Source: https://www.constructiondive.com, April 24, 2019
By: Kim Slowey
Another method of setting railings is to core-drill holes and place the rails directly into the concrete. Sleeves, however, might provide more stability in a university stadium scenario where fans occasionally sit, pull or lean on them. In any scenario, grouting those holes correctly — with sleeves or otherwise — so as to secure the rails and prevent water intrusion is also important.
When elements of most any structure fail, it’s typically due to either design errors or failure to build according to plans and specifications. When these flaws happen in places where the public gathers, that introduces safety concerns.
At another stadium project, at McKinney High School in McKinney, Texas, school district officials became concerned when they noticed cracks in the new football stadium’s concrete last summer as construction crews prepared the facility to host its first game. The school district hired an independent engineering firm to determine the cause of the cracking, and the company discovered that it was not a design error but a construction defect.
The consultant reported that too much water in the concrete mix caused excessive shrinkage of the concrete as it dried, which resulted in the cracking. There was also supposedly too little concrete in cross sections along pier lines and not enough reinforcing steel to help control shrinkage cracking.
The cracks do not present a safety problem unless cracks in some areas of the stadium expand so much that they become tripping hazards. They do, however, raise durability issues.
The same is true for concrete panels used during station construction for the $5.8 billion Silver Line in Washington, D.C. The panels’ air content was not in the specified range, and they will have to be treated with a special solution in order for them to last as long as originally intended. Like the cracks at the McKinney stadium, they present quality concerns unrelated to safety.