Search

This study introduces a method based on fine torque control to evaluate traction in rolling—liding line contacts under small slide-to-roll ratios (SRRs). To accomplish this, we engineered an innovative testing machine—a two-roller tribometer capable of precisely applying resisting torques to one of the rollers. Two types of tests were designed and conducted to validate our method and showcase the capabilities of the novel test setup. The first type, named the "Traction Decay Test", proved to be effective in evaluating changes in the SRR over time. The second, named the "Torque-Mode Traction Test", demonstrated its effectiveness in achieving ultra-low SRRs, in the order of 0.01%. As a result, traction curves with high resolution in the low SRR domain were constructed. This advancement provides the means for gaining a deeper understanding of traction coefficients, wear behavior, and tribological performance at ultra-low SRRs across diverse applications. [ABSTRACT FROM AUTHOR]

Steel structures, such as bridges, must be continuously maintained. Due to increasing traffic loads, design and execution shortcomings, many steel bridges are subject to various types of damage, such as cracks. The bridges must be maintained by crack removal and re‐welding the cracks. During this work, the bridge is closed for traffic in order to suppress the crack flank movement during welding. As a result, traffic loads on other routes are higher, which increases further damage on detour routes and subsequently additional welding work and costs on these structures. Therefore, the aim is to provide a method that allows welding work on steel structures under running traffic, respectively under cyclic loads. First, measurements at a representative steel bridge were conducted to derive gap opening parameters of amplitude and frequency for welding tests under cyclic loads. Monitoring cracks shows that the crack behavior is complex and the description of the force redistribution during welding is a challenge. In order to quantify the influence of different boundary conditions during welding on weld quality and fatigue, experimental investigations were carried out under displacement control only and force control only. For both, the weld quality and the fatigue strength was comparable to the standard requirements, so that welding under service conditions is possible under certain aspects. [ABSTRACT FROM AUTHOR]

Featured Application: Providing cyclic shear tests for full-scale walls. The SHS-Multirisk Project proposes a residence model that is simultaneously resistant to earthquakes and hurricanes within a specific range of magnitude to be defined in the project. It uses simple, low-cost, and environmentally friendly construction technologies compared with traditional alternatives or more technological, but less accessible ones. To reach the SHS-Multirisk objectives, an experimental campaign to carry on cyclic shear tests involved a set of 15 reinforced soil-cement compressed earth block walls. Within this program, a particular test system was developed, conditioned by the guidelines: simplicity, availability of resources (especially components, equipment, and workmanship), rationalization of the available space, and scalability of the tests. Considering the short time available for designing and manufacturing the test system and for carrying out the shear tests, it was decided to adopt a project management framework in Scrum mode. This article presents the system developed to conduct full-scale cyclic shear (combined with bending) tests on walls, exploring its characteristics, the development process, the experiment execution process, and a basic analysis of the main test outputs. [ABSTRACT FROM AUTHOR]

This paper investigates the potential of bidirectional charging using modular multilevel inverter-based reconfigurable battery systems via grid-parallel control. The system offers several advantages such as modularity, scalability, and fault-tolerance over conventional battery electric vehicle systems. It is designed for seamless integration with the grid, allowing bidirectional power flow and efficient energy storage. Within this study, the battery system is first simulated in Matlab/Simulink and later implemented into a hardware setup. Eventually, the simulation results and the measurements have been compared and evaluated. Thereby, startup sequences and constant current scenarios were investigated. It has been shown that the system is fully capable to charge and discharge the batteries in the grid-parallel connection, thus enabling bidirectional charging with close to full drive system power. The current total harmonic distortion complies with grid regulations and can potentially improve the grid quality. The proposed system offers significant potential for grid-integrated energy storage systems, addressing the challenges associated with renewable energy integration, grid stability, and energy management. In comparison to other publications on this topic, the proposed approach does not need additional dedicated power electronic hardware and has more degrees of freedom for current control. [ABSTRACT FROM AUTHOR]

The clevis-grip tensile test is usually employed to evaluate the mechanical properties of textile reinforced concrete (TRC) composites, which is actually a bond test and is unsuitable for determining reliable design parameters. Thus, the clevis-grip tensile test needs further improvement to obtain foreseeable results concerning TRC tensile behavior. This paper presents the experimental results of twenty-one tension tests performed on basalt TRC (BTRC) thin plates with different test setups, i.e., clevis-grip and improved clevis-grip, and with different textile ratios. The influences of test setups and textile ratios on crack patterns, failure mode, and tensile stress-strain curves with characteristic parameters were analyzed in depth to judge the feasibility of the new test setup. The results indicated that with the new test setup, BTRC composites exhibited textile rupture at failure; in addition, multi-cracks occurred to the BTRC composites as the textile ratio exceeded 1.44%. In this case, the obtained results relied on textile properties, which can be considered reliable for design purposes. The modified ACK model with a textile utilization rate of 50% provided accurate predictions for the tensile stress-strain behavior of the BTRC composite derived from the improved test setup. The proposed test setup enables the adequate utilization of BTRC composite and the reliability of obtained results related to the occurrence of textile rupture; nevertheless, further work is required to better understand the key parameters affecting the textile utilization rate, such as the strength of the concrete matrix. [ABSTRACT FROM AUTHOR]

Metal-oxide arresters (MOA) are widely used to protect equipment against transient electromagnetic disturbances (TED) like very fast transient overvoltage (VFTO), high-altitude electromagnetic pulse (HEMP), lightning pulse, et al. Researches on the performance of MOA under microsecond level rise-time TED are abundant, such as lightning pulse. However, when MOA is subjected to TED of rise-time at nanosecond level, the voltage/current responses of MOA are not fully studied due to the lack of a standardized and reliable test setup. In this paper, a test setup is proposed for acquiring the response behavior of MOA under nanosecond level pulse. The setup is comprised of a pulse generator, a two-branch transmission line system and a high voltage power divider. The generator can provide stable double exponential pulse with tunable rise-time ranging from 5 ns to 100 ns. The divider ensures an even distribution of voltage/current surge wave along the two-branch line. Through the numerical analysis, both impinging and residual surge waveforms could be retrieved from measurements. The proposed method has been applied to investigate response behavior of MOA subjected to nanosecond level rise-time pulses. [ABSTRACT FROM AUTHOR]

Electrolysis is one of the most promising technologies for green hydrogen production, and extensive research efforts are devoted towards discovering new active and stable catalyst materials, as well as developing novel porous electrode structures for both the anode and cathode. However, most lab-scale catalyst testing is performed in either rotating disk electrodes or beaker-type cells that hardly reflect the operating conditions in a technological electrolyzer. In this work, we provide a 3D-printable cell holder design that allows for lab-scale testing under zero- or controlled-gap electrode configuration while supporting the placement of a reference electrode in the middle of the separator. Polypropylene (PP) or high-performance thermoplastics like polyetheretherketone (PEEK) can be used as filaments, depending on the application. 3D-printing of the cell results in material savings of 70%, thereby reducing material waste and environmental impact. We demonstrate the holder in both zero-gap and controlled-gap configurations, assessing data quality and reproducibility, using Fe-free Ni electrodes in alkaline electrolysis as a test case. Furthermore, the holder was demonstrated for longterm stability tests of 250 h at 60 °C by applying a fixed current density of 500 mA/cm 2. The design is freely available for download as a CAD file. [Display omitted] • 3D-printable 3-electrode holder for testing of MEA (membrane electrode assemblies) cells. • Test case of oxygen evolution reaction on NiOOH showed excellent reproducibility. • Suited for long-term stability tests at industrial conditions. • SolidWorks and drawings files are freely available. [ABSTRACT FROM AUTHOR]

This study introduces a method based on fine torque control to evaluate traction in rolling—liding line contacts under small slide-to-roll ratios (SRRs). To accomplish this, we engineered an innovative testing machine—a two-roller tribometer capable of precisely applying resisting torques to one of the rollers. Two types of tests were designed and conducted to validate our method and showcase the capabilities of the novel test setup. The first type, named the “Traction Decay Test”, proved to be effective in evaluating changes in the SRR over time. The second, named the “Torque-Mode Traction Test”, demonstrated its effectiveness in achieving ultra-low SRRs, in the order of 0.01%. As a result, traction curves with high resolution in the low SRR domain were constructed. This advancement provides the means for gaining a deeper understanding of traction coefficients, wear behavior, and tribological performance at ultra-low SRRs across diverse applications.

The development of a numerical protection laboratory is implemented through industry-institute interaction under an MOU. This paper documents the contribution of the major project of final year students on using a digital over-current and earth-fault relay. The latest numerical protection relay has been provided as a replacement for an older version by ABB India Ltd. as a part of corporate social responsibility (CSR). The laboratory experimental panel has been developed through the major project of the final year student group. There was the active participation of ABB India Ltd. by way of providing dedicated training to the student group and faculty members involved in the installation, commissioning, and design of the experimental panel. The results obtained from various case studies are reported in this paper. The facilities created are used for regular laboratory practicals for undergraduate and postgraduate students. The laboratory manuals are prepared to facilitate the implementation of the experiments. The laboratory curriculum has been updated for the UG course "Power System Protection" and the PG course "Advanced Power System Protection and Switchgear". It has resulted in improvement in the placement of UG and PG students. The training of industry and state power utility engineers can also be performed on the experimental panel developed. The outcome of this academic innovation related to industry-institute interaction is that the industry readiness of students has increased. [ABSTRACT FROM AUTHOR]

The poor out-of-plane behaviour of masonry infill-walls (MIW) in recent earthquakes, resulted in several casualties and economic losses. The main objective of this work is to present an experimental campaign comprised of four out-of-plane tests of full-scale MIW with the main goal to assess the possible effect of the previous damage, workmanship and test setup in the MIW out-of-plane behaviour. From the results, it was observed that the existence of the prior damage reduced the out-of-plane strength and energy dissipation of about 30% and 70%, respectively. The workmanship can introduce variations in the MIW response from 10% to 30%. [ABSTRACT FROM AUTHOR]

The use of catheters and guide-wires in minimally invasive therapeutic approaches is an important part of clinical practice. In the neurovascular field, the unique nature of cerebral blood vessels necessitates very thin-walled and flexible catheters. The blood vessels in question are highly branched and at the same time can be less than one millimetre in diameter. This results in high demands on micro-catheters and guide-wires for successful endovascular therapy. The interaction of these surgical tools and the vessel wall is of especial interest. Depending on the catheter stiffness, this interaction can be friction, punctual collision or straightening. The work aims to design and implement a test setup for evaluation of these interactions with the vessel wall. For this purpose, a standardized vessel course with representative characteristics is necessary. Furthermore, by implementing suitable measuring equipment, an endovascular intervention can be simulated.

The SHS-Multirisk Project proposes a residence model that is simultaneously resistant to earthquakes and hurricanes within a specific range of magnitude to be defined in the project. It uses simple, low-cost, and environmentally friendly construction technologies compared with traditional alternatives or more technological, but less accessible ones. To reach the SHS-Multirisk objectives, an experimental campaign to carry on cyclic shear tests involved a set of 15 reinforced soil-cement compressed earth block walls. Within this program, a particular test system was developed, conditioned by the guidelines: simplicity, availability of resources (especially components, equipment, and workmanship), rationalization of the available space, and scalability of the tests. Considering the short time available for designing and manufacturing the test system and for carrying out the shear tests, it was decided to adopt a project management framework in Scrum mode. This article presents the system developed to conduct full-scale cyclic shear (combined with bending) tests on walls, exploring its characteristics, the development process, the experiment execution process, and a basic analysis of the main test outputs.

Glass fiber-reinforced polymer (GFRP) and carbon fiberreinforced polymer (CFRP) sheets bonded to concrete were investigated to evaluate bond behavior, including effective bond lengths under two conditions: sustained temperature (ST) or sustained load with increasing temperature (SL). Tests were conducted using either double shear or flexural shear. Effective bond lengths of 70 and 100 mm (2.8 and 3.9 in.) were inferred for GFRP and CFRP sheets, respectively, from the double-shear tests. The effective bond lengths were then used for elevated temperature specimens, which showed significant reductions in the bond strength beyond the glass-transition temperature (55°C [131°F]). For 60°C (140°F) ST condition, up to 73% and 52% bond strength reductions were observed in double-shear and flexure specimens, respectively. The elevated temperatures also shifted the failure mode from thin concrete shearing to adhesive failure. Due to adhesive failure, the SL specimens with 30% and 50% sustained loads failed around temperatures of 125 and 110°C (257 and 230°F), respectively, regardless of the fiber type. [ABSTRACT FROM AUTHOR]

Due to the complexity of friction phenomena, empirical analysis is the best way to predict the friction coefficient. To accomplish this, laboratory test rigs are needed. Although a rotary dynamic friction test bed was available to the authors, it had its limitations, such as low speed, inducement of lateral force, and the limitation of testing samples with different shapes. This paper will explain the process of designing and manufacturing a novel test setup for measuring friction and wear of the tire. The newly designed test rig can apply dynamic loading during the tests, and it can automatically measure the wear rate and temperature between cycles. In addition, it can be used for measuring the wear rate of rubber samples sliding on different types of surfaces. Therefore, experiments can be run under more controlled conditions. The designed linear friction tester can slide flat and round rubber samples approximately three meters across a large flat surface. The frictional force of rubber samples can be measured for various normal loads, velocities, and surface conditions. The new setup can automatically control the applied normal load on the sample using proportional–integral–derivative controller control. The important difference between this novel design and the existing testers used by other researchers is implementing the ball screw technology and the servo motor with high accuracy encoder to achieve highly accurate test results. In this design, the new mechanism for the ball screw is designed to increase the speed limit and eliminating vibrations while keeping the precision. In addition, in this design, the sample's mass can be measured automatically after each test cycle, thus providing a measure of the rate of wear of the rubber. In this study, the data collected by the linear friction tester is validated by comparing the data to the data collected by the dynamic friction tester (a validated rotary friction tester that exists in CenTiRe Lab). The data collected by the new setup was later used to benchmark the Persson analytical friction model. [ABSTRACT FROM AUTHOR]

Experimental and numerical behaviour of steel test specimens with various types of joints is investigated in this study. A drop weight test setup with necessary test equipment is used for this purpose. The mass and drop height of the hammer is taken to be constant so that the same impact energy can be applied on test specimens. The acceleration, displacement, impact load, drop numbers and drop durations, are obtained through experimental study. In addition, development of damage to test specimens is observed during tests. Numerical analyses of behaviour of test specimens under impact load are also conducted to verify test results using the Abaqus software, and a comparison of results is made.

Steel structures, such as bridges, must be continuously maintained. Due to increasing traffic loads, design and execution shortcomings, many steel bridges are subject to various types of damage, such as cracks. The bridges must be maintained by crack removal and re-welding the cracks. During this work, the bridge is closed for traffic in order to suppress the crack flank movement during welding. As a result, traffic loads on other routes are higher, which increases further damage on detour routes and subsequently additional welding work and costs on these structures. Therefore, the aim is to provide a method that allows welding work on steel structures under running traffic, respectively under cyclic loads. First, measurements at a representative steel bridge were conducted to derive gap opening parameters of amplitude and frequency for welding tests under cyclic loads. In a test setup for reproducible and comparable welding tests, specimen were welded under cyclic loads. Deep grinding of the root layer allowed defect-free welding within the range of 0.1 mm amplitude at a frequency of 2 Hz loadings. For such welds, the weld quality and the fatigue strength was comparable to the standard requirements. • Structural health monitoring was used to measure the gap opening of a typical crack. • Welding under service conditions is under certain aspects possible. • Optically defect-free welds were welded up to a limit of 0.1 mm amplitude. • Unavoidable smaller hot cracks have to remove by deep grinding of the root layer. • Weld seams can be realized with regard to weld quality and fatigue strength. [ABSTRACT FROM AUTHOR]

Important investments have been made worldwide in the modernization and construction of railway lines. Plans for new constructions have also been laid out. Recently, precast concrete has been widely employed in the construction of railway bridges and viaducts. Several precast solutions have been applied, namely: I-shaped or U-shaped precast girders and uni-cellular or bi-cellular precast box girders. Regarding the structural scheme in the longitudinal direction, either simple span or continuous decks have been used. In this context, this work aims to contribute to the knowledge about the real performance of these structures through the development of a laboratory tests setup, for the study of this type of structure, focusing on the connection between the precast beams. The setup will be implemented at the Laboratory of Earthquake and Structural Engineering (LESE), several experimental campaigns on the cyclic behaviour of reinforced concrete elements have been carried out.

In this study, an experimental methodology is presented for measuring power losses of rolling element bearings under combined radial and axial loading conditions. The setup developed for this purpose consists of a pair of test bearings and another pair of center bearings whose function is to transmit the radial load to the test bearings. The center bearings are isolated from any axial load that is carried by the test bearings. The proposed methodology relies on a family of separate measurements to (1) remove center bearing losses from the losses of the test bearings and (2) separate load-independent (spin) and load-dependent (mechanical) components of power losses of the test bearings. The setup includes a precise lubricant delivery system that controls flow rate and temperature of oil supplied to each test and center bearing individually. Because the bulk temperatures of bearings tested impact the measured power losses significantly, a heat management system is implemented to maintain the bearing bulk temperatures at the same value as the set levels of the oil inlet temperature. The methodology is demonstrated on two deep-groove ball bearings of different sizes, considering wide ranges of axial and radial forces, rotational speed, oil flow rate, and oil inlet temperature (oil viscosity). The influence of bearing bulk temperatures on power loss measurements is demonstrated as well as the repeatability of the proposed methodology. Furthermore, spin and mechanical loss measurements are compared to a widely used calculation method to assess their accuracy. [ABSTRACT FROM AUTHOR]

Hydrostatic high-pressure technology (HHD) devitalizes tissue quickly and gently, without negatively affecting the structural properties. HHD-treated tissues must be cleaned from devitalized cells. A partially automated, gentle, reproducible and timesaving rinsing test setup utilizing ultrasound is demonstrated in this study. The test setup is used to clean HHD-treated bone allografts of tissue residues and prevent microbiological contamination. A rinsing procedure is investigated. Residual DNA content determination is utilized to analyze cleaned bone allograft tissue for rinsing procedure evaluation.

Steel sections with four different joint types, subjected to sudden impact, are investigated in this study. A drop weight test setup was developed for this purpose. Impact tests were performed for two different energy levels. Acceleration-time, displacement-time, impact load-time, and impact load-displacement graphs were developed and presented. It was established that the behaviour of test specimens is affected by joint types and impact energy applied. Failure damage situation occurs earlier when rigidity of specimens decreases and when higher level of impact energy is applied.

The clevis-grip tensile test is usually employed to evaluate the mechanical properties of textile reinforced concrete (TRC) composites, which is actually a bond test and is unsuitable for determining reliable design parameters. Thus, the clevis-grip tensile test needs further improvement to obtain foreseeable results concerning TRC tensile behavior. This paper presents the experimental results of twenty-one tension tests performed on basalt TRC (BTRC) thin plates with different test setups, i.e., clevis-grip and improved clevis-grip, and with different textile ratios. The influences of test setups and textile ratios on crack patterns, failure mode, and tensile stress-strain curves with characteristic parameters were analyzed in depth to judge the feasibility of the new test setup. The results indicated that with the new test setup, BTRC composites exhibited textile rupture at failure; in addition, multi-cracks occurred to the BTRC composites as the textile ratio exceeded 1.44%. In this case, the obtained results relied on textile properties, which can be considered reliable for design purposes. The modified ACK model with a textile utilization rate of 50% provided accurate predictions for the tensile stress-strain behavior of the BTRC composite derived from the improved test setup. The proposed test setup enables the adequate utilization of BTRC composite and the reliability of obtained results related to the occurrence of textile rupture; nevertheless, further work is required to better understand the key parameters affecting the textile utilization rate, such as the strength of the concrete matrix.

It is widely accepted that further and more in-depth research is required on the out-of-plane seismic response of masonry infill walls to increase knowledge regarding this particular behaviour and to develop effective strengthening strategies for preventing their collapse. However, such experimental tests are difficult to perform and the scientific community recognizes the complexity inherent to the test apparatus, loading approaches and loading protocols. At the Laboratory for Earthquake and Structural Engineering (LESE), several efforts were carried out over the last years towards characterizing the out-of-plane behaviour of full-scale MIW. Two test setups were developed using two different approaches for applying the out-of-plane loadings. This manuscript provides an overview of the test setups adopted in the literature by other authors and discusses their implication in the MIW response. Therefore, the considerations assumed in the development of the test setups at the LESE laboratory are provided starting by describing the out-of-plane tests with airbags and after that with pneumatic jacks. Further information regarding both tests setups is described and discussed throughout the manuscript. Experimental results of two specimens tested with both approaches are presented, highlighting the main differences and similarities. [ABSTRACT FROM AUTHOR]

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

JIS B 8628, “Air-to-air heat and energy exchanger and ventilators” provides standards for evaluating the performance of the energy recovery ventilators. JIS B 8628 was established in 2000, and revised in 2003. In 2017, JIS B 8628 was revised furthermore to ensure consistency with ISO 16494, which was established in 2014. For that purpose, the two room setup and the ducted setup, which are prescribed in ISO 16494 with specified pressure conditions at inlet and outlet of energy recovery ventilators for the airflow test, the tracer gas test and the thermal performance test, were added in JIS B 8628 (2017). In Japan, either the two room setup or the ducted setup is being used by manufacturers to determine the performance values, which are referred to when the compliance of total building energy performance to the Building Energy Efficiency Act is claimed. However, no studies have yet focused on the difference of the test results between the two room setup and the ducted setup. In this study, authors applied those setups and the test setup prescribed in JIS B 8628 (2003) to four energy recovery ventilators and compared their results. As for the airflow-static pressure characteristics, the curves obtained by the three test setups generally correspond to each other, except for the curves for the air exhaust line obtained by JIS B 8628 (2003). The unit exhaust air transfer ratio values obtained by the ducted setup and JIS B 8628 (2003) tend to be greater than those by the two room setup. As for the thermal performance represented by the total effectiveness, differences among the three test setups can be observed when there is a difference of the unit exhaust air transfer ratio and/or the ratio of the supply airflow rate to the return airflow rate.

This paper presents the results of an interlaboratory study of the rheological properties of cement paste and ultrasound gel as reference substance. The goal was to quantify the comparability and reproducibility of measurements of the Bingham parameters yield stress and plastic viscosity when measured on one specific paste composition and one particular ultrasound gel in different laboratories using different rheometers and measurement geometries. The procedures for both in preparing the cement paste and carrying out the rheological measurements on cement paste and ultrasound gel were carefully defined for all of the study's participants. Different conversion schemes for comparing the results obtained with the different measurement setups are presented here and critically discussed. The procedure proposed in this paper ensured a reasonable comparability of the results with a coefficient of variation for the yield stress of 27% and for the plastic viscosity of 24%, despite the individual measurement series' having been performed in different labs with different rheometers and measurement geometries. [ABSTRACT FROM AUTHOR]

For the economical construction of fatigue loaded structures with textile reinforced concrete (TRC), it is necessary to investigate the fatigue behavior of the materials. Since next to the tensile load-bearing behavior, the bond behavior of a material is crucial as well, the present paper deals with the bond fatigue of TRC with epoxy-impregnated carbon textiles. First, static tests are carried out to determine the sufficient anchorage length of the investigated material combination. Afterwards, the influence of cyclic loading on the necessary anchorage length, deformation, stiffness, and residual strength is investigated. The results of the cyclic tests are summarized in stress-number of cycles to failure (S-N) diagrams. In the end, it can be said that the cyclic loading has no negative impact on the necessary anchorage length. If specimens withstand the cyclic loading, there is no difference between their residual strength and the reference strength. The failure of specimens occurs only at high load levels, provided that the anchorage length is sufficient. [ABSTRACT FROM AUTHOR]

Abstract The cracking of plastic concrete remains a problem in the construction industry due to its complexity and incomplete understanding. One of the reasons for this is the lack of knowledge regarding the tensile material properties of the plastic concrete. This paper describes and builds the appropriate test setup needed for the challenging tensile testing of plastic concrete as well as discusses the measured tensile properties. The tensile strength and Young's modulus increase exponentially near the final setting time and initial setting time respectively. The strain capacity and initial fracture energy decrease significantly between the initial and final setting times. The tensile properties develop faster and with higher values the greater the ambient temperature. Plastic concrete proved to be resilient and capable of withstanding multiple loading and ceased loading cycles, while a solid but still weak concrete could not. The tests also highlighted the need for further research regarding the influence of hydrostatic pressure and the relaxation of stresses in plastic concrete. [ABSTRACT FROM AUTHOR]

Abstract: Bond tests on carbon reinforced concrete under cyclic loading – Comparison of different test setups The material behavior of carbon reinforced concrete under static loading has been investigated for considerable time. That under cyclic loading however has still to be examined. For that suitable test setups have to be available. For the determination of the bond behavior of carbon reinforced concrete under cyclic loading two test setups – the end anchorage and the double sided pullout test, which have already been investigated in static tests – were proved and compared. Therefor static reference tests and cyclic tests under different loads were carried out. The results were analyzed in different categories for comparison, such as failure mechanisms, development of deformations and stiffness, and number of cycles to failure. Furthermore, the scattering of the test results was considered. After the discussion of the test results the double sided pullout test will be named more suitable. [ABSTRACT FROM AUTHOR]

Connecting reinforcement bars in their longitudinal direction is often needed in reinforced concrete structures. These connections must guarantee a correct stress transmission between bars without excessive cracking or inadmissible slips, and they are commonly executed by overlapping the reinforcement bars in a procedure known as a lap splice. In the absence of a standard or widely recognized test, three or four point bending tests are often used for the experimental study of lap-splices in tension. This test configuration shows inherent limitations, large costs and, usually, significant scatter. In this paper the authors have selected, fine-tuned and evaluated a specific test configuration for studying lap splices in reinforcement bars submitted to tensile forces. The proposed experiment was designed to be flexible and affordable in terms of cost, time consumption and required testing equipment. Consequently, it is possible to carry out multiple reruns of the experiments, minimizing the uncertainty and providing a good starting point for applying statistic methodologies. In contrast to the regular test configurations, the selected setup makes possible to directly obtain the bond-slip curves of the spliced bars. The experimental work carried out to assess the reliability, sensitivity and scatter of the proposed configuration shows promising results. [ABSTRACT FROM AUTHOR]

The effective stress transfer between the fiber reinforced polymers (FRP) and the steel substrate is crucial for the successful retrofit of existing steel structures with FRP composites. However, there are no standard tests for FRP-to-steel interfaces, wherefore different test configurations have been used in recent years to assess the bond behaviour in these interfaces. The present study shows that the choice of test configuration is highly important and leads to different transfer stresses between the FRP and steel composites and consequently, has a direct influence on the strength of the bonded joint. Therefore, it is important to understand the debonding process that occurs in each test and avoid misinterpretations, erroneous analyses and dangerous characterizations of the interfacial behaviour of these interfaces. The current study presents a new analytical approach for the prediction of the debonding of FRP-to-steel interfaces when double-lap pull or double-strap tests are used. [ABSTRACT FROM AUTHOR]

The paper presents the idea of a Cross Test Comparison (CTC) method for the analysis of Frequency Response measurement results. FRA is used to detect deformations or electric faults in transformer windings. At the current stage of FRA method development, it is possible to perform repetitive measurements, however there are still problems with interpretation of test results. Authors of this paper found that analysis of results coming from two test setups (end-to-end and interwinding capacitive), which is done simultaneously is a more sensitive tool to detect some faults, and in addition it binds the influence of both voltage sides of a transformer in a single test result. The paper contains results obtained from laboratory tests, where controlled deformations were introduced into windings and also measurements from industry. The CTC method combines both the end-to-end and capacitive interwinding measurements into a single dataset, by subtracting the amplitudes at the corresponding frequencies. The resulting combined dataset is more sensitive in identifying deviations from baseline measurements. [ABSTRACT FROM AUTHOR]

Pipelines are significant structural systems that transfer necessary materials from one place to another. They are under the effect of static and dynamic loads during their service lives. Investigations have become important to determine the effects of sudden dynamic loads with technological developments. Researchers study the mechanical properties of different materials and structural members under dynamic effects such as earthquake, wind, blast, rock falling and vehicle crushing. For this purpose, different test setups have been developed to investigate the behaviour of test members. In this study, galvanized and water filled galvanized pipe sections having three different diameter values are produced in a laboratory to perform tests under impact loading. The behaviour of the pipes is determined by free falling test apparatus. In addition, measurement devices as accelerometer, dynamic force sensor, lvdt, and data logger are used in the experimental program. So, acceleration, impact force, and displacement values are obtained during the tests. Besides, damage developments of the pipes are also observed to determine the impact resistances of test members. The results are compared to each other and it is stated that while acceleration and impact force values decrease, displacement values increase as the test members approach to collapse damage situation. [ABSTRACT FROM AUTHOR]