Engineering consultants are conducting tests and evaluations of structural columns in the basement of the 1925 Miami-Dade County Courthouse in downtown Miami after an inspection uncovered evidence of “significant’’ deterioration.
Results of the testing, which involve removing concrete covering the steel columns to evaluate their condition, will be ready by late February, said Miriam Singer, assistant director of Miami-Dade County’s Internal Services Department. Singer said the historic courthouse’s support columns will likely require extensive repairs.
But Singer and U.S. Structures Inc., the lead county consultant, stressed that the building housing the county’s civil courts remains stable and safe for use. USSi engineers have recommended closing the courthouse only in case of a hurricane, though they noted that could change based on further testing.
Once they conclude their evaluation, the consultants may also recommend temporary shoring while repairs are done, USSi engineer Jose Toledo told the county in a letter outlining their preliminary conclusions.
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“No one should be alarmed,’’ Singer said. “We are in good hands. We have a great deal of confidence in our two consulting firms. They have significant experience, specifically with historic preservation.”
Toledo’s letter pointed to one cause of the structural deterioration: Because the basement sits below the water table, it periodically floods, something he said a repair plan will have to remedy.
The finding comes as the courthouse, a landmark considered one of the most important historic structures in the city, undergoes a $30 million exterior renovation, needed in part to seal off the building interior from water intrusion, Singer said.
When it was originally finished, the steel-skeleton skyscraper, at 28 stories, was the tallest building south of the Washington Monument and housed courtrooms, the city’s main jail and Miami City Hall.
Singer said USSi and its subcontractor, G.M. Selby Inc., were involved in the structural renovation of the Biltmore Hotel in Coral Gables, which has a similar steel-frame construction.
At the courthouse, sounding and radar tests of the columns above the floor slab that were conducted earlier this year found a possible loss of steel from corrosion of as much as 50 percent in some of the concrete-covered supports, Toledo’s letter says. To evaluate the full extent of damage to the columns and the underlying support structure, inspectors are removing concrete around at least two test columns, he wrote.