Sharing the Burden

Firms and agencies scramble to meet SB 1953 seismic requirements

By Robert Carlsen

Healthcare construction is dominating the landscape of California with more than 3,000 projects currently underway, valued at $5.9 billion, according to the Office of Statewide Health Planning and Development's Facilities Development Division.

So many projects are underway, in planning or in-between that OSHPD, builders and architects are straining at the seams to find the bodies to do the design, construction and inspection.

What's driving the current boom is, naturally, the deadline for compliance of California State Senate Bill 1953, an amendment to the 1973 Hospital Facilities Seismic Safety Act that was passed following the 1972 Sylmar earthquake. SB-1953 came into existence as a result of the 1994 Northridge earthquake.

SB-1953 requires that all 450 acute care hospitals in California evaluate and report on both the structural and nonstructural safety of each of its hospital buildings. Hospitals were given until Dec. 31, 2000, to file their evaluation reports with OSHPD. Since then, various deadlines for project completion were approved, including last year's passage of SB 1661 that allows OSHPD to grant an additional extension of up to two years of the Jan. 1, 2013 deadline to meet seismic requirements.

In addition, SB-1953 requires all hospitals to retrofit, rebuild or close their general acute care inpatient hospital buildings by specific dates if they do not meet strict new seismic safety standards.

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The Facilities Development Division formed the Seismic Retrofit Program Unit to handle the massive review work. This group, headed by Chris Tokas, S.E., project manager of the SB 1953 regulations and comprised of structural engineers and architects, reviews and approves the seismic evaluation reports and compliance plans as they are submitted to OSHPD.

Inspectors for the unit travel around state construction project sites to review structural and nonstructural anchorage and bracing of equipment and systems to ensure compliance with the California Building Standards Code, as well as review OSHPD-approved plans and observe the construction work completed to make sure it is up to code.

However, because of the stress and strain of keeping up with so many projects, OSHPD has been having problems with inspector turnover.

"OSHPD is in a constant struggle to find and retain qualified inspectors," says Douglas Olson, Chong Partners Architecture's practice leader for health and associate partner/project director. "But we're all sharing this burden, which puts a strain on resources across the state. I give OSHPD lots of credit, though; they've worked very hard."

Chong Partners is working on a variety of high-profile hospital replacement projects for both Kaiser Permanente and Sutter Health, the big two. In fact, Kaiser, with 14 major replacement and expansion projects underway in the state, contracted with Chong and SmithGroup four years ago to develop a template hospital design plan, which has been used on three current projects and two in the planning stages. Template designs have also shortened the approval and delivery process.

Bob Eisenman, director of government relations with Kaiser Permanente, says that OSHPD has been "very supportive both with regards to shortening review times on template hospitals and seismic compliance."

Eisenman adds that Kaiser's challenges with the ambitious construction program are dealing with limited resources, the escalating cost of raw materials and labor, and timely completion based on the previous two challenges.

"Since healthcare construction requires specialized knowledge and experience, and there is a competitive market for skilled labor, it has been a challenge to get the best people and teams to work on our projects," he says.

Olson says that most healthcare firms are going for replacement facilities because the cost of remodeling and retrofitting existing structures is prohibitive.

Olson adds that in order to address major seismic safety concerns for projects sitting on or near major earthquake faults, Kaiser has agreed to use a new high performance bracing system on new template hospitals.

Suggested by the engineering firm Arup for, initially, the just completed $700 million Santa Clara Medical Center replacement project, the unbonded brace frame system, first introduced in Japan in response to the 1995 Kobe earthquake, is easier to construct and less costly than traditional welded braces.

Problem was: OSHPD had not signed off on the system and requires a formal field test to demonstrate its effectiveness.

Arup's new seismic system is comprised of 10 bays of UBs at each floor in the north/south and east/west direction. Arup said these UBs are strategically located across the floor plate to provide an integrated design response to allow maximum programming flexibility, balanced distribution of lateral stiffness as well as multiple lines of resistance.

Arup worked closely with OSHPD to set specific design criteria for the UBFs. Arup proposed that a dual-level seismic design to include both Design Base Earthquake and Upper Bound Earthquake. Design base shears were established by using unscaled site-specific response spectra.

In 2005, a full-scale test of a UBF was carried out at UC Berkeley. Arup said the test featured the construction of a full finite-element model, which explicitly modeled the members and connections, so that local behavior could be assessed. Arup said its virtual test simulations showed that current connection results in considerable yielding and concentrated stresses, which in turn place limits on the performance of the frame. Arup considered both chevron and diagonal brace arrangements. The chevron arrangement is more forgiving, as the central beam/brace connection provides more flexibility for the frame movement. The single diagonal arrangement has higher strains since the lateral force is concentrated through one gusset plate connection and because of plate pinching between the beam and column as the frame flexes from side to side.

Further, Arup said the compatibility between connection plate and frame member size is an important factor.

To control this issue for this project, Arup limited the drift to 1.25 percent for the design basis earthquake level (DBE) and 2.25 percent for the ultimate design basis earthquake (UBE). To date, Arup said it has used this brace in California on projects comprising more than 4 million sq ft and other engineers are following suit.