Textile-reinforced concrete (TRC) is a reinforced concrete, where steel reinforcement is replaced with textiles or fibers. Textile reinforcement is a material consisting of natural or synthetic ...singular technical fibres processed into yarns or rovings which are woven into multi-axial textile fabrics having an open mesh or grid structure. In the paper an overview of tests results related to mechanical properties, deformation properties and durability characteristics of textile meshs are presented. Applications of different textiles as reinforcement in TRC is analyzed through some realized projects. TRC has been successfully employed for strengthening or repair of damaged structural elements and lightweight, thin structural elements (precast thin-walled elements, shells, tanks, pipes, pedestrian bridge, waterproofing structure, integrated cladding systems, external insulation system).
The revitalization of existing masonry buildings, built decades ago, is a very topical and complex structural engineering issue, especially when the building was built in the area of significant ...seismic activity. A large number of masonry buildings in the city of Nis, as well as in other places in Serbia, were built in the period before the adoption of technical regulations on the design and construction of seismically resistant structures and they are at insufficient safety level in the event of an earthquake. Therefore, it is necessary that structural strengthening meets the seismic resistance requirements laid down in Eurocode 8 or other relevant codes. In order to choose the method of structural strengthening, detailed seismic analyses must be carried out in several variants along with the application of relevant technical regulations. The effects of five analyzed structural strengthening methods were checked against the provisions of Eurocode 8, Part 1 and Part 3, which relate to the recommendations for the geometric characteristics of shear walls, and they were applied on two types of existing masonry buildings in Nis. On the basis of the performed analyses, conclusions were drawn regarding the methodological approach of the assessment of the condition of the structure, its seismic resistance and decision-making on remediation and/or strengthening measures.
Belgrade fair hall 1 is well known for its dome, which is still the world largest self-supported construction made of pre-stressed concrete, with its diameter of 106 m. In this paper the Finite ...Element Method (FEM) was performed to analyze different loading and supporting conditions. At the same time, crack growth in a support column was simulated by the extended FEM (XFEM). Results of numerical calculations indicate ingenious design of such a complex structure which was based on “hand” calculation decades ago, without computers. In addition to classical engineering and more advanced numerical calculations, risk based analysis was performed taking into account artificially introduced crack and Failure Analysis Diagram, obtained using stress intensity factor and net stress, as well as fracture toughness and critical stress. This analysis, made for the first time for Belgrade fair hall 1, proved that its structural integrity is jeopardized only when a crack reaches half the thickness of a steel bar.
This paper investigates and analyzes a typical multi-zone office building?s
annual energy performance for the location and climate data of central
Belgrade. The aim is to evaluate the HVAC system?s ...and HR unit?s performance
in order to conduct the most preferable heating and cooling solution for the
typical climate of Belgrade city. The energy performance of four HVAC system
types (heat pump - air to air, gas-electricity, electrical and fan coil
system) was analyzed, compared and evaluated on a virtual office building
model in order to assess the total annual energy performance and to determine
the efficiency of the HR unit?s application. Further, the parameters of an
energy efficient building envelope, HVAC system, internal loads, building
operation schedules and occupancy intervals were implemented into the
multi-zone analysis model. The investigation was conducted in EnergyPlus
simulation engine using system thermodynamic algorithms and surface/air heat
balance modules. The comparison and evaluation of the obtained results was
achieved through the conversion of the calculated total energy demand into
primary energy. The goal is conduct the most preferable heating and cooling
solution (Best Case Scenario) for the climate of Belgrade city and outline
major criteria in qualitative enhancement.
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•Effects of bridge geometry and ground motion properties on seismic response are investigated.•Probabilistic seismic (PS) demand models for skew and curved bridges are proposed.•resPGV, resSd(T1) and ...resCord are found as most suitable measures to be used in PSA.•Skewness increases bridge fragility, particularly for bridges with rectangular piers.•Decrease of deck radius increases fragility, regardless the skewness and bent type.
The objective of this study is to investigate seismic response of bridges with unconventional configuration such as skewed and curved bridges. The influence of skewness and horizontal curvature on seismic performances of bridges, with a special focus on their influence on the probabilistic seismic demand model (PSDM), is analysed. Since the studies of seismic performances of bridges are nowadays formulated in probabilistic frameworks it is important that the established (PSDMs) meet specific criteria so they can be considered a reliable tool in seismic assessment of bridge structures. Twelve types of bridges are considered in this study by varying two bent types, three values of skewness and two values of curvature. Nonlinear dynamic analyses are conducted for all the considered samples. Longitudinal, transversal and resultant column drift ratios are considered as the bridge response. Five earthquake intensity measures are investigated and each of them are calculated from both horizontal components. In addition, the resultant measures are obtained by applying the SRSS rule on the components. The formed PSDMs are analysed in order to examine their efficiency, proficiency and sufficiency. Adverse effects of skewness and curvature on seismic performances of bridges are noticed in the conducted analyses by comparing mean values of column displacement ductility, established prediction models and fragility demand curves. It was noticed that these effects are more prominent for bridges with single pier bents with one weak direction in comparison with double pier bents. Finally, it is found that more accurate models (efficient and proficient) are obtained when structure dependant measures are used in PSDMs. Modified models including resultant measures and resultant response are proposed for fragility analysis of curved and skewed bridges.
•A new model for the prediction of strength degradation of composites is proposed.•The model could represent both the initial drop of strength and “sudden death”.•A single pair of parameters is ...sufficient for the whole range of load levels.•Good agreement with experimental data from different literature sources is shown.
Residual strength models are widely used for the fatigue analysis of composites subjected to both constant and variable amplitude fatigue. However, they often require large experimental efforts to determine the model parameters. The aim of this research is to develop a simplified mathematical model which uses a single set of parameter values to predict the strength degradation of the elements subjected to different load levels, and thus, to reduce the required experimental effort for the determination of model parameters for each load level separately. The new two-parameter model is developed here on the basis of normalization of the difference between the residual strength and maximal applied load in the constant amplitude cyclic loading, herein referred to as the strength reserve, with respect to initial conditions. The model is validated using different experimental data sets from the literature. High correlation with the experimental data is observed. Moreover, the curves obtained by using the single set values of parameters matched the curves of some of the most accurate residual strength models from the literature.
This paper elaborates the formulation and application of an integral methodology for overall energy performance improvement of office buildings and demonstrates its application. The developed ...multi-objective methodology is demonstrated on a reference office building located in a temperate climate zone with high annual temperature variations. The idea is to formulate a research based proposition in building science with a formulation of a general/integral methodology which could be applied widely in energy performance refurbishment of existing office buildings and help architects and engineers in the early-design stages of new projects. The goal was to formulate an optimized building envelope model using multi-criterion optimization methodology in order to determine efficient window to wall ratio (WWR) and window geometry (WG) in the function of indoor illumination quality, followed by the assessment of glazing parameters influence on the annual energy demand. The integral methodology for overall energy performance improvement of office buildings utilizes multi-criterion optimization method and highly detailed Building Information Modeling (BIM) programs and dynamic energy simulation engines. The developed coupled-integral methodology links together both building envelope construction optimization and user comfort. The methodology is both flexible and adaptable for application in various climatic conditions and for different construction types.
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•An integral methodology for overall energy performance improvement was formulated.•Multi-criterion optimization of envelope in the function of illumination quality.•Mutual correlations between WWR, WG and window properties were investigated.•Numerical spatial daylight dispersion simulations were performed in Radiance.•Envelope and internal heat gains influence on the overall energy performance.
The main objective of this paper is to evaluate the thermal properties of existing residential buildings built in industrial manner in Novi Sad from 1960 to 1990 based on building typology. Each of ...three analyzed building type has its characteristic facade, with thermal performances divided into periods according to the development of domestic thermal protection building codes. The necessary layer of subsequent insulation is determined by calculations in order to comply with European standards, also applied in Serbia from 2012. The proposed method of periodization simplifies the process of thermal performance assessment and it was checked through the case studies. Evaluation of energy consumption rationalization has been done through comparative analysis of energy losses. Based on the most common energy rehabilitation measures applied in Serbia, it was estimated that it was possible to reduce the energy losses in heating up to 60%. Acknowledgements. The work reported in this paper is a part of the investigation within the research project TR 36017 supported by the Ministry for Education and Science, Republic of Serbia
Research at faculties in Serbia after WWII, even though they were fruit of individual efforts, resulted in significant theoretical contributions. Organized, mostly applied research was conducted ...within institutes with participation of scholars and researchers of the faculties. Since 1952, the Association of Yugoslav Laboratories (AYL) consolidated the research, thus providing a considerable contribution to the structural engineering in Serbia. This contribution in the field of theory and practice was the basis for the notable achievements that glorified our structural engineering worldwide. Theoretical contributions contained in the doctoral dissertations in the field of Theory of structures and Geotechnics are significant, so they were listed in the paper. Majority of these studies became a part of research project as late as in 1976, and they are briefly presented in the paper. The synthesis of project results from fundamental and technological development research was published in numerous monographs, articles, papers and proceedings of scientific and professional meetings and some of them are commented in this paper. The necessity to introduce technical regulations which have already been adopted in the EU countries EN 1990 to 1999, i.e. the Eurocode, was emphasized. There is a brief discussion of several research directions which are topical nationwide as well as worldwide.
In this paper, the seismic response of a five-story reinforced concrete (RC) frame system building is analysed through fragility analysis. The structure is designed in accordance with structural ...Eurocodes EN1990, EN1991, EN1992 and EN1998, as a high-ductility (DCH) system. For the analysis of the response of a structural system to earthquake actions, the methods of nonlinear static (NSA) and nonlinear dynamic analyses (NDA) are applied and, based on the obtained results, fragility curves are constructed using statistical methods. A relationship between the intensity measure (IM) and engineering demand parameters (EDPs) is needed in order to estimate a fragility curve. Fragility functions represent a possibility for different states of damage to occur in a certain structural systems at the observed value of the specified IM. Ten accelerograms, used in NDA, are selected and scaled, according to EN1998 provisions, for the chosen elastic response spectrum and referent PGA. Obtained results are used for the statistical analysis and construction of fragility curves. Structural damage state threshold parameters are determined based on the Park and Ang modified damage index methodology and provisions given in FEMA, HAZUS, VISION 2000 and EN codes. Comparative analysis of the structural damage probability for the analysed RC building, calculated using different methodologies to determine damage states, is applied. The fragility analysis results showed the difference between the probabilities of the damage states to occur when different calculation methods are used. This reflects on the assessment of vulnerability curves as well. The obtained results, calculated using different methods, are analysed using comparative analysis.
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