The results of the experimental research program realized on a bridge model constructed by using the seismically isolated system upgraded with space-bar devices (USI-SB) are presented in the paper. The installed adaptable system for seismic protection of bridges utilizes double spherical rolling seismic bearings (DSRSB) as seismic isolators, while the qualitative improvement of seismic performances is achieved through the use of novel adjustable multi-directional space-bar energy dissipation (SB-ED) devices. The experimental program consisted of quasi-static testing of isolation and energy dissipation devices under the cyclic loading and extensive shaking-table testing of a large-scale bridge model with installed USI-SB system. For both types of devices, a very stable all-directional response during cycling tests, as well as the favorable hysteretic behavior of the energy dissipation devices along the entire range of applied large displacements were registered. In the dynamic testing, the system showed high seismic response modification performances needed for the efficient protection, exhibiting its large potential in the qualitative improvement of seismic performances of isolated bridges.

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Non-linear three-dimensional analytical models of bridges with laminated-rubber seismic bearing devices upgraded with multi-directional space-flange energy-dissipation (SF-ED) devices were experimentally validated under multi-directional seismic action by shaking table tests of large-scale prototypes. The experimentally verified hysteretic models were used to model the upgraded seismic isolation (USI) system. The seismic protection benefits of the USI were demonstrated through a comparative analysis of bridge prototypes with both standard and upgraded systems. It was confirmed that the SF-ED devices provided a qualitative contribution under very strong earthquakes in all directions. The variation of the structural characteristics of the devices illustrates the technological options for qualitative seismic upgrading of various types of isolated bridges with complex plane geometries under multi-directional seismic actions.

Purpose The novel metallic damper device for passive vibration control of structures, which is designed primarily for seismic protection of buildings, is described in this paper. It consists of the base plate, fixed into foundation, with two concentric cycles of vertical components and a middle steel activating plate anchored to the isolated structure. During an earthquake, the middle steel activating plate moves together with main structure causing bending of vertical components. Seismic energy is absorbed due to plastic deformation of the vertical components of the damper. The performance of various vertical components, the key elements of the novel damper is studied in this paper. The advantages of this type of damper reflect in its ability to adapt its own features depending on the intensity of the earthquake and that it has equivalent characteristics in every horizontal direction due to rotational symmetry. Methods Sixteen experimental tests of the vertical components of the damper, were conducted to obtain their hysteretic behaviour. Numerical models using the finite element method and the Abaqus/Standard software were developed, validated and verified with experimentally obtained results. Results The experimental results show significant energy absorption of the vertical components of the novel damper. Numerical models can be used in further research instead of expensive experimental tests. Conclusions The vertical components of the novel damper possess extraordinary hysteretic performance. If the components of the energy dissipation device are properly designed for maximum displacements, the device is not expected to suffer heavy damage or total failure during earthquakes.

Presented in this paper is an innovative, uniform seismic protection system of masonry and infilled frame buildings created on the basis of a specifically upgraded sliding isolation system with new SF devices. The new building sliding-space flange protection system (BSSF system) represents a specific research segment of the integral research project, led by the fourth author, conducted in the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Ss. Cyril and Methodius University (Skopje), during three and a half years, in the frames of 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 upgraded, seismically isolated sliding system with integrated space flange (SF) energy dissipation (ED) devices has been developed as a mechanical passive concept to provide harmonized response of building structures to strong earthquakes. It is formulated as an adaptive system, which follows the adopted concept of global optimization of seismic energy balance, through utilization of newly designed dissipation devices as a supplementary damping level to the building isolation. The new BSSF protection system is based on obligatory incorporation of the following three integrated complementary systems: (1) Sliding seismic isolation (SSI) system, (2) SF seismic energy dissipation (ED) system and (3) Earthquake displacement limiting (EDL) system. The proposed seismically resistant BSSF building system represents a qualitatively new strategy for construction of modern masonry and framed masonry buildings by applying traditional and new construction materials and providing simultaneously: (1) Full seismic safety of protected buildings, (2) Reduction of construction time, and (3) Profitable construction in seismic areas achieved by the special system characteristics.