Construction of precast reinforced concrete (PRC) industrial halls in seismically active areas has been increasing in recent decades. As connections are one of the most sensitive and vulnerable zones of PRC structures, there is a need to pay special attention to their investigation and modeling in seismic analysis. Knowing that each PRC system is specific and unique, this study aims to evaluate the actual seismic performances of PRC industrial halls built in the AMONT system, which represent a significant portion of the existing industrial building stock in Italy, the Balkans, and Turkey. As there is a lack of published research data on its specific joints, the results of the quasi-static full-scale experiments carried out up to failure on the models of four characteristic connections are presented. Since the implementation of nonlinear dynamic analysis in everyday engineering practice can be demanding, a simplified model of the structure considering the effects of the connections’ stiffness is proposed in this paper. The differences in the roof top displacements between the proposed model and the model with the rigid joints of the analyzed frames are in the range from 16.53% to 66.93%. The values of inter-story drift ratios are larger by 10–100% when the real stiffness of connections is considered, which is above the limit value provided by standard EN 1998-1. These results confirm the necessity of considering the nonlinear behavior and stiffness of connections in precast frame structures when determining displacements, which is particularly important for the verification of the serviceability limit state of structures in seismic regions.

Following the increasing demand for optimal protection of urban areas against natural multi-hazards, we developed an upgraded urban development planning (UUDP) method integrating four principal planning layers along with the initial zero-planning layer and its related sublayers that systematically characterize the potential natural disasters. The significance of pre-planning characterization for natural disasters was demonstrated through a flood disaster case study, which included the flood analysis options of the historic city of Peja. Herein, we systematically review the representative results from a study on the characteristics and magnitudes of flood waves in the Bistrica River generated by storm runoff within the basin, completed using advanced worldwide HEC-HMS software. Consequently, the advanced HEC-RAS analysis software was employed to evaluate the effects of 24-h precipitation events on both the extent and magnitude of flooding. Existing multi-hazard effects were systematically incorporated into planning through the upgraded zero multi-layered method, which involved a detailed characterization of all relevant multi-hazards. The original flood hazard analysis results, including total inundated area (141.5-432.8 ha), maximum water depth (4.28-5.94 m) and velocity (4.76-5.94 m/s), clearly demonstrated tangible improvements in implementing the new UUDP method for optimal urban multi-hazard protection solutions .

Presented in this paper is an innovative system efficient for seismic protection of sensitive infill in RC frame buildings created with upgrading of isolated buildings with developed specific uniform SB devices. Capability of the new seismic protection system of masonry infilled frame buildings was fully demonstrated with the conducted extensive seismic shaking table tests of large-scale models constructed with applied upgrading of its basic sliding isolation system with the created uniform SB devices. The specific research segment devoted to development of the present SB upgraded building system (SBBS system) was originally initiated by the second and fourth authors and represents a part of the integral research project realized in the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Ss. Cyril and Methodius University in 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 composed upgraded isolated sliding system with uniform multi-gap SB energy dissipation (ED) devices represents a suitable integrated passive mechanical building system providing harmonized response of integral buildings subjected to strong earthquakes. The adopted system is based on global optimization of seismic energy balance, achieved through the utilization of newly designed dissipation devices as a supplementary damping to building isolation. The new SBBS seismic protection system is based on the incorporation of the following three integrated complementary systems: (1) a basic sliding seismic isolation (BSSI) system, (2) a created SB energy dissipation (ED) system; and (3) a displacement-limiting (DL) system. The created SBBS building system represents a qualitatively new construction strategy providing qualitatively upgraded seismic structural safety and efficient seismic protection of sensitive infill in rapidly constructed RC frame buildings located in seismically active regions. Key words:building, RC frame, masonry, seismic response, seismic isolation, energy dissipation

In this paper are presented original results obtained from the realized well targeted laboratory tests of nonlinear response of the constructed large-scale prototype models of circular RC bridge piers under realistically simulated earthquake-like cyclic bending and different levels of the induced axial loads. Considering the obtained detailed results from the integral experimental investigation of the hysteretic behavior of RC bridge pier models with common circular cross-sections under simultaneously applied constant axial and reversed shear loads, the most important observations regarding advanced analytical modeling and accurate earthquake response analysis of RC bridge structures can be briefly summarized as follows: (1) The inelastic behavior of reinforced concrete bridge piers is characterized by a variety of complex influencing phenomena directly resulting from the successive degradation of the steel and concrete mechanical properties, representing their specific inelastic response characteristics and consequently resulting from additionally induced complex time dependent interactive loading effects. For a realistic analytical simulation of such complex nonlinear process, the effects of the most important influencing factors should be estimated and analytically represented. This can be achieved through development of the advanced refined (micro) analytical model and corresponding analytical procedure based on available data from the conducted representative experimental tests. (2) The present experimental results indicate that the inelastic behavior characteristics of the tested RC specimens have been significantly affected by the level of applied axial load, throughout the whole range of imposed displacements. Consequently, it becalmed clear from the tests that the earthquake-induced time-varying axial forces in the critical elements during structural vibration can introduce respective effects to the overall inelastic structural response in a more complex manner. To predict the inelastic earthquake response of specific bridges involving large spans and very tall RC bridge towers, the analytical model should be capable to account for the induced instantaneous interactive effects of bending and time -varying axial forces. Development of the advanced nonlinear analytical 3D micro-model reflecting to realistically simulate the above stated complex phenomena represent specific study objective of the next planned analytical phase of the present study.

An experimentally proved method for efficient seismic upgrading of isolated bridges exposed to very strong multi-directional near-field and far-field earthquakes is presented in this paper. The advanced capability of the upgraded bridge system was achieved by application of the developed uniform complex root (CR) energy dissipation devices. The new uniform complex root (UCR) bridge system was fully validated based on seismic tests on experimental models and analytical response simulation studies. The UCR system integrates the advances of seismic isolation and energy dissipation and represents an advanced technical solution for efficient protection of bridges located in seismic areas of the highest seismicity. The tested large-scale model of the UCR bridge system had double spherical rolling seismic bearings (DSRSB) as seismic isolation devices, while qualitative improvement of the seismic performances was achieved through the use of the created uniform CR energy dissipation devices. Extensive seismic testing of the UCR bridge model was conducted under simulated effects of near-field and far-field earthquakes, respectively.

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.

The seismic safety margins of seismically isolated bridges have not been thoroughly studied or comprehended due to a lack of actual on-site data observations. This study introduces a newly validated method for the efficient seismic protection of bridges that may be exposed to extremely strong, multidirectional near-source and critical far-source earthquakes. The isolated system was improved by incorporating innovative adaptive horizontal C-multigapped (HC-MG) energy dissipation devices to overcome the safety limitations associated with solely using isolated bridges under seismic loads. The newly developed adaptive C-gapped (ACG) bridge system was systematically validated through extensive experimental seismic tests on bridge models and additional analytical studies. The new ACG bridge system represents an advanced technical solution that integrates the benefits of seismic isolation and energy dissipation. The seismic isolation system for the largescale ACG bridge prototype was designed using double spherical rolling seismic bearings (DSRSB). The seismic performance of the system was enhanced with adaptive HC-MG energy dissipation devices. The improved seismic performance of the system was demonstrated through extensive seismic shaking-table tests on the ACG bridge prototype, simulating selected seismic inputs characteristic of typical near- and far-source earthquakes.

To meet the increasing demands for innovations in precast systems with high seismic resistance, in this study, we introduced a novel seismic upgrading technique for roof beam-column (RBC) connections, termed the targeted seismic upgrading (TSU) method, incorporating the innovative seismic safety key (SSK) devices we developed. These devices significantly enhance seismic resilience, offering a substantial improvement over traditional pin-based RBC connections in precast structures, which are known to have limited effectiveness. Our experimental tests on half-scale models of conventional RBC connections, coupled with comprehensive refined finite element method-based nonlinear analytical studies, conclusively demonstrated the enhanced seismic retrofitting capabilities of RBC connections augmented with SSK devices. The paper delineates a technical procedure for applying the SSK, our proprietary innovation, for the targeted seismic upgrading of RBC connections within modern precast systems. Notably, the SSK-upgraded RBC connections exhibited a marked increase in safety, as evidenced by results from experimentally validated nonlinear three-dimensional micro-analytical models. The incorporated flexible design elements in the TSU method ensure its high effectiveness and general applicability for seismic upgrading of both existing and new precast industrial hall structures, offering a significant advancement in this specific seismic engineering topic.

Steel- and composite-reinforced columns (SRC and CRC columns) provide alternative solutions for common and harsh environments. Although extensive research has been conducted on these columns, direct comparative studies of SRC and CRC columns under seismic conditions, with consistent testing and realistic load simulations, remain limited. This study examined the nonlinear seismic responses of nine ordinary steel-reinforced concrete column models constructed alternatively with normal-strength and high-strength concretes under simulated earthquakes and time-varying axial loads. A developed advanced HYLSER-2 seismic testing system was employed to conduct seismic tests. Spiral transversal reinforcement with pitches of 6.0 and 9.0 cm was used to explore the effects of concrete confinement. The HYLSER-2 seismic tests, conducted under various interactively simulated earthquake intensities and time-varying axial loads, yielded crucial experimental results. Additionally, an extensive complementary analytical study was conducted to provide comparative insights between steel-reinforced columns (SRC) and composite-reinforced columns (CRC) with novel glass fiber-reinforced (GFRP) bars. The analytical study was conducted using experimentally proven advanced nonlinear analytical micromodels. The analytical results highlight the hysteretic behavior of columns reinforced with ordinary steel and novel GFRP reinforcing bars under the simulated combined effects of reversed cyclic bending and time-varying axial loads. The findings form a critical basis for advancing seismic design strategies for SRC and CRC columns exposed to strong earthquakes and high-time variations in axial loads.

A method for enhancing the seismic performance of isolated bridges was developed using innovative vertical multigap (V-MG) devices based on extensive experimental and analytical research. Significant improvements in seismic performance were achieved by creating a unique type of uniform V-MG energy-dissipation device for a vertical-gaped bridge protection system (VG bridge system) that included double spherical rolling seismic bearings for seismic isolation as a complete set. Seismic shaking table tests on large-scale bridge models, which simulated real earthquake conditions, confirmed that the VG bridge system could significantly modify seismic response and enhance the seismic safety of isolated bridges under very strong earthquakes.

This paper reports on original findings from advanced HYLSER-1 seismic tests conducted on steel-reinforced concrete column models subjected to simulated low and high axial loads. The study includes a comparative analysis of steel-reinforced concrete (SRC) column models and composite-reinforced concrete (CRC) column models, using refined nonlinear analytical micro-models. The results demonstrate that earthquake intensity, axial load level, and concrete confinement are the primary factors influencing the complex hysteretic responses and failure of column models reinforced with either conventional steel bars or novel glass fibre-reinforced polymer (GFRP) bars. These findings are crucial for enhancing the seismic design of alternatively reinforced columns subjected to severe earthquakes.

Combined and extensive experimental and analytical study devoted to development of an integrated earthquake and flood protection (EFP) bridge system was performed. It represents an extension 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 and led by the fourth author. The presently introduced EFP bridge system represents a specific, extended segment of the integral research. The upgraded, seismically isolated (USI) system with integrated space flange (SF) energy dissipation (ED) devices has been developed as a mechanical passive concept to provide harmonized response of bridge structures to earthquakes. It was 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 bridge isolation. The new EFP-bridge system is based on obligatory incorporation of the following four integrated complementary systems: (1) Seismic isolation (SI) system, (2) Seismic energy dissipation (ED) system, (3) Combined earthquake and flood displacement limiting (EFDL) system composed of new and experimentally tested RB devices and (4) Uplift protection system (UP). With the extensive experimental quasi-static cyclic tests conducted by simulated, gradually increased displacement amplitudes, there were confirmed very stable hysteretic responses of the created prototype models of rubber buffer (RB) devices applicable for efficient protection of common and isolated bridges exposed to either strong earthquakes or flood disasters. Following the upgrading of the seismically isolated (USI) bridge system with energy dissipation devices, the adopted original rubber buffer (RB) devices represent an important additional line of defense against abrupt loadings due to earthquake and flood disasters.

Construction of modern, seismically safe bridge structures represents a permanent activity of the highest importance because bridge structures are important key elements responsible for providing continuous functioning of integral highway infrastructure systems. An extensive experimental and analytical research led by the third author was performed in the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Ss. Cyril and Methodius University in Skopje, lasting three and a half years, in the frames of the innovative NATO Science for Peace Project “Seismic Upgrading of Bridges in South-East Europe by Innovative Technologies (SFP: 983828)”, involving five countries. The specific project part included development of the innovative upgraded seismically isolated system USI with vertical multi gap V-MG representing an advanced technology for seismic isolation and seismic protection of bridges. By integrating the new uniform, vertical multi-gap (V-MG) energy dissipation devices, qualitative advances of the USI-V-MG system were achieved. The original observations resulting from the conducted complex, unique and critical near resonance shaking table tests of the constructed large-scale bridge model are presented and discussed in this paper. The extensive experimental research program was realized on a bridge model constructed by using the seismically isolated system upgraded with uniform vertical multi-gap energy dissipation devices (USI-V-MG). The installed adaptive system for seismic protection of bridges utilizes originally produced double spherical rolling seismic bearings (DSRSB) as seismic isolators, while qualitative improvement of the seismic performances is achieved through the use of novel, uniform vertical multi-gap energy dissipation (V-MG-ED) devices.

The design and construction of modern, globally upgraded and seismically safe industrial hall systems (SSIH Systems) is currently viewed as an activity of extraordinary importance since these structures most frequently house new advanced and robotically conceptualized industrial machines and equipment, whose value multiply exceeds the value of the integral structures. The SSIH systems are of vital importance because it is only by their practical application that efficient and continuous functioning of important production industrial systems and compounds is provided. The achieved safety margins, the actual seismic performances and the present limitations of the used pin-based floor-beam column connections of the existing precast N-system were integrally confirmed by the original results obtained from the conducted experimental tests of the constructed connection prototype models. The precast N-system is commonly used for intensive construction of large industrial structures in different regions and countries, including areas of Europe and wider characterized by high seismicity. The initial results obtained from the laboratory test of the constructed large-scale prototype model representing a common floor-beam column (CFBC) connection confirmed the actual bearing capacity of the connection, the damage propagation pattern and the specific total failure mode. To investigate possible upgrading of the connection safety, a specific supplementary test was performed using the created and constructed new experimental model, representing an upgraded floor-beam column (UFBC) connection by application of an improved concrete confinement and use of larger diameters of steel connection pins (dowels). The main conclusion regarding the safety increase was that such common upgrading concept of pin-based connections could not be considered as a basic adequate approach since it was able to provide only limited upgrading effects. The existing need for creation of a new, advanced, experimentally proved and effective innovative upgrading method was clearly pointed out.

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.

The precast N-system based on embedded-pin connections is used widely to construct large precast industrial halls in south-eastern Europe and further afield, including areas of high seismicity. To realistically assess the seismic performances, safety margins and limitations of the connections, experimental investigations are essential. Experimental results from laboratory tests on a large-scale prototype model of an original roof beam–column connection show its actual bearing capacity, damage propagation pattern and specific failure mode. The experimental study was then extended to a prototype model of an upgraded roof beam–column connection. To improve safety, the connection was upgraded with improved concrete confinement and stronger steel connecting pins. The experimental results show clearly that the method implemented to upgrade the pin-based connection provided very limited upgrading effects. To obtain much better and more reliable safety upgrading, an innovative and effective upgrading method had to be developed. The capability of the implemented refined nonlinear three-dimensional (3D) micro-modelling concept to realistically simulate the complex nonlinear response of the tested original and upgraded roof beam–column connections was demonstrated by an extensive analytical simulation study.

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.

The conducted extensive experimental seismic analysis showed seismic performances of a constructed large-scale bridge model representing system of upgraded isolated bridge with uniform gapped horizontal S-shaped devices (GHS System). The GHS system constituted double spherical rolling isolating bearings (DSRIB) and created original uniform horizontal S-shaped multi-gap (HS-MG) energy dissipation devices. With conducted laboratory cyclic tests, stable all-directional hysteretic responses were confirmed for both the DSRIB and HS-MG devices. In the dynamic seismic shaking table testing, the GHS bridge system showed favourable seismic response performances contributing to efficient bridge system protection. The established new GHS system exhibited large potential for qualitative improvement of seismic safety of isolated bridges exposed to very strong earthquakes.

Extensive analytical and experimental research has been done by the authors directed to mitigation of the effects of earthquakes on structures. The research results mainly represent parts of the realized several related international projects. A selected part of the analytical studies directed to comparison between conventional and seismically isolated frame structures is presented in this paper. The responses of the applied newely developed advanced seismic isolation system HC-RMS-GOSEB to the simulated input excitation of three representative earthquakes of intensity 0.50g, have shown that it is very effective for construction of vibro-isolated and seismically resistant buildings, providing activated multistage seismic response and globally optimized seismic energy balance. Its application achieves an increase in the vibration period of the structure, far enough from the dominant period of seismic excitation. The results of the research confirm that this system is a potential solution for achieving low-cost and highly efficient protection of buildings.

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.