On The Plastic Design Of Timber Beams With A Complex Cross-Section

For the design of steel and concrete structures, most modern international design codes allow the use of plastic stressstrain-diagrams for the analysis of the bending resistance of the cross-section in the ultimate limit state. Curiously, in Europe and most other parts of the world, timber structures are still designed for the ultimate limit state with the old, conservative concept of full elastic behavior till failure. The situation is rather funny for two main reasons. First, it is well known that under compressive loading, timber exhibits a much better ductile behavior than concrete, for example. Secondly, between the two World Wars, timber scientists developed refined calculation methods to explain test results which showed that the bending strength of small, clear timber specimens lies well above the compressive strength. It is curious that these findings have never been developed to the stage where they could be integrated into modern timber design codes.