Light sources and luminaires made in the LED technology are nowadays widely used in industry and at home. The use of these devices affects the operation of the power grid and energy efficiency. To estimate this impact, it is important to know the electrical parameters of light sources and luminaires, especially with the possibility of dimming. The article presents the results of measurements of electrical parameters as well as luminous flux of dimmable LED luminaires as a function of dimming and RMS supply voltage. On the basis of the performed measurements, a model of LED luminaire was developed for prediction of electrical parameters at set dimming values and RMS values of the supply voltage. The developed model of LED luminaire has 2 inputs and 26 outputs. This model is made based on 26 single models of electrical parameters, whose input signals are supply and control voltages. The linear regression method was used to develop the models. An example of the application of the developed model for the prediction of electrical parameters simulating the operation of an LED luminaire in an environment most similar to real working conditions is also presented.
Balconies are elements of some multi-storey buildings. Thermo-insulated fasteners are components that connect balcony slabs with the building structure. Their main task is the transfer of loads in connections of balcony slabs with the building while also minimizing thermal bridges. The article presents analytical calculations performed to develop the new type of thermal insulated fasteners and to determine their load-bearing capacity. The aim of this article is to demonstrate that analytical calculations based on commonly utilized principles of reinforced concrete and steel structure operation along enable the development of the effective design algorithm of insulated fasteners and allow for a quick analysis of various geometric variants of these fasteners. The article presents the adaptation of typical algorithms for calculation of steel and reinforced concrete structures for the analysis of non-typical load-bearing capacity states that occur during the calculation of insulated fasteners. The load-bearing capacities of individual fasteners are shown in M-V interaction diagrams (bending moment – shearing force).
Bydgoszcz University of Science and Technology, Faculty of Civil and Environmental Engineering and Architecture, Al. prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland
Glass is a material commonly used in construction. The development of technology related to it, and the increase in knowledge concerning its mechanical and strength properties offer opportunities for glass to be applied as a structural material. The advancement in glass structures, methods for their design, as well as guidelines and standards in this fields are being developed in parallel. This article describes the main assumptions contained in the German TRxV guidelines, the series of German DIN 18008 standards, and the European EN 16612, and EN 16613 standard. Moreover, the following article presents the concept of structural glass design included in the draft pre-standard prCEN/TS 19100, which provides the basis for the formulation of the European standard Eurocode 10. According to this pre-standard, structural elements of glass will be verified in four limit states, depending on the Limit State Scenario (LSS). Apart from the classic limit states, i.e., the ultimate limit state (ULS), and the serviceability limit state (SLS), it is also assumed to introduce a fracture limit state (FLS), and postfracture limit state (PFLS). The article also addresses the issue of laminated glass working in structural elements. Depending on the coupling between the glass panes and the polymer or ionomer interlayers, laminated glass can be divided into complete coupled or uncoupled, and can work in intermediate situations. The methods for determining the effective thickness contained in European standards and guidelines are discussed in this article.
Damage occurring on a reinforced concrete beam (e.g. spalling) can reduce beam’s capacity to withstand external loads. The damage becomes more critical if it is occurred in the shear span since it may lead to shear failure. Patching to the damage zone by suitable patch repair material could be the best option in restoring the shear capacity of the beam. This research investigates the shear recovery of patched reinforced concrete beams with web reinforcement. The patching material used is unsaturated polyester resin mortar. The shear recovery is assessed on the basis of the patched beam’s behavior under flexure-shear load in comparison with those of normal beams. The behavior observed include cracking failure mode, strains of the reinforcements, and load-deflection behavior. The results indicate that the UPR mortar is capable to restore the strength of the damage reinforced concrete beam. The characteristic of UPR mortar (low elastic modulus and high strength) can be the origin of the overall behavior of the patched reinforced concrete beams.
Elastic lateral-torsional buckling of double-tee section structural steelworks has been widely investigated with regard to the major axis bending of single structural elements as a result of certain loading conditions. No specific attention has been paid to the general formulation in which an arbitrary span load pattern was associated with unequal end moments as a result of the moment distribution between structural members of the load bearing system.Anumber of analytical solutionswere developed on the basis of the Vlasov theory of thin-walled members. Since the accurate closed-form solutions of lateral-torsional buckling (LTB) of beams may only be obtained for simple loading and boundary conditions, more complex situations are treated nowadays by using numerical finite element methods (FEM). Analytical and numerical methods are frequently combined for the purpose of: a) verification of approximate analytical formulae or b) presentation the results in the form of multiple curve nomograms to be used in design practice. Investigations presented in this paper deal with the energy method applied to LTB of any complex loading condition of elements of simple end boundary conditions, bent about the major axis. Firstly, a brief summary of the second-order based energy equation dealt with in this paper is presented and followed by its approximate solution using the so-called refined energy method that in the case of LTB coincides with the Timoshenko’s energy refinement. As a result, the LTB energy equation shape functions of twist rotation and minor axis displacement are chosen such that they cover both the symmetric and antisymmetric lateral-torsional buckling modes. The latter modes are chosen in relation to two lowest LTB eigenmodes of beams under uniform major axis bending. Finally, the explicit form of the general solution is presented as being dependent upon the dimensionless bending moment equations for symmetric and antisymmetric components, and the in-span loads. Solutions based on the present investigations are compared for selected loading conditions with those obtained in the previous studies and verified with use of the LTBeam software. Conclusions are drawn with regard to the application of obtained closed-form solutions in engineering practice.
The non-linear analysis of hollow-core concrete slabs requires the use of advanced numerical techniques, proper constitutive models both for concrete and steel as well as particular computational skills. If prestressing, cracking, crack opening, material softening, etc. are also to be taken into account, then the computational task can far exceed the capabilities of an ordinary engineer. In order for the calculations to be carried out in a traditional design office, simplified calculation methods are needed. They should be based on the linear finite element (FE) method with a simple approach that takes into account material nonlinearities. In this paper the simplified analysis of hollow-core slabs based on the generalized nonlinear constitutive law is presented. In the proposed method a simple decomposition of the traditional iterative linear finite element analysis and the non-linear algebraic analysis of the plate cross-section is used. Through independent analysis of the plate cross-section in different deformation states, a degraded plate stiffness can be obtained, which allows for iterative update of displacements and rotations in the nodes of the FE model. Which in turn allows to update the deformation state and then correct translations and rotations in the nodes again. The results obtained from the full detailed 3D nonlinear FEM model and from the proposed approach are compared for different slab cross-sections. The obtained results from both models are consistent.
Mechanical properties of FRP such as strength and stiffness as well as the bonding interface between FRP and concrete will be badly deteriorated when exposed to high temperature. Furthermore, the effect of thickness of insulation with different type of concrete strength has not yet been studied elsewhere in numerical studies. Therefore, this study is to assess the thermal-structural behaviour of insulated FRP strengthened RC beam exposed to elevated temperature using ABAQUS. The proposed numerical model of 200 ×300 mm RC beam subjected to 2 hours standard fire curve (ISO 834) had been validated with the analytical solution. The validated numerical model then is used in parametric study to investigate the behaviour of fire damaged normal strength concrete (40 MPa) and high strength concrete (60 MPa) of RC beam strengthened with CFRP using various fire insulation thickness of 12.5 mm, 25 mm and 40 mm, respectively. The result of steel characteristic strength reduction factor is compared with analytical using 500˚C Isotherm methods. The parametric studies indicated that the fire insulation layer is essential to provide fire protection to the CFRP strengthened RC beams when exposed to elevated temperature. The insulation layer thickness of 25 mm had been found to be the optimum thickness to be used as it is able to meet the criteria of temperature distribution and displacement requirement. In conclusion, the numerical model developed using ABAQUS in this study is to carry out assessment on the thermal-structural behaviour of the insulated CFRP-strengthened RC beams at elevated temperature.
Public Work Department, Jalan Sultan Salahuddin, 50582 Kuala Lumpur, Malaysia
School of Civil Engineering, University Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia
Institute of Noise and Vibration, University Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia
Candidate, School of Civil Engineering, University Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia
Engineering Seismology and Earthquake Engineering Research (eSEER), Institute of Noise and Vibration, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia
The problem of the arch barrel deformation in railway backfilled arch bridges caused by their typical service loads is analysed. The main attention is paid to vertical or radial displacements of characteristic points of the arch barrel. In the study results of deflection measurements carried out on single and multi-span backfilled arch bridges made of bricks or plain concrete during passages of various typical railway vehicles are used. On the basis of such results empirical influence functions of displacements are being created. In the next step, the results are utilised to estimate bending effects within the arch. The paper includes different procedures based on measurements of displacements in various points and directions. Using empirical influence functions arbitrary virtual load cases may be also considered. In this manner the proposed methodology shows a potential to be an effective tool of comprehensive calibration of numerical models of backfilled arch bridges on the basic of field tests carried out under any live loads.
The transport system is considered the “backbone” of the urban development. Along with the rapid economic development, the urban road transport system is being paid attention and invested by Hanoi city. By the year 2050, The Hanoi municipal government is expected to complete and hand over for use about 317 urban road transport projects. Due to the high demands of social and economic efficiency, the urban road transport projects in Hanoi face many risks. In which, there are 13 high dangerous risks for the urban road transport project in Hanoi. These risks have the high probability and severity impacted on the outcome of the projects. The project participant’s risk management standpoint will determine the solutions to respond the respective risks, thereby affecting the results of the project. In this paper, the authors compare the risk management standpoint of three main project participants, including owner/project management board, consultant and main contractor/subcontractor. The difference of the risk management standpoint is shown clearly by the project participants’ assessments of 13 high dangerous risks.
This research paper presents the results of the analyses of the course of technical wear over time carried out for residential masonry buildings located in the mining area of the Lublin Coal Basin (LCB). As a result of the conducted analyses, models of the course of technical wear over time were obtained for the entire building development and for groups of buildings, taking into account the conducted renovation works and preventive structural protection. By comparing the parameters of the developed models, statistically significant differences in the course of technical wear resulting from the quality of maintenance and the use of preventive measures were identified. In addition, the durability of individual groups of structures was estimated and compared. Based on a comparison of the course of technical wear of 22-year-old building structures, unrenovated and with similar structural and material solutions, it was found that the rate of increase in technical wear after 50 years of use is on average 3.5% lower than in the case of unprotected buildings. In addition, the use of preventive structural protection extends the durability of the analysed building structures by an average of over 13 years. The obtained results may e.g. help owners or managers optimise the Maintenance Management of building structures.
The hydraulic fill method of erecting dams was characterized. The main assumptions and practical aspects of sand spigot were discussed on the example of the spigot of the dam body of the Zelazny Most Tailings Storage Facility (TSF). The advantages and disadvantages of the method are discussed, and the directions of attempts to implement pipelines rising along with sedimenting waste are presented, which are to reduce earthworks.
In this work, the instability damage modes of yield state of a steel tube at the tension side of a rectangular steel tube-confined concrete (RCFST) column under eccentric compression were classified into two types based on the coupling effect of slenderness ratio (λ) and eccentricity ratio (γ). The two types include the unilateral compression yield failure mode with a smaller value of γ and tensile and compressive yield failure modes on both column sides with a larger value of γ. Further, the parametric analyses were performed by employing the finite element (FE) method and the analytical analysis to test 16 groups of RCFST columns by varying the γ value with different λ values. It was observed that the results of the analysis for the mechanical properties like the responses of load-strain ( P-ε) and RCFST column instability modes correlated well with the results obtained in the experiments. Furthermore, the proposed theoretical method could be used to investigate the roles of γ as a controller against the instability in RCFST columns when compared with λ.
In Eurocode 5, the stiffness equation for bolted steel-wood-steel is stated as a function ofwood density and fastener diameter only. In this research, an experimental study on various configurations of tested bolted steel-wood-steel (SWS) connections has been undertaken to predict the initial stiffness of each connection. In order to validate the Eurocode 5 stiffness equation, tests on 50 timber specimens (40 glued laminated timbers and 10 laminated veneer lumbers (LVL)) with steel plates were undertaken. The number of bolts was kept similar and the connector diameter, timber thickness, and wood density were varied. The results obtained in the experimental tests are compared with those obtained from the Eurocode 5 stiffness equation. From the analysis, it is signified that the stiffness equation specified in Eurocode 5 for bolted SWS connections does not adequately predict the initial stiffness. The results from Eurocode 5 stiffness equation are very far from the experimental values. The ratio of stiffness equation to experimental results ranges from 3.48 to 4.20, with the average at 3.77, where the equation overpredicted the experimental stiffness value for the connection. There is a need to consider or incorporated other parameters such as geometric configurations in Eurocode 5 stiffness equation to improve the ratio with the experimental data.
University Malaysia Perlis, Faculty of Civil Engineering Technology, 02600 Arau Perlis, Malaysia
2Sustainable Environment Research Group (SERG), Centre of Excellence Geopolymer and Green Technology (CEGeoGTech), University Malaysia Perlis (UniMAP), 01000 Kangar Perlis, Malaysia
University of Auckland, Faculty of Civil Engineering, Department of Civil and Environmental Engineering, Auckland, New Zealand
Department of Civil Engineering, College of Engineering, University Malaysia Pahang, 26300 Gambang Kuantan, Pahang Malaysia
Czestochowa University of Technology, Czestochowa, Poland
Centre of Excellence Geopolymer and Green Technology (CEGeoGTech), University Malaysia Perlis (UniMAP), 01000 Kangar Perlis, Malaysia
Sustainable Environment Research Group (SERG), Centre of Excellence Geopolymer and Green Technology (CEGeoGTech), University Malaysia Perlis (UniMAP), 01000 Kangar Perlis, Malaysia
University Malaysia Perlis, Faculty of Chemical Engineering Technology, 02600 Arau Perlis, Malaysia
Division of Materials Processing Technology and Computer Techniques in Materials Science, Silesian University of Technology, 44-100 Gliwice, Poland
Bridges are particularly vulnerable elements of transport infrastructures. In many cases, bridge structures may be subject to higher volumes of traffic and higher loads as well as more severe environmental conditions than it was designed. Sound procedures to ensure monitoring, quality control, and preventive maintenance systems are therefore vital. The paper presents main challenges and arriving possibilities in management of bridge structures, including: relationships between environment and bridge infrastructure, improvement of diagnostic technologies, advanced modelling of bridges in computer-based management systems, development of knowledge-based expert systems with application of artificial intelligence, applications of technology of Bridge Information Modelling (BrIM) with augmented and virtual reality techniques. Presented activities are focused on monitoring the safety of bridges for lowering the risk of an unexpected collapse significantly as well as on efficient maintenance of bridges as components of transport infrastructure – by means of integrated management systems. The proposed classification of Bridge Management Systems shows the history of creating such systems and indicates the expected directions of their development, taking into account changing challenges and integrating new developing technologies, including automation of decision-making processes.
Local roads in Poland, built for the most part in the previous economic system, are mostly unsuited to the ever-increasing traffic load, often built on a low-load organic substrate and need to be renovated. Linear objects are most often characterized by a significant variability in groundwater conditions in their area. The economical and safe design of the rebuild of a road structure often entails the need to implement ground improvement design of the low-bearing soil substrate, but areas of improvement should be adapted to the occurrence zones of low-bearing soil. The article presents a case study of the district road, for which ground and water conditions were recognized and organic soil were found. In addition to the rebuilding of the road structure to fulfill the requirements of the current traffic load and repairing the culverts, the reconstruction also included the ground improvement. The authors reviewed the types of road categories according to the admissible traffic loads (KR), the most important and commonly used methods of ground improvement, discussed the characteristics of the Benkelmann beam deflection method, proposed a design solution adapted to the existing conditions in the substrate and, after implementing it, presented the results of the deflection of the road before and after the reconstruction and soil improvement.
The goal of paper is the development and demonstration of efficiency of algorithm for form finding of a slack cable notwithstanding of the initial position chosen. This algorithm is based on product of two sets of coefficients, which restrict the rate of looking for cable geometry changes at each iteration. The first set restricts the maximum allowable change of absolute values of positions, angles and axial forces. The second set takes into account whether the process is the converging one (the signs of maximal change of parameters remain the same), so that it increases the allowable changes; or it is a diverging one, so that these changes are discarded. The proposed procedure is applied to two different methods of simple slack cable calculation under a number of concentrated forces. The first one is a typical finite element method, with the cable considered as consisting of number of straight elements, with unknown positions of their ends, and it is essentially an absolute coordinate method. The second method is a typical Irvine’s like analytical solution, which presents only two unknowns at the initial point of the cable; due to the peculiarity of implementation it is named here a shooting method. Convergence process is investigated for both solutions for arbitrary chosen, even very illogical initial positions for the ACM, and for angle and force at the left end for SM as well. Even if both methods provide the same correct convergent results, it is found that the ACM requires a much lower number of iterations.
Foamed concrete incorporating processed spent bleaching earth (PSBE) produces environmentally friendly foamed concrete. Compressive strength, porosity, and rapid chloride penetration tests were performed to investigate the potential application for building material due to its low density and porous concrete. Laboratory results show that 30% PSBE as cement replacement in foamed concrete produced higher compressive strength. Meanwhile, the porosity of the specimen produced by 30% PSBE was 45% lower than control foamed concrete. The porosity of foamed concrete incorporating PSBE decreases due to the fineness of PSBE that reduces the volume of void space between cement and fine aggregate. It was effectively blocking the pore and enhances the durability. Consistently, the positive effect of incorporating of PSBE has decreased the rapid chloride ion permeability compared to that control foamed concrete. According to ASTM C1202-19 the foamed concrete containing 30% PSBE was considered low moderate permeability based on its charge coulombs value of less than 4000. Besides, the high chloride ion permeability in foamed concrete is because the current quickly passes through the specimen due to its larger air volume. In conclusion, incorporating PSBE in foamed concrete generates an excellent pozzolanic effect, producing more calcium silicate hydrate and denser foamed concrete, making it greater, fewer voids, and higher resistance to chloride penetration.
One of the main causes of road pavement distress are low temperatures, and hence the need to thoroughly study the low temperature performance of all bituminous materials used in road construction. The purpose of this studywas to determine the performance of alternative and conventional bituminous mixtures in the temperature range between –25˚C and –10˚C using for this purpose the Tensile Creep Test (TCT). The low-temperature performance data were evaluated using the Burgers model, a tool that is widely used for evaluation of bituminous mixtures. This research focuses on bridge paving mixtures. These included both conventional (mastic asphalt) and alternative (SMAMA) materials. It was established, based on the test results and their analysis, that low temperature performance of a bituminous mixture is influenced, in the first place, by the characteristics of the asphalt binder it contains. Furthermore, SMA-MA mixtures showed better low temperature performance than conventional, mastic asphalt type mixtures.
This paper deals with the numerical analysis aimed at study the bearing capacity of pinended steel built-up columns under axial compression. Finite element (FE) models were performed for the columns presented in the literature. The main problem discussed in the article is the shape and magnitude of geometric imperfections introduced into the numerical FE model, necessary to obtain the load capacity consistent with the experimental strength tests. Three types of numerical analysis that can be used inAbaqus program to calculate the load bearing capacity have been described. The imperfections possible to introduce for built-up columns were presented and an equivalent imperfection corresponding to both imperfections recommended by Eurocode 3 (global of the entire column and local of the chord) for built-up members was proposed. The results of the geometrically and materially nonlinear static analysis were compared with the calculations according to the code procedures (Eurocode 3 and PN-B- 03200:1990) and the results of experimental tests.
In recent years, the application of pervious concrete (PC) in urban areas has expanded mainly due to its high potential for controlling and guiding surface waters and floods. However, its poor mechanical properties compared to conventional concrete hinder its widespread application and limit it to parking lots, sidewalks, and local streets. Therefore, identifying the parameters effective on PC’s physical and mechanical properties and durability could help resolve its weaknesses and enhance its performance. This review article investigated and discussed the PC’s performance properties and weaknesses and explore the solutions available for improving these properties. Based on a review of the literature, the solutions included the PC’s mix design basic property variations and the incorporation of various additives. The common mixture utilized in most studies contained a water-to-cement ratio of 0.25:0.35, resulting in compressive strength of 7–27 MPa, porosity of 15–35%, and permeability of 0.2–1.22 mm/s.
Glass-aluminum building facades, as well as glazed walls intended to construct internal partitions of various types with glass doors, the purpose of which is to create fire zones, must satisfy certain fire resistance requirements stated in the codes. The offer of domestic and foreign manufacturers consists of system fire resistant partitions manufactured in the EI 30 to EI 180 fire resistance classes. Fire retardant properties of such partitions are verified experimentally, and the technical approvals are issued based on the results of such tests. In this paper the results of fire tests performed on selected partitions made by the leading domestic maker of glass-aluminum systems and representative for the whole commercial offer of Aluprof S.A. are presented. Fire resistance of doors and partitions made of aluminum sections with fire protecting insulation in one or several chambers and Polflam glazing panes differing in thickness of swelling gel have been tested. In this paper a comparative analysis of the temperature increase curves obtained on the external surface of glass panes and aluminum sections forming the tested partitions has been performed. The relationships between the internal structure of aluminum sections and glazing panes and the shape of empirical curves have been indicated. A mixed tangent-secant linearization of these curves has been proposed as well as presentation of the experimental results in the non-dimensional coordinates. Such presentation form of final experimental results allows for a clear interpretation of laboratory tests with reliable documenting of nominal fire resistance requirements.
Inclinedweb box girders are widely used in urban areas because of their attractive appearance. However, there are few studies on the vehicle shear force distribution of this type of bridge. In this study, we established 62 three-dimensional finite element models in which the shear force of each web of the box girder can be extracted; furthermore, we investigated the shear force distribution law in webs of the box girder under live loads, including single-chamber and multichamber inclined web box girders. The main parameters studied include the number of vehicle lanes and chambers, slope of the inclined webs, and support conditions. The results reveal that an uneven distribution of web shear force exists in both the single-chamber box girder and multichamber girder under live loads, and the maximum value of the vehicle shear force distribution factor is greater than the average shear value shared by all webs. Therefore, the uneven distribution of shear force in the webs of the box girder cannot be ignored under eccentric vehicle loads. These values greatly exceed the safety factor of 1.15 that is used in conventional calculations.
The article analyzes factors that may have an impact on Occupational Safety in a construction company and the issues of work safety in construction were discussed. An attempt was made to analyze the management of work safety in construction companies in order to identify important factors and determine the significance of their participation in the occurrence of accidents at work. The research was carried out on the basis of data obtained from the register kept at the District Labor Inspectorate in Krakow. Cases which were discussed included accident protocols prepared pursuant to the law, as well as cases found in protocols of ad hoc inspections carried out on construction sites. There were quantitative and qualitative features in the analyzed data set. Logistic regression was used to analyze the data to build the model. Such action made it possible to model and determine the significance of the influence of individual variables characterizing the way of managing work safety in construction companies, in the case of an accident. The results obtained, and in particular the significance of factors shown in the model, even not directly related to the construction site, may be an indication for creating a functional strategy in the enterprise. The strategy assuming: smaller number of accidents or adverse events, shorter downtime will build a reputation of an institution that cares for the employee. This will allow the construction company to become more competitive and shall attract the best professionals available on the labor market. The end result is the identification of key factors that have a direct impact on work safety and the competitiveness of a construction company.
This article discusses the use of prefabricated concrete components in the work of the Polish architect Władysław Pienkowski (1907–1991), which are particularly representative of the author’s signature approach to contemporary sacred architecture. The evolution of the prefabricated components used and their properties are presented through the example of 8 churches of his design. They have been analysed in terms of their individual character, the potential to use similar components in a variety of designs and in terms of their aesthetic value. Contemporary and archived photographs, as well as design drawings from the archives of the architect’s family have been used to illustrate the examples. The presented examples prove that the use of prefabricated elements offers a wide range of options in the creation of architecture. Their repetitive nature, when skilfully used, becomes an asset rather than a hindrance in the design of diverse buildings. Drawing attention to this aspect can not only inspire the creation of new buildings, but also contribute to the revitalisation of existing architectural structures.