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In this paper experimental results of investigation on reinforced concrete (RC) beams strengthened with the near surface method (NSM) are analyzed considering the response under bending tests on two beams. One of the RC beams was damaged by bending until the yield of reinforcement and successively strengthened with carbon fiber polymer (CFRP) rod, while the second beam was strengthened with glass-FRP rod. Both the beams have been subjected to bending tests until failure. Experimental diagrams and discussion on static response are presented in the paper. It also places a particular emphasis on the non-linear response of RC sections strengthened with CFRP and GFRP rods under bending moment beyond the first elastic behavior.

In this paper, the short-term behavior of a new partially pre-cast and partially encased composite (PPEC) beam is studied. This paper reports the results of a 4-point bending test on a full-scale PPEC beam and sets out the load displacement response, short-term stiffness, peak load capacity and failure mode of the proposed PPEC beam. In addition, a finite element analysis of the PPEC beam is carried out, and the numerical simulation results are compared with the test results. The results show that the finite element model can reflect the bending response of the PPEC beam. In this paper, three different calculation methods are used to compare the deflection of the PPEC beam. The results show that the values calculated by the bending-shear coupling method formula agree relatively well with the test results.

To eliminate misalignment between stator and rotor (especially in large rotary machines) the thrust bearing with a system of very precise manufactured levers has started to be used. The article deals with the static tests of self-equalizing elements (levers) made of 34CrNiMo6 steel, which are the critical parts of a newly developing self-equalizing thrust bearing. To verify the stiffness of the newly designed levers by static tests, the real levers were produced, which according to preliminary experiments and numerical simulations have the potential to be used the most in turbines. Based on basic tests of the pairs samples, that represent types of geometries going in contact within real conditions, it was found out that in terms of the surface treatment, the best results show electroless nickel-plated samples. So, due to this reason, the real levers were produced and their surfaces were processed in this way by electroless nickel-plating. Within the presented research, they were statically tested intending to determine the surface integrity and whether there was any development of damage to the surface layer. The evaluation was done using a stereomicroscope and a scanning electron microscope. The tests confirm sufficient rigidity of the levers including a suitable method of surface processing. Although, in some cases, these were surface defects caused by surface treatment technology, but no defects were found after static loading. © 2020 The Authors. Published by Elsevier B.V., Ministry of Education of the Slovak Republic [KEGA 007TUKE-4/2018, APVV-19-0550, VEGA 1/0812/21, KEGA 005TUKE-4/2021]

According to existing rigid roofing projects, a new structure called the Levy hinged-beam cable dome is proposed. By replacing the upper flexible cables with hinged beams, rigid plates can be installed overhead. To fulfill the requirements of integral tow-lifting construction, the setting criteria for the temporary hinged joints on ridge beams were presented. An 8-m diameter specimen was manufactured and monitored to investigate the structural configurations during the accumulative traction-hoisting construction process. Finally, the specimen was tested under full-span and half-span loading conditions, while a numerical model was built to verify the experimental values. The results show that in the early stages of traction-hoisting, the structure establishes the overall prestress and finds its internal force balance, while the entire structure is in a shape of “ω”. As the component’s internal force increases during the construction steps, and the local deformations of the hinged beams gradually decrease, with the entire structure changing from “ω” to “m”, and finally reach their designed states. Under full-span loads, large local deformations occurred at the HB-3 hinges, while the bending stresses of these hinged beams were relatively small. Under half-span loads, the loading part exhibits a downward appearance, while the unloading part exhibits upward deflection.

There is a group of measurement techniques that can be used in the task of force identification in steel bolts. In this paper, the potential of elastic wave propagation signals was studied for possible application in force monitoring systems. A series of laboratory tests was carried out on flange connections subjected to static tensile tests. Each one contained six screws of the same diameter. Four bolts were equipped with washer load cells. Alternatively, selected bolts were equipped with piezoelectric transducers (actuator and sensor) in order to measure the elastic wave signals. Principal components analysis, time of arrival, and neural network compression were used for dimensionality reduction of the measured signals. Examples of the obtained results with respect to the studied connections show that the tension forces in bolts can be estimated with relatively good accuracy.

The core part of a hybrid truss bridge is the connection joint which combines the concrete chord and steel truss-web members. To study the mechanical behavior and failure mode of steel&ndash, concrete connection joints in a hybrid truss bridge, static model tests were carried out on two connection joints with the scale of 1:3 under the horizontal load which was provided by a loading jack mounted on the vertical reaction wall. The specimen design, experimental setup and testing procedure were introduced. In the experiment, the displacement, strain level, concrete crack and experimental phenomena were factually recorded. Compared with the previous study results, the experimental results in this study demonstrated that the connection joints had the excellent bearing capacity and deformability. The minimum ultimate load and displacement of the two connection joints were 5200 kN and 59.01 mm, respectively. Moreover, the connection joints exhibited multiple failure modes, including the fracture of gusset plates, the slippage of high-strength bolts, the local buckling of compressive splice plates, the fracture of tensile splice plates and concrete cracking. Additionally, the strain distribution of the steel&ndash, concrete connection joints followed certain rules. It is expected that the findings from this paper may provide a reference for the design and construction of steel&ndash, concrete connection joints in hybrid truss bridges.

The estimation of flexural stiffness from static loading test data is the basis of many methods assessing the condition of structural elements. These methods are usually developed under the assumption of having sufficiently accurate data available. Hence, their performance deteriorates as the differences between the measured and true values of the response, often denoted as noise, increase. The proposed methodology is specifically designed to mitigate errors derived from noisy static data when estimating flexural stiffness. It relies on the linearization of the equations relating displacements to stiffness through the unit-force theorem, combined with regularization tools such as L-Curve and generalized cross-validation. The methodology is tested using theoretical simulations of the static response of a simply supported beam subjected to a 4-point flexural test for several levels of noise, two types of responses (deflections and rotations) and different levels of discretization. Recommendations for selecting the optimal regularization tool and parameter are provided. The use of rotations as inputs for predicting stiffness is shown to outperform deflections. Finally, the methodology is extended to a statically indeterminate beam. Spanish Government

This article compares two nondestructive static methods used for the axial load assessment in prismatic beam-columns of space trusses. Examples include the struts and ties or the tension chords and diagonal braces of steel pipe racks or roof trusses. The first method requires knowledge of the beam-column’s flexural rigidity under investigation, whereas the second requires knowledge of the corresponding Euler buckling load. In both procedures, short-term flexural displacements must be measured at the given cross sections along the beam-column under examination and subjected to an additional transverse load. The proposed methods were verified by numerical and laboratory tests on beams of a small-scale space truss prototype made from aluminum alloy and rigid connections. In general, if the higher second-order effects are induced during testing and the corresponding total displacements are accurately measured, it would be easy to obtain tensile and compressive force estimations.

International audience; This paper identifies the failure modes of a commercial 130-nm ferroelectric random access memory. The devices were irradiated with heavy-ion and pulsed focused X-ray beams. Various failure modes are observed, which generate characteristic error patterns, affecting isolated bits, words, groups of pages, and sometimes entire regions of the memory array. The underlying mechanisms are discussed.

Steel open-web sandwich floors (SOSFs) have been applied in several pioneering industrial and public buildings. The traditional square tube shear key (STSK) is changed into a flanged cruciform section shear key (FCSK) to further improve the bearing capacity of SOSFs. A half-scale test model is designed. A graded static loading test is performed to measure deflection and strain. The calculation formula of the intersection beam analogy method (IBAM) considering the influence of shear stiffness is proposed. A finite element (FE) analysis was also performed. The results of the test, IBAM and FE method are compared. The maximum deviation of the deflection obtained by them is less than 5%, and the maximum strain error is less than 7%. These figures prove that all three methods have high precision in the elastic range. Compared SOSFs use a different shear keys with the same grid size and chords, the maximum Mises stress is reduced by 55.9% and the maximum displacement is reduced by 36.1%. The new shear key imparts the structure with improved bearing capacity and safety margin.

Prestressed concrete structures are used in various fields as they can reduce the cross-sectional area of members compared with reinforced concrete structures. In addition, the use of high-performance and strength concrete can help reduce weight and achieve excellent durability. Recently, structures have increasingly been constructed using high-performance and strength concrete, and therefore, structural verification is required. Thus, this study experimentally evaluated the structural performance of a long-span bridge deck slab joint, regarded as the weak point of structures. The specimens were designed with a 4 m span for application to cable-stayed bridges. To ensure the required load resistance and serviceability, the specimens comprised of 120 MPa high-performance fiber-reinforced concrete and were prestressed. The deck slabs satisfied all static and fatigue performance as well as serviceability requirements, although they were thinner than typical concrete bridge deck slabs. The study also verified whether the deck slabs were suitable to help implement precast segmental construction methods. Finally, the results confirmed that the structural performance of the developed prestressed concrete (PSC) deck slab was sufficient for the intended bridge application as it achieved a sufficiently large safety factor in the static and fatigue performance tests, relative to the design requirement.

This paper shows the design, development and experimental checking of a modified type of structural joint with limited length between concrete segments cast “in-situ”. The design concept is based on the development length of an anchorage hook stiffened by transverse reinforcement bars and is particularly suited for the case of in-situ construction of staged box girder bridges, seeking to the possibility of using lighter scaffolding. The studies focusing on the strength, stiffness and serviceability of the proposed joint are presented. The research work comprises the bending behaviour of reinforced concrete slabs with loop joints with regard to the diameter of loop bar, loop joint width and ultimate and fatigue load. The results are compared to the behaviour of reinforced concrete slabs without joints. A total of 16 slabs were tested by static and fatigue loading tests. The present paper evaluates the flexural behaviour under static loading test. The results of fatigue tests have also shown an excellent performance. In the static tests, crack width and crack pattern were observed at service load levels, and the ultimate behaviour was evaluated by means of up to failure tests. From the test results, the service performance of the loop joints was confirmed similar to slabs without joints. The static loading tests confirm the good performance and effectiveness of this loop joint type under static loads. Details of loop joints design criteria are also suggested.

The Taro bridge has a very long history since was built by Antonio Cocconcelli in 1820. The bridge is composed of 20 arch spans and is arranged in the shape of three center Perronet arches with flood holes in the piers. The road over the bridge has two lanes and is set for the highest truck loading category. After the second World War has been used intensively for road transportation and due to some intrinsic features of the structure, in recent times many brick and stone detachments occurred. Recently, in order to assess the health of the bridge, static and dynamic testing was carried out, by using a set of 8 trucks filled with sand. A Finite Element Model was worked out for the data interpretation, and the parameters of the model were identified on the basis of the vibration frequencies. In order to test the effectiveness of the model, a comparison is made with the static load testing, finding a very good agreement. The main identified parameter are the compliance of the foundation blocks, and the elastic modulus of the fill. The analysis shows that models with different number of spans are all capable to identify the main frequencies of the bridge, if the correct value of the main parameters is introduced.

Purpose.The vast majority of passenger car fleet of «Ukrzaliznytsia» have cars with outlasted service life. In this regard there is a need to find methods to justify the extending useful life of passenger cars and to assess the car body frame residual life conformity to the operating load for the next life time.Methodology. The selection of cars enforced technical diagnostics of cars to detect the level of corrosion and mechanical damage. The following steps provided the car body frame strength analysis on the basis of experimental static and impact strength tests, the longitudinal force effect endurance tests as well as assessment and forecasting of conformity of car body operating life for the next period.FindingsThe car survey before testing showed that the technical condition of sleeper cars (SSC) is better than that of open-type cars (SOC). So, in SSC cars the thinning of the main load-bearing elements due to corrosion does not exceed 10%, there are no cracks, deformations, rack breakages, etc. At the same time in SOC cars the thinning due to local corrosion reached 35%. There are deformations and corrosion damage of side sill Zshape of both cars, single corner post breakages, damage to the joints of longitudinal tie rod and span bolsters. The conducted static and impact strength tests with following strength assessment of the car structural members showed that the strength of the latter is provided according to the normative documents, and these cars pose no threat to traffic safety. The impact endurance tests showed that all the cars passed the endurance tests without damage, which would prevent from testing and could not be removed during the next depot repair or overhaul, and had life length that allows them to extend the useful life for the next period.Originality.The results of experimental studies show that passenger cars after 28 … 30 and 33… 35 years of operation meet the requirements of strength and safety in accordance with regulatory documents and allow, provided the impact endurance, reasonable extending of the car service life.Practical value.The part of the car fleet, which was to be written off based on the service life, may extend lifespan without additional measures.

Purpose. The scientific work supposed: 1) the search of accounting ways of the local corrosion damages influence to the car design, that were expired the appointed time, for the purpose of renewal; 2) experimental verification of conformity of material construction requirements of the normative documentation and justification for extending the services of passenger cars with pockets of corrosion after 30 years of operation; 3) the conformity assessment of residual life of the structure of car bodies operating pressures in the next 5 years of use. Methodology. The developed algorithm of technical diagnostics of cars with pockets of corrosion of the center sill contains several stages. First, a survey of technical condition of structures is conducted by a visual-optical method and nondestructive control methods, and the degree of damage is determined. In the next phase the experimental verification of conformity of the structure and mechanical properties of the center sill of the car with the pockets of corrosion to regulatory requirements are executed. Next, the study of strength of the supporting structures of car bodies on the basis of experimental static and impact tests of strength is executed. Finally, the endurance tests are conducted on the effect of the longitudinal forces and the evaluation and prediction of compliance resource car bodies for the next period are executed. Findings . The actual work is completed by obtaining the experimental data on the feasibility of extending the service life of passenger cars as from the point of view of an operating time of load-bearing elements of the car body to the resource, and from the point of view of chemical composition, structure and mechanical properties of the center sill with pockets of corrosion. The presence of local corrosion damages of the center sill of the presented size is not a threat to the structural strength and safety. Originality. The authors conducted a comprehensive study to validate the service life of passenger cars both on the part of the operating time of the car bodies elements on impact toughness and the evaluation the mechanical properties of the metal from which the elements of the car are produced. For the first time the possibility of further operation of cars with corrosion damages in the center sill is grounded. Practical value. The obtained results allow without the additional activities to extend the service life of passenger cars with pockets of corrosion in the center sill.

Within the civil engineering field, the use of the Finite Element Method has acquired a significant importance, since numerical simulations have been employed in a broad field, which encloses the design, analysis and prediction of the structural behaviour of constructions and infrastructures. Nevertheless, these mathematical simulations can only be useful if all the mechanical properties of the materials, boundary conditions and damages are properly modelled. Therefore, it is required not only experimental data (static and/or dynamic tests) to provide references parameters, but also robust calibration methods able to model damage or other special structural conditions. The present paper addresses the model calibration of a footbridge bridge tested with static loads and ambient vibrations. Damage assessment was also carried out based on a hybrid numerical procedure, which combines discrete damage functions with sets of piecewise linear damage functions. Results from the model calibration shows that the model reproduces with good accuracy the experimental behaviour of the bridge.

Research in cleaning procedures of reverse osmosis membranes used in seawater desalination to minimize costs and achieve high efficiency is necessary. Multi-step cleaning can represent a useful tool, since the cleaning efficiency can be improved by means of utilization of different chemicals with complementary cleaning mechanisms. The objective of this work was the optimization of a two-step cleaning procedure to recover the membrane properties and reduce power costs. Spent Hydranautics SWC3 membranes (USA) were supplied by a desalination plant. Cleaning tests were performed in three stages: one-step static cleaning, two-step static cleaning and characterization of the membrane surface after the cleaning process. Four cleaning agents at two different concentrations were used. All possible combinations of them were considered, including sequence effect. After the cleaning process, membrane surface was characterized by field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and atomic force microscopy. One-step static cleaning test indicated that sodium dodecyl sulphate 1% w/v was the most efficient cleaning solution, followed by NaOH 2% w/v. Two-step cleaning tests showed that the procedure that maximized permeate flux recovery was surfactant-alkaline cleaning, whereas the one that maximized the recovery of the salt rejection index was alkaline-acid sequence. Characterization of the membrane surface after the cleaning steps confirmed that fouling deposits were significantly removed., The authors wish to thank Abengoa Water, S.L. for the financial support given to this research through the project "Cleaning and re-use of reverse osmosis membranes in desalination plants", which belongs to the CENIT-Tecoagua research project, funded by the Spanish Ministry of Science and Innovation. The authors would like to gratefully acknowledge Vicente Fornes and Rosa Torrero from the CSIC-I.T.Q research centre from the Universitat Politecnica de Valencia for their support given in the ATR-FTIR analysis.

This paper presents a static method for the axial load identification of slender prismatic beams with uncertain length and unknown boundary conditions as is typical of struts and ties of truss structures or tie-rods of arches and vaults. The proposed method requires the knowledge of the beam flexural rigidity only. Flexural displacements or curvatures are measured at five cross sections of the beam subjected to an additional concentred lateral load. Unlike analogous dynamic methods, any set of experimental data may be used in the identification algorithm. The proposed algorithm is verified by means of many numerical and experimental tests on beams having different boundary conditions. Excellent estimates of the axial forces are obtained when the greatest possible distance between sensors is adopted, even if in the presence of high values of the axial forces very accurate displacement measurements are required.

International audience; Methodologies are proposed for in-depth statistical analysis of Single Event Upset data. The motivation for using these methodologies is to obtain precise information on the intrinsic defects and weaknesses of the tested devices, and to gain insight on their failure mechanisms, at no additional cost. The case study is a 65 nm SRAM irradiated with neutrons, protons and heavy ions. This publication is an extended version of a previous study.

Aircraft wings are usually optimized for a specific mission design point. However, since they operate in a wide variety of flight conditions, some of these have conflicting impacts on aircraft design process, as a single configuration may be efficient in one instance but perform poorly in others. A shape-shifting surface, or usually referred as 'morphing', potentially enables transport aircraft to reach maximum performance in any flight conditions. Within the framework of the Joint Technology Initiative Clean Sky (JTI-CS) project, and during the first phase of the Green Regional Aircraft Integrated Technological Demonstration (GRA-ITD), the authors focused on the design and technological demonstration of an innovative bi-modal morphing outer wing flap to be installed on the next generation open rotor green regional aircraft. A novel active rib layout was designed to enable the articulation of the entire flap structure by means of multi-box arrangement. In order to prove structural load-carrying capabilities with the reference to a relevant environment, the full-scale morphing flap was properly analyzed by means of detailed finite element model analysis. To the authors' knowledge, there is no morphing concept in literature based on a similar architecture based on distributed servo-mechanical actuators. Hence, a rational review of the potential problems associated with actuators off-design conditions has been conducted to investigate the maturity of the concept and safety issues concerning the flap ground static test. In addition, useful insights have been provided to effectively detect potential failure conditions in service.

International audience; Various failure scenarios may occur during irradiation testing of SRAMs, which may generate different characteristic Multiple Cell Upset (MCU) error patterns. This work proposes a method based on spatial and temporal criteria to identify them.

Full scale aircraft static test is a very important process of aircraft design, it is costly and time consuming. The testing accuracy and validity mainly depend on the rationality of the test scheme design. When the aircraft is being tested, the specimen's safety mainly depends on monitoring and understanding the testing data by way of evaluating the coherence with the digital simulation data synchyononsly. The test digital simulation can aid realizing above requirements and improving the test efficiency significantly during test scheme design stage or testing stage respectively. The key technologies and the solving methods of test digital simulation are presented and the application example is given.

The CFRP composite materials due to their excellent mechanical properties are more and more often used in civil engineering. In recent more than ten years one could have observed f.e. much more wider application of FRP in bridge construction. The main goal of the ongoing research project was to develop and demonstrate FRP composite bridge girder, including their technical design, material research, manufacturing technique selection and structural testing on full scale model. The objective of the paper is the development and research on a new FRP bridge girder fabricated by VARTM manufacturing technique. The reduced scale prototype girder with the total length of 13,5 m was tested to evaluate its carrying capacity, overall behavior under ultimate static load, as well as modes of failure. The girder met the prescribed serviceability and safety criteria and is likely to be implemented on-site soon for bridge construction. The output of the research project gives a very promising future for the FRP application in bridge engineering.

An experimental investigation has been carried out in single-lap bolted composite joints in order to point out the influence of geometrical and material characteristics on the damage onset and propagation under tensile loading conditions. Protruding and countersunk joints have been considered, with different bolt diameters and different interfaces (composite-to-composite and composite-toaluminum). First, static tensile tests have been performed on single-lap joints. Then, non-destructive ultrasonic evaluations have been conducted at intermediate load levels and at final failure in order to show the real onset and evolution of damage inside the joints in terms of fibers and matrix breakage.

Weight deduction is one of the key steps in full-scale aircraft static strength test. It will keep the experimental craft zero-gravity during the full-scale aircraft static strength test and fatigue strength test to make the test status as real flight condition of the plane more truly. In consideration of the necessary and benefit of weight deduction, a complete scheme of weight deduction in full-scale aircraft static structural test was presented, which including the method for calculating the weight of test piece, method for deducting the weight of test piece and loading device and the design of the weight deduction device. The full-scale static strength test of one type of aircraft was used as research object. The test was successfully completed and valid test result was obtained by deducting the weight of test piece and loading device based on the above-mentioned scheme. The result shows that the method for calculating weight deducted is scientific and logical, and the weight deduction scheme is viable. The proposed scheme could deduct the weight of test piece and loading device effectively, reduce the weight effect on test results and has important reference value to similar test.

The objective of this research is to overcome natural and artificial barriers that prevent the safe movement of pedestrians and cyclists on footbridges. The most recent trend is to build footbridges of glued laminated wood. Wood itself is an organic material. Therefore, it is important to protect it and thus ensure the longevity of objects produced from it. It is important to correct sizing of the structure and its subsequent maintenance. Revealing critical places and factors may lead to the correct choice of design, construction details and a clearly given maintenance plan, which does not currently exist, thus ensuring longevity of emerging and existing footbridges.

Background Tibial head depression fractures demand a high level of fracture stabilization to prevent a secondary loss of reduction after surgery. Elderly individuals are at an increased risk of developing these fractures, and biomechanical investigations of the fractures are rare. Therefore, the aim of this study was to systematically analyze different types of osteosyntheses in combination with two commonly used bone substitutes. Methods Lateral tibial head depression fractures were created in synthetic bones. After reduction, the fractures were stabilized with eight different treatment options of osteosynthesis alone or in combination with a bone substitute. Two screws, 4 screws and a lateral buttress plate were investigated. As a bone substitute, two common clinically used calcium phosphate cements, Norian® Drillable and ChronOS™ Inject, were applied. Displacement of the articular fracture fragment (mm) during cyclic loading, stiffness (N/mm) and maximum load (N) in Load-to-Failure tests were measured. Results The three different osteosyntheses (Group 1: 2 screws, group 2: 4 screws, group 3: plate) alone revealed a significantly higher displacement compared to the control group (Group 7: ChronOS™ Inject only) (Group 1, 7 [p