Seismic Risk Assessment of Masonry Walls and Risk Reduction by Means of Prestressing: Fid-Bau Portal

Seismic Risk Assessment of Masonry Walls and Risk Reduction by Means of Prestressing

Sperbeck, Silvio

The basis for the management of seismic risk is a developed risk management chain with definitions of its important components. Demandable knowledge about masonry, earthquakes, their probabilistic description, transient structural analyses and modern demands for aseismic design is provided. The main focus lies on the analysis of vulnerability of unreinforced and vertical prestressed masonry. Its results are physical damages that are used for the above mentioned risk estimation. The impact of vertical prestressing and its dependency on practical methods of execution on the meaningful ductility is asserted, described and theoretically explained by an interaction between internal tendons and the wall itself. Numerical methods and three material laws for masonry are elucidated that are used for the extensive simulations. By means of the experimental tests, the numerical models are calibrated. The impact of prestressing on the dynamic behaviour is pointed out. Furthermore, influencing factors on the structural behaviour and simulations results are investigated. Sensitivities and correlations are results of extensive probabilistic simulations. However, the estimation of probability density functions for different damage parameters is the main aim of the probabilistic simulations. As an outcome, vertical prestressing of masonry is only conditionally useful in case of seismic action. It depends on several factors, for instance properties of structures and earthquakes, degree of prestressing or considered damage parameters. In general, the mortar damage is reduced, but the unit damage is increased. Further ideas are taken into account and developed to reduce the damage of masonry in case of seismic action. It closes with the application of the suggested risk management concept to an example in the region of Aachen, Germany. The risks are calculated and compared.