Roberta Apostolska - Academia.edu (original) (raw)

Papers by Roberta Apostolska

Journal of International Environmental Application and Science, Sep 30, 2016

Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground fl... more Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground floor, which is less resistant to horizontal seismic forces than the upper storys. On the other hand, such inadequate stiffness causes disproportional displacement focused on that story. As a result, the ground floor becomes weak and susceptible to partial or complete damage to its structural elements, which in turn, results in collapse of the entire building. The results obtained from the performed linear and nonlinear pushover analyses show that the flexible story may result in a drastic change of the period of vibrations, which will further lead to a change of the seismic design force, the maximal relative story drifts and ductility of the considered structure. Within this paper, the effect of the flexible story on seismic performance of building has been explored through comparison between a structure with regular story heights and a structure with a flexible story. The effects of upgrading the critical story by appropriate structural interventions like enlargement of the base columns cross-section and/or insertion of RC walls are also investigated.

1st Croatian Conference on Earthquake Engineering, Mar 22, 2021

The Joint Research Centre (JRC) of the European Commission is engaged in activities supporting th... more The Joint Research Centre (JRC) of the European Commission is engaged in activities supporting the implementation, further development and promotion of European policies and standards for sustainable construction. Such activities include the Eurocodes (EN 1990-EN 1999), the European Standards providing common rules for the design of buildings and other construction works to check their strength and stability. Among the countries that have shown strong commitment and progress in the adoption of the Eurocodes are the non-EU Balkan countries. In the period 2013-2016, the JRC, within the Enlargement and Integration (E&I) Action, has organized specialized dissemination and training events to support the adoption and implementation of the Eurocodes in the region. A roadmap for continuing the activities was elaborated in 2016 anticipating technical assistance at implementation, practical use and maintenance level. A workshop in Tirana (2018) focused on the implementation level in the National Regulatory Framework (NRF). It was shown that significant progress has been achieved by all non-EU countries in the Balkan region in the adoption of the Eurocodes since 2016. However, there was still lack of sufficient coordination between the National Authorities and the National Standardization Bodies on the implementation of the Eurocodes. Due to the high seismicity of the Balkan region, most non-EU countries in the region are close to, or are intending to, formally adopt EN 1998 ("Eurocode 8: Design of structures for earthquake resistance"). JRC plans to provide technical assistance for the Eurocode 8 implementation by the practitioners, addressing the seismic design of concrete buildings through a Eurocodes Balkan Summer School. The paper provides an overview of the JRC Eurocodes training activities held and planned for the Balkan region, along with an update on the Eurocodes implementation status.

1st Croatian Conference on Earthquake Engineering, Mar 22, 2021

During the past earthquakes, we have witnessed extensive structural damage on modern highrise bui... more During the past earthquakes, we have witnessed extensive structural damage on modern highrise buildings. The use of flat-slab or partially flat-slab system, inadequate seismic dilatation joints, occurrence of plastic hinges in columns, short columns mechanism, building additional storeys on already designed/constructed structures, inadequate transverse reinforcement in columns and beams and so on. The solution to the problem is in implementing the most recent knowledge in analysis, design and construction. The Institute of Earthquake Engineering and Engineering Seismology has established a methodology to improve the current practice procedures, enabling analysis and design of robust and economical reinforced concrete structures with controlled and conducted ductile behaviour of elements and systems in general, up to ultimate limit states of the strength and deformability. The process of designing stable and economic structures is extremely complex, due to the necessary harmonization of a series of parameters related to the construction on one hand and its response to actual earthquakes on the other. The methodology and the dynamic response of real reinforced concrete buildings is presented here, through block diagrams and results from analysed examples. The reinforced concrete structures are designed with controlled and dictated ductile behaviour of the structural elements and the structure as a whole, for gravity/static loads and also for seismic/dynamic impacts that are expected for the defined location.

Engineering Structures, Aug 1, 2008

The paper deals with application of an originally developed methodology for repair and seismic st... more The paper deals with application of an originally developed methodology for repair and seismic strengthening of St. Clement's Church, Plaoshnik, Ohrid. To renovate the structure based on the original foundation dating back to the 9th century, complex multidisciplinary investigations were performed in the field of archaeology, conservation, engineering and construction. Presented in this paper are the investigations related to the design of the structural system based on elaborated architectonic bases that are to preserve the authenticity of the structure, performed geotechnical investigations of the site and defined input seismic parameters. A linear-elastic and nonlinear dynamic analysis of the structure was performed. Based on the obtained results, the concept of repair and seismic strengthening of the church was adopted. It consisted of incorporation of horizontal and vertical steel ties in the bearing walls of the structure. This method, which is based on the philosophy of "minimal intervention-maximal protection", had originally been developed at IZIIS, Skopje and it has been experimentally and analytically verified. The techniques of consolidation of the authentic foundation of the structure and the existing walls with original fresco-paintings are also presented.

The main objective of the energy-based design (EBD) is by controlling of the dissipative capacity... more The main objective of the energy-based design (EBD) is by controlling of the dissipative capacity and the ductility of the potential post-elastic mechanisms to reduce the risk of losing global stability and collapse of the structures during the limit design event. Following this design philosophy, investigations of the influence of different parameters of the hysteretic models on nonlinear performance of SDOF expressed via energy indicators are carried out. The most important parameters which are the subject of the study are: the stiffness after the yielding point , the factor of stiffness degradation at unloading USDP (unloading stiffness degradation parameter), the FYRP (force yield relation parameter) parameter, the initial stiffness and the level of the first cracks in concrete, as well as some specific parameters that are specific for the shear models only. Selected results concerning influence of these parameters on the maximum values of dissipated hysteretic energy (Emax) and its index (Eh) are presented in the paper.

The IZIIS' contribution to development of high quality materials has been seen in realization of ... more The IZIIS' contribution to development of high quality materials has been seen in realization of several scientific-research projects in the field of high strength concrete, (HSC) in the period from 1992 to 2006. Within the frames of these projects, synthesis of investigations reported in world literature has been made and complex laboratory-experimental-analytical investigations have been performed to contribute to: definition of the methodology for obtaining HSC exclusively from domestic resources; joint behaviour of high strength materials and elements in nonlinear range as well as definition of criteria and recommendations for application of these materials in seismically active regions. The selected results from these investigations are presented in the paper.

ICCES: International Conference on Computational & Experimental Engineering and Sciences, Feb 1, 2008

The IZIIS’ contribution to development of high quality materials has been seen in realization of ... more The IZIIS’ contribution to development of high quality materials has been seen in realization of several scientific-research projects in the field of high strength concrete in the period from 1992 to 2006. Within the frames of these projects complex laboratory-experimental-analytical investigations have been performed to contribute to definition of the methodology for obtaining high stength concrete exclusively from domestic resources, to investigate joint behaviour of high strength materials and elements in nonlinear range as well as to define dynamic behaviour high strength concrete buildings exposed to seismic actions. The selected results from these investigations are presented in the paper.

The critical point which defines behavior of precast buildings under cyclic loading is connection... more The critical point which defines behavior of precast buildings under cyclic loading is connections. The experience gathered from the past earthquakes together with existing analytical and experimental investigations are not sufficient enough to explain their seismic behavior. Therefore, experimental investigations of existing beam-column dowel connections were carried out by Slovenian researchers at the University of Ljubljana, (Fischinger at al, 2011). In parallel, analytical investigations of nonlinear behavior of the above beam-column connections under earthquake loading were realized at UKIM-IZIIS, Skopje (Apostolska, Necevska-Cvetanovska at al, 2011). Based on the above investigations, the numerical model for connection behavior is proposed. Presented in the paper are selected results from experimental and analytical research of the obtained response parameters for different types of beam-column connections under seismic action.

Flat-slab building structures possesses major advantages over traditional slab-beam-column struct... more Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural-functional and economical aspects. Because of the absence of deep beams and shear walls, flat-slab structural system is significantly more flexible for lateral loads then traditional RC frame system and that make the system more vulnerable under seismic events. The results from the analysis for few types of construction systems which is presented in the paper show that flat slab system with certain modifications (design of beam in the perimeter of the building and/or RC walls) can achieve rational factor of behaviour considering EC8 and can be consider as a system with acceptable seismic risk. Modifications with additional construction elements improve small bearing capacity of the system and increase strength and stiffness, improving seismic behaviour of flat-slab construction system. Selected result from the analysis are presented in the paper.

Increasing energy efficiency of final energy consumption is a very actual and important topic, in... more Increasing energy efficiency of final energy consumption is a very actual and important topic, in parallel with activities and measures worldwide targeting an increased share of renewable energy sources. Despite recent expansion in building construction, old buildings characterized by high energy consumption still represent a great majority of both residential and public building stock in many countries in the Balkan region. Located in seismicprone countries, such as the Republic of North Macedonia, these old buildings are also characterized by the high risk of partial or complete destruction during earthquakes. This imposes the need for mandatory screening at the outset of an energy efficiency program, which will categorize buildings according to seismic risk and thus determine which buildings are suitable for energy efficiency investments. This paper presents how the methodology for high-level seismic screening, originally proposed in the World Bank's Country Report (North Macedonia), is extended and customized by the Institute of Earthquake Engineering and Engineering Seismology, IZIIS, Skopje to correspond to the country specificities, i.e., to be based on overall knowledge on aseismic design and construction practice in the country, detailed on-site inspection of each particular building, and to be carried out by structural engineers with appropriate knowledge and experience in earthquake engineering. The high-level seismic screening was performed in the Republic of North Macedonia, applying this extended and customized methodology, for a total number of 27 medical facilities, dominantly healthcare centers, and 50 municipality buildings (schools, kindergartens, and municipal buildings).

The critical point which defines behavior of precast buildings under cyclic loading is connection... more The critical point which defines behavior of precast buildings under cyclic loading is connections. The experience gathered from the past earthquakes together with existing analytical and experimental investigations are not sufficient enough to explain their seismic behavior. Therefore, experimental investigations of existing beam-column dowel connections were carried out by Slovenian researchers at the University of Ljubljana, (Fischinger at al, 2011). In parallel, analytical investigations of nonlinear behavior of the above beam-column connections under earthquake loading were realized at UKIM-IZIIS, Skopje (Apostolska, Necevska-Cvetanovska at al, 2011). Based on the above investigations, the numerical model for connection behavior is proposed. Presented in the paper are selected results from experimental and analytical research of the obtained response parameters for different types of beam-column connections under seismic action.

The paper deals with application of an originally developed methodology for rehabilitation and se... more The paper deals with application of an originally developed methodology for rehabilitation and seismic strengthening of St. Clement’s Church, Plaoshnik, Ohrid. To renovate the structure based on the original foundation dating back to the IX century, complex multidisciplinary investigations were performed in the field of archaeology, conservation, engineering and construction. Presented in this paper are the investigations related to the design of the structural system based on elaborated architectonic floor plans that are to preserve the authenticity of the structure, performed geotechnical investigations of the site and defined input seismic parameters. A linear-elastic and nonlinear dynamic analysis of the structure was performed. Based on the obtained results, the concept of repair and seismic strengthening of the church was adopted. It consisted of incorporation of horizontal and vertical steel ties in the bearing walls of the structure. This method, which is based on the philosophy of “minimal intervention – maximal protection” has originally been developed at IZIIS, Skopje and it has been experimentally and analytically verified. The techniques of consolidation of the authentic foundation of the structure and the existing walls with original fresco-paintings are also presented.

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

This paper aims to describe the CRISIS web-based platform (WBP) in all its parts and functionalit... more This paper aims to describe the CRISIS web-based platform (WBP) in all its parts and functionalities. The platform is the main result of the two-year EU-funded project CRISIS (Comprehensive RISk assessment of basic services and transport InfraStructure). It has been developed by EUCENTRE (European Centre for Training and Research in Earthquake Engineering) using the most up-to-date web programming frameworks and technologies. The CRISIS WBP is a user-friendly tool intended to support disaster and emergency management authorities in case of earthquakes and/or seismo-induced landslides in the cross-border region of Albania, North Macedonia, and Greece. It has been designed to collect, organise, and visualise for the project target area: i) the exposure data of educational facilities, health facilities, and bridges; ii) the seismic and landslide hazard data; iii) the earthquake damage scenarios (calculated both for selected historical events and in real-time); and iv) the landslide ris...

Lecture notes in civil engineering, 2023

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

In recent years, the improvement of disaster and emergency management through building a harmoniz... more In recent years, the improvement of disaster and emergency management through building a harmonized and efficient system for risk assessment of structures in the cross-border region (CBR) has become increasingly popular. Harmonization of the risk exposure model for cross border regions is first and most important step for assessment of risk in the region. Different countries, even neighboring ones, have different frameworks in which buildings for basic services and transport infrastructures are designed, built and maintained. Hence, they involve different institutions and employ different ways of gathering information on existing structures within their networks. Each of them may use different methods and systems for keeping records on their assets. Therefore, there is no readily available inventory which covers the entire stock of bridges and buildings for basic services in any of the CRISIS adjacent partner countries. The harmonized regional risk exposure model is result of the ac...

Flat-slab building structures possesses major advantages over traditional slab-beam-column struct... more Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural –functional and economical aspects. Because of the absence of deep beams and shear walls, flat-slab structural system is significantly more flexible for lateral loads then traditional RC frame system and that make the system more vulnerable under seismic events. The results from the analysis for few types of construction systems which is presented in the paper show that flat slab system with certain modifications (design of beam in the perimeter of the building and/or RC walls) can achieve rational factor of behaviour considering EC8 and can be consider as a system with acceptable seismic risk. Modifications with additional construction elements improve small bearing capacity of the system and increase strength and stiffness, improving seismic behaviour of flat-slab construction system. Selected result fro...

Geotechnical, Geological and Earthquake Engineering, 2015

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

The impact of present building code requirements for seismic design of new buildings can readily ... more The impact of present building code requirements for seismic design of new buildings can readily be acknowledged, however applying regulation to existing buildings is an area less well defined. Presently, there is a diverse list of existing code references which could be interpreted to require seismic upgrades of existing structures. Unfortunately, these references do not provide a clear path toward addressing the hazards, evaluation and retrofitting of existing buildings. And when it comes to existing old buildings and monuments, constructed with low or no seismic consideration, the topic becomes much more complex and challenging. The problem of earthquake protection of historic buildings and monuments is radically different from that of other existing structures, due to the priority given to preservation of aesthetic, architectonic and historic values instead of keeping the structure operational. In providing the protection of these structures in a manner that requires the least i...

Sažetak: In frame-wall systems with competent and uniformly distributed walls, the infill walls s... more Sažetak: In frame-wall systems with competent and uniformly distributed walls, the infill walls stiffen the frame and reduce the first-mode period leading to a reduction in drift response to strong ground motion. At the same time, the addition of the masonry wall to the frame ...

Journal of International Environmental Application and Science, Sep 30, 2016

Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground fl... more Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground floor, which is less resistant to horizontal seismic forces than the upper storys. On the other hand, such inadequate stiffness causes disproportional displacement focused on that story. As a result, the ground floor becomes weak and susceptible to partial or complete damage to its structural elements, which in turn, results in collapse of the entire building. The results obtained from the performed linear and nonlinear pushover analyses show that the flexible story may result in a drastic change of the period of vibrations, which will further lead to a change of the seismic design force, the maximal relative story drifts and ductility of the considered structure. Within this paper, the effect of the flexible story on seismic performance of building has been explored through comparison between a structure with regular story heights and a structure with a flexible story. The effects of upgrading the critical story by appropriate structural interventions like enlargement of the base columns cross-section and/or insertion of RC walls are also investigated.

Journal of International Environmental Application and Science, Sep 30, 2016

Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground fl... more Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground floor, which is less resistant to horizontal seismic forces than the upper storys. On the other hand, such inadequate stiffness causes disproportional displacement focused on that story. As a result, the ground floor becomes weak and susceptible to partial or complete damage to its structural elements, which in turn, results in collapse of the entire building. The results obtained from the performed linear and nonlinear pushover analyses show that the flexible story may result in a drastic change of the period of vibrations, which will further lead to a change of the seismic design force, the maximal relative story drifts and ductility of the considered structure. Within this paper, the effect of the flexible story on seismic performance of building has been explored through comparison between a structure with regular story heights and a structure with a flexible story. The effects of upgrading the critical story by appropriate structural interventions like enlargement of the base columns cross-section and/or insertion of RC walls are also investigated.

1st Croatian Conference on Earthquake Engineering, Mar 22, 2021

The Joint Research Centre (JRC) of the European Commission is engaged in activities supporting th... more The Joint Research Centre (JRC) of the European Commission is engaged in activities supporting the implementation, further development and promotion of European policies and standards for sustainable construction. Such activities include the Eurocodes (EN 1990-EN 1999), the European Standards providing common rules for the design of buildings and other construction works to check their strength and stability. Among the countries that have shown strong commitment and progress in the adoption of the Eurocodes are the non-EU Balkan countries. In the period 2013-2016, the JRC, within the Enlargement and Integration (E&I) Action, has organized specialized dissemination and training events to support the adoption and implementation of the Eurocodes in the region. A roadmap for continuing the activities was elaborated in 2016 anticipating technical assistance at implementation, practical use and maintenance level. A workshop in Tirana (2018) focused on the implementation level in the National Regulatory Framework (NRF). It was shown that significant progress has been achieved by all non-EU countries in the Balkan region in the adoption of the Eurocodes since 2016. However, there was still lack of sufficient coordination between the National Authorities and the National Standardization Bodies on the implementation of the Eurocodes. Due to the high seismicity of the Balkan region, most non-EU countries in the region are close to, or are intending to, formally adopt EN 1998 ("Eurocode 8: Design of structures for earthquake resistance"). JRC plans to provide technical assistance for the Eurocode 8 implementation by the practitioners, addressing the seismic design of concrete buildings through a Eurocodes Balkan Summer School. The paper provides an overview of the JRC Eurocodes training activities held and planned for the Balkan region, along with an update on the Eurocodes implementation status.

1st Croatian Conference on Earthquake Engineering, Mar 22, 2021

During the past earthquakes, we have witnessed extensive structural damage on modern highrise bui... more During the past earthquakes, we have witnessed extensive structural damage on modern highrise buildings. The use of flat-slab or partially flat-slab system, inadequate seismic dilatation joints, occurrence of plastic hinges in columns, short columns mechanism, building additional storeys on already designed/constructed structures, inadequate transverse reinforcement in columns and beams and so on. The solution to the problem is in implementing the most recent knowledge in analysis, design and construction. The Institute of Earthquake Engineering and Engineering Seismology has established a methodology to improve the current practice procedures, enabling analysis and design of robust and economical reinforced concrete structures with controlled and conducted ductile behaviour of elements and systems in general, up to ultimate limit states of the strength and deformability. The process of designing stable and economic structures is extremely complex, due to the necessary harmonization of a series of parameters related to the construction on one hand and its response to actual earthquakes on the other. The methodology and the dynamic response of real reinforced concrete buildings is presented here, through block diagrams and results from analysed examples. The reinforced concrete structures are designed with controlled and dictated ductile behaviour of the structural elements and the structure as a whole, for gravity/static loads and also for seismic/dynamic impacts that are expected for the defined location.

Engineering Structures, Aug 1, 2008

The paper deals with application of an originally developed methodology for repair and seismic st... more The paper deals with application of an originally developed methodology for repair and seismic strengthening of St. Clement's Church, Plaoshnik, Ohrid. To renovate the structure based on the original foundation dating back to the 9th century, complex multidisciplinary investigations were performed in the field of archaeology, conservation, engineering and construction. Presented in this paper are the investigations related to the design of the structural system based on elaborated architectonic bases that are to preserve the authenticity of the structure, performed geotechnical investigations of the site and defined input seismic parameters. A linear-elastic and nonlinear dynamic analysis of the structure was performed. Based on the obtained results, the concept of repair and seismic strengthening of the church was adopted. It consisted of incorporation of horizontal and vertical steel ties in the bearing walls of the structure. This method, which is based on the philosophy of "minimal intervention-maximal protection", had originally been developed at IZIIS, Skopje and it has been experimentally and analytically verified. The techniques of consolidation of the authentic foundation of the structure and the existing walls with original fresco-paintings are also presented.

The main objective of the energy-based design (EBD) is by controlling of the dissipative capacity... more The main objective of the energy-based design (EBD) is by controlling of the dissipative capacity and the ductility of the potential post-elastic mechanisms to reduce the risk of losing global stability and collapse of the structures during the limit design event. Following this design philosophy, investigations of the influence of different parameters of the hysteretic models on nonlinear performance of SDOF expressed via energy indicators are carried out. The most important parameters which are the subject of the study are: the stiffness after the yielding point , the factor of stiffness degradation at unloading USDP (unloading stiffness degradation parameter), the FYRP (force yield relation parameter) parameter, the initial stiffness and the level of the first cracks in concrete, as well as some specific parameters that are specific for the shear models only. Selected results concerning influence of these parameters on the maximum values of dissipated hysteretic energy (Emax) and its index (Eh) are presented in the paper.

The IZIIS' contribution to development of high quality materials has been seen in realization of ... more The IZIIS' contribution to development of high quality materials has been seen in realization of several scientific-research projects in the field of high strength concrete, (HSC) in the period from 1992 to 2006. Within the frames of these projects, synthesis of investigations reported in world literature has been made and complex laboratory-experimental-analytical investigations have been performed to contribute to: definition of the methodology for obtaining HSC exclusively from domestic resources; joint behaviour of high strength materials and elements in nonlinear range as well as definition of criteria and recommendations for application of these materials in seismically active regions. The selected results from these investigations are presented in the paper.

ICCES: International Conference on Computational & Experimental Engineering and Sciences, Feb 1, 2008

The IZIIS’ contribution to development of high quality materials has been seen in realization of ... more The IZIIS’ contribution to development of high quality materials has been seen in realization of several scientific-research projects in the field of high strength concrete in the period from 1992 to 2006. Within the frames of these projects complex laboratory-experimental-analytical investigations have been performed to contribute to definition of the methodology for obtaining high stength concrete exclusively from domestic resources, to investigate joint behaviour of high strength materials and elements in nonlinear range as well as to define dynamic behaviour high strength concrete buildings exposed to seismic actions. The selected results from these investigations are presented in the paper.

The critical point which defines behavior of precast buildings under cyclic loading is connection... more The critical point which defines behavior of precast buildings under cyclic loading is connections. The experience gathered from the past earthquakes together with existing analytical and experimental investigations are not sufficient enough to explain their seismic behavior. Therefore, experimental investigations of existing beam-column dowel connections were carried out by Slovenian researchers at the University of Ljubljana, (Fischinger at al, 2011). In parallel, analytical investigations of nonlinear behavior of the above beam-column connections under earthquake loading were realized at UKIM-IZIIS, Skopje (Apostolska, Necevska-Cvetanovska at al, 2011). Based on the above investigations, the numerical model for connection behavior is proposed. Presented in the paper are selected results from experimental and analytical research of the obtained response parameters for different types of beam-column connections under seismic action.

Flat-slab building structures possesses major advantages over traditional slab-beam-column struct... more Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural-functional and economical aspects. Because of the absence of deep beams and shear walls, flat-slab structural system is significantly more flexible for lateral loads then traditional RC frame system and that make the system more vulnerable under seismic events. The results from the analysis for few types of construction systems which is presented in the paper show that flat slab system with certain modifications (design of beam in the perimeter of the building and/or RC walls) can achieve rational factor of behaviour considering EC8 and can be consider as a system with acceptable seismic risk. Modifications with additional construction elements improve small bearing capacity of the system and increase strength and stiffness, improving seismic behaviour of flat-slab construction system. Selected result from the analysis are presented in the paper.

Increasing energy efficiency of final energy consumption is a very actual and important topic, in... more Increasing energy efficiency of final energy consumption is a very actual and important topic, in parallel with activities and measures worldwide targeting an increased share of renewable energy sources. Despite recent expansion in building construction, old buildings characterized by high energy consumption still represent a great majority of both residential and public building stock in many countries in the Balkan region. Located in seismicprone countries, such as the Republic of North Macedonia, these old buildings are also characterized by the high risk of partial or complete destruction during earthquakes. This imposes the need for mandatory screening at the outset of an energy efficiency program, which will categorize buildings according to seismic risk and thus determine which buildings are suitable for energy efficiency investments. This paper presents how the methodology for high-level seismic screening, originally proposed in the World Bank's Country Report (North Macedonia), is extended and customized by the Institute of Earthquake Engineering and Engineering Seismology, IZIIS, Skopje to correspond to the country specificities, i.e., to be based on overall knowledge on aseismic design and construction practice in the country, detailed on-site inspection of each particular building, and to be carried out by structural engineers with appropriate knowledge and experience in earthquake engineering. The high-level seismic screening was performed in the Republic of North Macedonia, applying this extended and customized methodology, for a total number of 27 medical facilities, dominantly healthcare centers, and 50 municipality buildings (schools, kindergartens, and municipal buildings).

The critical point which defines behavior of precast buildings under cyclic loading is connection... more The critical point which defines behavior of precast buildings under cyclic loading is connections. The experience gathered from the past earthquakes together with existing analytical and experimental investigations are not sufficient enough to explain their seismic behavior. Therefore, experimental investigations of existing beam-column dowel connections were carried out by Slovenian researchers at the University of Ljubljana, (Fischinger at al, 2011). In parallel, analytical investigations of nonlinear behavior of the above beam-column connections under earthquake loading were realized at UKIM-IZIIS, Skopje (Apostolska, Necevska-Cvetanovska at al, 2011). Based on the above investigations, the numerical model for connection behavior is proposed. Presented in the paper are selected results from experimental and analytical research of the obtained response parameters for different types of beam-column connections under seismic action.

The paper deals with application of an originally developed methodology for rehabilitation and se... more The paper deals with application of an originally developed methodology for rehabilitation and seismic strengthening of St. Clement’s Church, Plaoshnik, Ohrid. To renovate the structure based on the original foundation dating back to the IX century, complex multidisciplinary investigations were performed in the field of archaeology, conservation, engineering and construction. Presented in this paper are the investigations related to the design of the structural system based on elaborated architectonic floor plans that are to preserve the authenticity of the structure, performed geotechnical investigations of the site and defined input seismic parameters. A linear-elastic and nonlinear dynamic analysis of the structure was performed. Based on the obtained results, the concept of repair and seismic strengthening of the church was adopted. It consisted of incorporation of horizontal and vertical steel ties in the bearing walls of the structure. This method, which is based on the philosophy of “minimal intervention – maximal protection” has originally been developed at IZIIS, Skopje and it has been experimentally and analytically verified. The techniques of consolidation of the authentic foundation of the structure and the existing walls with original fresco-paintings are also presented.

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

This paper aims to describe the CRISIS web-based platform (WBP) in all its parts and functionalit... more This paper aims to describe the CRISIS web-based platform (WBP) in all its parts and functionalities. The platform is the main result of the two-year EU-funded project CRISIS (Comprehensive RISk assessment of basic services and transport InfraStructure). It has been developed by EUCENTRE (European Centre for Training and Research in Earthquake Engineering) using the most up-to-date web programming frameworks and technologies. The CRISIS WBP is a user-friendly tool intended to support disaster and emergency management authorities in case of earthquakes and/or seismo-induced landslides in the cross-border region of Albania, North Macedonia, and Greece. It has been designed to collect, organise, and visualise for the project target area: i) the exposure data of educational facilities, health facilities, and bridges; ii) the seismic and landslide hazard data; iii) the earthquake damage scenarios (calculated both for selected historical events and in real-time); and iv) the landslide ris...

Lecture notes in civil engineering, 2023

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

In recent years, the improvement of disaster and emergency management through building a harmoniz... more In recent years, the improvement of disaster and emergency management through building a harmonized and efficient system for risk assessment of structures in the cross-border region (CBR) has become increasingly popular. Harmonization of the risk exposure model for cross border regions is first and most important step for assessment of risk in the region. Different countries, even neighboring ones, have different frameworks in which buildings for basic services and transport infrastructures are designed, built and maintained. Hence, they involve different institutions and employ different ways of gathering information on existing structures within their networks. Each of them may use different methods and systems for keeping records on their assets. Therefore, there is no readily available inventory which covers the entire stock of bridges and buildings for basic services in any of the CRISIS adjacent partner countries. The harmonized regional risk exposure model is result of the ac...

Flat-slab building structures possesses major advantages over traditional slab-beam-column struct... more Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural –functional and economical aspects. Because of the absence of deep beams and shear walls, flat-slab structural system is significantly more flexible for lateral loads then traditional RC frame system and that make the system more vulnerable under seismic events. The results from the analysis for few types of construction systems which is presented in the paper show that flat slab system with certain modifications (design of beam in the perimeter of the building and/or RC walls) can achieve rational factor of behaviour considering EC8 and can be consider as a system with acceptable seismic risk. Modifications with additional construction elements improve small bearing capacity of the system and increase strength and stiffness, improving seismic behaviour of flat-slab construction system. Selected result fro...

Geotechnical, Geological and Earthquake Engineering, 2015

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

2nd Croatian Conference on Earthquake Engineering ‒ 2CroCEE

The impact of present building code requirements for seismic design of new buildings can readily ... more The impact of present building code requirements for seismic design of new buildings can readily be acknowledged, however applying regulation to existing buildings is an area less well defined. Presently, there is a diverse list of existing code references which could be interpreted to require seismic upgrades of existing structures. Unfortunately, these references do not provide a clear path toward addressing the hazards, evaluation and retrofitting of existing buildings. And when it comes to existing old buildings and monuments, constructed with low or no seismic consideration, the topic becomes much more complex and challenging. The problem of earthquake protection of historic buildings and monuments is radically different from that of other existing structures, due to the priority given to preservation of aesthetic, architectonic and historic values instead of keeping the structure operational. In providing the protection of these structures in a manner that requires the least i...

Sažetak: In frame-wall systems with competent and uniformly distributed walls, the infill walls s... more Sažetak: In frame-wall systems with competent and uniformly distributed walls, the infill walls stiffen the frame and reduce the first-mode period leading to a reduction in drift response to strong ground motion. At the same time, the addition of the masonry wall to the frame ...

Journal of International Environmental Application and Science, Sep 30, 2016

Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground fl... more Soft-story buildings are characterized by an inadequate stiffness or flexibility of the ground floor, which is less resistant to horizontal seismic forces than the upper storys. On the other hand, such inadequate stiffness causes disproportional displacement focused on that story. As a result, the ground floor becomes weak and susceptible to partial or complete damage to its structural elements, which in turn, results in collapse of the entire building. The results obtained from the performed linear and nonlinear pushover analyses show that the flexible story may result in a drastic change of the period of vibrations, which will further lead to a change of the seismic design force, the maximal relative story drifts and ductility of the considered structure. Within this paper, the effect of the flexible story on seismic performance of building has been explored through comparison between a structure with regular story heights and a structure with a flexible story. The effects of upgrading the critical story by appropriate structural interventions like enlargement of the base columns cross-section and/or insertion of RC walls are also investigated.