Reliability Analysis of Timber Elements Under Different Load Types and Identification of Critical Scenarios for the Evaluation of Existing Structures

This contribution presents reliability analyses of structural members made from timber under different load combinations relevant for common structures. The study embraces members under strain induced by permanent action and live load, as well as permanent action and snow/wind load. Snow and wind load are superimposed applying the Ferry Borges and Castanheta load combination rule. Results are analysed to identify critical design situation from a statistical point of view assuming a one-hundred percent workload of the semi-probabilistic design situation considering partial safety factors from current design codes. Studies are performed for a reference period of 50 years. The studies show that small rooms under high load fluctuation (live load) are critical in terms of calculated reliability. What is more, a high load share of snow load is also particular critical. Thus, flat roofs are to be investigated with certain care. Results are used to identify and classify design situation for modification of partial safety factors on the material side. In this respect, different design situations can be treated more optimal and thus load-bearing capacities in existing timber structure may be activated and considered if available.