Archives of Civil Engineering

Cracks in concrete are inevitable but fortunately cracking enables the structures to get rid of its bending moment peaks. The reduction is due to the redistribution of the load induced moments and cut of the temperatureimposed moments. However, cracking becomes completely harmless if the crack widths are controlled properly by reinforcement. In this regard a method for crack width prediction is presented in this paper which thanks its reliability is widely accepted in the standards EN 13084, CICIND and DIN 1056.

This paper presents the results of a dynamic response evaluation of a segmental bridge during two construction stages: before connecting the final segment of the bridge and after connecting the final segment of the bridge but prior to opening the bridge to traffic. The vibration signals obtained from Ambient Vibration Testing (AVT) campaigns were processed in order to obtain the modal parameters of the bridge during the two construction stages. Modal parameters experimentally obtained for the first stage were compared with those obtained from Finite Element (FE) models considering different construction loads scenarios. Finally, modal parameters experimentally obtained for the second stage were used to update its corresponding FE model considering two scenarios, before and after the installation of the asphalt pavement. The results presented in this paper demonstrated that a rigorous construction control is needed in order to effectively calibrate FE models during the construction process of segmental bridges.

In this research, nonlinear analysis of composite shear walls (CSWs) with a gap between reinforced concrete wall and steel frame is investigated under cyclic loading by the use of the finite element method (FEM) software ABAQUS. For the purpose of the verification, an experimental test is modelled and comparison of its obtained result with that of the experimental test demonstrates an inconsiderable difference between them; therefore, the reasonable accuracy of the modelling is revealed. Then, effects of different parameters on the behaviour of the CSWs are examined. Gap size between reinforced concrete wall and steel frame, reinforcement percentage, steel sections of beams and columns, and existence of reinforced concrete wall are considered as parameters. It is concluded that change of the parameters affects the ultimate strength, ductility, and energy dissipation of the system. A steel shear wall (SSW) is also modelled and compared with the CSWs. Buckling of the walls is presented as well.

The article discusses the technical condition of buildings. An attempt was made to compare the technical condition and the degree of technical wear of two multi-family residential buildings erected at the interval of 25 years. The list of such objects is intended to illustrate that even relatively young buildings may exhibit differing levels of wear and technical condition of building elements.

Reliable evaluation of stress-strain characteristics can be done only in the laboratory where boundary conditions with respect to stress and strain can be controlled. The most popular laboratory equipment is a triaxial apparatus. Unfortunately, standard version of triaxial apparatus can reliable measure strain not smaller than 0.1 %. Such accuracy does not allow to determine stiffness referred to strain range most often mobilized in situ i.e. 10-3 ÷ 10-1%, in which stiffness distribution is highly nonlinear. In order to overcome this problem fundamental modifications of standard triaxial apparatus should be done. The first one concerns construction of the cell. The second refers to method of measurement of vertical and horizontal deformation of a specimen. The paper compares three versions of triaxial equipment i.e. standard cell, the modified one and the cell with system of internal measurement of deformation. The comparison was made with respect to capability of stiffness measurement in strain range relevant for typical geotechnical applications. Examples of some test results are given, which are to illustrate an universal potential of the laboratory triaxial apparatus with proximity transducers capable to trace stress-strain response of soil in a reliable way.

Cost estimation in the pre-design phase both for the contractor as well as the investor is an important aspect from the point of view of budget planning for a construction project. Constantly growing commercial market, especially the one of public utility constructions, makes the contractor, at the stage of development the design concept, initially estimate the cost of the facade, e.g. office buildings, commercial buildings, etc., which are most often implemented in the form of aluminum-glass facades or ventilated elevations. The valuation of facade systems is of an individual calculation nature, which makes the process complicated, time-consuming, and requiring a high cost estimation work. The authors suggest using a model for estimating the cost of facade systems with the use of statistical methods based on multiple and stepwise regression. The data base used to form statistical models is the result of quantitative-qualitative research of the design and cost documentation of completed public facilities. Basing on the obtained information, the factors that shape the costs of construction façade systems were identified; which then constitute the input variables to the suggested cost estimation models.

This study presents an artificial intelligence technique based on ensemble of artificial neural networks for the purposes of analysis and prediction of labour productivity. The study focuses on the development of model that combines several artificial neural networks on the basis of real-life data collected on a construction site for steel reinforcement works. The data includes conditions, characteristics, features of steel reinforcement works and related efficiencies of workers assigned to particular tasks recorded on site. The proposed ensemble based model combines five supervised learning models — five different multilayer perceptron networks, which contribution in the prediction is weighted due to the application of generalised averaging approach. Testing results show that the proposed ensemble based model achieves the satisfactory evaluation criteria for coefficient of correlation (0.989), root-mean-squared error (2.548), mean absolute percentage error (4.65%) and maximum absolute percentage error (8.98%).

The article concerns modern, flexible adhesive joints, which might be used in timber construction. The article discusses the test results carried out for timber elements joints using polymeric adhesives produced by Sika®. The scope of the tests includes the analysis of strength criteria, tests of polymer adhesion to the timber with a pull-off method, tests of polymer layer shearing between timber elements as well as examination of bending of timber elements joined with polymer. The conclusions indicate the types of these polymers which are recommended for the creation of polymeric joints of timber-polymeric type in timber constructions.

Paper presents the issue related to the selection of slab formwork taking into account the criteria that are currently the most important The in the process of the construction project execution. The analysis included selected, modern system solutions, which significantly accelerate the tempo of reinforced concrete works and, as a consequence, increase the effectiveness of the construction project execution. The innovative system of drop heads, which the analysed slab formwork is equipped with, is offered by various formwork producers. The offered solutions, however, differ not only in the construction of the drophead itself, but also in the arrangement and variety of other system elements, as well as the scheme of their operation, which may ultimately significantly affect the effectiveness of their application. For that reason, the choice of formwork for specific buildings should be made from among carefully analysed several variants of the wide market offer. The paper presents the results of analysis and evaluation of formwork systems with dropheads according to the proposed methodology, including multi-criteria analysis.

The general standards and guidelines recommendations for PCC suggest alternating conditions of curing: starting with wet conditions for effective hydration of Portland cement followed by air-dry conditions for polymer hardening. The often accepted curing regime of PCC covers 5 days of wet curing and then the air-dry curing but it is not the optimum one. The aim of the investigation was to find the best scenario for PCC with two types of polymer modifiers: two-component epoxy resin and water dispersion of polyacrylates. The following exploitation properties were accepted as the criteria of evaluation of PCC curing effectiveness: compressive strength, tensile splitting strength, surface tensile strength (by pull-off method), wear resistance, water penetration under pressure and resistance to carbonation. The optimum time of PCC wet curing is possibly between 7 and 14 days, however, it have to be verified experimentally for specific PCC composition.

The paper presents the problem of building disturbances, which are usually an inseparable element during the implementation of construction projects. They were classified, their causes and sides of the construction process responsible for their creation were identified on the basis of the analyzed construction investment. In addition, using the Earned Value Management method, the scale of delays arising in construction works and the related effects were determined. The important role of close cooperation and good communication between all participants of the construction process was emphasized, which would reduce the phenomenon of building disturbances, but also mitigate the negative effects of delays that have already occurred.

The article discusses results of pull-off adhesion strength tests on poly-p- phenylene benzobisoxazole (PBO) mesh bonded to fir timber beams using epoxy resin. The tests were performed in accordance with the PN-EN 1542 standard. Timber elements reinforced with PBO fibres were subjected to pull-off tests to measure the adhesive strength of the mesh to the beams.The factors occurring during the test were also characterized, which may affect its results such as the method of application of the tearing force, selection of epoxy glue, surface preparation of the tested elements, occurrence of material defects in the wood and types of substrate destruction.The experimental data show that failure of the timber layer was not observed in all the specimens tested.

The article presents a new approach to testing the strength of asphalt interlayer bonding. Two loading methods were used: static load and cyclic load. Before carrying out static shear strength tests, the interlayer bonding was subjected to cyclic loads with a constant number of cycles but with different frequencies. A number of layered samples with and without geosynthetic interlayers were tested at the set temperature. The comparative analyses allowed to determine the functions approximating the impact of the cyclic load frequency on the static strength of bonding at selected interlayer contact conditions. It was also possible to indicate the frequency of cyclic load at which this parameter has the largest and smallest impact on the static strength of the asphalt interlayer bonding.

Recently, new materials have been developed in the field of bridge design, one of which is FRP composite. To investigate this topic, the Polish National Centre for Research and Development has founded a research project, whose objectives are to develop, manufacture and test a typical FRP bridge superstructures. Two innovative ideas of FRP composite girder-deck structural systems for small and medium span bridges have been proposed. This paper describes the demonstrative bridges and presents the research results on their development and deployment. The finite element analysis and design procedure, structural evaluation in the laboratory and some results of the proof tests carried out on both bridge systems have been briefly presented.

Throughout the world, considerable quantities of water treatment sludge (WTS) and sewage sludge (SS) are produced as waste. This study assessed in the laboratory, the possibility to use both waste products when they are incorporated as filler at 1% with relation to the total mass of a hot mix asphalt - HMA. To this end, both waste products were initially reduced to ash through a calcination process. Resistance tests under monotonic load (Marshall and indirect tension tests), and cyclic load (resilient modulus test) were applied on mixes that contained WTS and SS. Besides, moisture damage (modified Lotmman test), and abrasion (Cantabro) resistance were assessed. An analysis of variance (ANOVA) test was performed in order to verify if the results are statically equal or not to those of the control HMA. As a general conclusion, it is reported that both materials show a resistance increase under monotonic load and higher stiffness under cyclic load (cohesion) when they are incorporated into the mix as filler despite the fact that the asphalt content used was less than the control mix. However, some problems are observed associated with moisture damage resistance, and friction wear (adherence).

The present paper discusses static and dynamic characteristics of various under sleeper pads (USP) that are to be used in the ballasted track systems as resilient vibroacoustic isolators. Four different USP samples were put to fatigue tests and static and dynamic bedding moduli were determined. The purpose of the tests, which were carried out up to 500 thousand load cycles, was to determine which USP have favourable and which unfavourable properties, taking into account their potential application as the elements used for energy dissipation and reduction of noise and vibration. The obtained results allowed the authors to indicate samples with a potential for further analysis and to reject those, which did not satisfy the adopted criteria.

An analysis of the dynamic load - carrying capacity of rectangular reinforced concrete deep beam considering the physical nonlinearities of structural materials: concrete and reinforcing steel, is the aim of the paper. The model of the elastic/visco-perfectly plastic material including dynamic yield criterion was applied for the reinforcing steel. The non-standard model of dynamic deformation, regarding the dynamic strength criterion and material softening was applied for the concrete. The method for description of deformation parameters of high strength concrete was included in the model. The method of structure effort analysis was developed using the finite element method. The comparative analyses of the obtained results for three different values of high strengths of concrete and one value of high yield stress for reinforcing steel were carried out in relation to the numerical results obtained for ordinary concrete and steel in case of dynamic loading. In these cases, the significant differences in behavior of reinforced concrete deep beams have been observed and described in detail. The effectiveness of the method analysis and computational algorithms for the problems of numerical simulation of reinforced concrete deep beam dynamic behavior was indicated in the paper.

The article discusses the dangers arising from construction disasters. This phenomenon is the most serious effect of the risk that may occur in construction. I presented this on the basis of an analysis of all construction disasters that have taken place in Poland in the last twenty years. I made a detailed analysis of the events that occurred during the maintenance of building facilities, taking into account the reasons for their occurrence and the effects they cause. The aim of this analysis is to identify areas of risk in order to eliminate the hazard and, as a consequence, take appropriate actions to counteract this type of events. Unfortunately, one should be aware that despite technical progress building disasters cannot be completely avoided in our surrounding, but one must use the knowledge acquired on this basis to minimize their number.

This paper presents a suggested approach for forensic investigation of bridge decks in which Ground penetrating radar (GPR) consisting of two antennas is used to assess the current conditions. The methodology was tested on a bridge deck in central Sicily. The acquired data were analyzed for identifying the asphalt overlay thickness, concrete cover depth and deck thickness and location of the rebar reinforcement. In the proposed approach for assessing bridge deck conditions the GPR survey was complemented with (i) a site investigation on layer thicknesses for calibration/verification purposes of the GPR response and (ii) a Terrestrial Laser Scanning system (TLS) to verify the bridge design slab curvature. The study shows that this methodology has significant merits on accurately assessing such bridge deck components when bridge design records are non-existing, and by using non-invasive methods such as laser scanning and GPR. The great advantage provided by the TLS technique is the possibility to obtain a 3D output model of the scanned element with the accuracy of the best topographic instruments in order to complement GPR data surveys for bridge inspection.

The problem of determining displacements of objects is an important and current issue, in particular in terms of operational safety. This is a requirement that covers geodetic, periodic control measurements in order to determine horizontal and vertical displacements. The paper is focused on the analysis of vertical displacements. Geodetic measurements and their interpretation allow to reduce the risk of possible structural catastrophes. The major research topic of the majority of available papers is displacement determination of individual controlled points, in a situation where there are identified as fixed reference points. There are cases making identification of such points difficult or impossible to use in displacement analysis. This paper addresses a rare case of determining vertical displacements in unstable reference systems. Due to the fact that most of the existing and known literature methods do not always bring satisfactory results, the paper propose a new method of vertical displacement determination in the absence of reference points in the local coordinate system. Practical considerations on simulated data show that the presented method performs the task correctly.

Fatigue properties of orthotropic steel bridge deck of Xinghai Bay Cross-sea Bridge in Dalian were analyzed. The segment model of orthotropic bridge deck was established by using the finite element software Abaqus. The intersection between diaphragm and U-rib was selected to analysis. The fatigue loading model III was adopted which was provided by “Specifications for Design of Highway Steel Bridge”. First, the transverse stress influence line and the transverse severest loading position were determined. Then, five loading regions were selected near the transverse severest position. The stress amplitude of the intersection was ascertained through loading on the longitudinal bridge for each region. Finally, the fatigue checking for the intersection was carried out. The results showed that the maximum fatigue stress amplitude of orthotropic deck in Xinghai Bay Cross-sea Bridge met the requirements of "Specifications for Design of Highway Steel Bridge".