Press Clippings
Engineering News-Record
December, 1998

Planning Ahead Eases Pain
By: Paul Rosta in Pasadena, Calif.

A $28-million addition to Huntington Memorial Hospital in Pasadena, Calif., is showing that the best laid plans can be under foot. When the eight-year-old hospital was first built, a footing was tucked beneath the radiology department. Almost a decade later, the footing provided a base for a tower crane to erect 1,300 tons of structural steel for the rest of the facility, constructed on top of the operating hospital. The foresight prevented a logistical nightmare.

The work was phased for financial considerations, says William J. Naprstek, project manager for HDR Architecture Inc., Omaha, Neb., the architect for both phases. But that meant thinking ahead about staging and logistics for the uppermost 31/2 levels, 260x130-ft in plan, which sit on a 340x160-ft, 21/2-level base. So in 1989, a T-in-plan concrete footing, one leg 40 ft long, the other 24 ft, was cast under a 10-ft-square room with an 18.5-ft ceiling, some 10 ft from the exterior wall of the first floor.

To erect the 180-ft-tall tower crane, with its boom radius of 246 ft, the Newport Beach, Calif., office of McCarthy first removed a 10-ft-square knockout slab from the first level roof deck. Though the older section is generally 21/2 levels, the crane room was kept to one.

Crews also took out a 10-ft-square, 5-ft-deep section of the foundation and some fill. The goal was to expose only the 10-ft-square section of the footing that contained the anchor bolts, says Barry Lloyd, project manager for McCarthy, the general contractor for both phases. Workers then used a truck-mounted crane to erect the mast and boom.

Connections

After 1994's Northridge quake, inspection revealed no damage to any of the existing facility's 193 column-beam connections. But discovery of damage to steel frames elsewhere prompted the Office of Statewide Health Planning and Development to require the retrofitting of all connections in the hospital. OSHPD also mandated redesign of the addition's joints.

To reduce stress at the column web-beam flange, Taylor & Gaines, the job's local structural engineer, developed a detail with a 2-ft-long haunch welded to the underside of the beam flange. The detail moves the plastic hinge point 2 ft away from the connection, says Mark Harper, Taylor & Gaines' project manager.

In the existing facility, plates were added to the underside of the top beam flange to increase flange thickness. The retrofit had to be 90% complete before OSHPD would permit the casting of the addition's concrete slabs, says Lloyd.

In a change aimed at reducing the building's drift to levels compatible with a 1995 Uniform Building Code update, Taylor & Gaines shaved the addition's height by 16 ft by eliminating one level.

Because construction took place directly above 18 functional operating rooms, more disruptive work was usually scheduled at night, Lloyd says. The addition is opening this month, turning the hospital back into a quiet zone.

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