David Koren | University of Ljubljana (original) (raw)

Papers by David Koren

Springer eBooks, 2022

Based on the literature review and current practice regarding energy-efficient buildings and thei... more Based on the literature review and current practice regarding energy-efficient buildings and their details (Chap. 3), we proposed a methodology with which structural details on the building envelope could be evaluated. The methodology was devised on the basis of various regulations (environmental, energy, construction, etc.), and facilitates the evaluation of details in view of environmental and energy-efficiency and structural requirements, which are frequently contradictory. We attempted to illustrate the complexity of designing details in energy-efficient buildings characterised by numerous requirements aiming to ensure that details correspond to technical and structural as well as environmental and energy-efficiency conditions. The structural detail design concept includes various disciplines and experts, particularly architects, and civil and mechanical engineers. When designing structural details, they must provide particularly: • a clever design taking into account the determined structural assemblies (the material of the load-bearing structure, the position and material of protective layers-waterproofing, thermal insulation, etc.); • sufficient structural safety for all foreseen load cases; • the prevention of thermal bridges or good energy efficiency; • durability and sustainability; • thermal comfort, etc. Several impact parameters can be simply incorporated with the proposed methodology, allowing for the recognition of problematic details and facilitating the search for solutions for their improvement. It can be used to design new buildings, or for energy or structural renovation of buildings. The problem of energy-efficient buildings in earthquake-prone areas, whose crucial element is a well-designed earthquake-resistant structure that complies with the requirements for earthquake-resistant construction, was particularly considered in

1st Croatian Conference on Earthquake Engineering

The seismic performance assessment of an urban system can help raise awareness and improve a comm... more The seismic performance assessment of an urban system can help raise awareness and improve a community's preparedness for extreme earthquake events. Addressing this issue, the authors' first attempt at a quantitative evaluation of a city's performance in the event of an earthquake is presented in this paper. The assumed city model comprised of four main urban components (buildings, transportation infrastructure, social community, and open spaces) takes into consideration their relationships and interactions. A set of preliminary analyses on the test model were performed using the GIS tools and graph theory. The analysed model was generated based on the combination of real (city layout, buildings' heights and footprints, road network configuration and length) and fictitious data (earthquake scenarios, structural fragility of the investigated building stock, the use of a building, etc.). In the main part of the study, several scenarios of possible earthquake events with various degrees of intensity and with different locations of damaged buildings were considered, and the assessment of a city's performance in terms of connectivity and accessibility (the graph theory measure of global efficiency) was carried out. The impact of building debris on the roads as a result of the earthquake damage and/or the collapse of nearby buildings and their non-structural components was included in the analysis as well by applying the measure of a building's impact radius and assessing the road traffic disruptions. Furthermore, certain practical results in relation to the analysed urban system were taken under observation and are discussed in the paper (travel time, affected population when considering the day-/night-time scenarios, etc.). The proposed framework has proven to be a viable tool for identifying network weaknesses and quantifying the loss of the city network functionality.

Assessment of Energy-Efficient Building Details for Seismic Regions

In this chapter the proposed methodology was used for evaluation of several most common building ... more In this chapter the proposed methodology was used for evaluation of several most common building details/connections. It was shown how the proposed methodology can be used to separate better detail solutions from poorer ones, by recognizing inappropriate load-bearing capacity, stiffness, interruptions, asymmetrical solutions, and other important characteristics that affect the quality of a detail to be used in earthquake-resistant structure.

Assessment of Energy-Efficient Building Details for Seismic Regions

In order to meet the EU Green Deal requirements, the thermal envelope of a modern energy-efficien... more In order to meet the EU Green Deal requirements, the thermal envelope of a modern energy-efficient building must be “wrapped” all around the building with no thermal bridges. This chapter describes the most important structural details and their effects on energy consumption and seismic resistance of the building as a whole. Those details where the energy efficiency might be inversely proportional to its earthquake resistance, are further explored and analysed.

Springer Tracts in Civil Engineering

sharing, adaptation, distribution and reproduction in any medium or format, as long as you give a... more sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The images or other third party material in this book are included in the book's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the book's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. 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.

Assessment of Energy-Efficient Building Details for Seismic Regions

The chapter describes the theory of designing the thermal insulation envelope of energyefficient ... more The chapter describes the theory of designing the thermal insulation envelope of energyefficient buildings. The procedure of functional analysis of the building connection details is described and presented for three structural assembly connection types (»L«, »T«, »+«). Such theoretical knowledge of structural detailing is essential to eliminate thermal bridges and their negative impacts.

At the beginning of the present work nonlinear contact finite elements (»Nllink« elements) offere... more At the beginning of the present work nonlinear contact finite elements (»Nllink« elements) offered by SAP2000 commercial software program are presented. The behaviour of the most typical elements (linear and nonlinear axial springs, axial springs of the »Gap«, »Hook« and »Plastic« types and also linear and nonlinear springs in shear and bending direction) is shown in simple examples. Such springs are then used for the modeling the behaviour of structural elements with imperfect connections, among which the connections in layered beams are presented in detail (cantilever, T beam, layered timber beam with nailed interfaces). Nonlinearities in restraints and groundwork are also modeled with the presented springs (beam, base plate). Last of all, an example of a stone wall with cracks modeled with springs is analysed. Different types of analyses are used: linear analysis, nonlinear analysis (geometric linear and geometric nonlinear) and buckling analysis. The results of our models are co...

Bauingenieur

In diesem Beitrag wird die Erdbebenantwort von Stahlbeton-Balkonen analysiert, die mit vorgeferti... more In diesem Beitrag wird die Erdbebenantwort von Stahlbeton-Balkonen analysiert, die mit vorgefertigten Elementen zur Verhinderung von Wärmebrücken in das Gebäude verankert und auf keine sonstige Weise gestützt sind. Bisher wurden sie vorwiegend in Gebieten mit niedriger seismischer Aktivität eingesetzt, während ihre Verwendung in Regionen mit stärkerer Erdbebenaktivität bisher nicht eingehend untersucht wurde. So können sich solche Elemente in seismischen Gebieten vom Gesichtspunkt der Erdbebensicherheit als mangelhaft erweisen und die Erdbebenantwort des Bauwerks sowie eines Teils davon verschlechtern. In diesem Artikel ist die Erdbebenanalyse ausgewählter Typenkonsolen bei vertikalen Beschleunigungen dargestellt, die durch Erdbebeneinwirkung auftreten. Die Schlussfolgerungen können auch auf andere ähnliche Lösungen von Balkoneinspannungen verallgemeinert werden. Die Erdbebenanalysen haben Folgendes ergeben: 1) wärmegedämmte Konsolen sind nachgiebiger als eingespannte Konsolen, wesh...

Modern low-energy house standards suggest that the thermal envelope of the building should be des... more Modern low-energy house standards suggest that the thermal envelope of the building should be designed as a continuous and uniform thermal insulation (TI) layer, so that it encloses the whole building implemented also under its RC foundation slab. However, the insertion of a soft thermal insulation layer under the foundations of the building is unfavourable from several points of view of earthquake resistance: (a) it increases the compressive and shear stresses in the TI layer, (b) it increases the negative effects on the superstructure (increased rocking phenomena), and (c) it prolongs the fundamental period of the superstructure (changing dynamic characteristics of the building). The main goal of the paper is to identify the possible negative influences of the soft TI layer on seismic response of low-energy buildings with technical solutions, which have already been developed for non earthquake-prone regions, and to propose structural measures and their application in earthquake-p...

izvlecek In the paper the seismic response of precast balcony cantilever structural elements for ... more izvlecek In the paper the seismic response of precast balcony cantilever structural elements for prevention of thermal bridges was analysed. This solution has been developed in seismic non-prone areas with the main purpose of eliminating a thermal bridge at the point where the balcony is fixed to the building. The solution has been specially made to withstand vertical static loading, not accounting for eventual vertical seismic loads in the case of transferring the solution to more active seismic zones. This paper deals with the seismic analysis of existent precast cantilever elements exposed to vertical accelerations and has proven that some elements in the case of lifting are not sufficient from the safety point of view. The results of the main research results obtained by numerous seismic analyses can be summarized as follows: 1) the insertion of a precast load-bearing thermal insulation element increases the flexibility of RC fixed base cantilevers and therefore limits their len...

V diplomski nalogi so najprej predstavljeni nelinearni kontaktni koncni elementi, ki jih ponuja k... more V diplomski nalogi so najprej predstavljeni nelinearni kontaktni koncni elementi, ki jih ponuja komercialni racunalniski program SAP2000 (»Nllink« elementi). Na enostavnih primerih je prikazano delovanje najbolj tipicnih izmed njih: linearne in nelinearne osne vzmeti, osne vzmeti tipa »Gap«, »Hook« in »Plastic« ter linearne in nelinearne strižne in zasucne vzmeti. V nadaljevanju pa so le-te uporabljene za modeliranje obnasanja gradbenih konstrukcijskih elementov z neidealnimi stiki, med katerimi so detajlno predstavljeni stiki med sloji slojevitih nosilcev (konzola, T nosilec, žebljani I nosilec) in nelinearni kontakti, ki se pojavljajo v podporah oziroma pri temeljenju (nosilec, temeljna plosca). Na koncu je prikazan se primer analize razpokane kamnite stene modelirane z vzmetmi. Uporabljene so razlicne vrste analiz: linearna analiza, nelinearna analiza (geometrijsko linearna in geometrijsko nelinearna) ter uklonska analiza. Dobljene rezultate primerjamo tudi z resitvami iz literat...

The paper examines the usage of a simplified nonlinear method for seismic analysis and performanc... more The paper examines the usage of a simplified nonlinear method for seismic analysis and performance evaluation (N2 method) for analysis of base isolated structures. In the paper the N2 method is applied for analysis of a fixed base and base isolated simple four-storey frame building designed according to EC8. Two different sets of base isolation devices were investigated: a simple rubber (RB) and a similar lead rubber bearing (LRB) base isolation system. For each system a Soft, Normal and Hard rubber stiffness and three different damping values were used. The paper shows how we can obtain base displacement and top (relative) displacement for different bearing stiffness and selected damping. The target base displacement was determined as an intersection of the capacity curve of single degree of freedom system with rigid behavior of the superstructure and demand spectrum curve for selected damping of isolators. In the following step the pushover analysis of the whole isolated structure...

Recently, an increasing trend of passive and lowenergy buildings transferring from non-earthquake... more Recently, an increasing trend of passive and lowenergy buildings transferring from non-earthquake prone to earthquake-prone regions has thrown out the question about the seismic safety of such buildings. The paper describes two most commonly used structural details of energy efficient construction, which could be critical from the point of view of earthquake resistance: i) Foundation of a building on thermal insulation (TI) layers and ii) Fixing of precast balcony element without thermal bridge. The first part of the paper describes the problematics of founding of a building on TI and presents the authors' proposal of seismic fuse assembled out of TI boards and waterproofing (foil) layers, which have been commonly used under the RC foundation slabs of passive buildings. The main idea is to reduce the seismic forces on the superstructure by allowing controlled lateral sliding between the individual layers of the TI boards. The feasibility of the proposed solution has been analysed by means of nonlinear dynamic analyses for selected 2-and 4-storeyed passive buildings founded on TI boards made of extruded polystyrene (XPS). The second part of the paper analyses the seismic response of precast balcony cantilever structural elements, which have been recently developed in seismic non-prone areas in order to prevent the thermal bridge at the point where the cantilever is fixed to the building. Such balcony elements have been made primarily to withstand vertical static loading neglecting the eventual vertical seismic loads in the case of an earthquake. It has been found out that those cantilevers in the case of uplift might not be designed with adequate safety, since they lack sufficient reinforcement on the bottom side. In order to reduce their seismic vulnerability some changes of precast load-bearing TI elements have been proposed.

The paper deals with the applicability of a simplified nonlinear method (N2 method) to base-isola... more The paper deals with the applicability of a simplified nonlinear method (N2 method) to base-isolated plan-asymmetric building structures. In the first part of the paper the modifi- cations that have been implemented into the originally proposed N2 method - such as the new three-linear idealization and inclusion of isolator damping by reduction factor R - are shortly described. In the paper the proposed procedure is used for the seismic analysis of a base-isolated 4-storey RC asymmetric building isolated with lead rubber bearings (LRBs). For the base isolation system we have considered three different types of isolators with differ- ent stiffness. The results of nonlinear dynamic time-history analyses are compared with the results of the N2 method in terms of obtained top, base and relative displacements. Compari- sons of the results of the simplified method with the 'exact' results of the nonlinear dynamic analyses have shown a very good agreement. It has been shown that th...

Razmatra se torzijski odziv potresno izoliranih nesimetri nih višekatnih armiranobetonskih okvirn... more Razmatra se torzijski odziv potresno izoliranih nesimetri nih višekatnih armiranobetonskih okvirnih konstrukcija pri jakom seizmi kom djelovanju. Analizirano je više varijanti (3 stupnja torzijske krutosti, 3 stupnja ekscentri nosti mase) izvorno simetri ne konstrukcije, s razli ito raspore enim elastomernim ležajevima. Rezultati dokazuju da pravilno raspore eni protupotresni izolatori mogu bitno reducirati nepoželjne torzijske utjecaje gornje konstrukcije i izolacijskog sustava.

Journal of the Croatian Association of Civil Engineers

Thermal insulation under the building foundation plate or under the strip foundations prevents th... more Thermal insulation under the building foundation plate or under the strip foundations prevents the thermal bridge on the contact between the building and supporting terrain and reduces the energy consumption in modern passive and low energy houses. In the paper the seismic behaviour of buildings with different heights, floor plan dimensions, on different soil conditions and on different thermal insulation layers have been analysed. The results of simplified seismic analyses have shown, that the potentially negative influences of inserting the insulation under the foundation plate could be expected only for buildings with more than two or three storeys.

IOP Conference Series: Materials Science and Engineering

Sustainability

For a city to perform successfully, and its citizens to feel safe and comfortable, the health of ... more For a city to perform successfully, and its citizens to feel safe and comfortable, the health of basic urban components and the overall resilience of the urban system is crucial. As the importance of the resilient urban system has been recognized in the scientific literature, many studies have been done on this topic. Therefore, to find out the gaps in the existing literature and the opportunities for further research, a new systematic literature review has been performed in three stages. Different bibliographic techniques (co-occurrence and co-citation analysis) have been applied and, in the final stage of the analysis, an in-depth study of the content of the selected papers addressing open space in relation to urban seismic resilience has been carried out. The obtained results and trends have shown a lack of research on the potential of open space for enhancing urban seismic resilience, as well as a challenge for its quantitative assessment. The ability of the affected resilient s...

International Journal of Disaster Risk Reduction

Springer eBooks, 2022

Based on the literature review and current practice regarding energy-efficient buildings and thei... more Based on the literature review and current practice regarding energy-efficient buildings and their details (Chap. 3), we proposed a methodology with which structural details on the building envelope could be evaluated. The methodology was devised on the basis of various regulations (environmental, energy, construction, etc.), and facilitates the evaluation of details in view of environmental and energy-efficiency and structural requirements, which are frequently contradictory. We attempted to illustrate the complexity of designing details in energy-efficient buildings characterised by numerous requirements aiming to ensure that details correspond to technical and structural as well as environmental and energy-efficiency conditions. The structural detail design concept includes various disciplines and experts, particularly architects, and civil and mechanical engineers. When designing structural details, they must provide particularly: • a clever design taking into account the determined structural assemblies (the material of the load-bearing structure, the position and material of protective layers-waterproofing, thermal insulation, etc.); • sufficient structural safety for all foreseen load cases; • the prevention of thermal bridges or good energy efficiency; • durability and sustainability; • thermal comfort, etc. Several impact parameters can be simply incorporated with the proposed methodology, allowing for the recognition of problematic details and facilitating the search for solutions for their improvement. It can be used to design new buildings, or for energy or structural renovation of buildings. The problem of energy-efficient buildings in earthquake-prone areas, whose crucial element is a well-designed earthquake-resistant structure that complies with the requirements for earthquake-resistant construction, was particularly considered in

1st Croatian Conference on Earthquake Engineering

The seismic performance assessment of an urban system can help raise awareness and improve a comm... more The seismic performance assessment of an urban system can help raise awareness and improve a community's preparedness for extreme earthquake events. Addressing this issue, the authors' first attempt at a quantitative evaluation of a city's performance in the event of an earthquake is presented in this paper. The assumed city model comprised of four main urban components (buildings, transportation infrastructure, social community, and open spaces) takes into consideration their relationships and interactions. A set of preliminary analyses on the test model were performed using the GIS tools and graph theory. The analysed model was generated based on the combination of real (city layout, buildings' heights and footprints, road network configuration and length) and fictitious data (earthquake scenarios, structural fragility of the investigated building stock, the use of a building, etc.). In the main part of the study, several scenarios of possible earthquake events with various degrees of intensity and with different locations of damaged buildings were considered, and the assessment of a city's performance in terms of connectivity and accessibility (the graph theory measure of global efficiency) was carried out. The impact of building debris on the roads as a result of the earthquake damage and/or the collapse of nearby buildings and their non-structural components was included in the analysis as well by applying the measure of a building's impact radius and assessing the road traffic disruptions. Furthermore, certain practical results in relation to the analysed urban system were taken under observation and are discussed in the paper (travel time, affected population when considering the day-/night-time scenarios, etc.). The proposed framework has proven to be a viable tool for identifying network weaknesses and quantifying the loss of the city network functionality.

Assessment of Energy-Efficient Building Details for Seismic Regions

In this chapter the proposed methodology was used for evaluation of several most common building ... more In this chapter the proposed methodology was used for evaluation of several most common building details/connections. It was shown how the proposed methodology can be used to separate better detail solutions from poorer ones, by recognizing inappropriate load-bearing capacity, stiffness, interruptions, asymmetrical solutions, and other important characteristics that affect the quality of a detail to be used in earthquake-resistant structure.

Assessment of Energy-Efficient Building Details for Seismic Regions

In order to meet the EU Green Deal requirements, the thermal envelope of a modern energy-efficien... more In order to meet the EU Green Deal requirements, the thermal envelope of a modern energy-efficient building must be “wrapped” all around the building with no thermal bridges. This chapter describes the most important structural details and their effects on energy consumption and seismic resistance of the building as a whole. Those details where the energy efficiency might be inversely proportional to its earthquake resistance, are further explored and analysed.

Springer Tracts in Civil Engineering

sharing, adaptation, distribution and reproduction in any medium or format, as long as you give a... more sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The images or other third party material in this book are included in the book's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the book's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. 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.

Assessment of Energy-Efficient Building Details for Seismic Regions

The chapter describes the theory of designing the thermal insulation envelope of energyefficient ... more The chapter describes the theory of designing the thermal insulation envelope of energyefficient buildings. The procedure of functional analysis of the building connection details is described and presented for three structural assembly connection types (»L«, »T«, »+«). Such theoretical knowledge of structural detailing is essential to eliminate thermal bridges and their negative impacts.

At the beginning of the present work nonlinear contact finite elements (»Nllink« elements) offere... more At the beginning of the present work nonlinear contact finite elements (»Nllink« elements) offered by SAP2000 commercial software program are presented. The behaviour of the most typical elements (linear and nonlinear axial springs, axial springs of the »Gap«, »Hook« and »Plastic« types and also linear and nonlinear springs in shear and bending direction) is shown in simple examples. Such springs are then used for the modeling the behaviour of structural elements with imperfect connections, among which the connections in layered beams are presented in detail (cantilever, T beam, layered timber beam with nailed interfaces). Nonlinearities in restraints and groundwork are also modeled with the presented springs (beam, base plate). Last of all, an example of a stone wall with cracks modeled with springs is analysed. Different types of analyses are used: linear analysis, nonlinear analysis (geometric linear and geometric nonlinear) and buckling analysis. The results of our models are co...

Bauingenieur

In diesem Beitrag wird die Erdbebenantwort von Stahlbeton-Balkonen analysiert, die mit vorgeferti... more In diesem Beitrag wird die Erdbebenantwort von Stahlbeton-Balkonen analysiert, die mit vorgefertigten Elementen zur Verhinderung von Wärmebrücken in das Gebäude verankert und auf keine sonstige Weise gestützt sind. Bisher wurden sie vorwiegend in Gebieten mit niedriger seismischer Aktivität eingesetzt, während ihre Verwendung in Regionen mit stärkerer Erdbebenaktivität bisher nicht eingehend untersucht wurde. So können sich solche Elemente in seismischen Gebieten vom Gesichtspunkt der Erdbebensicherheit als mangelhaft erweisen und die Erdbebenantwort des Bauwerks sowie eines Teils davon verschlechtern. In diesem Artikel ist die Erdbebenanalyse ausgewählter Typenkonsolen bei vertikalen Beschleunigungen dargestellt, die durch Erdbebeneinwirkung auftreten. Die Schlussfolgerungen können auch auf andere ähnliche Lösungen von Balkoneinspannungen verallgemeinert werden. Die Erdbebenanalysen haben Folgendes ergeben: 1) wärmegedämmte Konsolen sind nachgiebiger als eingespannte Konsolen, wesh...

Modern low-energy house standards suggest that the thermal envelope of the building should be des... more Modern low-energy house standards suggest that the thermal envelope of the building should be designed as a continuous and uniform thermal insulation (TI) layer, so that it encloses the whole building implemented also under its RC foundation slab. However, the insertion of a soft thermal insulation layer under the foundations of the building is unfavourable from several points of view of earthquake resistance: (a) it increases the compressive and shear stresses in the TI layer, (b) it increases the negative effects on the superstructure (increased rocking phenomena), and (c) it prolongs the fundamental period of the superstructure (changing dynamic characteristics of the building). The main goal of the paper is to identify the possible negative influences of the soft TI layer on seismic response of low-energy buildings with technical solutions, which have already been developed for non earthquake-prone regions, and to propose structural measures and their application in earthquake-p...

izvlecek In the paper the seismic response of precast balcony cantilever structural elements for ... more izvlecek In the paper the seismic response of precast balcony cantilever structural elements for prevention of thermal bridges was analysed. This solution has been developed in seismic non-prone areas with the main purpose of eliminating a thermal bridge at the point where the balcony is fixed to the building. The solution has been specially made to withstand vertical static loading, not accounting for eventual vertical seismic loads in the case of transferring the solution to more active seismic zones. This paper deals with the seismic analysis of existent precast cantilever elements exposed to vertical accelerations and has proven that some elements in the case of lifting are not sufficient from the safety point of view. The results of the main research results obtained by numerous seismic analyses can be summarized as follows: 1) the insertion of a precast load-bearing thermal insulation element increases the flexibility of RC fixed base cantilevers and therefore limits their len...

V diplomski nalogi so najprej predstavljeni nelinearni kontaktni koncni elementi, ki jih ponuja k... more V diplomski nalogi so najprej predstavljeni nelinearni kontaktni koncni elementi, ki jih ponuja komercialni racunalniski program SAP2000 (»Nllink« elementi). Na enostavnih primerih je prikazano delovanje najbolj tipicnih izmed njih: linearne in nelinearne osne vzmeti, osne vzmeti tipa »Gap«, »Hook« in »Plastic« ter linearne in nelinearne strižne in zasucne vzmeti. V nadaljevanju pa so le-te uporabljene za modeliranje obnasanja gradbenih konstrukcijskih elementov z neidealnimi stiki, med katerimi so detajlno predstavljeni stiki med sloji slojevitih nosilcev (konzola, T nosilec, žebljani I nosilec) in nelinearni kontakti, ki se pojavljajo v podporah oziroma pri temeljenju (nosilec, temeljna plosca). Na koncu je prikazan se primer analize razpokane kamnite stene modelirane z vzmetmi. Uporabljene so razlicne vrste analiz: linearna analiza, nelinearna analiza (geometrijsko linearna in geometrijsko nelinearna) ter uklonska analiza. Dobljene rezultate primerjamo tudi z resitvami iz literat...

The paper examines the usage of a simplified nonlinear method for seismic analysis and performanc... more The paper examines the usage of a simplified nonlinear method for seismic analysis and performance evaluation (N2 method) for analysis of base isolated structures. In the paper the N2 method is applied for analysis of a fixed base and base isolated simple four-storey frame building designed according to EC8. Two different sets of base isolation devices were investigated: a simple rubber (RB) and a similar lead rubber bearing (LRB) base isolation system. For each system a Soft, Normal and Hard rubber stiffness and three different damping values were used. The paper shows how we can obtain base displacement and top (relative) displacement for different bearing stiffness and selected damping. The target base displacement was determined as an intersection of the capacity curve of single degree of freedom system with rigid behavior of the superstructure and demand spectrum curve for selected damping of isolators. In the following step the pushover analysis of the whole isolated structure...

Recently, an increasing trend of passive and lowenergy buildings transferring from non-earthquake... more Recently, an increasing trend of passive and lowenergy buildings transferring from non-earthquake prone to earthquake-prone regions has thrown out the question about the seismic safety of such buildings. The paper describes two most commonly used structural details of energy efficient construction, which could be critical from the point of view of earthquake resistance: i) Foundation of a building on thermal insulation (TI) layers and ii) Fixing of precast balcony element without thermal bridge. The first part of the paper describes the problematics of founding of a building on TI and presents the authors' proposal of seismic fuse assembled out of TI boards and waterproofing (foil) layers, which have been commonly used under the RC foundation slabs of passive buildings. The main idea is to reduce the seismic forces on the superstructure by allowing controlled lateral sliding between the individual layers of the TI boards. The feasibility of the proposed solution has been analysed by means of nonlinear dynamic analyses for selected 2-and 4-storeyed passive buildings founded on TI boards made of extruded polystyrene (XPS). The second part of the paper analyses the seismic response of precast balcony cantilever structural elements, which have been recently developed in seismic non-prone areas in order to prevent the thermal bridge at the point where the cantilever is fixed to the building. Such balcony elements have been made primarily to withstand vertical static loading neglecting the eventual vertical seismic loads in the case of an earthquake. It has been found out that those cantilevers in the case of uplift might not be designed with adequate safety, since they lack sufficient reinforcement on the bottom side. In order to reduce their seismic vulnerability some changes of precast load-bearing TI elements have been proposed.

The paper deals with the applicability of a simplified nonlinear method (N2 method) to base-isola... more The paper deals with the applicability of a simplified nonlinear method (N2 method) to base-isolated plan-asymmetric building structures. In the first part of the paper the modifi- cations that have been implemented into the originally proposed N2 method - such as the new three-linear idealization and inclusion of isolator damping by reduction factor R - are shortly described. In the paper the proposed procedure is used for the seismic analysis of a base-isolated 4-storey RC asymmetric building isolated with lead rubber bearings (LRBs). For the base isolation system we have considered three different types of isolators with differ- ent stiffness. The results of nonlinear dynamic time-history analyses are compared with the results of the N2 method in terms of obtained top, base and relative displacements. Compari- sons of the results of the simplified method with the 'exact' results of the nonlinear dynamic analyses have shown a very good agreement. It has been shown that th...

Razmatra se torzijski odziv potresno izoliranih nesimetri nih višekatnih armiranobetonskih okvirn... more Razmatra se torzijski odziv potresno izoliranih nesimetri nih višekatnih armiranobetonskih okvirnih konstrukcija pri jakom seizmi kom djelovanju. Analizirano je više varijanti (3 stupnja torzijske krutosti, 3 stupnja ekscentri nosti mase) izvorno simetri ne konstrukcije, s razli ito raspore enim elastomernim ležajevima. Rezultati dokazuju da pravilno raspore eni protupotresni izolatori mogu bitno reducirati nepoželjne torzijske utjecaje gornje konstrukcije i izolacijskog sustava.

Journal of the Croatian Association of Civil Engineers

Thermal insulation under the building foundation plate or under the strip foundations prevents th... more Thermal insulation under the building foundation plate or under the strip foundations prevents the thermal bridge on the contact between the building and supporting terrain and reduces the energy consumption in modern passive and low energy houses. In the paper the seismic behaviour of buildings with different heights, floor plan dimensions, on different soil conditions and on different thermal insulation layers have been analysed. The results of simplified seismic analyses have shown, that the potentially negative influences of inserting the insulation under the foundation plate could be expected only for buildings with more than two or three storeys.

IOP Conference Series: Materials Science and Engineering

Sustainability

For a city to perform successfully, and its citizens to feel safe and comfortable, the health of ... more For a city to perform successfully, and its citizens to feel safe and comfortable, the health of basic urban components and the overall resilience of the urban system is crucial. As the importance of the resilient urban system has been recognized in the scientific literature, many studies have been done on this topic. Therefore, to find out the gaps in the existing literature and the opportunities for further research, a new systematic literature review has been performed in three stages. Different bibliographic techniques (co-occurrence and co-citation analysis) have been applied and, in the final stage of the analysis, an in-depth study of the content of the selected papers addressing open space in relation to urban seismic resilience has been carried out. The obtained results and trends have shown a lack of research on the potential of open space for enhancing urban seismic resilience, as well as a challenge for its quantitative assessment. The ability of the affected resilient s...

International Journal of Disaster Risk Reduction