“The weather and site restrictions and their effect on maintaining the budget and schedule was the most unique challenge to solve on this project. The willingness of both the design and construction teams to use BIM and a collaborative workflow and to push both of them to new levels mitigated the potential problems that could have occurred.”— R. Wayne Muir, P.E. Photo: Solaris

Solaris is a mixed-use project located in the heart of Vail, Colo., consisting of six stories of condominiums and more than three stories of retail, office, and parking facilities. In addition to two stories of restaurant and retail space, amenities include a 10-lane bowling alley, three movie theaters, an enclosed pool/fitness area, 300 enclosed parking spaces, and a loading dock that accommodates delivery trucks (including 18-wheel tractor/trailer combinations). The structure is nine stories tall on the north side and seven stories tall on the south side, and it wraps around a plaza that functions as a central gathering location for the town of Vail. The plaza serves multiple functions in the summer and is used as an ice-skating rink during the winter. The plaza also is used to display $1 million worth of artwork (consisting of three individual pieces).

The following slideshow highlights more stunning details of Solaris (all photos: Michael Calanan, www.calanan.com).

Luxurious additions such as a pool allow residents to enjoy what Solaris' website calls "the amenities of a grand hotel with the intimacy of a fine residence."

Whenever possible, both the exterior building materials and interior finish selections consisted of sustainable products, notes Scott Nevin, architect of record on the Solaris project.

Beneath its residential units, Solaris provides elegant dining, open-air ice skating, state-of-the-art movie theaters, bowling, and a shopping center. In fact, an Aug. 4 article in the Vail Daily says Solaris has seen various retail tenants opening for business, many of which already have a Vail store or have decided to close another location in order to relocate to the mixed-use property.

Solaris marks the first time Structural Consultants, Inc. (SCI), used a BIM model as the structural engineer of record on a project. Previously, SCI used BIM models for assisting in the design of performance specified elements such as steel connection design for the Denver Art Museum.

Solaris is nine stories tall on the north side and seven stories tall on the south side, and it wraps around a plaza that functions as a central gathering location for the town of Vail.

Schedule
The project’s preliminary design began in 2004, and because of the extended amount of time required for the owner to obtain final approval by the town of Vail, the design team was not given notice to proceed with final design until January 2007. In order to maintain the original occupancy schedule, the structural engineer was asked to accelerate his workflow to deliver a building permit set of structural documents on Oct. 1, 2007, and to issue a final contract document (CD) set on Nov. 1, 2007. The architectural and mechanical, electrical, and plumbing (MEP) design-development documents were issued June 20, 2007, and final architectural and MEP CDs were issued on Aug. 8, 2008. In order to mitigate the risk associated with the accelerated schedule, our experienced structural engineering team assisted the general contractor in coordinating building information modeling (BIM) models for the detailing, fabrication, and erection of the major structural system subcontractors — the concrete foundation, structural steel, and precast suppliers. Steel fabrication began five months prior to the issuance of architectural and mechanical CDs. Steel erection began on July 7, 2008; foundations were completed Sept. 1, 2008; precast erection was completed Oct. 15, 2008; and structural steel erection was completed in March 2009.

The design
At the inception of the project, the owner challenged the team to seek out the latest technology and use any state-of–the-art methods necessary to improve workflow to create a “world-class project.” In response to the challenge, our structural engineering team — who was contracted directly with the owner — recommended that implementing BIM and an integrated-project-delivery (IPD) approach. We felt strongly that IPD would enable the design team to meet the project requirements, which included complicated load paths, on-time delivery of all structural components despite the site constraints, as well as the integration of complicated mechanical systems into a desired minimal floor-to-floor height. BIM also allowed the owner and design team to visualize and coordinate the very complicated structural levels below the residential units, including bowling alleys, movie theaters, a pool, a loading dock, mechanical-equipment rooms, and underground parking.

The structure
The building foundation is a cast-in-place concrete mat varying in thickness from 2 to 12.5 feet that extends up to 20 feet into the underground water table, which at peak runoff times has a calculated flow rate of 1,800 gallons per minute. The exterior foundation walls; buttress walls located along the north, east, and west foundation walls; and interior stair and elevator cores are precast concrete elements that resist the lateral loads caused by geotechnical, seismic, and wind forces. The superstructure below grade consists of precast double tees, inverted tee beams, columns, and walls below the residential units on the north side of the site, and a structural steel frame supporting composite concrete floors below the plaza on the south side.

A structural steel superstructure frame supporting composite concrete floors was used for the residential and commercial levels. The residential level column layout conflicted with the retail and parking-level layouts below, hence transfer elements were used to transition the column loads down to major load-bearing precast walls, which were located on 60-foot grids between parking bays. Heavily reinforced steel and precast beams and girders were used as the transfer elements along with four, structural steel, full-story trusses (three over the loading dock and one over the main parking entry). The largest truss over the movie theater area spans 49 feet, and its bottom chord weighed 42,000 pounds, which required a coordinated tandem lift with two tower cranes.

Because of the required floor-to-floor heights and the desire to use a steel framing system to accelerate the schedule in a high-mountain construction environment, the team decided to design the steel frame to include the penetrations needed for mechanical system routing. Approximately 18,500 penetrations through the steel beams and girders were designed and modeled prior to fabrication. A complicated hip-and-valley steel roof structure was designed to support a 200-pounds-per-square-foot (psf) snow load, which included drifting effects. The exterior walls use 6-inch cold-formed steel studs as the backup to a full-dimensioned stone veneer.

The structural system includes a steel superstructure above grade and a precast structure in the below grade parking structure. As a result of the extreme winter conditions and an aggressive schedule, the team chose to use precast walls for the stair and elevator cores and the lateral buttress walls in lieu of cast-in-place concrete. Photo: Michael Calanan, www.calanan.com The entire project team — the structural engineer, architect, construction manager, MEP engineers, electrical and fire protection subcontractors, and major structural subcontractors — used a fabrication-tolerance BIM for this project. This is the combined architectural and structural model in Tekla Structures. Image: Structural Consultants Inc. and Davis Partnership Architects The use of BIM allowed for the successful incorporation of approximately 18,500 penetrations in the steel structure, which enabled an entire additional floor of salable units. Photo: Structural Consultants Inc.

BIM
BIM was used by the structural engineer, architect, construction manager, MEP engineers, electrical and fire protection subcontractors, and major structural subcontractors to enhance the collaborative approach taken by the design and construction teams. BIM allowed for a high degree of understanding of the impacts of the tight floor-to-floor structure coupled with a desire for tall ceilings, while accommodating the infrastructure needs of a varying residential floor-plan arrangement that often did not allow for an efficient “stacked” structural system. The floor-to-floor heights forced the MEP systems into the same plane as the structural steel, which allowed nine stories above-grade without exceeding the building-height limitations. While many penetrations were understood and designed prior to erection, many others were requested after steel was in place. The use of BIM technology gave the design team, as well as the fabricators and erectors, the ability to select the best placement for added penetrations considering both design and constructability. The interaction using models created to fabrication tolerances instilled confidence in all the parties involved that the solutions contemplated were correct. BIM also helped involve the owner and his development team in a meaningful and helpful way by allowing them to visualize the architectural spaces, as well as the infrastructure, very clearly. The impacts of changes in the design were easy to illustrate to the affected parties, which resulted in the avoidance of guess work in the office and rework in the field.

Preliminary review of the project’s very complicated vertical-load path and the complex geometry of the roof structure indicated that a traditional 2D approach to producing construction documents would be extremely difficult, if not inadequate. Our structural engineering team recommended to the owner that we approach the town of Vail together for acceptance of the 3D structural BIM model of the roof as the building department permit submittal along with the traditional set of 2D contract documents and specifications; the 2D documents would govern for all of the structure except the roof, and the 3D model would govern only for the roof. The town of Vail agreed to this approach, and we assisted the town’s structural plan examiner in viewing and understanding the BIM model during his review.

To meet an aggressive steel fabrication and erection schedule, the contractor and design team agreed to a five-day shop-drawing review period, with the structural engineer using the last three days to do a review and coordinate and incorporate the comments of the other team members into one set of drawings that were returned to the fabricator. The structural BIM model, which had originated in the structural engineer’s office, was being further developed by the steel detailer, fabricator, erector, and general contractor. The models were continuously being exchanged between the parties and reviewed using video and web conferencing to solve conflicts rapidly. To minimize changes to the detailed design once shop drawings were issued, the fully detailed steel model was transmitted to the structural engineer for his review prior to publishing the shop drawings. As a result, the majority of the shop-drawing-review effort was complete prior to the team receiving the 2D shop drawings; typically, only connection welds were left for final review.

Project results
Some of the tightest fit-up issues associated with the project were at the interface of the buttress wall connections to the mat foundation. Of a total 870 pieces of precast, only two were recast prior to being shipped to the site. The as-built precast erection was to a 3/8-inch tolerance, which allowed for an efficient erection of the steel frame. There were no major fit-up problems in the field, since the extensive use of BIM during the shop-drawing phase allowed for quick and accurate coordination of the connections between the structural steel and the precast concrete, and no major fit-up problems were encountered during the simultaneous precast and steel erection.

The use of BIM allowed for the successful incorporation of approximately 18,500 penetrations in the steel structure and design modifications to the roof during construction without schedule delay. BIM also provided the level of efficiency required to accommodate on-time delivery of all construction materials with extremely limited access to the site.

Using a construction-tolerance model to compress the shop drawing approval process enabled the team to meet an aggressive steel fabrication and erection schedule. Photo: LPR Construction Co.

The degree of interoperability between the team member’s BIM platforms increased dramatically over the course of the project, as software improved and the entire team gained experience working in a collaborative environment. The result was the ability to deliver a complicated project constructed during four seasons (including ski seasons) in the mountains of Colorado at an 8,000-foot elevation.

Solaris Owner Solaris Property Owner LLC, Vail, Colo. Structural engineer Structural Consultants, Inc., Denver Design architect Barnes Coy Architects, Edwards, Colo. Technical architect Davis Partnership Architects (Architect of record), Edwards, Colo. MEP engineer Flack and Kurtz, San Francisco Geotechnical engineer CTL Thompson, Inc., Denver Construction manager The Weitz Company, Denver

R. Wayne Muir, P.E. Photo: Michael Calanan, www.calanan.com Spotlight: Structural Consultants, Inc., Denver Q&A with the structural engineer R. Wayne Muir, P.E. (RWM), a principal at Structural Consultants, Inc. (SCI), and the structural engineer of record for Solaris, shared some insights about the project with Structural Engineering & Design Editor Jennifer Goupil, P.E. (JG). JG: What was most interesting thing about this project that inspired you during the design process? RWM: The opportunity to work directly with the owner to use our previous experience [with] and knowledge [of] BIM and IPD to meet the goals of the project. JG: What was the first task you needed to do to get started on the design? RWM: Understand the complexity involved with the geometry created by the overlaying of residential framing on top of commercial framing on top of a precast parking garage while incorporating a major loading dock and movie theaters into the structure. JG: What software did the design team use for the project design? RWM: Tekla Structures was used as the platform for the modeling of the structure and the overlay of other team members’ models. The use of this program greatly enhanced our ability to lead the structural design/detailing/fabrication team and coordination of the structure with the other design and construction team members in an IPD approach to project delivery. JG: To what extent was BIM used on this project? RWM: BIM was used from the start of the project and the decision was made to model to fabrication dimensional accuracy to reduce errors and lower the costs of the structural systems and components. The structural model was used for extensive coordination, for handling of 3D RFIs, as a tool for checking shop drawings, and as a means to communicate using a 3D environment. JG: What was the most challenging aspect of the structural design? RWM: The different spacing of vertical-load-carrying members for the different functional spaces stacked on top of each other. Major steel and precast transfer elements were used to accommodate the complicated load paths. JG: What new design innovations were employed by the structural design team? RWM: It was the first time we used a BIM model as the structural engineer of record on a project. Previously, BIM models only were used by SCI for assisting in the design of performance specified elements such as steel connection design for the Denver Art Museum. JG: Were there any surprises? How did you adapt to them? RWM: The geotechnical consultant indicated that there was a very high seasonal water table below the site, and that the flow rate was in the range of 2,000 gallons per minute. Firm Facts Structural Consultants, Inc. (SCI), established in 1977, is a full-service structural engineering consulting firm located in Denver. It provides comprehensive design and consulting services to architects, owners, developers, general contractors, sub-contractors, fabricators, and suppliers. SCI has extensive design experience in the commercial, medical, educational, hospitality, financial, industrial, and recreational industries. It offers unique design services in the areas of renovation/rehabilitation, preservation of historical structures, tunnel formed concrete structures, and specialized medical facilities to house sensitive equipment such as MRIs, linear accelerators, and gamma knives.

Q&A with the architect Scott Nevin (SN), a principal-in-charge at David Partnership Architects, the architect-of-record for Solaris, shared the following information about the project. JG: What was one of the most interesting things about the design? SN: To comment on one of the more interesting structural items, the loading dock located over the movie theater and under multiple stories of condominiums required an interesting design solution. The loading dock had to be designed to resist the vibration of the trucks, and the spans required for the fully enclosed loading dock also required a full-floor truss above the loading dock. This truss took the column loads from the floors above; it had to integrate itself by hiding within a condominium unit and transferring the loads to a loading dock. JG: What was the most unique problem to solve on the project? SN: One of the more unique problems to solve on this project was finding how to distribute the MEP systems in the interstitial space between floors while maximizing the ceiling heights within the units. The simple solution would have been to remove a floor, but this would have removed too much sellable square footage, so we elected to literally cut as many holes into the steel structure to distribute all the MEP systems. What is not seen on this project is the fact there is more going on between the floors than is evident on the surface. The steel structure therefore shared the same zone as the MEP systems. The only way to solve this and know it could be built was to utilize the BIM technology and model for the structure. JG: What unique challenges were solved with direct collaboration with the structural engineering team that would have been difficult otherwise? SN: This project would not have been a success if SCI and Davis Partnership had not worked together on other BIM/REVIT projects. BIM allowed this very complex design and structure to be built with the precasters and multiple steel fabricators without a hitch.

By the numbers: Solaris Size, shape, and type Number of square feet: 527,316 Number of stories: North side: 9 South side: 7 Structural system: Precast core walls for the full height of the building; precast walls and steel columns for vertical loads Underground parking: Precast double tees and girders Above-grade: Structural steel frame with composite steel deck slabs anchored to precast concrete elevator/stair cores for lateral stability Foundation type: Cast-in-place concrete mat foundation and precast foundation with buttress walls. Quantities Tons of structural steel: 6,210 Tons of rebar in mat slab: 1,400 Cubic yards of concrete in mat slab: 19,000 Square feet of concrete flatwork: 620,000 Schedule and Cost Structural design: 10 months Architectural and MEP design: 19 months Construction: 37 months Cost: More than $200 million

R. Wayne Muir, P.E., has been a principal and owner of Structural Consultants, Inc., a Denver-based structural engineering consulting firm, since 1984. He can be reached at 303-399-5154 or wayne@sci-denver.com.