The structural engineer investigating the June 24 collapse of the 40-year-old Champlain Towers South oceanfront residential condominium for Surfside, Fla., also is doing 60- to 90-minute walk-throughs, looking for safety issues, of 15 other buildings of similar vintage in Surfside.
To date, of five buildings reviewed, KCE Structural Engineers has recommended that one needs further investigation by an independent structural engineer and another needs shoring. The buildings have not been identified.
In addition, one 2.5-story building had already been shored recently, says Allyn Kilsheimer, KCE's founder, chairman and CEO.
There are currently 97 identified fatalities associated with the June 24 failure of one wing of the 12-story building, according to a spokesperson for the Surfside Joint Information Center. The remaining unstable wing of the building, which was an L in plan, was imploded on July 4. As of July 21, the debris and rubble had been moved from the site, either to a warehouse or to a lot elsewhere.
“There are ongoing meetings to discuss when Miami-Dade Fire Rescue and Police will vacate the site,” says the spokesperson, who adds that personnel from the Federal Emergency Management Agency (FEMA) and the National Institute of Standards and Technology (NIST), which is investigating the collapse, were also still on site collecting evidence.
NIST Technical Probe Not Started
NIST also is in the process of assembling the National Construction Safety Team that will lead the technical phase of the investigation. No further details are available. "One of the conditions we have to consider before launching an investigation is if funds are available," says Jennifer L. Huergo, a spokesperson for NIST.
NIST reports its team in Surfside, which is north of Miami Beach, is still refining procedures for evidence identification, marking and tagging. As of last week, investigators had collected more than 200 building elements including columns, beams and pieces of concrete slab. The Miami-Dade Police Department is preserving the evidence.
In addition to representatives from FEMA, the NIST team is supported by representatives of Florida State University, the Miami-Dade Fire Rescue, the National Science Foundation, the U.S. Army Corps of Engineers and the U.S. Geological Survey.
Lidar Scans of Debris
NIST had been coordinating remote sensing efforts to determine the location of pieces of evidence in the debris pile. The investigators used light detection and ranging technology, known as lidar, that sends out rapid pulses of light and records the reflections to create a type of map.
Lidar was used at the site to record locations of building materials or elements of potential interest and changes to the site as debris was removed. NIST took daily high- and low-resolution lidar scans of the site from balconies on adjacent buildings to the north and south of the Champlain Towers South site. Time-lapse cameras also recorded the changing scene, says NIST.
NIST reports deployed an electronic evidence tagging system that uses radio frequency identification chips so that electronic records are associated with every piece of evidence collected.
Working with the Rapid Response Research (RAPID) Facility of NSF’s Natural Hazards Engineering Research Infrastructure Program, NIST has installed accelerometers to measure building vibrations and a seismometer to measure ground vibrations at the 12-story Champlain Towers North condominium, which is a near-twin of the building that collapsed. The data will be used to validate computer modeling of Champlain Towers South, says NIST, not to evaluate the condition of Champlain Towers North.
KCE arrived in Surfside on June 25, first to probe the Champlain Towers South collapse for the town. KCE’s scope of work was then expanded to include visual inspections of the other buildings and a more-in-depth safety evaluation of Champlain Towers North.
The investigation of the near-twin, which includes taking concrete core samples of the flat-plate floors, is ongoing, says Kilsheimer, who to date has not found any problems with the structure or the construction of the North building.
The construction of the 15 buildings being examined by KCE are not all the same. Some have “mild-steel reinforced” flat plates, some have mild-steel reinforced slabs; some have reinforced post-tensioned slabs; some have precast floors and there is one wood building, says Kilsheimer, who has original drawings of nine of the 15, none of which is above 12 stories.
All the buildings have parking underneath, sometimes at grade, sometimes below grade and sometimes both, says Kilsheimer. None have more than one basement.
KCE has not been allowed into the site Champlain Towers South site, which is under the control of the police. But the KCE team is “close to having a full 3D model of the original structure done,” says Kilsheimer.
As-Built 3D Model Not Complete
But because no evidence has been released from the site or from off-site stored materials, the as-built model, with material strengths, is not complete. “We are working around what we don’t have,” says Kilsheimer. Regarding the cause or causes of the failure, “all we can do are ‘what-ifs’” that are useless, he adds, saying it might be as long as a month before samples are released to investigators.
Kilsheimer adds he has turned down about 300 requests for safety checks from owners of buildings up and down the coast of Florida. To date, KCE is only working for the town of Surfside, though would consider working for other jurisdictions, with a caveat. "We will only work for jurisdictions if they allow full transparency" regarding observations about the condition of surveyed buildings. “I would need to be able to release what I want to, without seeking permission from the jurisdiction,” says Kilsheimer.