טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKats David
SubjectSeismic Protection of Reinforced Concrete Bridges by Means
of Base Isolation
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Emeritus Avigdor Rutenberg
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The idea behind Base Isolation is about separating as much as possible the building, or bridge in this case, from the earthquake. Isolation physically uncouples a bridge superstructure from the horizontal components of earthquake ground motion. The aim of the work is to provide available knowledge and tools to enable the engineer to carry out this separation in a correct way.

There are many kinds of elements for base isolation and energy dissipation. Uncoupling is achieved by interposing these mechanical elements with very low horizontal stiffness between the superstructure and substructure. Thus, when an isolated bridge is subjected to an earthquake, the deformation occurs mainly in the isolators rather than in the substructure. This greatly reduces the seismic forces and displacements transmitted from the substructure to the superstructure elements.

This investigation presents the essence of existing knowledge on the subject, focusing on the devices, standards and methods that are likely to be implemented in Israel in terms of financial viability. It expands the subject of elements and a selection of methods with solutions to numerical examples, and provides advanced tools and practical recommendations for engineers.

The methodology focuses on an extensive review of literature and on the compilation of relevant information contained, with special emphasis on the technical data required for practical design. The work consists in achieving these goals gradually, investigating the material, progressing chapter by chapter: from explanations of the general basic elements of the subject, through different methods of analysis, investigation of the current standards, detailing the various existing isolation elements, presentation of the principal technical data demonstrating the design and describing the main equations for each isolation element; description of the modeling process and the preliminary design process, to the analysis and design methods selected. Two numerical examples, the first of a bridge with isolation sliding device and the other with lead core laminated rubber isolator, demonstrate the practical application. The result is a document providing the material needed for the design of base isolated reinforced concrete bridges.

The main conclusions of this work are: base isolation provides the most economic and efficient solution for the design of reinforced concrete bridges. The design of a bridge combining base isolation is no more complex than that of a normal bridge, and the current knowledge combined with the modern analysis tools enable effective design with a high level of safety.