A METHOD FOR SEISMIC PROTECTION OF BRIDGES USING NEW UPGRADED NVF-ISOLATION SYSTEM: SHAKING TABLE TESTS OF BRIDGE MODEL

<p>Presented in this paper is a new method representing efficient innovative system for seismic protection of bridges, created with upgrading of isolated bridge with developed specific uniform NVF devices. Capability of the new NVF seismic protection system for bridges was fully demonstrated with the conducted extensive seismic shaking table tests of large-scale bridge prototype model. The constructed bridge prototype model was assembled based on optimal upgrading of its basic isolation system, comprised of specific double spherical rolling seismic bearing (DSRSB) devices, with the originally created efficient uniform vertical fixed (NVF) complementary upgrading devices. The specific research segment devoted to development of the present NVF upgraded bridge system was originally created and realized by the authors as a part of innovative research project. The presented research segment was realized at the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Ss. Cyril and Methodius University in Skopje, North Macedonia, within the innovative NATO Science for Peace and Security Project “Seismic Upgrading of Bridges in South-East Europe by Innovative Technologies (SFP: 983828)”, involving five European countries. The composed upgraded isolated rolling system with uniform NVF energy dissipation (ED) devices represent suitable integrated passive mechanical bridge system providing harmonized response of integral bridge structure subjected to strong earthquakes. The adopted system is based on global optimization of seismic energy balance, achieved through utilization of newly designed dissipation devices as a supplementary damping to the bridge isolation. The new NVF seismic protection system is based on incorporation of the following three integrated complementary systems: (1) Double spherical rolling seismic isolation (DSRSB) system, (2) Created NVF energy dissipation (ED) system and (3) Displacement limiting (DL) system. The created NVF bridge system represents a qualitatively new construction strategy providing upgraded structural seismic safety and efficient modification of the seismic response in bridges located in seismically active regions.</p>