Experimental determination of the stress in a plaster column dating from the 11th century and listed as a protected historic monument

The use of experimental investigative methodsin building and civil engineering, particularlyfor assessing the safe load-bearing capacity ofan existing building material, has received asignificant boost in recent years due to the successfulconclusion of cooperative researchprojects EXTRA I and EXTRA II.

The use of experimental investigative methodsin building and civil engineering, particularlyfor assessing the safe load-bearing capacity ofan existing building material, has received asignificant boost in recent years due to the successfulconclusion of cooperative researchprojects EXTRA I and EXTRA II [Lit. 1 and 2]. Experimental methods usefully complementtried and tested computational procedures. Theusual computational proof assumes knowledgeof a number of important characteristic valueswhich are an absolutely indispensable basis forthe computation. The procedure requiresknowledge not only of the geometry, the supportand the loading, but also of all the essentialcharacteristics of materials and states. Inreality, however, cases occur in which at leastone of the assumptions for computationalproof of safe load-bearing capacity is eitherunknown or cannot be defined with certainty. An experimental assessment of safe load-bearingcapacity on the basis of the actual loadstate has the advantage that the result includesall states of the materials and componentsconcerned that can affect load-carryingcapacity, even when hidden and not revealedby preliminary investigations [Lit. 3].