[caption id="attachment_98225" align="alignleft" width="360"] While the 30 Napa Valley Unified School District campuses had no structural damage, a common problem found was unsecured bookcases and other furniture that fell over and blocked exits. (credit: Quattrocchi Kwok Architects)[/caption]
NAPA -- The lack of structural damage to the 30 Napa Valley Unified School District compared with nearby commercial buildings and residences is a good illustration that the sometimes frustratingly meticulous state review of education-related construction projects and money spent on shoring up old and masonry buildings against earthquakes like the 6.0 magnitude south valley temblor on Aug. 24 are worth it, according to local architects and engineers who recommended reopening of the schools.
"Most interesting and pleasing to me was that when you look at the damage to commercial buildings in Napa and compare it to the schools, all 30 schools had no damage to the structural system -- the roof, walls and floor systems," said Mark Quattrochi, principal architect of Santa Rosa-based Quattrocchi Kwok Architects, which has been working with the school district for two decades on new and remodeled projects. "They not only were able to stand, but they were able to stand without serious damage."
To be sure, the triad of three-person teams -- each with an architect from Quattrocchi Kwok, an engineer from ZFA Structural Engineers and a district official -- that fanned out to evaluate 10 schools each during 15-hour days that Monday and Tuesday, Aug. 25--26, found plenty of damage to nonstructural elements such as toppled bookcases and file cabinets, cracked wall and floor coverings, and fallen light fixtures and suspended-ceiling grids, especially in campuses nearest to the epicenter.
The teams mobilized after talking with Don Evans, district director of school planning and construction, just hours after the 3:20 a.m. Sunday quake. But by early afternoon that Tuesday, the teams recommended classes could resume the following day.'Big wakeup call'
"It was a big wakeup call for teachers I talked to about putting heavy stuff on ledges and not anchoring bookcases," said Chris Jonas, S.E., of Santa Rosa-based ZFA, which has been engineering almost all the district's jobs for the past decade. The firm also sent six teams the week of the quake to aid city and county building inspectors in verifying red and yellow tags on structures, indicating whether they are uninhabitable or just require extreme care in certain portions.
Thankfully, the quake happened very early on a Sunday morning, when students and faculty weren't around to be hit by flying books and other objects or try to exit from doors blocked by toppled bookcases, Mr. Quattrocchi said.
"The thought of 30 students trying to leave the classroom because things are falling and light fixtures are swaying is chilling," he said.
Federal Emergency Management Agency guidelines generally are for people to stay put and seek shelter under something sturdy during the quake because of the risk of injury from flying items and falling fixtures.Reasons for less damage
The differences in building performance in the Napa quake between schools from nearby commercial and local public buildings of comparable age and construction can be traced to the stringent approval process for school projects and recent retrofitting of older buildings to strengthen them, according to Mr. Quattrocchi.
[caption id="attachment_98227" align="alignleft" width="315"] A deciding factor in the extent of damage to masonry buildings in Napa from the Aug. 24 quake were whether they had been seismically retrofitted. (credit: ZFA Structural Engineers)[/caption]
School and hospital projects are reviewed by the Division of the State Architect and the Office of Statewide Health Planning and Development, respectively. Such jobs are held to higher standards for withstanding strong side-to-side shaking than is common in building codes used by local planning departments, Mr. Quattrocchi said.
The DSA review process checks all building connections and structural calculations methodically, challenging all assumptions and figures in the documents. That can take sometimes six months to complete.
"As an architect trying to get a project approved through the DSA, it can be maddening how long it takes, but when you look at the result of the process -- that buildings stand up through a quake -- it is worth the effort," Mr. Quattrocchi said.
Such review on commercial buildings would make them cost-prohibitive, he said.
And there is a big difference during construction. Instead of inspectors visiting a job site periodically and at certain phases of commercial projects, school projects must have a full-time inspector at the site from beginning to completion, checking all critical elements such as how the steel is connected to the foundation to handle stronger forces, called loads.
