"We didnt have a bad storm. Its going to take considerable study to see exactly what did happen," says Herbert S. Saffir, consulting engineer in Coral Gables, Fla., and co-developer of the Saffir-Simpson hurricane-severity scale.
The highest gust reported in Fort Lauderdale barely exceeded 100 mph. Miami reported less. But hundreds of windows shattered in high-rises in the two cities, some in signature new construction, and up to 16,000 Florida Power & Light Co. poles need replacing. Damage was also reported at 241 substations in flat, rural areas, which company officials say is unusual for a category 3 storm. FPL has not tabulated repair costs.
"It looks like tornados or microbursts," says FPL spokesperson Tom Veenstra. "It took giant, concrete transmission poles and snapped them in half. The last time I saw that was Andrew. Large, metal, H-frame, 500-kv line structures...it twisted them around like pretzels. Its unheard of."
Window and curtain wall damage in high-rises was extensive. Miamis 36-story Espirito Santo Plaza and 70-story Four Seasons Hotel & Tower, both finished in 2003 by New York City-based Bovis Lend Lease, were victims. "The causes are unknown..." says Mary Costello, vice president of corporate affairs at Bovis, although she says experts suspect tornadoes or flying debris.
Hector Lima, director of Miamis building department, would not speculate about cause. But says the newer buildings with losses got building permits before wind resistance codes were raised to 146 mph from 110 mph in 2002.
Rick Dixon, executive director of the Florida Building Commission, says he saw buildings that had lost glass from top to bottom that showed both stress and impact damage. "In some cases, glass at lower levels had stress fractures...they yielded to the wind pressure. Certainly the glass should have been able to resist the wind pressure," he says.
Spokespersons for Four Seasons and the Conrad hotel at Espirito Santo Plaza say much breakage was in the outer panes of insulated windows. Julie Schimmelpenningh, vice president of the Glass Association of North America, says outer panes are often designed to be sacrificial, with inner glass protected by a laminate. Schimmelpenningh says installers in Miami tell her the shattering was primarily "small missile damage." Until recently small missile tests used river rock, rather than ball bearings, the current, more demanding standard, she says.
Scott D. Schiff, professor of civil engineering at Clemson University, Clemson, S.C., suspects flying roof gravel may have contributed. Greater wind speeds at higher elevations also could have broken windows and then rained shards on lower levels, in turn breaking more glass, Schiff says. "In newer buildings, it tells me either the debris in the air was bigger or moving faster than the standards, or [the windows] were really not impact resistant," he says.
Florida codes allow gravel roofs, but contractors are using them less, due to cost, says Steven C. Bassett, a member of the Florida Building Commission.
Saffir says the damages raise questions about design, workmanship and code enforcement. "Some local city building departments may not have enforced the code as rigorously as they could have," he says. He points out that two high-rises in Coral Gables withstood the storm, while a neighboring building lost 80% of its windows. The 14-story glass curtain wall of a new U.S. courthouse in Miami was also pelted by debris, but lost only one ground-floor window hit by equipment, says Gene Budler, vice president of operations for Dick Corp., Pittsburgh. The company is finishing construction on the courthouse now.ngineers and inspectors analyzing damage to buildings and utilities from Hurricane Wilmas Oct. 24 rip through South Florida are puzzled by the extent of power pole damage and glass breakage from what they say was a relatively weak storm.