The University of Utah Hospital in Salt Lake City is a major health care provider for the state. The hospital has aggressively grown in recent years to meet the needs of the growing community. Beginning in 2001, a major facilities expansion began. The new Eccles Critical Care Pavilion was completed in 2003, as well as a new, nearby two-level parking structure with a heli-pad on top.
In 2006, a $100-million contract was awarded, and construction began on the vertical expansion of the Eccles Critical Care Pavilion and a new West Pavilion. That contract included adding two floors to the Eccles Critical Care Pavilion, which had been completed only three years earlier. These contracts were all awarded to The Layton Companies Inc. of Sandy, UT.
This project is complex and challenging. The fact that the parking structure was not designed for vertical expansion was simple to solve compared to many other difficulties on the project.
The owner organizational chart for the project is a little unusual in that the University Hospital is part of “University Health Care” that functions as the owner, under the overview of the University of Utah. The state of Utah provides authorization and funding. That means any significant changes might be facing all of those levels for authorization. In spite of this complexity, the Layton management says the process is “nimble” in addressing such changes.
Reinforced Foundations
In order to build onto the existing parking structure, foundations had to be reinforced to essentially support the addition as a new structure attached to the existing one. Combinations of micro-piling and/or spread footings accomplished this.
The support columns in place were essentially doubled with a new column attached. Additional columns were constructed between the existing columns to meet loading requirements.
The exterior walls are cast-in-place concrete, precast concrete and brick veneer. The floors are suspended concrete slabs with post-tensioning and steel reinforcing. During the construction of the parking structure addition, the helicopter landings were temporarily relocated to the east side of the hospital.
Construction designs in Utah are very responsive to heightened levels of concern about seismic activity. All of the structures, especially the actual hospital buildings, are being built to address those concerns. The Wasatch Range bordering greater Salt Lake City area on the east is known to have numerous fault lines that show a history and increased risk of seismic activity.
The west expansion is designed with a structural steel frame with special core braces used for the lateral bracing system to stabilize the structure in a major seismic event. The core bracing is adjustable until welded into the final position. The principle of the core bracing is to make triangles from parallelograms, as triangles are almost inflexible. That principle has been used in construction for over a century.
The steel frame at the lowest levels has 14-inch web by 500-pounds-per-linear-foot columns. As the columns rise, the weight per foot of the steel member is reduced according to the lessened loading requirements. For example, columns on the next level are 14 inches wide by 455 pounds per linear foot. These very heavy steel columns had to be imported from Belgium.
The floors are cast-in-place concrete poured into corrugated steel deck pans with Nelson Studs that are left in place. The concrete for the floors is a lightweight mix design.
The steel erection and concrete placement involved such significant weights and at high-reach radius that the project team brought in a special crane that has the largest lift capacity of any crane in Utah. The reach radius problem is aggravated by the limited access to much of the construction area. The tower crane on site is not placed within an elevator tower, as is normally the case, because of the hazard it would be to the nearby helicopter landing locations. This factor limited reach, requiring use of a conventional crane. Part of the time, a crawler crane has been used. At other times, a truck crane is used.
Exterior walls at ground level and below are cast-in-place concrete with thickness between 14 inches and 30 inches, based on loading. Above the ground floor, exterior walls are stud metal framed with brick veneer supported on galvanized Ledger angles at 12-foot centers. These walls are freestanding with ties. The walls have air spaces behind the brick veneer, “densgold” sheeting, exterior insulation, vapor barrier, and drywall. Hospitals are known to be major energy users; however, this project has a very energy-efficient design.
Heating and cooling systems are connected to the University of Utah central plant. Part of the contract is to provide a backup boiler plant to protect the hospital from interruptions of those basic services in the event of the failure of the University central plant or the failure of the existing underground distribution piping system on campus. The hospital's existing backup boiler had insufficient capacity and was significantly aged.
Planning Key to Success
The planning was so critical for the successful execution of the project that a six-month preconstruction planning period was needed to be certain that all issues were properly addressed. A critical path method of scheduling and planning was implemented. A major factor was that the Layton team came to the table defining the problems and proposing solutions. The owner at all levels has been very responsive to the solutions offered, Layton officials said.
As mentioned above, the crane placement presented real challenges for the construction team, especially to maintain emergency helicopter service. The completion of the work on the parking structure was an eight-month rush schedule in order to return the helipad to service at that location.
The location of the hospital near a major canyon created special challenges with the winds. With changes in barometric pressure differences on either side of the Wasatch Mountain, the canyon wind velocities can be double or triple the normal winds in the area at the same time. In addition, the wind directions can vary by 180 degrees in a short time interval. This challenge, combined with the usual practice of letting tower cranes weather vane during non-working hours caused major concerns. Due to emergency helicopter traffic, the tower crane could not be allowed to swing freely with the winds.
A primary challenge has been to keep the facility open and unobstructed for all users. This has meant full access for all vehicles, including buses. Construction of hospital floors vertically over patient-occupied rooms required special sensitivity and unusual construction methods.
Contractors are accustomed to having a work zone free of people not involved in the construction of the project. It is relatively easy to build a project on an isolated site or even adjacent to a busy site. The area is given restricted access to construction workers only. But on this difficult hospital project, that simply could not be the case. The work zone has some restricted areas, but the entire project is so involved with the facility users that the safety of those users had to be the foremost concern at all times.
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