Direct Methods for Limit State Assessment of Structures (Cancelled)
June 25, 2007 — June 29, 2007
Coordinators:
- Dieter Weichert (R.W.T.H. Aachen, Aachen, Germany)
- Alan Robert S. Ponter (The University of Leicester, Leicester, Great Britain)
Direct Methods, based on the shakedown theorems and the theorems of limit analysis, allow predicting load limits of mechanical structures operating beyond its elastic limit without performing step-by-step calculations. Particularly important is the fact that in case of variable loads a knowledge of the exact loading path is not needed, which meets the service conditions of most industrial design systems. This makes Direct Methods precious tools for the assessment of structures with respect of the risk of loss of integrity and deterioration due to inelastic effects.
Two major handicaps of these methods have been alleviated in recent years, as a result of which these methods are diffusing now rather quickly into the design departments of industrial companies. One problem was the rather narrow range of admissible class of material behavior for this kind of analysis, and the other, the sometimes prohibitive time consuming calculations for systems with a large number of degrees of freedom, as usually occurs in industry.
In both areas, important progress has been achieved so that today a large class of material laws has been implemented in the theory including e.g. porous materials, geotechnic materials, damage and fracture, behavior in excess of shakedown and where time-dependent effects are significant, multi-phase and more generally multi-physical effects. On the numerical side, high performance optimization codes, building upon the core of Shakedown and Limit-Analysis (SA and LA) have been developed, allowing for numbers of degrees of freedom in the range of 10*5, which is roughly one-hundred times more than 5 years ago.
To this may be added progress in taking stochastic uncertainty into account including the sensitivities of optimal load factors with respect to (random) parameters, reliability- and expected-cost-based approaches to LA and SA and others.
This material is in general not included in the curricula of the educational programs for engineers. The aims of the course are therefore:
– to give participants the background knowledge to understand these methods;
– to introduce participants to recent developments in the field;
– to present illustrative examples how to solve industrial problems;
– to enable participants to use these methods on an industrial level for design and assessment.
The course is addressed to:
Students in mechanical and civil engineering at master level, doctoral students, researchers in the fields of structural mechanics and material design as well as to exercising engineers involved in design and assessment of structures in mechanical and civil engineering.