Kid-Friendly Hospital Requires Concrete-Friendly Expertise
Kid-Friendly Hospital Requires Concrete-Friendly ExpertiseNew Saint Francis Children’s Hospital in Tulsa relies on Putzmeister pumps to assist with several varied concrete techniques
STURTEVANT, WI (February 1, 2007) – Drilled piers, round columns, square columns, irregular shaped forms, waffle pan slabs, jut-outs and jazzy colored sidewalks. These are just a handful of the many elements requiring specialized concrete expertise during construction of the new Saint Francis Children's Hospital in Tulsa, Oklahoma.
With the goal of creating a positive environment for children, the new 104-bed facility has embraced a welcoming façade outside, bright cheerful colors inside and a modern architectural style. These choices meant selecting materials, equipment and contractors that would not only be kid-friendly, but construction-friendly, as well.
Tulsa-based Manhattan Construction Company and Cantera Concrete Company each found challenges on the project in their roles as construction manager and concrete contractor, respectively.
“Construction of the 243,500 sq. ft. hospital involves almost every concrete technique ever performed in this industry,” says Kerry Hoff, Project Manager at Cantera. “With special design characteristics geared toward kids, the eight-story structure will be as unique as the many different procedures involved in its construction.”
Achieving the desired results required an abundance of specialized formwork and numerous ready mix designs. This, in turn, required expert concrete placement on a jam-packed job site and Putzmeister concrete pumps that could handle any specialty placing form task, unusual job site condition or unique mix.
No straight and easy path
“It was a demanding schedule to meet,” says Hoff, “and a challenging shape to rise out of the ground.”
Two below grade levels in particular presented a high degree of complexity. Crews faced the arduous task of drilling several 24" to 60" diameter foundation piers into firm shale. Once secured into rock sockets, the piers were pumped with concrete when the first boom pump and mixer trucks rolled on-site in April.
Adding to the job’s complexities, the foundation was not the typical box design. In fact, straight lines were virtually non-existent. Instead, varying angles were the norm. Therefore, an extraordinary amount of specialty formwork was needed for angular walls, radius walls as well as for round and square columns and even a tie-in to an angled tunnel from an existing parking garage. Two full time field engineers were on-site to assist with the irregularities of the formwork and the numerous methods being used simultaneously.
Pumping the concrete offered its own set of challenges, which Williams Concrete Pumping of Inola, Oklahoma, was prepared to handle. Cantera relied upon the variety of reach capabilities and high volume outputs of Williams’ exclusive fleet of Putzmeister concrete pumps and its own extensive experience to keep the project moving at full speed.
“We consistently require high outputs from these pumps,” notes Hoff. “Our goal is nothing less than 100 cu. yds. an hour and the equipment achieved this without difficulty. In fact, the pumps are capable of up to 200 cu. yds.”
“The Cantera crew runs in high gear, so we can get pours done fast,” says Richard Williams, co-owner of the 26-year-old pumping company. “When we could set up close to the columns, we would quickly pump several of them with our smaller sized 32- and 36-Meter boom pumps. Obviously, when we couldn’t get an ideal setup spot, we had to use our larger 43Z-Meter unit.”
“To avoid dragging hose and achieve faster concrete placement,” adds Williams, “we also provided our longer reaching 52Z-Meter model to pump 800 cu. yds. of concrete for a 36,000 sq. ft. slab-on-grade in the basement level.”
Looks like a waffle
Dun Par of Kansas City was sub-contracted to perform the elevated formwork. With concrete beams stretched across cast-in-place columns, a distinctive “waffle pan” approach was employed for the slabs. The two-way version of pan joists uses prefabricated hollow sheet-metal domes. By creating a grid pattern of voids in a solid floor slab, which look like an inverted waffle, the technique is designed to save material without reducing the slab's strength.
“This type of slab is really tough to pump, as we needed to thoroughly fill all the so-called ditches or grooves with concrete before we could pump the top layer,” says Richard. “Because of the unusual reaches involved, our largest 52Z-Meter did the majority of this work.”
Even the wall’s façade isn’t a straight shot up to the top of the 122 ft. structure. On the east and west side of the structure, the building’s edges will be formed as triangular jut-outs and pumped with concrete. Designed for added interest, the jut-outs resemble a triangle and will horizontally extend eight foot outward from the corners, creating public solariums.
A 52Z-Meter pump will be needed for its long 170 ft. vertical reach and smooth concrete output to handle this unusual architectural design feature.
Six different concrete mix designs were required during the project, all being supplied by Twin Cities Ready Mix, Inc. of Tulsa. The concrete producer dispatched from two local batch plants.
“Basically, we had a shopping list of mixes,” says Hoff. “In particular, we used a special 7,000 psi concrete mix for the lower level forms, which isn’t common in our area.”
The specifically developed 7,000 psi super-plasticized mix was utilized for all shear walls and columns on the first four levels. It provided ease of pumping, plus achieved an early 75% strength in three days. As forms could be removed in such a short amount of time, the project could swiftly move forward.
From the fifth through eighth levels, the mix was modified to a 5,000 psi with a mid-range water reducer that resulted in a restrictive slump. Designed to maintain a fast production cycle, the modified mix proved to be a contractor-friendly slump and was pumped without difficulty.
Jam-packed job site
Situated in southeast Tulsa, the job site was extremely congested. It offered minimal storage space, no on-site parking and unpredictable traffic with an ambulance route nearby. As a result, deliveries were precisely coordinated, employees bused to the site and construction equipment, especially ready mix trucks, required to exercise extreme caution. The concrete pumps also were forced to work around overcrowded work site conditions.
“With the site located on a hillside, it cut down on accessibility,” says Richard Williams. “Plus, it was so congested that we often had to use a bigger pump with longer reach just because of obstacles in the way.”
“With access from only three sides of the foundation, the appropriate boom pump was scheduled based on reach requirements,” says co-owner Barbara Williams. “Because we’d often start pumping at four o’clock in the morning on one part of the job, finish up and move the unit to pump a different section of the job, we always had to make sure we sent a pump with enough reach to handle both pours.”
In February 2006, initial construction began. By June 2006, the crew started framing the first elevated level. The hospital was topped out in February 2007. The two top floors are being “shelled in” and will be eventually built out when patient volumes require additional space.
Designed by Ritchie Organization/TRO architectural firm, the new facility will provide greater medical/surgical capabilities, pediatric intensive care services as well as outpatient and inpatient infusion therapies for children. In its kid-friendly style, the exterior will be a combination of blue, yellow and pink metal panels, and a circular drive with brightly colored concrete sidewalks at its entrance will welcome patients. Inside, the hospital will be highlighted with fun murals and a colorful flooring system.
The hospital will comprise approximately 18,000 cu. yds. of concrete when it is ready for occupancy in spring 2008. To support the facility, a new parking garage was completed in January 2006.