San antonio parking garage failure

The garage had temporary bracing in place, but it wasn't strong enough to stabilize the structure with ungrouted joints. Those are the conclusions of a six-month investigation by Houston-based structural and engineering firm Walter P. Moore and Associates. In addition to interviewing workers and project staff during four site visits, investigators also reviewed security video of the collapse, tested samples collected from the rubble and built and demolished computer models of the structure at the time of the collapse.

Copies of the six-page report were released to the University Health System board of managers and the Express-News on Wednesday. There were no fatalities when the 16,square-foot North Prow section of the garage collapsed, although two workers were injured, one seriously. The cost of rebuilding the garage, as well as the collapse investigation, is all being paid for by the general contractor's insurance, according to Mark Webb , the health system's vice president of facilities development and project management.

The grout that should have been used hardens to form one continuous concrete connection from one part of a column to another. According to the report, the general contractor on the garage project is Urban Concrete, and its subcontractor Precast Erectors was responsible for the column work. Urban's engineer, CEG, designed the precast portion of the project. Moments after the initial collapse, other columns toppled and the entire structure was destroyed.

The video, shot from a camera mounted on a light pole with a view of the scene, showed images of a parking lot with the concrete skeleton of the garage in the background. The collapse injured two workers, one critically. The toll could have been much higher, but emergency air horns at the construction site alerted workers who fled to safety.

Officials with the Occupational Safety and Health Administration , forensic engineers and city inspectors are investigating. One phase of the garage at Medical Drive and Wurzbach Road had nearly been completed. The part that collapsed was a second phase in its early stages.

Zachry Vaughn Layton , a consortium of construction companies, is overseeing the capital improvements projects at University Hospital. Jeff Johnson , project executive for Zachry Vaughn Layton, said Tuesday that 12 to 15 columns had collapsed. Speaking at a University Health System board of managers meeting, Johnson said the top of the columns appeared to crush downward.

The pillars closest to the finished parking structure then fell inward, as if pulled. This could explain why observers reported hearing two crashes, he said. Read an update about the collapse sent to City Council members.

Read a report about the collapse from the San Antonio Fire Department. Garage collapse timeline. Asked by board member Ira Smith Jr. Broadnax to City Council members, the garage was composed of poured-in-place, reinforced concrete columns that support horizontal, precast beams and girders that were manufactured off-site. Webb said the column bases were poured at the site, and then prefabricated segments were stacked on top. The columns reached a height of six or seven stories, Webb said, and no floors had yet been built.