The aborted attempt to lift London's Millennium Wheel demonstrates that rotation is sometimes not achieved in real structures with pin joints or those with simple supports.
Structural testing of whole structures and components to failure at the Transport Research Laboratory has often demonstrated the presence of significant 'fixing' moments when little has been anticipated. End fixity is achieved when external restraints are present to prevent free rotation of a structural member. In this case, it is highly likely that friction between the pin and its contact surfaces has been sufficient to prevent rotation due to the applied moment induced by misalignment of the temporary cable.
John Lane, structures manager, Transport Research Laboratory, Old Wokingham Road, Crowthorne, Berkshire