Q.: What went wrong with the concrete at the Hyatt Regency Hotel in Kansas City? We've had several questions on this and don't know just how to answer them.

A.: So far as we know, there was nothing wrong with the concrete. Many people who saw pictures of the collapsed walkways were aware of significant amounts of concrete rubble and may have assumed the concrete was at fault. Actually the concrete came down when its steel supports gave way. The July 30, 1981 issue of Engineering News-Record (page 11) shows that the concrete was placed on metal decking, which was supported on 16-inch-deep wide flange beams. The wide flange beams were welded to transverse box beams, each built up of two steel channels. The channels were suspended on rods, some of which remained hanging from the atrium ceiling after the walkway collapse. It appears that connecting nuts and washers actually pulled through the box beams during the collapse. Technical investigations are still continuing.