll-curves structural steel, pipe, sheet and plate to a specified radius for the construction industry at facilities in Chicago IL, Kansas City, MO, and Bryson City, NC.

Fully five years before its completion, John Zils, senior structural engineer at Skidmore, Owings and Merrill, consulted Chicago Metal Rolled Products about curving steel pipe for the music pavilion trellis at Millennium Park. SOM contacted Chicago Metal because of its reputation for curving the largest sections of structural steel and pipe. “We like to design structures and come up with ideas that are not only responsive to the architecture but also have a practical sense to them, that can be built and fabricated properly,” Zils says. “It’s very normal for us during the design to meet with, if it’s a steel structure, some fabricators or potential fabricators . . . to vet the design a little bit, to see what their input is and what their suggestions might be and how we can maybe improve what we’re doing.”

Architect Frank O. Gehry’s design called for 570 tons of pipe up to 20” OD curved in two planes with multiple radii. Although Chicago Metal could have followed this design, its architecturally trained estimator suggested that each arch be curved in one plane and that the radii—ranging from 100 to 1000 feet-- change at each arch’s four nodal junctions. Gehry and Associates agreed and chose to tilt each arch a little to the side. This design change simplified the geometry for roll-curving, for fabrication and for erection thereby reducing costs and construction time without compromising aesthetics. “We were able to quite substantially reduce the number of different radiuses and still achieve the same basic profile,” Zils says. “It wasn’t exactly the same, but for all intents and purposes, it was very similar. According to Zils, this reworked design “was a significant contribution to the project.”

Early involvement on the part of a subcontractor, however, is not without its risks. Usually there is no guarantee that a subcontractor will be awarded a contract. Consequently, considerable time and energy could be spent on a project that would not bring any benefit to the subcontractor. The worst case for a subcontractor would be for the customer to take the best ideas of the subcontractor and share them with the subcontractor’s competition. Each subcontractor, therefore, must analyze the costs and benefits before expending resources on any given project. In many cases the decision may be based on the resources of the subcontractor. For example, Chicago Metal Rolled Products employs full-time four engineers and one architect solely to provide its customers with solutions to the specific challenges of curving steel.

In the case of Millennium Park, Chicago Metal’s early commitment to provide the following earned it the contract: its expert bending technology; well-defined AESS quality (e.g. no scratches on the pipe that would snag a fingernail); representation on the jobsite to resolve any problems; and speed and flexibility in delivery. The close-up photo illustrates how accurately the trellis had to connect to the steel-clad, curvaceous ribbons which adorn the stage. Walsh Construction (the general contractor); Acme Structural (AISC member fabricator); and Danny’s Construction (AISC member erector) all remarked about how “the trellis pieces went together so well.” Collaborating on the design, fabrication and erection from the beginning, all parties helped create the trellis for the Pritzker Pavilion (AISC Engineering Award of Excellence, Merit Award 2005)

Before designing the Ratner Athletic Center at the University of Chicago, the architect, Cesar Pelli concluded that “Everyone we spoke to at the University wanted a place that would be not just functional, but exciting—exciting on the inside and from the outside.”

His solution of a cable-stayed waved roof with soaring masts makes the building instantly recognizable and exciting. Early in the project, OWP&P, the architect of record, contacted Dan Wendt, an engineer at Chicago Metal Rolled Products, to ask if it was possible to create an “S” curve within one beam with no weld splicing thereby saving time and money while improving the appearance. Dan and the machine operators agreed that the company could indeed roll the 8 pieces of W33 x 169# x 93’ ft. long beams each to an 85’ radius (14’ arc) followed by a 22’ straight tangent followed by a 146’ radius bend (reverse) (12’ arc). Again, early involvement of a subcontractor improved the project.

Chicago Metal proceeded to roll-curve these beams and others for a total 310 tons of steel cold bent about the strong axis to complete the flattened-S-curved roof. Picking the best of 60 specialized machines for each application, the company maintained AESS quality. The architects, engineers, general contractor, and fabricator—AISC member, Lejeune Steel of Minneapolis--all visited the shop to witness the bending. Larry Kloiber of Lejuene said that Chicago Metal’s curved beams “were delivered on time, were within tolerance, and went together well.” Early involvement, planning and teamwork shortened the time needed for curving while actually allowing more time for planning and communication.

Chicago Metal’s involvement in this project began as most do—with the question, Can this be done? This is the initial opportunity for a subcontractor to become involved. Subcontractors like Chicago Metal often have specialized knowledge acquired from years of experience. They maintain detailed records of what can and can not be done. Furthermore, many subcontractors are willing to experiment providing sample parts for evaluation. Again, if the subcontractor deems the cost and time to be a prudent investment, his expenditures can reap rewards for all involved.

In this case, the architect’s early consulting with a subcontractor helped transform Pelli’s combination of curved beams, masts, and cables into the Gerald Ratner Athletic Center. (Engineering Award of Excellence National Winner 2004). A new student center at the Illinois Institute of Technology in Chicago, designed by Dutch architect Rem Koolhaas, was to be linked to Chicago's elevated "El" train system. Koolhaas' solution to train noise was to create a steel-and-concrete tube to encase trains as they pass over the single-story building.

Invited by AISC-member fabricator K & K Iron Works of Mc Cook, IL, Chicago Metal participated in the bidders’ planning meetings. K & K won the contract to fabricate and erect the steel and purchased the bending services from Chicago Metal, partly because the two companies had worked together with the architect even before a general contractor had been chosen.

To form the tube, Chicago Metal Rolled Products roll-curved 52 tons of W12 x 58# beams the "hard way" to form a series of half ellipses with many radiuses down to 12’.
Dan Wendt of Chicago Metal Rolled said, “We knew we could easily roll 12” beams for the top of the tunnel where the ellipse has the larger radii, but we were especially happy to provide K & K with the extremely tight 12’ radius on the sides. We were helped by the excellent detailing provided by K & K.”

K&K praised the roll-curved beams for being distortion-free and for having a profile tolerance of less than 3/8". "The product that we got from Chicago Metal Rolled was almost perfect--they've always done a great job for us," said K&K Vice President Jerry Kulhanek. Again, early involvement with the architect and continuing teamwork between the subcontractor and steel fabricator produced the train tube for the McCormick Tribune Student Center, another architecturally significant structure.

These three projects all succeeded because of early involvement of all the players—including the subcontractors--and a spirit of teamwork to resolve difficult issues. In each case the design challenged the fabricators and subcontractors, and to some degree the fabricators and subcontractors influenced the design. With the resulting collaboration, new technology led to new designs and new designs led to new technology.In every project, of course, cooperation between all the parties is necessary. But these three extraordinary structures—a massive trellis, a cable-stayed sinuous roof, and an elliptical train tube—called for extraordinary coordination and cooperation from the architects to the subcontractors to the fabricators to the erectors.

Many subcontractors are willing and able to work with any of the members of a given project. The key is to ask us to be involved. In Chicago Metal’s experience, that invitation can come from the engineers (SOM, in the case of the Pritzker Pavilion); from the architect of record (OWP&P, in the case of the Ratner Athletic Center); or from the fabricator (K & K Iron Works, in the case of the McCormick Tribune Student Center.)

If getting subcontractors involved early can help, not contacting them early can hurt. In Chicago Metal’s experience, mistakes have been made when its customers have assumed that, for example, an S curve required a weld splice, or when they chose to estimate the costs for curving steel without consultation. Most often, subcontractors like Chicago Metal can provide quick, accurate quotations as well as cost-saving suggestions.

Chicago Metal Rolled Products was happy to cooperate early and often with the parties involved in these three projects sharing the knowledge of curving steel developed since its founding in 1908. Moreover, the company has conducted seminars on roll-curving for architectural firms like HOK, Teng and Associates, CUH2A, and OWP&P; for engineering firms like Graef, Anhalt, Schloemer & Associates; as well as for organizations like the Chicago Architectural Foundation and the Structural Steel Fabricators of New England. In each case the company highlighted the affordability, availability, and structural integrity of curved steel thereby promoting the use of steel in construction. Such outreach helps convey a subcontractor’s ability and willingness to do the “up front” work to demonstrate the value it can add to a given project.