"[A] list of factors combined to make thin shell concrete a less desirable solution for long spans by the 1970s. ...material efficiency could no longer off set the labor premiums demanded by complex formworks ...shapes were more difficult to create when an insulating layer was required ...A third challenge posed to compressive structures ...was the rapid development of s. ’s experiments with tensile membranes were mature enough in 1972 that they were used on Munich’s Olympic Stadium."