NY earthquake code given jolt.

The seismological event in California last week reopened discussion about constructing New York City buildings to enable them to survive earthquakes. The Dept. of Buildings has already conducted elaborate studies and developed a legislative package requiring modifications only for new building construction and substantial alterations.

The package saw no action last year and will soon be reintroduced to the City Council with a major initiative. The Building Dept. estimates the overall added project cost for new construction would be 2.1 percent, with a 7.3 percent jump in structural dollars. Most of the costs would be incurred in the construction of shorter buildings, as modern skyscrapers substantially comply with the suggested code.

While the Real Estate Board of New York took part in the studies, they are fearful of adding any more expenses to building in New York City, particularly in the affordable low-rise housing sector that would be most affected by new structural requirements.

Meanwhile, New York State has conducted similar studies and written draft regulations comparable to those being requested by the City's Building Dept. and the Federal Emergency Management Agency (FEMA) is also about to recommend corresponding measures for structures built with Federal funds.

A memorandum of support for the city code changes, written by former Building Commissioner Rudolf Rinaldi, discusses the need for this legislation. A 1988 city conference on Earthquake Hazards and the Design of Constructed Facilities in the Eastern United States pointed out that history shows a moderate pattern of seismic disturbances in the New York City area.

"An earthquake can have a profound effect on a high population density and a large number of older buildings," Rinaldi's memo says. Additionally, the seven page discussion notes that East Coast seismological events are such that they can cause major amplifications of shaking at large distances from the epicenter.

A study made by the State University of New York at Buffalo and released in 1989 examined what would happen to the city's over 800,000 buildings if a tremor of 6.0 hit 17 miles southeast of City Hall, in an area off the Rockaways at around the same location in Jamaica Bay as a 5.0 quake hit in 1884.

Although the damage estimates were made at the height of the real estate market, that study estimated the building stock would sustain roughly $11.2 billion in damage in all five boroughs.

At 11 miles from City Hall, the quake would cause $18 billion in structural damage and at five miles from City Hall, with an epicenter in Prospect Park, the damage would soar to $25.9 billion. Places like Downtown Manhattan, and those nearer the epicenter, would sustain the most damage.

Small Buildings at Risk

"The hardest hit structured, would not be New York's famed towers," Rinaldi's memo states, "but rather its numerous old brownstones and row-houses, its unreinforced masonry structures."

Dr. Leonardo Seeber, a research associate with the Lamont Doherty Geological Observatory in Palisades, New York, agrees that most skyscrapers already would fulfill most of the requirements to protect against earthquake damage.

"The most dangerous thing is windows coming off," he said. "In terms of buildings collapsing, it's a very small chance. But there is serious concern for buildings banging into each other."

Dr. Seeber said the scientists worry the most about the middle size and small size buildings because those are the ones that are vulnerable if built on soft soil.

"That kind of building and any new buildings of that kind should be submitted to earthquake hazard scrutiny," he said. "If society has enough resources, they should be retrofitted."

The city's plan only calls for studying the effects of retrofitting. The structures that should be retrofitted first, experts say, are the ones most needed in emergencies, such as those that house schools-because aside from being sites in the past of many deaths in quakes, they are often used as community emergency sites - hospitals, police stations, fire engines and ambulances. "You don't want the fire engine stuck in the collapsed fire house," noted Dr. Seeber.

Deborah Beck, executive vice president of REBNY, is anxious about the costs involved in constructing smaller buildings that serve as the most affordable housing sector for the city.

"The serious concerns we expressed from the industry side was that the code would eliminate the competitiveness from load bearing plank construction because of the added reinforcement that would be needed to comply," she said. "It would not be less costly, but equivalent to the costs for concrete. Losing that competitive edge for that kind of construction that is so widely used was a concern."

Joseph B. Rose, executive director of the Citizens Housing and Planning Council, affordable housing advocates, was incredulous that seismic codes would be considered for something he considered so remote. It would very adversely affect that segment of the market, he said, a market that is already tottering from increased water and sewer charges and real estate tax costs.

Beck would also like to have the city take another look at the proposed New York City code, since there may be either new technology or experiences that can help fine tune the regs since they were developed two years ago.

Under the proposed codes, only new one and two family residences of not more than three stories would be exempted. Additionally, enlargements that increase the footprint of a building, whether constructed on new or existing foundations, would also require seismic design. Rinaldi's memo indicates the issue of seismic rehabilitation or retrofitting calls for careful additional study because of economic impacts.

He does note, however, that action plans for reducing earthquake hazards of existing buildings are already written with the support of FEMA, the lead agency for the National Earthquake Hazards Reduction Program (NEHRP), and include methodology for rapid visual screening of buildings for potential seismic hazards.

Further plans for the city, Rinaldi's memo continues, might include recommendations for existing buildings and the Post Earthquake Safety Evaluation of Buildings.

FEMA is going to issue regulations this year that will require any city that obtains Federal money for new building construction to come up with modified codes, and in fact, they are using portions of the New York City proposal as a guideline for the Northeast. The new Federal Courthouses in Manhattan have both been designed with seismic criteria, the engineers say.

Structural engineer Guy Nordenson, principal of Ove Arup & Partners, and chair of the NYC Seismic Code Committee and Dr. Klaus Jacob of Lamont Doherty Geological Observatory, who both sat on the city's Seismic Code Committee, are also working with FEMA and introduced the ideas into the FEMA provisions. "They are now getting built into that program," said Nordenson.

In the future, he said, the Federal recommendations may have some kind of menu so that builders can decide how much they want to spend for varying results. "If people are interested in flipping properties they will look at it a certain way and if they are interested in long-term management they will look at it another way," Nordenson said.

"If you're a financial company in New York you may want to consider ways to protect your facility and data base so you don't get put out of business," he added.

Many builder/developers are beginning to ask how much seismic protection would costs for new structures, said Joseph Kelly, P.E., a senior consulting engineer with the Port Authority of New York & New Jersey, who is chairman of the Seismic Code Committee for New York State. The Port Authority has a policy to design to seismic loads for new structures, he noted, while most bridges are also built to withstand seismic forces.

City Faults

Earthquake faults are not unknown in this city. Several that are part of the Dobbs Ferry family run under the Bronx and Manhattan and there are probably others under Brooklyn and Queens.

One fault, known as the 125th Street fault, was exposed during the construction of the Water Tunnel and Dr. Seeber was brought to observe the fault briefly by a consultant. "Right after that, they covered the fault with cement, so there was no proper study of it," he said sadly. "It was by chance that we found out. So at least we got to see it and got a picture."

A spokesperson from the Dept. of Environmental Protection did not respond to inquiries about the cover-up of the fault before it was studied by scientists.

Kelly said a fault in such a tunnel would not be of too much concern, since the solid rock would probably not shift greatly in an earthquake.

"You're talking about rock moving rock. You're talking a sizeable tunnel and a shift may not be significant compared to the diameter of the tunnel," he said, noting that during the 1987 San Francisco earthquake, its subway system did not experience a problem.

Dr. Seeber said faults also run under 14th Street and up to the Eastern end of the Lincoln Tunnel, while another runs across Canal Street.

Proposed Code

In April of 1989, the Building Commissioner at the time, Charles Smith, formed a Seismic Committee that included representatives from engineering concerns, industry associations, universities, the Real Estate Board of New York, the New York State Urban Development Corp., the Port Authority of New York and New Jersey and the Building Seismic Safety Council.

The legislation was drafted after two years of extensive analysis of national codes and conditions unique to New York City, and included a study of economic factors by the scientists and practitioners from around the country.

"The group agreed it should be life safety first, rather than minimizing business interruption," recalled Beck of REBNY. Using the California code as a model, the group made changes that would apply to city building techniques.

Because the rock in New York is strong, Nordenson said they allowed buildings constructed on hard rock to have a reduced force level in comparison to other sites. "That was a new idea that we introduced," he said, and as a consultant to FEMA, he said that concept is now being adopted by FEMA for the Northeast portion of the country.