Investigation into W Austin Falling Glass Continues

Experts and engineers are continuing to investigate what caused glass panels to break and fall from the W Austin Hotel. Curtain Wall Design Consultants (CDC) based in Dallas served as the independent inspection engineering firm, but declined to comment on the ongoing investigation. However, a June 11, 2011, report on the initial incident that was prepared by CDC says “in an effort to locate the initial source of possible falling debris, we have confirmed that a pattern of damage does exist emanating partially from the slab edge at level 27 directly above the failed units. Based on our initial observation of this area, it appears that high strength grout applied to the slab edge has been dislodged adjacent to a post tension cable head location. The high strength grout appears to have fallen onto the top edge of the glass unit at level 25. Cementicious debris collected on levels 25, 24 and the pool deck is consistent with the missing grout on level 27.”

In its conclusions and recommendations, CDC’s report said, “due to the location of the point supported glass in-fill panels any falling debris could likely damage the top edge of glass causing catastrophic failure. Per the GANA glazing manual smooth edge shallow ‘flake chips’ such as that observed at the glass damaged by the falling glass debris is not necessarily a weakening factor to the glass, In addition ASTM C1036 states that ‘shell chips’ are permitted. However the GANA glazing manual states that all heat-treated glass will break when the compression layer is completely penetrated and ASTM C1036 provides guidance in Table 6 as to acceptance criteria for this type of damage. The compression layer as defined by GANA has a depth equal to 20 percent of the glass lite thickness and ASTM C 1036 Table 6 states chip depth cannot exceed 50 percent of glass thickness, chip width cannot exceed glass thickness or ¼-inch whichever is greater, and chip length cannot exceed two times (2x) chip depth.”