1st Croatian Conference on Earthquake Engineering 1CroCEE 2021

The proper seismic design of bridge structural bearings and expansion joints enables avoiding high repair costs after earthquakes. The paper discusses some experiences of the authors in design of bridge bearings and expansion joints according to Eurocodes. Within the scope of the detailed design of several new road overpasses, railway underpasses and railway bridges in the Republic of Macedonia, a special project on design of structural bearings and expansion joints has been realized.
Based on the performed analyses, several issues are discussed. First, it has become evident that the geometry and the layout of the bridge structures have an influence on the layout and the fixation of the bearings (i.e., fixed, guided in one direction or bearings movable in all directions). The bridge shape in plane, the number of spans, the alignment disposition, etc. have also affected the adoption of bearing types and dimensions. Finally, the dynamic parameters and seismic behaviour of the bridges have appeared to be crucial in the design of the bearings. The paper also includes a comparison between design of bearings according to the Eurocodes and the Macedonian codes.
For the purpose of comparative investigation of different layout solutions for the bearings’ fixation, apart from static analyses, dynamic non-linear time-history analyses, using time-history ground acceleration records that correspond to the Eurocode 8 design spectra, have also been performed. From the analyses, the most superior layouts in terms of fixation, position and number of bearings have been obtained for each treated bridge structure.
Precious experience has been gained during realization of the project. Since the Eurocodes’ design philosophy has already moved toward development of new technologies for bearings, it is inevitable to make changes in the Macedonian practice. This philosophy has brought more freedom to the design process, especially in making decisions in obtaining optimum solutions depending on predominant actions, especially seismic ones.