Bewertungsverfahren zur Beurteilung der Erdbebensicherheit von Brückenbauwerken

After the occurrence of an earthquake the safety of bridge structures is of crucial importance to the operability of an infrastructural network. It is a complex and costly task to estimate the earthquake endangerment of bridges due to the large number of different types and ages of bridges. In this work, a solution utilizing a systematic procedure for the evaluation of the earthquake resistance of the bridge inventory is presented. First, the bridge to be judged is classified according to the bridge type. Subsequently, the structural importance of the bridge is estimated and the seismic site hazard is determined. Based on this information the seismic safety is determined by a three-stage investigation scheme. Within the first investigation stage the bridge is evaluated on the basis of fragility curves. Additionally, the individual construction details of the bridge can be considered by an extensive evaluation and ranking system for each type of bridge. Weak points of a bridge with regards to earthquake loads can already be identified with this first estimation. This investigation can be accomplished with small expenditure of time and serves as decision basis on whether further investigation steps are necessary. Furthermore, a prioritization catalogue of the assessed bridges can be set up quickly by the comparison of the results. The second investigation stage contains a computational investigation of the bridge with a simplified linear computer model of the overall system using the multi-modal response spectrum method. Here, bridge-type-dependent templates which allow as far as possible an automatic generation of the numerical models are used. The result of the second investigation level is the examination of the earthquake resistance on basis of the computed internal forces, moments and deformations. The third investigation stage consists of a detailed evaluation of all bridge documents, a bridge inspection with vibration measurement and a detailed three-dimensional time-history simulation with consideration of physically and geometrically nonlinear effects. For the execution of the nonlinear transient analysis of reinforced concrete bridges, a nonlinear material model for beam elements was implemented into the FE-Software ANSYS. A coupled Boundary Element Method - Finite Element Method approach, which was also implemented in ANSYS, considers the soil-structure interaction. The presented method enables an evaluation of the earthquake safety and stability of bridges within a three-stage investigation concept. The systematic procedure allows a problem-oriented analysis with a minimum expenditure of time and costs. The practical application of the procedure which has been implemented as a novel management system with connection to the countrywide used bridge database SIB-Bauwerke is demonstrated through bridges in the Cologne area