Steel Mesh-Reinforced Cementitious Composites (SMRCC) (traditionally known as ferrocement) have been in existence for few decades, but have some limitations set on element thickness and number of reinforcing mesh layers and the resulting deflection ductility. Therefore, the author has made an attempt to explore whether deflection ductility will improve in mesh-reinforced cementitious composites (25 mm thick) if discontinuous fibres are added to slab elements. For this purpose, thin slab elements of dimensions 700 mm (length) × 200 mm (width) × 25 mm (thickness) were cast and subjected to four point bending tests. Based on the flexural tests conducted on SMRCC (Control Slab Elements, cast with Steel Mesh Volume of reinforcement, MVr = 0.78, 0.94, and 1.23%) and Hybrid Mesh-and-Fibre-Reinforced Cement Based Composite (HMFRCBC) (Test Slab Elements, combining MVr = 0.78, 0.94 and 1.23% and Polyolefin Fibre Volume fraction, PO-FVf = 0.5‒2.5% of volume of specimens, with 0.5% interval), load-deflection and the deflection ductility index were analyzed. From the flexural load-deflection curves it has been observed that HMFRCBC slabs demonstrate higher flexural load-carrying capacity and deflection ductility when compared to SMRCC slabs. This study shows that higher the polyolefin fibre volume fraction (PO-FVf) from 0.5 to 2.5% (with a 0.5% interval) in HMFRCBC slabs, the higher the flexural deflection ductility. The Deflection Ductility Index (DDI) of HMFRCBC (with 5 layers of mesh and PO-FVf = 2.5%) is 4.5 times that of SMRCC. This study recommends that HMFRCBC can be used as an innovative construction material due to its higher flexural ductility characteristics.

The steel pipe umbrella is a widely used technology when tunnelling in weak soils in order to create pre-support ahead of the tunnel face. The design of steel pipes is frequently done through simplified analytical approaches which are easy to apply but require proper assessment of the loads acting on the pipe. To provide information on this key design aspect, the results of the comparison between a three-dimensional numerical model developed with the code FLAC 3D and an analytical model based on the approach of a beam on yielding supports is presented and discussed. The comparison refers to a shallow tunnel with an overburden of three times its diameter for two different types of weak rock masses. The obtained results provide suggestions about the load that has to be applied in the analytical model for the design phase.

The paper describes experimental research of slab-column connections examined on specimendesigned as a part of reinforced concrete structure with flat slabs. The aim of the research wasto verify the efficiency of slab reinforcement concept against punching shear by increasing slab’smechanical reinforcement ratio by applying additional external reinforcement in the form of carbonfiber reinforced polymer (CFRP) strips.

The capacity enhancement in comparison to unstrengthened slab obtained 36%.

The church of Santa Ana in Moratalaz, Madrid, Spain (1965-1971), is an emblematic work of the architect Miguel Fisac. In his long career include interventions in the religious field, constituting one of the most important contributions to Spanish religious architecture of the last century. This church is a singular place of worship and architecturally significant, in which the acoustics played an important role in the configuration of the spatiality of the church. This paper studies the acoustic behaviour of the church and its relationship with its unique structural, spatial and coating material characteristics. The analysis of the current acoustic conditions, with high reverberation times (up to 6 seconds) and poor intelligibility on the audience, serve as the basis for making an acoustic rehabilitation proposal that contributes to improving the sound conditions of the building for the intended use, without distorting the spatial, formal and material aspects with which the architect conceived the project.

Refinement is one of the most energy consuming technological process, aimed at obtaining mineral raw materials of the proper grain size.

Cast structural elements such as jaws or hammers in crushing machines operate under conditions of an intensive wear. The data indicate

that 80 % of failures of machines and devices is caused by wearing of rubbing surfaces. This problem became the subject of several

scientific and industrial investigations carried out in the whole world in order to produce materials ultra- wear resistant. Methods allowing

to obtain wear resistant composite castings are discussed in the hereby paper. Within the performed research microstructures of the

produced composite zones were presented and the comparative analysis with regard to mechanical and functional properties of local

composite reinforcements in relation to the commercial alloys of increased wear resistance was performed. The results show almost twenty

five times increase in wear resistance compared to manganese cast steel containing 18 % Mn.

Compared with the robots, humans can learn to perform various contact tasks in unstructured environments by modulating arm impedance characteristics. In this article, we consider endowing this compliant ability to the industrial robots to effectively learn to perform repetitive force-sensitive tasks. Current learning impedance control methods usually suffer from inefficiency. This paper establishes an efficient variable impedance control method. To improve the learning efficiency, we employ the probabilistic Gaussian process model as the transition dynamics of the system for internal simulation, permitting long-term inference and planning in a Bayesian manner. Then, the optimal impedance regulation strategy is searched using a model-based reinforcement learning algorithm. The effectiveness and efficiency of the proposed method are verified through force control tasks using a 6-DoFs Reinovo industrial manipulator.

“Polyurea coatings as a possible structural reinforcement system” is a research project aimed at exploring possible applications of polyurea coatings for improving structural performance (including steel, concrete, wooden and other structures used in the construction industry). As part of the project, this paper focuses on evaluating the performance of bent reinforced concrete (RC) beams covered with a polyurea coating system. Easy polyurea application and its numerous advantages can prove very useful when existing RC structural elements are repaired or retrofitted. Laboratory tests of three types of RC beams with three different longitudinal reinforcement ratios were performed for the purposes of this paper. The tests were designed to determine the bending strength, performance and cracking patterns of the coated RC beams. In addition, a theoretical model was developed to predict the impact of the polyurea coating on the bending strength of the RC beams. On this basis, the effect of the coating on the bending strength and the performance of the coated beams at the ultimate limit state (ULS) was examined and analyzed. The results showed that the use of the polyurea coating has a positive impact on the cracking state of the RC beams subject to bending and little effect on their bending strength.

In the paper the problem of strengthening of flat slabs against punching shear was discussed. Selected methods verified on the basis of experimental tests such as increasing size of the support, applying post-installed shear reinforcement or increasing the main reinforcement by installing additional steel flat bars, were presented. The previous studies demonstrated, that the last method allows for an increase in punching shear resistance of up to 90%, depending on the longitudinal reinforcement ratio. The example of the application of such strengthening technique in the real structure was described. The use of steel flat bars located in the vicinity of the columns and additionally anchored to the slab made possible to compensate for the load capacity deficiencies that occurred due to execution errors (lowering of the main reinforcement within the support zones).

The primary aim of this research study was to model acoustic conditions of the Courtyard of the Gdańsk University of Technology Main Building, and then to design a sound reinforcement system for this interior. First, results of measurements of the parameters of the acoustic field are presented. Then, the comparison between measured and predicted values using the ODEON program is shown. Collected data indicate a long reverberation time which results in poor speech intelligibility. Then, a thorough analysis is perform to improve the acoustic properties of the model of the interior investigated. On the basis of the improved acoustic model two options of a sound reinforcement system for this interior are proposed, and then analyzed. After applying sound absorbing material it was noted that the predicted speech intelligibility increased from bad/poor rating to good category.

In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by

means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of

the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive

infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy,

using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of

composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese

cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ballon-disc

wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in

the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base

alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the

composite zone was five times lower than chromium white cast iron containing 20 % Cr.

In this work, a novel approach to designing an on-line tracking controller for a nonholonomic wheeled mobile robot (WMR) is presented. The controller consists of nonlinear neural feedback compensator, PD control law and supervisory element, which assure stability of the system. Neural network for feedback compensation is learned through approximate dynamic programming (ADP). To obtain stability in the learning phase and robustness in face of disturbances, an additional control signal derived from Lyapunov stability theorem based on the variable structure systems theory is provided. Verification of the proposed control algorithm was realized on a wheeled mobile robot Pioneer–2DX, and confirmed the assumed behavior of the control system.

The aim of the paper is to investigate the shear failure mechanisms in T-shape, single span and simply supported beams exclusively reinforced with longitudinal glass fiber reinforced polymer (GFRP) bars. Usually the critical shear crack in RC beams without stirrups develops through the theoretical compression strut reducing the shear strength following the shear failure. The main parameter affecting the crack pattern and the shear strength of the beams is the shear slenderness. However, the test results presented in the paper indicated the new arching effect due to the bond losing between the GFRP flexural reinforcement and concrete. This failure mode revealed unexpected critical crack pattern and failure mode. The research of concrete beams flexurally reinforced with GFRP bars without stirrups indicated two failure modes: typical shear-compression and a new one leading by the bond losing between the ordinary reinforcement and concrete.

This paper describes the analyses of the fatigue life of the asphalt pavement reinforced with geogrid interlayer under traffic loading. Finite Element ANSYS package with using nCode applications, as well as macros specially designed in APDL programming script and VBA were used to model the considered problem. Our analysis included computation of stress, fatigue life, damage matrix and rainflow matrix. The method applied was the one of fatigue calculation: stress – number of cycles in short S-N. On the basis of the performed high cycle fatigue analysis, the influence of the location of the used geogrid and of its bond with asphalt layers on the fatigue life and the work of the asphalt pavement structure were determined. The study was carried out for three temperature seasons i.e. spring and fall (assumed as one season), winter and summer. The variability of the traffic conditions were taken into account by assuming weekly blocks of traffic loading. The calculations were made using the real values of loading measured in field tests on the German highways by means of HS-WIM weighing system. As a result of the performed tests, it was proved that the use of geogrid-reinforcement may prolong the fatigue life of the asphalt pavement. However, it is required that: the geogrid should be located in the tension zone as low as possible in the structure of the asphalt layers. Moreover, it is necessary to provide high stiffness of the bond between the geogrid and the asphalt layers.

The design of suitable thermophysical properties of reinforced ice as well as employing the novel material in feasible ways represent key aspects towards alternative building sustainability. In this overview research studies dealing with reinforced ice structures have been presented with an emphasis on construction parameters and reinforcement materials of the structures. The main focus of the study is directed to the identification of the main issues related to the construction of reinforced ice structures as well as the environmental and economic impact of such structures. Obtained research data shows that the compressive, tensile, and bending strength of reinforced ice can be increased up to 6 times compared to plain ice. The application of reinforcement materials decreases creep rate, enhances ductility, and reduces brittle behaviour of ice. Assessed reinforced ice structures were mainly found to be environmentally friendly and economically viable. However, in most of the analysed studies construction parameters and physical properties were not defined precisely. The conducted overview indicates the necessity for more comprehensive and more accurate data regarding reinforced ice construction, applied methods, and processes, and preparation of ice composites in general.

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.

Development of the transport infrastructure in Poland has contributed to the implementation of various technologies of construction of bridges and their components. Use of reinforced soil for construction of embankments, retaining structures (RSS walls) and abutments is one of the solutions which has been frequently used for the past twenty years. Shortly after its development, the technology proposed by Henri Vidal in 1966 also gained appreciation in Poland [4]. Reinforced soil bridge abutments started to be widely used in Poland at the turn of the 20th century. The bridge facilities at the junction of Trasa Siekierkowska route and Wał Miedzeszyński Street in Warsaw, which were built in the years 2000÷2002, are an example of structures from that period. The authors of this paper have been particularly interested in the outermost supports of the reinforced concrete flyovers which were constructed in the form of intermediate reinforced soil abutments. Offsets – the vertical displacements, in the range of 15÷25mm, emerging between the level of the road surface and the steel elements of the expansion joints which separate the flyover’s structure from the embankment – were observed in 2015, in the course of regular inspections. While accounting for the observations which have been made, the surveying measurements and the ground investigation, the paper diagnoses and describes the mechanism which led to the emergence of the offsets. Potential patterns of the occurrence of additional settlements, as the reason for emergence of the offsets, were identified and analyzed. The settlement of the outermost support (abutment), as a result of increase of relative density of alluvial sands due to the dynamic interaction of the roadways of Wał Miedzeszyński Street, was analyzed. Analytical and numeric approaches were used in the course of analysis while relying on PLAXIS and MIDAS software.

In the present paper tensile stresses perpendicular to the grain in reinforced double-tapered beams made of glued laminated timber are discussed. The beams are analysed using the finite element method within the linear elasticity theory with the influence of orthotropic material properties. The main objective is to assess the influence of transverse reinforcement on the values and distributions of the analysed stresses and to identify the most efficient scheme of reinforcement. The obtained results prove that, with the use of the proposed tools, it is possible to assess the level of stress, including delaminating stress, and to indicate the areas of occurrence of such stress with high precision.

Traditional methods of restoring historical buildings typically consisted in replacing the damaged elements or additional steel and reinforced concrete elements were inserted into the old structure. They significantly interfered with the statics and aesthetics of buildings. Current composite materials used in restoration damage the old structure only slightly and can usually be removed in the future. Due to these advantages they comply with the conservation lawin force. This paper presents a few examples of practical applications of composites the authors have designed for structural reinforcement and protection of historical buildings. Repairs of columns, vaults, masonry walls, stone facades and wooden beams with the use of steel screw-shaped bars and high strength fibres in epoxy resin or cement matrix were presented. Problems of ensuring the proper bond of the composite to the old substrate and insufficient coverage of the fibers with the cement matrix were considered. Although the threats and structural damages which occur in most historical buildings tend to be similar, individual design solutions are required in each case. Historical investigation and detailed measurement of geometry and deflections have to be made before choosing the appropriate method of reinforcing the old structure. It can be predicted that prestressing composite materials used for historical structures will also be applied.

Prediction of propagation time of corrosion is a key element in evaluating the service life of corroded reinforced concrete (RC) structures. Corroded steel products often expand in volume and thus generate tensile stress in the concrete cover. When this tensile stress exceeds the tensile strength of the concrete, cracking occurs. The tensile stresses in concrete due to corrosion are usually perpendicular to the longitudinal axis of the reinforcement. In the reinforced concrete beams, tensile stresses in concrete due to bending is perpendicular to the longitudinal direction of stirrups. In the reinforced concrete slabs, the tensile stresses in concrete due to bending is also perpendicular to the axis of longitudinal reinforcement subjected to bending in the other direction. In such cases, the tensile stresses in concrete due to corrosion of reinforcement has the same direction as the tensile stress caused by bending. When the load-induced stress in the concrete has the same direction as that of the corrosion-induced stress, cracks will likely appear more quickly and vice versa. The main objective of this paper is to build a predictive model of corrosion propagation time taking into account: (1) the effect of stresses due to load; (2) the change of corrosion current density. The model was implemented on Matlab software. The results show the influence of the load, and other parameters on the corrosion propagation stage, when considering the end of this corrosion propagation stage is cracking of concrete cover.

Optimization of industrial processes such as manufacturing or processing of specific materials is a point of interest for many researchers, and its application can lead not only to speeding up the processes in question, but also to reducing the energy cost incurred during them. This article presents a novel approach to optimizing the spindle motion of a computer numeric control (CNC) machine. The proposed solution is to use deep learning with reinforcement to map the performance of the Reference Points Realization Optimization (RPRO) algorithm used in industry. A detailed study was conducted to see how well the proposed method performs the targeted task. In addition, the influence of a number of different factors and hyperparameters of the learning process on the performance of the trained agent was investigated. The proposed solution achieved very good results, not only satisfactorily replicating the performance of the benchmark algorithm, but also, speeding up the machining process and providing significantly higher accuracy.

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.

In recent years, carbon fibres have been extensively used to strengthen concrete structures. In most cases, the lamination process is carried out using epoxy resin as matrix. In some cases, especially when strengthen structural elements made of weak concrete, it is possible to replace the epoxy resin with an inorganic, cement matrix, while at the same time maintaining a sufficient efficiency of strengthen understood as the percentage increase in the compressive strength of concrete samples due to the applied reinforcement in relation to the reference concrete. In these studies, elements of carbon fibres mats that are reinforced with a cement matrix were used as the starting product for fibre recovery. The laminate, which was used to reinforce concrete elements, was detached from the concrete surface and subjected to processing in order to obtain clean carbon fibre scraps without cement matrix. Then, the obtained carbon material, in shaped form, was used to strengthen self-compacting, high performance, fibre reinforced concrete (SCHPFRC). For comparative purposes, this concrete was also strengthened by carbon fibre mats (with one and three layers of CFRP). Each samples were tested in uniaxial compression test. The compressive strength of concrete reinforced with 1 and 3 layers of CFRP was higher by 37.9 and 96.3%, respectively, compared to the reference concrete. On the other hand, the compressive strength of concrete reinforced with 1 and 3 layers of carbon fibre scrapswas higher by 11.8 and 40.1%, respectively. Regardless of the reinforcement technique used, the composite elements showed a higher deformability limit in comparison plain concrete. The obtained results showed that it is possible to reuse carbon fibre to strengthen structural elements made of SCHPFRC effectively, using simple processing methods.

New approach using direct crack width calculations of the minimum reinforcement in tensile RC elements is presented. Verification involves checking whether the provided reinforcement ensures that the crack width that may result from the thermal-shrinkage effects does not exceed the limit value. The Eurocode provisions were enriched with addendums derived from the German national annex. Three levels of accuracy of the analysis were defined - the higher the level applied, the more significant reduction in the amount of reinforcement required can be achieved. A methodology of determining the minimum reinforcement for crack width control on the example of a RC retaining wall is presented. In the analysis the influence of residual and restraint stresses caused by hydration heat release and shrinkage was considered.

RC flat slabs are one of the most popular and effective methods of shaping plates in buildings. Although failures of entire structures are relatively rare, they cannot be excluded from the occupancy cycle of the facility. The research analysis presented in this paper is an attempt to understand more precisely the phenomena that occur in the RC flat slab system and to assess the influence of the additional protection of the flat slabs against progressive collapse in the case of failure of one of the supports. The results were obtained from destructive experimental investigations of a flat reinforced concrete slab made in scale 1:3. The collapse in the analysed model was simulated by removing three edge columns and additional loading by means of hydraulic actuator. In place of the columns removed, differential tie reinforcement was applied. The results obtained confirm that the structure achieved a much higher ultimate load than the one resulting from the design calculations.