Günther ACHS

Seismic Hazard of Historic Residential Buildings.
Evaluation, Classification, and Experimental Investigations (in German)

 

Reliability of existing buildings is a major issue of a comprehensive seismic hazard assessment. Particularly in urban areas with a huge amount of historic buildings the evaluation and assessment of those buildings is indispensable. In the city centre of Vienna so-called Gründerzeithäuser, structures, which were erected within the building phase between 1840 and 1918, represent the predominant type of building. Mostly, these structures have been retained unchanged without considerable structural improvement for decades, but nevertheless are typically still used as residential buildings. Especially the lack of information and scientific investigations about the material properties, the detailed construction and the dynamic behavior of those buildings has led to many discussions about their vulnerability under seismic loading.
It is therefore the main intent of the Doctoral Thesis to carry out a comprehensive assessment and evaluation methodology based on visual inspections for the considered historic buildings in Vienna in order to obtain a realistic estimation of the damage potential under seismic loading of this particular building type. According to existing assessments an efficient method was developed to assess and evaluate a large amount of buildings within an adequate period. The essential information for the development of the method was made available from historic documents as well as from current scientific research results. Hence the evaluation and assessment method for Gründerzeithäuser in Vienna consists of various parameters to describe the actual condition of the structure and the damage potential of the building in case of an earthquake event. After the evaluation and assessment of a certain structure, the building will be classified in order to estimate the possible damages due to an earthquake. In an application of the evaluation and assessment methodology a large amount of Gründerzeithäuser in the 20th district of Vienna was investigated. Subsequent to the classification of the buildings a seismic hazard map of the reviewed area was plotted to identify local damages due to a local earthquake event.
In a further part of the Doctoral Thesis basic information about the dynamic system of the considered historic buildings in Vienna was obtained by means of in-situ investigations in order to derive scientific findings on the dynamic behavior under seismic loading of these structures. One of the biggest advantages of experimental investigations on existing buildings is the recording of the actual condition of a structure. In particular the most interesting parameters of the present historic buildings are the modifications of the dynamic behavior during structural changes. These modifications can be favorably identified by comparison of the structural behavior with and without certain changes.
During a further investigation of the test object Spittelbreitengasse the contribution of non-structural elements on the dynamic behavior of the building could be identified. Especially the influence of partition walls and wooden floors on the global stiffness of the building could be verified. In addition the experimental results were checked by means of a numerical model of the structures. The conclusions therefore provide important technical expertise for the seismic vulnerability assessment of the Gründerzeithäuser in Vienna.


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