Nauki Techniczne

Archives of Civil Engineering

Zawartość

Archives of Civil Engineering | 2020 | Vol. 66 | No 3 |

Abstrakt

The paper presents pursuits of the truth in building materials engineering. Some definitions of “what truth is” were presented. Partial truths were specified: the truth of scientific reasoning, the truth of scientific assessment, the truth of development directions and the splendour of scientific truth. All categories are addressed to the building materials engineering. In the chapter “Load capacity and stability vs entropy” definitions of entropy and exergy were presented followed by their influence on building construction, illustrated by the “Seneca cliff” and “Energy pyramid”. Chapter 3 presents the truth of scientific reasoning was presented. Three partial truths were indicated: the truth of experimental fact, the truth of scientific reasoning and the truth of scientific presentation. In the chapter “Truth of scientific assessment” two main assessment methods were presented: peer review and a bibliometric parametric assessment as well as their impact on the results and authors. The risks associated with the sole parametric assessment were shown as the two basic factors of a parametric assessment – citation number and Hirsch index – need time to "mature". Additionally, the influence of digitalisation of the assessment of a scientist and a scientific unit on the commoditisation and dehumanisation of science was outlined. In the chapter “Truth of development directions: defined past – fuzzy future” the megatrends observed in technology in the last few decades years were indicated along with new possible trends. Milestones in the development of C-PCs (Concrete-Polymer Composites) were presented. The new paradigm for the new development cycle was proposed.

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Autorzy i Afiliacje

Lech Czarnecki

Abstrakt

The manuscript presents the condition of circular economy in Poland in diversified approach: subjective (waste streams, energy), sectoral (construction, wastewater treatment, coal energy), related to the resources (phosphorous and anthropogenic minerals) and considering proper energy management (almost zero energy buildings). The achievements reached in different sectors as well as the requirements towards implementation of CE are presented. The advancement of recycling technologies does not deviate from the global level, in terms of areas specific to Poland. Limiting the exploitation of natural resources and usage of new materials as well as producing more durable products are of CE concern. Also energy and heat recovery in buildings and technological processes (e.g. during wastewater treatment), ways of utilization of combustion by-products and water decarbonization waste are described. The implementation of CE in Poland needs not only research and technical activities, but also the modification of technological processes, the right policy, overcoming crosssectoral barriers, developing legal regulations and support schemes for CE.

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Autorzy i Afiliacje

Zbigniew Kledyński
Anna Bogdan
Wioletta Jackiewicz-Rek
Krystyna Lelicińska-Serafin
Agnieszka Machowska
Piotr Manczarski
Dagmara Masłowska
Anna Rolewicz-Kalińska
Joanna Rucińska
Tomasz Szczygielski
Justyna Walczak
Małgorzata Wojtkowska
Monika Zubrowska-Sudol

Abstrakt

In this study, the results of experiment research on building mortars based on dry mixtures with the use of granite dust are given. It also shows the possibilities of their industrial release. In the conditions of energy resources shortage, gradual exhaustion of natural raw materials, aggravation of environmental problems, an important direction in the production of building mixtures is the development of mixes with waste materials from various industries. In particular, granite dust, which simultaneously allows to rationally use natural mineral material and solve environmental problems. Based on the obtained data, experimental and statistical models of physical and mechanical properties of fresh and hardened mortar are constructed and ways of optimizing their compositions and improving the properties of mortars are analyzed. It is established that the use of granite dust and some additives provides high standardized parameters for mortar mixture and bricklaying process, including plasticity, compressive strength and others at the low level of cement consumption. Fresh mortar mixtures have a prolonged slump retention.

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Grzegorz Prokopski
Vitaliy Marchuk
Andriy Huts

Abstrakt

The concrete-filled section of columns has been widely in construction used due to its structural elements. As a result, the usage of composite columns has recently increased all over the world. However, using foamed concrete alone does not result in much improvements in strength. Therefore, this paper examines the use of foamed concrete containing fibre to improve the strength of composite columns. Specifically, this study aims to determine the bond strength of concrete-filled hollow section (CFHS) with modified fibrous foamed concrete. Two types of fibre are used in this work, namely, steel fibre and polypropylene fibre, with rice husk ash (RHA) as a sand replacement to improve the compressive strength of foamed concrete. The CFHS with modified fibrous foamed concrete is tested by using the push-out method, and the results show that CFHS with steel fibre has a highest bond strength.

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S.A.A. Khairuddin
N.A. Rahman
N. Jamaluddin
Z.M. Jaini
A. Elamin
R.H.M. Rum

Abstrakt

The paper presents a method of structural monitoring with the use of angular and linear displacement measurements performed using inclinometer and laser measuring devices. The focus is mainly on the inclinometer measurement method, which is a solution free from the basic disadvantages of optical methods, such as sensitivity to any type of visibility restrictions, pollution or influence of weather conditions. Testing of this method was carried out in practical application in an wireless monitoring system, installed in a large-area industrial building. The measurement results performed using the inclinometers were compared with simultaneous measurements of linear displacements performed with the use of proven methods based on laser rangefinders. The research and analysis show that the method of measuring angular displacements using the inclinometers with MEMS sensors of appropriate quality is a very good, better than typical optical methods, solution of structural monitoring systems that allows to obtain accurate and reliable results.

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Stanisław Wierzbicki
Zbigniew Pióro
Marcin Osiniak
Edward Antoszkiewicz

Abstrakt

Drinking water systems are critical to society. They protect residents from waterborne illnesses and encourage economic success of businesses by providing consistent water supplies to industries and supporting a healthy work force. This paper shows a study on water quality management in a treatment plant (TP) using the Box-Jenkins method. A comparative analysis was carried out between concentrations of water quality parameters, and Colombian legislation and guidelines established by the World Health Organization. We also studied the rainfall influence in relation to variations in water quality supplied by the TP. A correlation analysis between water quality parameters was carried out to identify management parameters during the TP operation. Results showed the usefulness of the Box-Jenkins method for analyzing the TP operation from a weekly timescale (mediumterm), and not from a daily timescale (short-term). This was probably due to significant daily variations in the management parameters of water quality in the TP. The application of a weekly moving average transformation to the daily time series of water quality parameter concentrations significantly decreased the mean absolute percentage error in the forecasts of Box-Jenkins models developed. Box-Jenkins analysis suggested an influence of the water quality parameter concentrations observed in the TP during previous weeks (between 2-3 weeks). This study was probably constituted as a medium-term planning tool in relation to atypical events or contingencies observed during the TP operation. Finally, the findings in this study will be useful for companies or designers of drinking water treatment systems to take operational decisions within the public health framework.

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E.A. Redondo-Peñuela
H.A. Rondón-Quintana
C.A. Zafra-Mejía

Abstrakt

In this study, cubic and cylindrical cement mortar specimens were first subjected to high temperatures, then the cubic and cylindrical specimens were taken out and conducted with uniaxial compressive test and splitting tensile test, respectively. The effect of the length to side ratio on the uniaxial compressive properties and the effect of thickness-to-diameter ratio on the splitting tensile properties of cement mortar specimens after high temperature were studied. Test results show that: (1) With temperature increasing from 25°C (room temperature) to 400°C, the compressive strength and elastic modulus of cubic specimens with three kinds of side lengths decrease; the decreasing rates of compressive strength and elastic modulus of cubic specimen with side length of 70.7 mm is higher than those of cubic specimens with side length of 100 mm and 150 mm, and the strain at the peak stress of cubic specimens with three kinds of side lengths increase. (2) After the same temperature, the tensile strength of cylindrical specimen decreases with the thickness-to-diameter ratio increasing from 0.5 to 1.0. The decreasing rate of tensile strength of cylindrical specimen with thickness-to-diameter ratio is highest when the temperature is 25°C (room temperature), followed by that after the temperature of 200°C, and that after the temperature of 400°C is the lowest.

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L.X. Xiong
X.J. Zhang
Z.Y. Xu
D.X. Geng

Abstrakt

The paper describes studies on the influence of humidity on the electrical resistance of a textile sensor made of carbon fibres. The concept of the sensor refers to externally bonded fibre reinforcement commonly used for strengthening of structures, however the zig-zag arrangement of carbon fibre tow allows for measuring its strain. The sensor tests showed its high sensitivity to the temperature and humidity changes which unfavourably affects the readings and their interpretation. The influence of these factors must be compensated. Due to the size of the sensor, there is not possible electrical compensation by the combining of “dummy” sensors into the half or full Wheatstone bridge circuit. Only mathematical compensation based on known humidity resistance functions is possible. The described research is the first step to develop such relations. The tests were carried out at temperatures of 10°C, 20°C, 30°C and humidity in the range of 30-90%.

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Marcin Górski
Rafał Krzywoń
Sofija Kekez

Abstrakt

From the construction made in the “white box” technology, first of all tightness is required - on the structural elements there should not be any cracks or scratches, through which water could penetrate, which in consequence may lead to deformation of structural elements and even loosing of their load-bearing capacity. Among the methods enabling the location of weakened places in watertight concrete, the ground penetrating radar (GPR) method is effective because the local occurrence of water in the structure evokes a clear and unambiguous anomaly on the radargram. In addition, the GPR method allows you to indicate places where water flows without the necessity of excluding the object from use and interference in the construction layers. The designation of such locations will make it possible to undertake technical activities that can facilitate the takeover of water and thus ensure the desired load-bearing capacity and usability of the object. Using the GPR method, you can also designate places that have already been deformed – discontinuities or breaking. The article presents a case study of investigations that determine the causes of leakage of tunnels made in the “white box” technology in: twice within the bottom slab of the tunnel (1 GHz air-coupled and 400 MHz ground-coupled antenna) and once in the case of tunnel walls (1.6 GHz ground-coupled antenna).

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Anna Lejzerowicz
Małgorzata Wutke

Abstrakt

The basic tests that allow the mechanical properties of grained material to be evaluated are tests of an aggregate’s resistance to crushing - the Los Angeles coefficient, and resistance to abrasion - the micro-Deval coefficient. These parameters primarily depend on the physical and mechanical properties of the raw material from which they are produced. The available literature widely describes the relationship between these parameters and bulk density, porosity, ultrasonic wave velocity, compression strength, tensile strength and point strength. This paper presents the relationship between the mechanical properties of aggregates and their geometrical properties. The analysis was carried out for the relationship between the Los Angeles and micro- Deval coefficients and the flatness and shape indices. As a result of the conducted considerations, the influence of the aggregate assortment on the analysed coefficients was also noted. All of the tests were carried out for aggregates (arch stones and mixtures) produced from sandstones from the Magura, Cergo and Krosno layers.

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Joanna Hydzik-Wiśniewska

Abstrakt

The purpose of this study is to investigate a structure’s response to blast loading when composite columns are used instead of conventional reinforced concrete (RC) cross sections and when a conventional structure is retrofitted with braces. The study includes conducting dynamic analyses on three different structures: a conventional reference RC structure, a modified structure utilizing composite columns, and a modified structure retrofitted with steel braces. The two modified structures were designed in order to investigate their performance when subjected to blast loading compared to the conventional design. During the dynamic analyses, the structures were exposed to simulated blast loads of multiple intensities using the finite-element modelling software, SeismoStruct. To evaluate their performance, the responses of the modified structures were analyzed and compared with the response of the conventional structure. It was concluded that both the structure with composite columns and the steel brace structure experienced less damage than the conventional model. The best performance was obtained through the steel brace structure.

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Y.E. Ibrahim
M. Almustafa

Abstrakt

The problem of setting out in civil engineering applications has been addressed in the literature for a long time. However, technological development has provided researchers with an opportunity of having other procedures in line with modern techniques in surveying sciences. One of the most important procedures in erecting steel structures, bridges, and precast columns of a building is the accurate placement of the anchorage system in concrete. The traditional method for staking out anchor bolts relies on sight rails, string lines, and tape measure. The precision of this art depends not only on the accuracy of observed offset distances during layout operations but also on the centerline of the anchoring template itself. Nowadays, the process of designing structures is executed using software that can perform a digital plan in CAD environment, where the coordinates of each anchor bolt can be defined. This research presents an accurate approach of positioning anchor bolts based on the second problem in surveying and total station. Error analysis and field application are described to evaluate the performance of the proposed method. However, the results indicate that the developed technique increases productivity, reduces the cost, and improves the positional accuracy.

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M. Habib
A. Malkawi
M. Awwad

Abstrakt

The mechanical properties of cement paste modified by nano-TiO2 (nT) and nano-SiO2 (nS) were experimentally studied. The compressive strength increased first and then decreased with the increase of nanoparticle content. When nanoparticles were added into the cement paste as a filler to improve the microstructure, the two kinds of particles both could form a tighter mesh structure, which would enhance the density and strength of the structure. The elastic modulus increased rapidly with the increase of the nT content and reached a peak when the nanoparticle content is about 3%, which was about twice the elastic modulus of ordinary cement paste. The Scanning electron microscopy (SEM) observation results showed that the microstructure of cement was network connection and fiber tube. The hydration progress of ordinary cement slurry was insufficient, and many unreacted cement particles remained. With the addition of nanoparticles, the internal structure of the cement became denser, with fewer pore cracks, smaller pore diameters, more complex fiber tube arrangements, and significant anisotropy, thereby improving strength and mechanical properties.

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Autorzy i Afiliacje

Zhi Wang
Wenjing Qin
Lijuan Zhang

Abstrakt

The dynamic analyses are of key importance in the cognitive process in terms of the correct operation of structures loaded with time alternating forces. The development of vehicle industry, which directly results in an increase in the speed of moving vehicles, forces the design of engineering structures that ensure their safe use. The authors of the paper verified the influence of speed and vehicle parameters such as mass, width of track of wheels and their number on the values of displacements and accelerations of selected bridge elements. The problem was treated as the case study, because the analyses were made for one bridge and the passage of three types of locomotives. The response of the structure depends on the technological solutions adopted in the bridge, its technical condition, as well as the quotient of the length of the object and vehicle. A new bridge structure was analyzed and dynamic tests were carried out for trainsets consisting of one and two locomotives. During the actual dynamic tests, the structure was loaded with a locomotive moving at a maximum speed of 160 km/h.

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Michał Jukowski
Artur Zbiciak
Bartosz Skulski

Abstrakt

In order to investigate the progressive collapse performance of steel open-web sandwich plate structure, the sensitivity index and the importance coefficient of the bars are analyzed by the alternate path method. The condition that the model has perimeter supports with different parameters shows the result that: the redundancy index of structure increases at the structural edge, and the redundancy index will be reduced to changing degrees at the middle structure, when the stiffness of higher ribs increases. The redundancy index has little change, when the stiffness of lower ribs or shear keys increases. The sensitivity index of the shear keys dropped significantly, but the sensitivity index of the higher ribs and lower ribs increase, when the span to depth ratio increases. The sensitivity index of the higher ribs in L1 line increases significantly, when the span to depth ratio declines. So it is advisable to strengthen the higher ribs to avoid excessive sensitivity of ribs, when the span to depth ratio declines.

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Weiyi Zeng
Jie Luo
Jianchun Xiao

Abstrakt

Tensile structures in general, achieve their load-carrying capability only after the process of initial form-finding. From the mechanical point of view, this process can be considered as a problem in statics. As cable systems are close siblings of trusses (cables, however, can carry tensile forces only), in our study we refer to equilibrium equation similar to those known from the theory of the latter. In particular, the paper regards designing pre-tensioned cable systems, with a goal to make them kinematically stable and such that the weight of so designed system is lowest possible. Unlike in typical topology optimization problems, our goal is not to optimize the structural layout against a particular applied load. However, our method uses much the same pattern. First, we formulate the variational problem of form-finding and next we describe the corresponding iterative numerical procedure for determining the optimum location of nodes of the cable system mesh. We base our study on the concept of force density which is a ratio of an axial force in cable segment to its length.

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Grzegorz Michał Dzierżanowski
Izabela Wójcik-Grząba

Abstrakt

The article presents research on modelling fracture in softwood bent elements. This kind of timber is the one most exploited for construction. Authors present a brief review on the subject with emphasis on three basic attempts: Linear Elastic Fracture Mechanics (LEFM), Continuum Damage Mechanics (CDM) and Hill’s Function (HF). Proposed 3D solution bases on Hill’s Function applied in the ABAQUS FEM code. The new idea includes isolating theoretical compression and tension zones in a model. Then, it is possible to distinguish between compressive and tensile strength and predict a real behaviour of bent elements. Introducing general dependencies between material properties leads to the need of determining only longitudinal elastic modulus (EL) and modulus of rupture (MOR). It is practical because these parameters are the main reported in a scientific and technical literature. Authors describe all of the assumptions in details. The experimental tests and Digital Image Correlation method (DIC) validate the FEM model.

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Bartosz Kawecki
Jerzy Podgórski

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This article presents a method for detecting linear objects with a defined direction based on image and lidar data. It was decided to use Gabor waves for this purpose. The Gabor wavelet is a sinusoid modulated by the Gauss function. The orientation angle of the sinusoid means that the waveform can only operate in strictly defined directions. It should, therefore, provide an appropriate solution to the problem posed by the publication. The research problem focused in the first stage on determining the approximate location of only the analysed objects, and in the next step on correct and accurate detection. The first stage was carried out using Gabor filters, the second - using the Hough transform. The tests were performed for both laser data and image data. In both cases, good results were obtained for both stages: approximate location and precise detection.

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Urszula Marmol
Natalia Borowiec

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Work safety control and analysis of accidents during the construction performance are some of the most important issues of the construction management. The paper focuses on the post-accident absence as an element of the occupational safety management. The occurrence of the post-accident absence of workers can be then treated as an indicator of building performance safety. The ability to estimate its length can also facilitate works planning and scheduling in case of the accident. The paper attempts to answer the question whether it is possible and how to use decision trees and their ensembles to predict the severity of the post-accident absence and which classification algorithm is the most promising to solve the prediction problem. The paper clarifies the model of the prediction problem, introduces 5 different decision tress and different aggregation algorithms in order to build the model. Thanks to the use of aggregation methods it is possible to build classifiers that predict precisely and do not require any initial data treatment, which simplifies the prediction process significantly. To identify the most promising classifier or classifier ensemble the prediction accuracy measures of selected classification algorithms were analyzed. The data to build the model was gathered on national (Polish) construction sites and was taken from literature. Models obtained within simulations can be used to build advisory or safety management systems allowing to detect threats while construction works are being planned or carried out.

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Anna Krawczyńska-Piechna

Abstrakt

Crane selection is an important issue in assembly works planning. Tower and telescopic, stationary and mobile cranes used in construction have essentially different properties. Assembly planning begins in analyzing the possibilities of assembly with a given crane. This is called technical aspect of crane selection. Cranes that meet the technical criteria are then analyzed in terms of other criteria related to the effectiveness of their use on the construction site. The article presents the assessment of the selection criteria and the method of crane selection itself. Surveys conducted among construction managers and planners in Polish companies dealing with assembly works allowed to determine the significance of the selection criteria. For this purpose, an example using SAW (Simple Additive Weighting) and FSAW (Fuzzy Simple Additive Weighting) methods was presented. They also allowed to propose a technique for determining preferences in the use of selected construction cranes. The aim of the research was to increase the usability of computer applications supporting assembly planning by acquiring expert knowledge for the initial selection of organizational solutions.

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Roman Marcinkowski
Maciej Banach

Abstrakt

Types of wind storms in Poland and examples of economic damage, threats to human life and health caused by two extreme wind events are presented. Then, a house with the roof blown-off during the derecho wind storm in Poland on August 11-12, 2017, is considered. Based on the rafter framing of the house, i.e. wooden roof structure elements and roof covered, the weight of the roof is calculated. Two cases of the strong connection between rafter plates and knee walls are estimated. With the estimation of connection strength between rafter plates and knee walls, it was possible to calculate the total force required to blow-off the roof of the house. Next, an aerodynamic force acting on the house is calculated using pressure coefficients for a low-rise house with a gable roof. The pressure coefficients were taken from the Tokyo Polytechnic University aerodynamic database. The aerodynamic force acting on the roof blown-off was calculated for a low-rise building with a gable roof for similar ratios for length, width, and height. Three wind directions, for the unknown orientation of the building, were considered, i.e. the wind direction perpendicular, parallel, and oblique to the gable wall. By comparison, the aerodynamic force with the total force required to blow-off the roof of the house, it was possible to calculate the critical wind speed needed for the roof blown-off. This wind speed is much bigger than measured by meteorological stations on the path of the derecho.

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Tadeusz Chmielewski
Barbara Kaleta
Henryk Nowak

Abstrakt

Recently, textile reinforced concrete (TRC) has been intensively studied for strengthening reinforced concrete (RC) and masonry structures. This study is to experimentally explore the effectiveness of application of carbon TRC to strengthen RC beam in flexure and shear. Concerning the cracks formation, failure modes, ultimate strength and overall stiffness, the performance of the strengthened beams compared to the control beams were evaluated from two groups of tests. The test results confirm that the TRC layers significantly enhance both shear and flexural capacity of RC beams in cracking, yielding and ultimate loads. All of the tested specimens were also modelled using ABAQUS/CAE software, in order to validate the experimental results. The numerical results show that the simulation models have good adaptability and high accuracy.

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Cuong Huy Nguyen
Quang Dang Ngo

Abstrakt

The fracture and fragmentation of concrete under static and dynamic loads are studied. The uniaxial compressive strength test is employed to study the concrete behavior under static loads while the split Hopkinson pressure bar is used to study the dynamic behavior of the concrete under static loads. The theories for acquiring the stress, strain and strain rate of the concrete in the dynamic test by Hopkinson pressure bar has been introduced. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture and fragmentation of the specimen under dynamic loads have been acquired and the stress-strain curves of concrete under various impact loads are obtained. The stress-strain curve indicates a typical brittle material failure process which includes existing micro-fracture closure stage, linear-elastic stage, nonlinear-elastic stage, and post-failure stages. The influence of the loading rate for the compressive strength of the concrete has compared. Compared with the concrete under static loads, the dynamic loads can produce more fractures and fragments. The concrete strength is influenced by the strain rate and the strength increases almost linearly with the increase of the strain rate.

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Huaming An
Lei Liu

Abstrakt

The paper contains synthetic and analytical test results and model solutions for technical maintenance and wear problems of apartment houses traditionally structured. The crucial methodological aspect of the research is striving to minimize the subjectivity of expert assessment while technical investigation of old buildings. The cause and effect between the occurrence of damage to the elements of the rental houses, treated as an expression of the conditions for their maintenance, and the size of the technical process of wear of these elements was determined on a representative, purpose-appropriate, sample of 102 residential buildings erected in the second half of the 19th and early 20th centuries in downtown Wrocław (Poland) district. Rational maintenance of existing buildings is nowadays significant issue for their proprieties. Therefore, there is constant need to find a research method that may lead to well thought out building maintenance management. The goal of undergone research was to search influence of apartment houses maintenance on the grade and intensity of their deterioration. As to fulfil the research objective the group of engineers identified symptoms of the technical wear growth, which means performed identification of causes and effects responsible for the defects appearance. The range of the work demanded elaboration of a new qualitative model of detected defects and its transfer into a quantitative model. Therefore, such approach enabled to establish the reason - effect connection ‘defect - technical wear’ related to the crucial structural parts of investigated apartment houses.

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Jarosław Konior

Abstrakt

The paper presents analysis of the vibrational environment on scaffoldings. It is based on the results obtained in the project considering workers safety on scaffoldings. The total number of 120 façade scaffoldings was analysed over a period of two years. One of the issues considered in this project was the vibrations influence on scaffoldings and workers safety. The values of natural frequencies were obtained based on in-situ measurements of free vibrations. Analysis of the tests results made it possible to verify the elaborated numerical models. Values of natural frequencies and displacements in mode shaped from numerical modal analyses were compared with test results. Measurements of forced vibrations were also made with various sources of vibrations active at scaffoldings. The detailed numerical dynamic analysis was performed considering excitation forces variable in time. The obtained results were compared with allowable values according to the appropriate Polish standards. Most influential sources of vibrations for human comfort were indicated in the conclusions.

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Jarosław Bęc
Ewa Błazik-Borowa
Paulina Jamińska-Gadomska
Tomasz Lipecki

Abstrakt

The following work analyzes the effect of the composition of a hemp-lime composite on key mechanical and physical properties. The article contains results from testing the compressive strength, vapor permeability, and thermal conductivity of the composite, depending on the composition of the mix. The mixes differed from each other in binder composition and in the proportion of binder to hemp shives. The obtained results were compared with the results from other scientific literature. Based on this, conclusions were drawn that the binder composition is of secondary importance for the analyzed physical and mechanical properties of the hemp-lime composite. The main property that determines the values of the thermal conductivity coefficient as well as the compression strength is the density of the material, which depends on the proportion of binder to aggregate and the level of compaction of the mix. The value of the diffusion resistance coefficient of the analyzed material was very low regardless of the composition of the composite.

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Wojciech Piątkiewicz
Piotr Narloch
Barbara Pietruszka

Abstrakt

The article presents a new optimization tool supporting supply chain management in the multi-criteria aspect. This tool was implemented in the EPLOS system (European Logistics Services Portal system). The EPLOS system is an integrated IT system supporting the process of creating a supply and distribution network in supply chains. This system consists of many modules e.g. optimization module which are responsible for data processing, generating results. The main objective of the research was to develop a system to determine the parameters of the supply chain, which affect its efficiency in the process of managing the goods flow between individual links in the chain. These parameters were taken into account in the mathematical model as decision variables in order to determine them in the optimization process. The assessment of supply chain management effectiveness was carried out on the basis of the global function of the criterion consisting of partial functions of the criteria described in the mathematical model. The starting point for the study was the assumption that the effectiveness of chain management is determined by two important decision-making problems that are important for managers in the supply chain management process, i.e. the problem of assigning vehicles to tasks and the problem of locating logistics facilities in the supply chain. In order to solve the problem, an innovative approach to the genetic algorithm was proposed, which was adapted to the developed mathematical model. The correctness of the genetic algorithm has been confirmed in the process of its verification.

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Mariusz Izdebski
Ilona Jacyna-Gołda
Piotr Gołębiowski
Jaroslav Plandor

Abstrakt

The paper considers parametric optimization problems for the steel bar structures formulated as nonlinear programming ones with variable unknown cross-sectional sizes of the structural members, as well as initial prestressing forces introduced into the specified redundant members of the structure. The system of constraints covers load-bearing capacity constraints for all the design sections of the structural members subjected to all the design load combinations at ultimate limit state, as well as displacement constraints for the specified nodes of the bar system, subjected to all design load combinations at serviceability limit state. The method of the objective function gradient projection onto the active constraints surface with simultaneous correction of the constraints violations has been used to solve the parametric optimization problem. A numerical technique to determine the optimal number of the redundant members to introduce the initial prestressing forces has been offered for high-order statically indeterminate bar structures. It reduces the dimension for the design variable vector of unknown initial prestressing forces for considered optimization problems.

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Vitalina Yurchenko
Ivan Peleshko

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Inaccurate estimation in highway projects represents a major problem facing planners and estimators, especially when data and information about the projects are not available, and therefore the need to use modern technologies that addresses the problem of inaccuracy of estimation arises. The current methods and techniques used to estimate earned value indexes in Iraq are weak and inefficient. In addition, there is a need to adopt new and advanced technologies to estimate earned value indexes that are fast, accurate and flexible to use. The main objective of this research is to use an advanced method known as artificial neural networks to estimate the TSPI of highway buildings. The application of artificial neural networks as a new digital technology in the construction industrial in Republic of Iraq is absolutely necessary to ensure successful project management. One model built to predict the TCSPI of highway projects. In this current study, artificial neural network model were used to model the process of estimating earned value indexes, and several cases related to the construction of artificial neural networks have been studied, including network architecture and internal factors and the extent of their impact on the performance of artificial neural network models. Easy equation was developed to calculate that TSPI. It was found that these networks have the ability to predict the TSPI of highway projects with a very outstanding saucepan of reliability (97.00%), and the accounting coefficients (R) (95.43%).

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Autorzy i Afiliacje

Nidal A. Jasim
Shelan M. Maruf
Hadi S.M. Aljumaily
Faiq M.S. Al-Zwainy

Abstrakt

This paper presents probabilistic assessment of load-bearing capacity and reliability for different STM of beams loaded with a torsional and bending moment. Three beams having different reinforcement arrangement obtained on the basis of STM but the same overall geometry and loading pattern were analysed. Stochastic modelling of this beams were performed in order to assess probabilistic load-bearing capacity. In the analysis, the random character of input data - concrete and steel was assumed. During the randomization of variables the Monte Carlo simulation with the reduce the number of simulations the Latin Hypercube Sampling (LHS) method was applied. The use of simulation methods allows for approximation of implicit response functions for complex in description and non-linear reinforced concrete structures. On the basis of the analyses and examples presented in the paper, it has been shown that the adoption of different ST models determines the different reliability of the analysed systems and elements.

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Autorzy i Afiliacje

Lidia Buda-Ożóg
Katarzyna Sieńkowska
Izabela Skrzypczak

Abstrakt

High-pressure jet grouting pile is a kind of stratum reinforcement technology developed in recent years. Due to its characteristics of high solid strength, fast construction, low noise, safety and reliability, low cost, controllable reinforcement diameter, strong adaptability to stratum, and good reinforcement effect for soft soil, loose soil and water-rich stratum, high-pressure jet grouting pile technology has been more and more widely used in foundation treatment, water stop, and seepage prevention, tunnel lining and other fields in recent years. As a country with a relatively late development of underground construction engineering, Vietnam has little research on special geotechnical reinforcement technology, especially on special geotechnical reinforcement technology around urban underground construction engineering, especially on its theoretical analysis and practical application. Therefore, this thesis combines the Vietnam Trung Hoa tunnel project as an example, using the theoretical calculation formula and field monitoring measurement comparing the two methods, the high pressure jet grouting pile system research in Vietnam in the underground engineering reinforcement principle and application effect, get to the actual engineering design and construction has a guiding significance to the research, provides the reference for future similar projects. Finally, the application effect of high-pressure jet grouting pile in underground building reinforcement project is evaluated, which proves that high-pressure jet grouting pile has good applicability and economic benefit in underground building reinforcement project in Vietnam.

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Autorzy i Afiliacje

Xuan Loi Nguyen
Li Wu
Khanh Tung Nguyen
Quang Anh Bui

Abstrakt

Most architects and construction engineers need to use modern energy analysis software for the purpose of improving their design. There is software within the BIM (Building Information Modeling) that are specific to energy which help to get the calculations of energy in an easy way. Building energy analysis studies in Iraq are few and limited and insufficient attention is given to this important stage in building design which is one of the necessary and important stages to obtain a good design In this paper, one of the existing buildings in one of the regions of Iraq was modelled by using BIM modelling software (Autodeck Revit). The energy analysis was then carried out by the (Autodesk Ecotect) software after exporting the previously modelled model. The results obtained are necessary to achieve the best design in terms of energy with the assumption of future changes in buildings that are similar in style and area conditions in order to optimize energy.

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Autorzy i Afiliacje

Wadhah Amer Hatem

Abstrakt

The scope of the paper is to investigate analytically and determine experimentally the shear resistance of low height reinforced precast concrete lintels. The chosen procedures included in national and international standards applied for the design of structural concrete elements to an estimation of shear behaviour of reinforced concrete elements are described. The characteristic and designed shear strength of precast concrete lintels are determined and compared with experimentally obtained results. The shear resistance for precast concrete lintels was determined by laboratory tests according to a European standard. The assessment of the in-situ compressive strength of concrete in precast concrete lintel is specified. The designed compressive strength class is confirmed. The real reinforcement distribution is verified to assess the wide scatter of experimentally obtained failure forces. A short literature outlook of the papers concerning investigations on lintels and shear resistance of concrete is given also. The paper can provide scientists, engineers, and designers a theoretical and experimental basis in the field of precast concrete lintels shear resistance.

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Autorzy i Afiliacje

Andrzej Ambroziak
Jarosław Kondrat
Marek Wesołowski

Abstrakt

The aim of the paper was to assess the bending strength of steel plate - concrete composite members, based on an experimental study performed by the authors together with theoretical and numerical analyses. The values of the mechanical parameters of the materials the beams were made from were adopted on the basis of the tests results. The proposed solutions have been verified by experiment. For this purpose the results of tests performed by the authors and other researchers have been used. The former ones are original, and the way of their presentation makes them applicable by other researchers. Following the results it can be stated that with respect to bending strengths from the experimental study the results obtained from the theoretical analysis are underestimated 6,6 % on average. The results based on the numerical analysis, on the other hand, are overestimated by - 7,5 % on average. The results of the theoretical and numerical analyses indicate that the interface slip between the steel plate and concrete part affect the bending strength of steel plate-concrete composite beams only slightly (about 2% on average).

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Autorzy i Afiliacje

Dawid Kisała
Kazimierz Furtak

Abstrakt

Most scheduling methods used in the construction industry to plan repetitive projects assume that process durations are deterministic. This assumption is acceptable if actions are taken to reduce the impact of random phenomena or if the impact is low. However, construction projects at large are notorious for their susceptibility to the naturally volatile conditions of their implementation. It is unwise to ignore this fact while preparing construction schedules. Repetitive scheduling methods developed so far do respond to many constructionspecific needs, e.g. of smooth resource flow (continuity of work of construction crews) and the continuity of works. The main focus of schedule optimization is minimizing the total time to complete. This means reducing idle time, but idle time may serve as a buffer in case of disruptions. Disruptions just happen and make optimized schedules expire. As process durations are random, the project may be delayed and the crews’ workflow may be severely affected to the detriment of the project budget and profits. For this reason, the authors put forward a novel approach to scheduling repetitive processes. It aims to reduce the probability of missing the deadline and, at the same time, to reduce resource idle time. Discrete simulation is applied to evaluate feasible solutions (sequence of units) in terms of schedule robustness.

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Autorzy i Afiliacje

Piotr Jaśkowski
Sławomir Biruk
Michał Krzemiński

Abstrakt

Tension-strut systems consist of thin cables and membranes capable of carrying only tensile forces and compressed struts cooperating with them. They make very effective use of strength properties of materials. They are lightweight and common in large span structures such as bridges and stadium roofs. However, they may also be advantageous in reinforcing and repairing historical buildings as they conform to conservation law in force. This paper presents a few examples of such applications of tension-strut system. Stabilization of historic brick and stone vaults with buttresses and iron bowstrings often turns out inadequate to resist thrust forces transmitted from the vault to the walls which cause cracks and deformations of the vault. Properly designed tension-strut structure can resist the thrust forces calculated in a theoretical way. Moreover, it can be hidden in the attic of building. Old timber roof structures are usually deformed and excessively deflected. Skilfully assembled tensionstrut systems enable straightening and geometrical adjustment of a roof structure. Although similar threats and structural damages occur in most buildings which are a few hundred years old, individual design solutions are required in each case. Historical investigation and detailed measurement of geometry and deflections have to be made before choosing the apprioprate method of reinforcing the old structure.

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Autorzy i Afiliacje

Stanisław Jurczakiewicz
Stanisław Karczmarczyk

Abstrakt

An advanced evaluation technique, helpful in the fire resistance assessment of a simple steel structure exposed to fire is presented and discussed in detail on the example of an unrestrained and uniformly heated steel beam. The proposed design methodology deals with the generalised probability-based approach in which the most probable failure point is formally identified. The random nature of all variables considered in the detailed analysis is taken into account. The critical temperature of the steel from which the considered beam is made of is accepted here as the authoritative safety measure. This temperature value is associated with the fire resistance limit state defined for the maximum acceptable value of failure probability. When forecasting the failure probability, not only the risk of a potential fire being initiated but also not being effectively extinguished is included in the calculation. Various levels of the target failure probability may be assumed in such the analysis, depending on the selected reliability class. They are specified in general by setting an appropriate value of the required reliability index fire req  . In the presented design algorithm no representative values of the considered random variables are specified. The critical temperature estimates obtained from these calculations are always less restrictive in comparison with the corresponding solutions computed after applying the conventional standard procedure.

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Autorzy i Afiliacje

Mariusz Maślak

Abstrakt

The strength of recycled aggregate (RA) is low, which makes the performance of recycled aggregate concrete (RAC) poor, and the addition of fiber can make up for the shortcoming of RAC. In this paper, the mechanical properties of RAC which was added with steel fiber were studied. The specimens with RA content of 0%, 40%, 70% 100% and steel fiber content of 0%, 0.5% and 1% were prepared, and their mechanical properties were tested. The results showed that the slump reduced 73.75% after the addition of 100% RA and 37.5% after the addition of 1% steel fiber compared to R0S0; from the perspective of mechanical properties, the larger the content of steel fiber, the better the mechanical properties of the specimen; the improvement of the tensile strength was the most obvious after the addition of steel fiber. The experimental results show that steel fiber can improve the performance of RAC and make it perform better in practical application.

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Autorzy i Afiliacje

Qing Su

Abstrakt

This paper presents the results of Finite Element Method (FEM) modeling of double-twisted steel hexagonal wire mesh used to construct gabion cages. Gabion cages, filled with soil (usually rock particles) are commonly used in civil engineering (for example in order to form a retaining wall). Static tensile tests are modeled and the obtained force - displacements curves are compared with the laboratory test results (known from literature). Good accordance between numerical and laboratory test results is observed. Three different material models for single wire and double twist are tested. Special attention is paid to double-twist modelling. Simulations of the damaged mesh are also performed, strength and stiffness reduction is analyzed. Anisotropic membrane model for mesh is proposed and calibrated. Parameters for homogenized Coulomb - Mohr media for gabion (filling and mesh) are estimated. Such homogenized Coulomb - Mohr model could be used in engineering practice to model behaviour of real gabion structures.

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Autorzy i Afiliacje

Michał Grodecki

Redakcja

Editor-in-Chief
Henryk Zobel


Scientific Advisory Committee
:
Andrzej M. Brandt
Werner Brilon (Germany)
Jacek Chróścielewski
Luc Courard (Belgium)
Andrzej Garbacz
Andrzej Garstecki
Wojciech Gilewski
Marian Giżejowski
Oleg Kapliński
Piotr Konderla
Aleksander Kozłowski
Marian Kwietniewski
Zbigniew Młynarek
Andrzej S. Nowak (USA)
Anna Siemińska-Lewandowska
Jan Szwabowski
Waldemar Świdziński
Andrew P. Tarko (USA)
Marian Tracz
Edmundas K. Zavadskas (Lithuania)
Jerzy Ziółko

Secretary
Dorota Walesiak

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Archives of Civil Engineering jest czasopismem wydawanym w wolnym dostępie na licencji CC BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

Archives of Civil Engineering is an open access journal with all content available with no charge in full text version. The journal content is available under the licencse CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/.

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