We have mentioned several times that there is something mysterious in the relationship between reference stress, limit load and in particular plastic collapse at plastic hinges, skeletal point and redistribution nodes in inelastic (plastic and creeping) structures. While this apparent simplicity in complex inelastic structural behavior has always been recognized it was certainly not expected at the time that the whole situation would be simplified even further through the simple device of carrying out a couple of elastic finite element analyses where the relative elastic modulii of the individual elements were adjusted to redistribute the stress. For the historically curious, it is perhaps interesting to note that the suggestion to modify the elastic modulus in this way in fact came from Marriott. Indeed the authors often wonder what research in inelastic and high temperature creep design could have achieved if this simple technique had been known at the 1970 or 1980 Creep in Structures Symposium. In 1983, the first author wrote of the reference stress method: "... it is one of few results in creep mechanics which contains an element of surprise - if all else fails it should be treasured for this ...". It seems the surprises continue - perhaps the structures and components are prompting us to keep looking for something even more profound.
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