Thanks to an inventive collaborative approach that assigned key personnel from the construction firms and the design firms to a centralized project center and a concerted effort to reduce materials costs, Chicago’s new McCormick Place West Building was delivered under budget and ahead of schedule. By Steven C. Ball, P.E., S.E., LEED AP
The dramatic roof overhang on the north elevation of the McCormick Place West Building shelters the outdoor dining terrace and the vip and ballroom drop-off; internally illuminated pylons mark the building’s City Gate entrance in the far right of the photo. James Steinkamp
he largest convention center in the United States, Chicago’s McCormick Place is a campus of premier convention and hospitality facilities that has evolved over more than 40 years and today attracts close to 3 million visitors each year. The campus is composed of four convention facilities, a high‑rise hotel, a conference center, parking structures, and a central energy facility.
Owned and operated by the Metropolitan Pier and Exposition Authority (MPEA)—an independent corporation jointly directed by the City of Chicago and the State of Illinois—the McCormick Place campus boasts 2.7 million sq ft (250,830 m²) of exhibition space and 700,000 sq ft (65,030 m²) of meeting rooms, grand ballrooms, public assembly areas, theaters, parking facilities, hotel accommodations, retail shops, cafés, restaurants, and grand public spaces interconnected via a series of pedestrian promenades and pedestrian bridges.
The first building to be constructed on the site—the Lakeside Center—opened to the public in 1960 and provided 320,000 sq ft (29,728 m²) of exhibition space, 23 meeting rooms, and a 5,000-seat theater. Destroyed by fire in 1967, the building was redesigned, rebuilt, and then reopened to the public in 1971 with 522,000 sq ft (48,494 m²) of exhibition space, 20 meeting rooms, and additional theaters. By today’s standards the building is well suited to serve midsized exhibitions and meetings.
In response to increased demand for exhibition space during the 1980s, the North Building opened in 1986, encompassing 700,000 sq ft (65,030 m²) of exhibition space. It houses 29 meeting rooms and continues to serve large exhibitions.
The ensuing years brought even greater demand for additional exhibition space, and as a result the South Building became part of the campus in 1996. It added 2.9 million sq ft (269,410 m²) of building space, including 840,000 sq ft (78,036 m²) of exhibition space, 160,000 sq ft (14,860 m²) of meeting rooms, a grand ballroom, retail space, cafés, restaurants, and architecturally and structurally expressive public spaces. The South Building also serves large exhibitions and meetings. The design and construction delivery method for this building differed from the traditional design/bid/build delivery methods used for the Lakeside Center and the North Building. The South Building was delivered using the design/build approach with a guarantee not to exceed construction cost. The design/build delivery system turned out to be very successful; indeed, the project was delivered to the MPEA ahead of schedule and under budget.
The fact that the McCormick Place campus was now attracting millions of visitors each year increased the need for hospitality facilities. As a result, the Hyatt Regency McCormick Place Hotel was designed and constructed by the same design/build team that was delivering the South Building. The hotel project was added to the campus in 1998, providing 800 hotel rooms and a 600-car parking structure. Here too the design/build delivery system proved its worth, again resulting in delivery ahead of schedule and under budget.
Soon after the opening of the hotel, a dedicated conference center and a six-level parking structure were designed to further supplement the campus. These additional facilities opened to the public within a few years of the hotel’s opening. They were delivered using the design/build process by teams other than those that delivered the South Building and hotel projects.
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REALVIEWS by Cesar Russ |
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A monumental glazed opening, above, frames floor-to-ceiling views of the Chicago skyline from the ballroom prefunction area. Glazed walls above the City Gate entrance, below, frame panoramic views of the venerable Motor Row district. |
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James Steinkamp |
The convention industry was continuing to evolve and was seeing more of a focus on facilities for professional, academic, and medical events. Market emphasis was being placed on a larger ratio of meeting rooms to exhibition space for any new facilities. In response, the MPEA in 2001 authorized the design and construction of the West Building. This structure added another 2.3 million sq ft (213,670 m²) to the campus, offering 475,000 sq ft (44,128 m²) of exhibition space, 125,000 sq ft (11,612 m²) of meeting rooms, the largest—100,000 sq ft (9,290 m²)—ballroom in Chicago, retail space, cafés, restaurants, architecturally and structurally expressive public spaces, and an architectural extension of the signature grand concourse from the South Building. The building serves exhibitions of all sizes and provides the premier meeting space within the campus. The primary members of the design/build team that delivered the South Building and the Hyatt Regency McCormick Place Hotel also figured in the design/build team that delivered the West Building. The West Building opened to the public in 2007 and became the largest building in the United States to obtain certification in the category of new construction from the U.S. Green Building Council. The certification is part of that body’s Leadership in Energy and Environmental Design (LEED) Green Building Rating System.
In 2001 the MPEA authorized the design and construction of the West Building. This article discusses the design and delivery of the McCormick West Building and the ways in which the various challenges were addressed. Attention is also given to the way in which the design and construction team responded to unforeseen market conditions related to steel materials in order to adhere to the preestablished construction budget for the project. With respect to those segments of the article that focus on design, the primary emphasis is on the structural design.
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| A. Epstein and Sons, International, Inc. |
As a result of their favorable experiences with the design/build delivery system for the South Building and the Hyatt Regency McCormick Place Hotel, the MPEA solicited design/build proposals that would include a guarantee not to exceed the preestablished construction cost. The primary members of the design/build team that delivered those two previous projects reconvened to form a design/build team for this new building. One of the strategies for reconvening the team was to draw on the experience gained by the designers, the constructors, and the MPEA on the previous projects. The new design/build team was formed as Mc4West, LLC, and was composed of Clark Construction Group, LLC, of Bethesda, Maryland; Hunt Construction Group, Inc., of Scottsdale, Arizona; and the Chicago-based firms Mota Construction Company; II‑in‑One Contractors, Inc.; McKissack & McKissack Midwest; Cotter Consulting, Inc.; Pentad, Inc.; Mesirow Stein Development Services, Inc.; A. Epstein and Sons International, Inc.; and Globetrotters Engineering Corporation. The architecture and engineering designs were the responsibility of A. Epstein and Sons and Globetrotters Engineering Corporation. Numerous consultants were subsequently engaged by these design firms to assist with the design process.
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| A. Epstein and Sons, International, Inc. |
As part of the request for proposals (RFP), the MPEA provided schematic designs to the various design/build bidders. It hired the architects Thompson, Ventulett, Stainback & Associates (TVS) to prepare concept designs and design criteria for the project as a basis for soliciting design/build bids within an $850-million budget. It would become the responsibility of the successful design/build team to prepare architectural and engineering designs that would satisfy the intent of the concept designs presented by TVS within that budget.
The Mc4West design/build team convened to develop the most cost-effective and responsive architectural and engineering solutions that would meet the criteria in the RFP. In developing representative designs for the various framing systems, the structural team considered various building materials. Alternative designs were developed and compared with respect to material costs, material availability, lead time for procurement, fabrication costs, transportation of materials, erection costs, speed of construction, structural responsiveness to the criteria in the RFP, local and customary practices, and suitability for future design modifications by the design/build team or by the MPEA. The alternative designs that were prepared and compared were precast-concrete framing, cast‑in‑place-concrete framing, structural steel framing, and a hybrid combination of those systems. There were also various subsets of each of those systems in which various alternative solutions were developed and compared. The most viable framing systems were precast concrete, structural steel, or a hybrid combination of those two systems. As a result, the design/build team developed detailed quantity estimates and associated costs for each of those systems. The material quantity estimates dictated the budget imposed upon the design team for preparing the final designs in the event that the team was awarded the project. The estimated costs were integrated into the cost proposal submitted to the MPEA in response to the RFP.
All of the bids submitted to the MPEA exceeded the $850-million budget for the project by $300 million or more. As a result, the bidding teams were offered the opportunity to submit alternative designs deviating from the original concept design prepared by TVS. The Mc4West design/build team developed approximately 160 alternatives of various scopes and extents. Some of the most prominent alternatives included significant building reconfigurations and modifications to the truck transportation systems.
The design/build team proposed reconfiguring the building. The reconfigured building eliminated a secondary ballroom, relocated the main ballroom to a more favorable column grid, eliminated approximately 120,000 sq ft (11,148 m²) of dedicated exhibition space, eliminated some meeting rooms, consolidated mechanical rooms, eliminated a secondary truck dock, eliminated a significant bridge system for transporting trucks from the marshaling yard to the new facility, eliminated a secondary pedestrian bridge, reduced the height of the building, and shortened the length of the building.
Dedicated exhibition space that was eliminated was regained by situating the relocated ballroom adjacent to the remaining exhibition space and designing the ballroom to also serve light exhibitions. The existing truck marshaling systems for the South Building were integrated into the designs for the new West Building to eliminate a significant portion of the bridge system that was part of the original design concept.
| A. Epstein and Sons, International, Inc. |
Cross Section of Typical Megacolumn |
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The relocated Platt Luggage Building facade screens the existing central energy facility and reestablishes a relationship with earlier buildings. |
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The structural, mechanical, and civil engineers were an integral part of the building reconfiguration effort. They found opportunities for reducing the costs of their systems and worked with the architects to collectively formulate reconfiguration strategies that would exploit those cost-saving opportunities while satisfying the program requirements and ensuring that the architectural vision for the building was realized.
All of the alternatives maintained the scope and functionality of the original design concept presented by the MPEA. The end result was a cost proposal presented by the Mc4West design/build team that was within the $850-million budget. The Mc4West team was selected.
The final architectural designs were prepared through continuous collaboration between TVS and Epstein. TVS was retained by the MPEA to serve as an adviser on the revised program that was prepared and presented by Epstein. The architects from both firms had a common vision for the project. They wanted a building whose exterior designs would be an expression of its function and whose formal entries, masses, and facades would be reflective of its internal character. Internally, the building relies on a clean “front-of-house/back-of-house” separation that enables visitors to circulate, socialize, and relax beyond the view of the back-of-house functions.
The urban plan reflects a front-of-house function by engaging the outer perimeter streets with street-level entrances that become drop‑off points as well as points for entering and leaving the neighborhood. A back of house is created by a dedicated service roadway that bisects the first level of the building and serves as a new entry to the existing parking structure at the northeast corner of the building.
At the north end of the site, a formal ballroom drop‑off runs below the overhanging mass of the ballroom. The ballroom mass is expressed in an open glass portal that faces downtown Chicago; its characteristic cantilevered roof shelters a formal roof terrace. The prefunction space adjacent to the ballroom is infused with natural light and features full-height glass that frames views of the neighborhood from the interior and offers views of the canted, striated walls of the ballroom from the street.
The City Gate entry, along the west elevation, is the main street-side entry to the building. The full-height glazed entry features a 120 ft (36.5 m) tall lantern that provides a sense of place and serves as a beacon to approaching visitors. Metal and glass canopies over six entry gates provide entry into the main registration rooms, central concourse, and transportation center. The transportation center is an internal transit node that provides charter bus marshaling directly to the building from downtown Chicago via a dedicated bus way. The interior of the transportation center features a glazed lighted screen wall that separates it from the adjacent service roadway, a glass entry wall that opens into the City Gate, and coffered ceilings that suggest the motion of the buses that dock within.
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REALVIEWS by Cesar Russ
The suspended glazed lantern, left, signals the main public entry, or City Gate entrance, to the building. The west prefunction and canted architectural wall encloses the ballroom, above.
James Steinkamp |
At 470,000 sq ft (43,663 m²), the exhibit hall is the largest functional element in the building. Its mass is expressed on the west side by an elevated brick masonry wall punctuated by rhythmic glass bays in a gesture to the historically important Motor Row neighborhood across the street, which makes heavy use of masonry. The south elevation serves as the freight-loading and service dock, providing berths for 40 semitrailers and ramps into the structure for direct drive-in, setup, and teardown functions. A 30 ft (9 m) deep and 700 ft (213 m) long suspended canopy protects the dock from rain and snow and, with its detailed hangers and slender profile, provides aesthetic relief to the scale of the building. The loading berths are served by a new, elevated 120 ft (36.5 m) wide and 700 ft (213 m) long roadway that provides a link to the freight marshaling yards that are 0.75 mi (1.2 km) away by connecting to the existing roadways at the South Building. The extent of the elevated dock is screened from public view by architectural precast walls that form an elevated planter wall on its south face.
The facade of the structure is a blend of materials that relate to McCormick Place’s existing buildings and bridge the way to the Motor Row neighborhood to the west. Architectural precast concrete, composite- and foam-filled metal panels, aluminum and glass curtain walls, and cavity wall brick and block masonry systems were used in combinations suited to their locations to create a balance of opaque and transparent surfaces. An exhibit hall is generally best built without windows, but clerestory windows were provided below the roof overhangs along with screened bay windows to channel ambient, but not direct, daylight into the space.
A neighborhood portal was constructed along the edge of the campus that signals an arrival to both the McCormick Place campus and the historically important Bronzeville neighborhood, to the south of the campus. This cable structure spans 180 ft (55 m) over a complex roadway intersection. While the design of the portal structure is decidedly high tech, it strikes a balance with references to older bridge architecture, reflecting the way in which the technology of McCormick Place complements the older neighborhood it abuts.
he design/build team decided to develop an environment that would be fully dedicated to the design and construction of the project—one that would promote continuous collaboration between the client, the constructors, and the designers. To that end the team established a project center at Epstein’s offices in Chicago—an unconventional but highly effective approach during the design and preconstruction phase of the project. Approximately 24,000 sq ft (2,230 m²) of office space was dedicated to personnel working on the project. All of the designers from the various design disciplines, together with the constructors and key people from outside consultants, worked full-time out of this center. The center was relocated on-site within a facility of equivalent size once the project went into construction. Key personnel relocated and worked full-time out of the on-site center during the construction phase of the project. Creating these environments was instrumental in the success attained in the project’s design and construction.
The constructors were continuously engaged during the design process. They continuously influenced design decisions and provided regular feedback with regard to material costs, material availability, procurement, fabrication costs, transportation of materials, erection costs, speed of construction, and local practices. The designers were likewise engaged in the bidding and procurement processes in that they reviewed bid packages, considered alternative materials presented by bidders, and assessed alternative designs proposed by bidders.
Epstein and Globetrotters were responsible for the architectural and engineering designs, and they provided project management for those designs, served as the principal designers, and also served as the architects and engineers of record for the project. Numerous consultants were engaged and were instrumental in developing successful designs. Epstein engaged several structural consultants with relevant convention center experience to assist with the structural designs. Instead of the traditional approach of assigning different systems or portions of the building to each consulting firm and allowing each firm to work remotely out of its offices, Epstein implemented an unconventional approach, soliciting each structural consulting firm to contribute key people to work full-time out of the project center in Chicago as part of a single structural design team. There would be no division between firms within the team. Each member of the team would identify himself or herself as part of the Mc4West structural group rather than as a member of his or her firm. Moreover, team members would have the opportunity to work on any portion of the project that interested them without preferential treatment or consideration, and the project would not be subdivided into portions or tasks meted out to people from a particular firm. The goal was to create an environment that would integrate strong personnel into a single team with one set of goals and standards in a manner that was devoid of any self‑serving interests and would make it possible for each team member to gain the most rewarding experiences possible. There is unanimous consensus that this strategy proved enormously successful.
he first floor incorporates large column‑free meeting rooms, a secondary ballroom, mechanical spaces, and administration spaces. A roadway bisects the building to provide ingress to and egress from the parking structure, access to public transportation facilities, and truck docks for back-of-house support. The structural system for the first floor is a conventional slab on grade. There are approximately 1,050 column locations supported by isolated foundation elements. The site is extraordinarily large for a single project, and it was not surprising that soil conditions varied dramatically across the site. There is a relatively shallow rock‑bearing stratum at the south end of the site, but it tapers to greater depths toward the north end. Two foundation systems were investigated: a rock‑bearing driven steel pile system and a drilled caisson system. Full designs for each system were prepared and tested in the market for related costs. The drilled caisson system proved to be the most cost effective for the project. There are three types of drilled caissons. The caissons at the northern portion of the site are belled and bear on stiff hardpan clay with an allowable bearing pressure of 16 ksf (766 kPa). The caissons at the southern portion of the site are not belled and bear on rock with an allowable bearing pressure of 75 tsf (7,182 kPa). The caissons between the northern and southern portions are belled and bear on stiff hardpan clay with an allowable bearing pressure of 30 ksf (1,436.4 kPa).
Various challenges were encountered in the design and construction of the foundation systems. The site had been occupied by several generations of buildings since the early 1830s. The previous generation of buildings was predominantly industrial. Some had underground fuel tanks and contributed other contaminants, making the overall site a significant brownfield remediation project. A substantial extent of urban fill had to be evaluated for suitability to support the slab on grade and various grade beam systems. Moreover, underground telephone and electrical cable ducts serve much of the surrounding area. The foundation systems had to be designed to bridge those existing utilities without encroachment; otherwise, there was a risk of inadvertently cutting off services to the adjacent neighborhoods and nearby hospital. Construction work at the southernmost portion of the site was hampered by the proximity of a major interstate highway and various local roadways. Furthermore, access and time limits were imposed by the local and state transportation authorities for the construction of foundation systems near those roadways.
Full designs for the superstructure utilizing precast-concrete framing and full designs utilizing structural steel framing were developed. Hybrid combinations also were developed. The various designs were tested in the marketplace. The ability of the systems to accommodate future modifications by the design/build team or the MPEA also was assessed. Generally speaking, the structural steel solutions prevailed.
The second floor provides space for crate storage, a public food court, and mechanical spaces. The existing South Building and the new West Building uniquely provide dedicated crate storage to make it possible for exhibitors to store crates away from the exhibition areas. This keeps the crates out of sight and provides space for organizing them. The structural bays at this level vary from 30 to 90 ft (9 to 27 m) and are bound with structural steel columns. Most of the floor was required to support 250 psf (11.97 kPa) of superimposed loading as well as loading from forklifts and other types of equipment. The floor slab is typically 7.5 in. (191 mm) thick overall with a 3 in. (76 mm) deep composite steel deck. The slab typically spans 10 ft (3 m) and is supported by structural steel beams that are compositely engaged with the slab. The design and detailing of the framing at this level were challenged by complex horizontal and vertical geometries. In addition to numerous voids, openings, and discontinuities in the floor plate, there are numerous elevation changes throughout the floor. Accounting for these issues was challenging for the design of the framing. It also posed problems for the floor diaphragms, in particular, how the diaphragms would brace the columns against buckling. The second floor spans the roadway that bisects the building; hence, special fire protection considerations affected the structural designs.
| James Steinkamp |
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| At the southeast corner of the exhibit hall the glazed entry admits visitors into a dedicated concourse and exhibit functions during split-hall events. |
The third floor houses the building’s main public facilities. The grand ballroom and exhibition space are located on this floor. The ballroom encompasses more than 100,000 sq ft (9,290 m²), making it the largest ballroom in Chicago. The ballroom also serves light exhibitions, thus requiring the integration of exhibition services and facilities, which had to be concealed owing to the architectural distinctiveness of the ballroom area. Architecturally and structurally expressive public space surrounds the ballroom. Approximately 475,000 sq ft (44,128 m²) of dedicated exhibition space is located south of the ballroom. The dedicated exhibition space is class A space and thus is capable of accommodating the requirements of the most demanding exhibitors. The clearances in the ballroom and the dedicated exhibition space exceed 40 ft (12 m). The central concourse is a grand, voluminous public space that is architecturally and structurally expressive and separates the ballroom from the dedicated exhibition space. The clearances in the central concourse vary from 80 to 100 ft (24 to 30 m), creating a visually striking space. The truck dock apron, which is part of the transportation system connecting the truck marshaling yard with the building, is immediately south of the dedicated exhibition space.
The structural bays that support the ballroom floor typically vary from 30 to 90 ft (9 to 27 m). The bays above the ballroom floor are typically 90 by 180 ft (27 to 55 m). The structural bays that support the dedicated exhibition floor also vary from 30 to 90 ft (9 to 27 m). The bays above the exhibition floor vary from 120 to 180 ft (36 to 55 m). Because both spaces offer exhibition capabilities, a network of floor ports that are interconnected with service ducts in the floors were integrated into those spaces. The floor ports are the lifeline of the exhibitors, providing electrical service, data service, compressed air, gas, water, and drains. The floor ports are placed on a convenient grid to give exhibitors easy access regardless of the layout of their exhibit. The floor ports are interconnected by a grid of ducts in the floor that network the various services. The design/build team evaluated various options for accommodating the floor ports. The selected option was to cast a base slab and a topping slab. The floor ports and floor ducts were placed on top of the base slab, and a topping slab was cast to encapsulate the floor ports and ducts. The base slab was 9 in. (229 mm) thick overall with a 3 in. (76 mm) composite steel deck. The topping slab was 9 in. (229 mm) thick, which was sufficient to encapsulate the floor ports and provide sufficient concrete thickness to span the floor ducts. The slab typically spans 10 ft (3 m) and is supported by structural steel beams or plate girders that are compositely engaged with the slab. Those beams are supported by composite steel rolled girders or plate girders cantilevering over the columns that terminate immediately below this floor. This was an economical solution because the girder design was optimized by negative bending moments that offset some of the positive bending moments. Alternative designs were evaluated with regard to the topping slab. One alternative stipulated that the topping slab not be bonded to the base slab; another stipulated that it be bonded. The bonded alternative reduced the structural steel material but increased the labor and material costs to bond the two slabs. After evaluating the various costs at that point in time, the unbonded alternative prevailed.
The load demands upon the floor framing at the third floor are extraordinary. In addition to the thick base slab and thick topping slab, significant superimposed loads were considered. The ballroom floor must support 250 psf (11.97 kPa) of superimposed live load or a 16 kip (71,171 N) concentrated load anywhere on the floor over a 12 by 12 in. (305 by 305 mm) area. The dedicated exhibition floor must support 350 psf (16.76 kPa) of superimposed live load or a 50 kip (222,410 N) concentrated load anywhere on the floor over a 12 by 12 in. (305 by 305 mm) area to account for outrigger loading from lift equipment. The central concourse floor that connects the two areas must support loadings consistent with the ballroom area. The third floor was also designed for some special loadings related to construction. The design/build team opted to design the base slab to allow loaded concrete trucks to travel across the floor while placing concrete for the topping slab. That was a strategy for potentially accelerating the construction schedule. Other criteria included designing the floor framing at the ballroom area so as not to transmit objectionable vibrations when subjected to dancing or other similar rhythmic loadings.
The columns that project above the third floor (see the cross section above) are relatively large. They form 90 by 180 ft (27 by 54 m) bays in the ballroom area and bays that are typically 120 by 120 ft (36.5 by 36.5 m) in the exhibition area. Though sized for supporting the significant loadings from above, the columns are primarily sized to impart sufficient lateral stiffness to the building above the third floor. The lateral resistance system for the building uses diagonal braced frames below the third floor and moment frames above the third floor. The moment frames were developed by connecting the top and bottom chords of the roof trusses to the megacolumns in both orthogonal directions. Rolled columns that are not part of the lateral resistance system support intermediate roofs and other various geometries. Those columns are generally concealed from view.
Space for housing mechanical equipment is adjacent to the ballroom at the fourth floor. Meeting rooms are located south of the central concourse. A food service area is located at the center of the exhibition space. The most challenging design issues at this floor had to do with the meeting rooms. The framing at that area typically spans 90 ft (27 m). The framing is suspended from the roof trusses above that vary in span from 120 to 180 ft (36.5 to 54 m). The client wanted framing that would not exhibit noticeable vibrations from the various activities. The dynamic properties of the roof framing and floor framing are very different and are three-dimensionally linked. The design team developed a detailed three-dimensional model of the floor framing, slabs, and roof trusses and imposed synchronized dynamic impulse loadings along various paths to simulate activities on the floor. The accelerations resulting from this time-history analysis were compared with acceptable threshold limits, and the framing was modified until those limits were satisfied.
The roof structure is typically framed with trusses. The roof has “green” features as part of the strategy to achieve the LEED certification. Steel roof deck was typically used throughout. Conventional 1.5 in. (38 mm) deep roof deck was used over the dedicated exhibition area, and 3 in. (76 mm) deep acoustical roof deck was used over the ballroom. The spacing of secondary trusses and roof purlins was optimized to exploit the span capabilities of the various deck profiles. The roof deck also acted as a flexible diaphragm for distributing lateral loads to the lateral resistance system.
The geometry of the roof at the ballroom area is relatively complex, and its numerous elevations challenged the detailing of load paths for distributing lateral loads to the lateral resistance system. The location of effective brace points for columns had to be carefully considered. The framing directly over the ballroom uses trusses spanning 180 ft (54 m). The framing north of the ballroom cantilevers 45 ft (13.7 m) to the north, forming the dramatic overhang for the north elevation. The architects desired a slender profile for the overhang. In response, tapered plate girders were used for the cantilevered framing. An intermediate roof terrace directly beneath the overhang with plush landscaping is integrated into an outdoor dining area. The framing for the outdoor dining area also was designed to mitigate vibrations from dancing.
The roof over the dedicated exhibition space is generally framed with trusses. There are primary trusses that frame to the megacolumns at 120 ft (36.5 m) spacing, secondary trusses spaced at 30 ft that frame between the primary trusses, and purlins spaced at 7.5 ft (2.3 m) spanning between the secondary trusses. The trusses typically cantilever 30 ft (9 m) along the east and south elevations to form the overhangs associated with the architectural expressions for those elevations, matching the corresponding architecture at the adjacent South Building. The trusses above the exhibition area also support a heavily loaded mechanical penthouse. The trusses are further challenged in that they must support the fourth floor meeting rooms that are hung from the trusses while contributing adequate dynamic properties to mitigate vibrations from the penthouse area or from the meeting rooms below.
The roof trusses are typically 13.5 ft (4 m) deep as measured from the centers of the chords. That proved to be an efficient depth for both structural and functional purposes. A network of service catwalks makes its way through the trusses. There are also many large mechanical ducts. The depth of the trusses not only had to be sufficient to produce efficient structural elements but also had to provide adequate clearances for those walking on the catwalks, even at duct crossings. The depth was also chosen to allow truck transportation of fabricated trusses without the need for special permits. That was a critical cost and scheduling consideration. The trusses were typically fabricated in two or three segments that were subsequently spliced together in the field.
Additional load demands upon the trusses included accommodating hanging loads imposed by the exhibitors. The trusses in the dedicated exhibition space allow for a 6 kip (26,689 N) hanging load at each panel point. Moreover, the bottom chord bracing and the roof purlins allow for two 500 lb (227 kg) hanging loads from those elements. The trusses and secondary framing in the ballroom roof provide similar capabilities but of lesser magnitude since that area is dedicated to lighter convention exhibits.
The central concourse is an architectural extension of the grand concourse at the South Building. The clearances in the central concourse vary from 80 to 100 ft (24 to 30.5 m). The structural steel columns, roof beams, roof purlins, and roof trusses are architecturally exposed to final view. The detailing of those elements and associated connections had to be carefully implemented in accordance with American Institute of Steel Construction requirements for architecturally exposed structural steel along with additional requirements imposed by the architects. The columns are box shaped and are built up from plates. Box beams frame to the box columns in the north–south direction to provide a moment frame for the lateral resistance system. Rolled shaped purlins span between the box beams. The purlins support the steel roof deck. Roof trusses in the east–west direction frame to the box columns at the north and south edges of the concourse. Though primarily for architectural expression, the trusses are also used to create moment frames. There are two structurally significant trusses at the west end of the concourse that provide the fundamental support for the City Gate entry at the west elevation. The City Gate entry features a 120 ft (36.5 m) tall lantern that serves as a beacon to approaching visitors. These two trusses are connected to create a three‑dimensional truss element. The box truss is approximately 275 ft (84 m) long and cantilevers approximately 45 ft (13.7 m) to the west as part of the City Gate entrance. Floor framing at the third floor is suspended approximately 100 ft (30.5 m) below from the box truss. The box truss also supports a tall glazing system. It had to cantilever in both the vertical and horizontal directions to resist both gravity loads and lateral wind loads from the tall glass facade. Vertical and horizontal deflection criteria were stringent, and meeting them proved challenging.
There are numerous facade systems on the building. Each building elevation creates a unique expression that relates to the neighborhood adjoining those elevations. Highly articulated, architecturally expressive, and geometrically challenging, the facades span great distances because of the large clearances within the building spaces. Other complementary features include glass canopies, cable-supported canopies, overhangs, soffits, and other elements similar in nature for supplementing the three‑dimensional quality of the facades. The complex geometries required various structural systems for the facades and these other features. Geometry, deflection, and loading criteria were stringent and posed many design challenges.
The truck transportation structures that connect the truck marshaling yard to both the South Building and the new West Building include an elevated bridge between the South Building and the West Building, a new elevated truck apron at the south end of the new building, and new ramps onto the apron. The transportation structures pass over a major street, are above major streets, and are immediately adjacent to an interstate highway. The proximity to those roadways posed many difficulties with regard to design and construction. Numerous infrastructure utilities had to be located and avoided. Moreover, the transportation authorities imposed various design criteria and restrictions, and construction was restricted to certain times and conditions. The transportation authorities were also concerned about views from the roadways and possible sight obstructions. The design team responded by designing architectural precast walls with planters for screening the transportation structures from view. Sight lines were carefully evaluated and approved by the authorities.
The new truck transportation structures were integrated with the existing systems at the South Building. When the existing truck transportation systems at the South Building were designed, it was not envisioned that there would one day be a connection for a building to the west. Hence, substantial modifications were required to the South Building to integrate these new transportation structures. A new junction had to be created in the South Building’s internal ramping system. That made it necessary to remove a portion of a corner from the South Building, modify the existing roof framing, and modify the underlying structure at the new junction, tasks that proved particularly challenging. Structural elements supporting substantial in‑place loads at the exhibition area at the South Building were removed and supplemented with new framing to create a new geometry. Existing diagonal bracing for the South Building had to be relocated and modified. Existing facade elements had to be salvaged and replaced in the new geometry. All of these modifications had to be implemented without adversely affecting ongoing convention activities at the South Building. The designs had to complement that type of implementation.
The transportation structures were designed for truck loadings as defined by the American Association of State Highway and Transportation Officials. The structures also had to support very large chilled-water lines that were added between the central energy building and the new West Building. The new transportation structures provided a convenient and concealed path for the new pipes to the new building. The design of the structures had to satisfy various clearance requirements while meeting predefined elevations at the existing South Building and the new West Building.
The original framing concept for the truck transportation structures specified steel columns, steel box girders for the piers, and steel stringers spanning between the box girders. One of the bidders, a firm that specializes in concrete construction, suggested modifying the structure to use concrete framing and offered associated cost savings. The design/build team responded by preparing an alternative design, in a design/assist mode, to use concrete columns, posttensioned-concrete girders for the piers, and I-beam stringers of precast, prestressed concrete spanning between the piers. The alternative design proved to be the most economical solution and was the one that was constructed.
Integrating the new West Building into the campus required other modifications to the existing South Building. New escalators, elevators, and stairs were added to the existing building. Some of the lobbies of the South Hall were modified to enhance those entries. Bays were removed from the existing posttensioned parking structure and existing conference center to make way for the new building. Portions of the existing parking structure were modified to accommodate new emergency egress paths from the new building. New mechanical equipment was placed on top of the existing parking structure. An expansion joint at the existing conference center was moved to the interface with the new building. Existing framing at the South Building had to be supplemented to enable the framing to support very large service pipes from the central energy building to the new building. All of these modifications had to be implemented without adversely affecting any activities at those existing facilities. Design concepts had to facilitate construction under such circumstances.
An original facade from the old Platt Luggage Building had been salvaged during the construction of the conference center and parking structure by previous designers and contractors for those structures. The location of this facade now interfered with the planned layout of the new West Building. As part of this project, the facade was moved to another location approximately a block away, where it formed the front of the existing central energy building. A structural steel support system cantilevering from the ground was designed and constructed in front of the central energy building for supporting the relocated facade. The facade was carefully dismantled brick by brick, the location of each brick and cornice element being cataloged. It was then reassembled in the new location, each brick and cornice element replaced in its original position. All of this work was supervised and approved by experts in the field of historic preservation.
A neighborhood portal was constructed along the edge of the campus that signals arrival at both the McCormick Place campus and the Bronzeville neighborhood to the south. It is a cable structure that spans 180 ft (55 m) in crossing a complex roadway intersection. The cable structure receives point-supported glass and metal panel cladding without hiding the cable structure. The structure is flexible and sensitive to wind-induced vibrations. Climatic data were collected and the structure was analyzed considering geometric nonlinearities while subjected to dynamic loadings that modeled various wind conditions. Dynamic analyses in the time domain as well as stochastic dynamic analyses in the frequency domain were performed for various wind gust conditions. The structure was proportioned, pretensioned, and detailed to eliminate flutter from the various wind conditions.
he building, as mentioned above, qualified for LEED certification, a first for a building of this scale. The green strategies included implementing energy-efficient designs, using recycled materials, ensuring that recycling was carried out by the contractors, implementing designs focused on water efficiency, and recycling storm water.
More than 30,000 tons (27,216 metric tons) of structural steel used for the project utilized recycled materials. During construction, the constructors spared landfills nearly 15,000 tons (13,608 metric tons) of waste materials. Mechanical designs focused on energy efficiency. Designs reduced water usage by more than 35 percent. The storm-water management strategy used for this project sent nearly 60 million gal (227,100 m³) of clean rainwater back to Lake Michigan through a 3,385 ft (1,032 m) long storm-water tunnel. Also part of the storm-water management is the use of green roofing systems. Nearly 150,000 sq ft (13,935 m²) of vegetated roof area reduce runoff of storm water. The selection of roofing was also instrumental in improving energy efficiency. Approximately 850,000 sq ft (78,965 m²) of highly reflective roofing lowers air-conditioning energy expenditures as well as the urban heat island effect.
One of the LEED innovation points earned for the project came from the use of a storm-water tunnel. The inspiration for the tunnel system came from the city’s history. Built on what was essentially swampland and now developed with buildings, parks, and parking lots, Chicago has long battled water management. The city’s sewer system is based on the antiquated concept of “combined sewers,” wherein storm water is conveyed to treatment plants in the same underground piping system that carries sanitary waste. Heavy rains routinely overwhelm the city’s combined sewer system, flooding roadways and basements and, worse, occasionally forcing the release of untreated wastewater into the Chicago River and Lake Michigan, which are Chicago’s primary source of freshwater.
In 2003 the City of Chicago, under the leadership of Mayor Richard M. Daley, unveiled an agenda for water management that, among other goals, “recognizes that managing storm water, protecting water quality, and promoting conservation are all part of the same goal.” In close cooperation with the mayor’s office, the city’s Department of Water Management, and the U.S. Army Corps of Engineers, the McCormick Place West expansion became the first development in Chicago to make use of a storm-water tunnel to convey clean rainwater back to Lake Michigan.
The drainage tunnel is 12.5 ft (3.8 m) in diameter and 3,385 ft (1.032 m) long and was installed in solid rock at an elevation approximately 150 ft (45 m) below grade. The difference in elevation between the inlet shaft and the outlet shaft allows the pressure head to force the storm water through the tunnel and out into Lake Michigan without the use of pumps. An inlet shaft near the intersection of Prairie Avenue and Cermak Road and an outfall shaft at the southern end of Northerly Island provide the beginning and end of a siphon-based drain capable of returning roughly 61 million gal (230,885 m³) of water to Lake Michigan each year. That same quantity of water no longer burdens the city’s water treatment system, saving energy, sparing the antiquated combined sewer system a great deal of water, and passively recharging Lake Michigan. The system was commissioned in May 2006.
he structural designs commenced in June 2003 in the schematic design phase. The foundation designs went out for bid in January 2004 and the structural steel designs, along with the concrete designs, went out for bid the following month. As previously mentioned, material quantities for the various structural systems were established before the project was awarded to the design/build team. Those budgeted quantities were developed from preliminary, but detailed, engineering studies. The bidding process would reveal how the quantities associated with the final designs compared with the budgeted quantities.
The bids for the foundation and concrete designs indicated that the quantities were within budget, as were the costs. The structural steel bids revealed both good news and bad news. The good news was that the quantities were within budget; the bad news was that the cost of the structural steel was significantly above budget. The cost overrun was a result of some relatively recent and unforeseen market conditions.
The structural steel was put out for bidding in early 2004, a time of record-setting prices for structural steel and related work. Material costs, the availability of plate material, and erection costs were unusually critical for this project. Many project elements required plate material as a result of the unusual spans, the extraordinary loadings, the geometry, and the architectural requirements. Not as many steel erectors bid on the project as anticipated, to some extent because of the great size of the project and the general abundance of work already under contract. The lack of sufficient competitive pressure on the erection bids resulted in unusually high bids, even relative to material costs that were setting records. This forced the design/build team to create cost-saving opportunities with a particular focus on material quantities, plate usage, and erection costs. Prospect Steel Company, of Little Rock, Arkansas, was selected as the steel fabricator and worked with the design team in reducing costs. Time was of the essence because it was imperative to mill order the steel within the next three months for cost and scheduling reasons.
The design/build team developed more than 70 cost reduction ideas. The structural designs of various systems were modified to incorporate many of those ideas within the time that was allotted. Following are some of the cost reduction strategies:
- Bonded topping slab at third floor: The design/build team revisited the idea of bonding the 9 in. (229 mm) thick topping slab to the 9 in. (229 mm) thick base slab at the third floor. It had previously been determined that it would be more cost effective not to bond the topping slab to the base slab. However, with the cost of steel material at record levels, the results of that cost formula were likely to change. Studies were performed to evaluate the effect of discontinuities in the topping slab from the floor ports and floor ducts. The floor framing was then redesigned, and the reduction in structural steel material exceeded 500 tons (454 metric tons). The net result was a cost reduction despite the increased labor and ancillary material costs to bond the slabs. The bonding was accomplished by roughening the surface of the base slab and also applying a bonding agent.
- Plate material: The availability of plate material was of paramount importance. The project designs used a substantial amount of plate. Opportunities to reduce the amount of plate material were investigated. Box columns built up from plates were designed for use in the central concourse, at the north elevation of the building, and at a few other locations. The use of box columns was primarily for architectural reasons although the beneficial shape was structurally exploited. Those columns were exposed to view above the third floor; however, they were not exposed to view below that floor. The columns were converted to rolled sections below the third floor while maintaining the box shape above. The transition in shapes was unusual in appearance until the architectural treatments were in place but resulted in an effective use of materials.
Box beams built up from plates were designed for use in the central concourse. The use of box-shaped beams was also primarily for architectural reasons because they were to be exposed to final view. The beams were converted to hybrid sections. A rolled section was used with cover plates welded between the flanges on each side. That imparted the appearance desired by the architects. The overall weight of the beams increased but the use of plate material decreased. The net effects were cost savings as well as time savings for procurement.
The fabricator offered a suggestion that also reduced the use of plate material: a configuration for eliminating gusset plates at trusses that used double‑angle web members. The chords were turned in such a way that the webs were horizontal. The angles from the double‑angle web members were separated and welded directly to the outside of the chord flanges. The new truss configuration did not always allow the intersection of centerlines from adjacent web members to coincide with the centerline of the chords. The eccentricities that resulted were subsequently considered during the redesigns. The end result was an increase in rolled section and angle materials, but that cost increase was substantially offset by reductions in the fabrication labor, fabrication time, and procurement time associated with gusset plates.
There were more than 5 mi (8.1 km) of slab edge conditions. Bent steel plate was detailed at many edge conditions because of the length of overhang and various loading conditions. Redesigns focused on reducing the length of some of the overhangs. Where that was not possible, a light-gauge edge angle that was internally stiffened with small horizontal outrigger angles was considered. Both endeavors substantially reduced the extent of bent steel plate.
- Modifications to framing layout: As previously described, the erection costs were of overriding importance on this project. Investigations focused primarily on reducing those costs. The framing layout at various areas was modified to eliminate columns and use beams that would span greater distances, an unconventional approach for reducing costs. The goal was to reduce the number of pieces to be handled by the erector, even at the expense of increasing the weight of material. This proved to be a successful strategy at various areas of the building.
- Roof joists versus roof beams: The original design used joists for the roof purlins, generally regarded as an economical framing scheme. However, the apparent steel erector for the project voiced a preference to erect steel beams instead of joists. Considering the unusual premium on erection costs for this project, the design/build team responded to that suggestion. An alternative design using rolled beam purlins was developed. That particular erector, Danny’s Construction Company, Inc., of Chicago, was ultimately selected for the project; hence, the rolled beam alternative proved to be the most economical solution despite the increase in material weight.
- Steel erection: As a result of the high erection bids, the constructors considered performing the steel erection themselves and made appropriate arrangements. That added another competitor to the field and perhaps was instrumental in achieving improved bids for the erection work.
Most of the above strategies were unconventional. In many instances, the material quantities were increased; however, the savings realized from reduced labor costs more than offset those increases. The common perception is that less material saves money. These strategies proved otherwise for this particular project. The resulting cost savings were sufficient to keep the structural costs within budget.
Steel erection commenced in November 2004. The designers and constructors worked closely throughout the construction phase to ensure prompt review of shop drawings, prompt responses to requests for information, and collaboration to resolve field issues. As was the case prior to construction, the collaboration was extremely effective. The results demonstrated the benefits of a design/build delivery system. The project was delivered to the MPEA in August 2007, nine months ahead of schedule.
Steven C. Ball, P.E., S.E., LEED AP, is a senior vice president and the director of structural engineering for A. Epstein and Sons International, Inc., in Chicago. He served as the structural project director, lead structural designer, and structural engineer of record for the McCormick West Building expansion project.
Project Credits
Owner: Metropolitan Pier and Exposition Authority, Chicago
Concept architect for owner: Thompson, Ventulett, Stainback & Associates, Chicago
Mc4West, LLC partners:
Clark Construction Group, LLC, Bethesda, Maryland
Hunt Construction Group, Inc., Scottsdale, Arizona
A. Epstein and Sons International, Inc., Chicago
Mesirow Stein Development Services, Inc., Chicago
Globetrotters Engineering Corporation, Chicago
II-in-One Contractors, Inc., Chicago
Mota Construction Company, Chicago
Pentad, Inc., Chicago
Cotter Consulting, Inc., Chicago
McKissack & McKissack Midwest, Chicago
Take II, LLC—Design Architects and Engineers, Chicago
Design team leaders:
Mickey Kupperman (Epstein), project principal
Michael Damore (Epstein), project executive and architect of record
John Adams Dix, AIA (Epstein), project director
Carl Gergits, AIA (Epstein), project director
Mike Parlato, P.E. (Epstein), assistant project manager
Dean Mamalakis, AIA, LEED AP (Epstein), director of architectural design
Rael Slutsky, AIA (Epstein), deputy director of architectural design
Steven C. Ball, P.E., S.E., LEED AP (Epstein), structural project director and structural engineer of record
Zygmont Boxer (Globetrotters), mechanical, electrical, plumbing, and fire protection coordinator
Ken Beilke, P.E. (Epstein), lead mechanical engineer and engineer of record
Sal Hamdi-Pache, P.E. (Globetrotters), lead plumbing engineer and engineer of record
Frank Kloht, P.E. (Globetrotters), lead electrical engineer
Keith Klodzen (Epstein), lead civil engineer
Dan O’Connor, P.E. (Schirmer Engineering, Chicago), life safety and fire protection engineer and fire protection engineer of record
Paul Rogas, P.E. (Epstein), lead electrical engineer and engineer of record
Tom Smiles, P.E. (Epstein), civil design coordinator and engineer of record
William Wagner (Epstein), senior technical architect
Structural team:
A. Epstein and Sons International, Inc., Chicago
Walter P. Moore and Associates, Tampa, Florida
Graef, Anhalt, Schloemer & Associates, Inc., Milwaukee
Matrix Engineering Corporation, Chicago