Gesamtkonzept zur Ermittlung der seismischen Vulnerabilität von Bauwerken am Beispiel unterirdischer Rohrleitungen

Abstract

Earthquakes are one of the natural phenomena which present a high risk for the safety of human lives and man-made structures. Since the early history of mankind catastrophic earthquakes have occurred. Damages of buildings as well as faults at the ground surface are the most spectacular consequences and can be easily observed. In the last century the pipe networks to ensure the supply of the population have been greatly extended. Therefore more underground infrastructure has been damaged due to earthquakes. These damages are generally less spectacular, yet determine the amount of consequential damage of an earthquake (e.g. by the fire water supply) and the possibility to supply the population after an earthquake effectively and sufficiently. Within the present work an overall concept for evaluating the seismic vulnerability of structures exemplified through underground pipelines is developed. With it the following questions are to be answered: - How big is the seismic vulnerability of existing pipelines? The investigations necessary to answer this question shall be carried out on three different levels of accuracy. - How big are the financial consequences that are to be expected? This question is especially important for insurance companies and the budgeting of public authorities. The computations on level I are based on simple empirical relationships between seismic action and damage rate. Although such approaches are often used in practice to determine earthquake scenarios of whole regions the results are reliable only for areas which have been considered for the identification of these empirical relationships. On level II analytical relationships between the seismic action and the mechanical reaction of the pipeline (stresses, strains, etc.) are employed. Even more accurate are on level III the finite element simulations to analyse structures under seismic load. Here the emphasis is on the modelling of the pipeline and the seismic action while the soil is represented in a simplified way. Based on parameter studies the reliability of the different methods is investigated and using sensitivity analyses the relevant input parameters for the damage are identified. Since the required input values for the calculations on all three levels are subject to partly large variations all methods have been extended by the possibility of a probabilistic calculation to take into account these variations. The computations on level II and III are followed in a second step by the determination of the damage rate from the mechanical response of the structure. For this purpose as well as for the following calculation of the financial losses failure indices have been developed within the present work. With them finally the annual insurance premium of a pipeline is calculated based on confidence intervals. Since all types of structures are affected by the seismic hazard it is very important to build up a common platform to link the investigations of different building types, e.g. for the development of regional scenarios. Additionally this ensures the sustainability and long term availability of results from different research areas. Within this work such a central web-based platform has been used for the first time for seismic vulnerability assessments and all methods implemented within this work are accessible via this platform