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Copyright of Archives of Civil Engineering (Polish Academy of Sciences) is the property of Polish Academy of Sciences 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.)

This paper investigated the analytical solution of the bond strength between ribbed steel bar and engineered cementitious composites (ECC). In this method, ECC cover was regarded as a thick‐walled cylinder subjected to the uniform internal pressure which consisted of an elastic uncracked outer ring and a partially cracked inner ring. For the uncracked outer ring, it can be solved by the elastic mechanics theory. To solve the partially cracked inner ring, two key problems that had to be investigated were the crack width and the tensile stress–crack width relationship of ECC. According to the steady‐state cracking mode, the hoop deformation of ECC was expressed by the equal distribution and then the crack width can be determined. Besides, the fictitious crack model in fracture mechanic was introduced to describe the crack propagation process. Then a trilinear model was applied to reflect the tensile stress–crack width relationship of ECC materials, which considered the combined action of aggregate bridging and fiber bridging on the crack surface. Finally, the comparison between the calculation results and experimental results was carried out to prove the validity of the analytic method of bond strength proposed in this paper. Results indicated that the analytical solution and the experimental data fitted in well with each other. Then parameter analyses were conducted based on the analytical method proposed in this paper. [ABSTRACT FROM AUTHOR]

Investigation on the behaviour of hybrid beams is presented. Hybrid beam stands for an element with hybrid cross sections. This means sections that consist of steel and concrete parts, connected together with composite dowels, and both are considered for shear flow analysis. In practice, a more general solution may be used for bridges in the form of a beam in which the span sections are hybrid and the support sections are concrete. For the first time in the world, it was decided to introduce a girder in bridge construction, in which a concrete web with a thickness of only 20 cm was formed, directly connected to the steel web, so that a hybrid cross-section is created in accordance with the new European design regulations currently being developed (1994-1-102). The solution is new itself and requires also a new approach for internal forces determination. In this paper a parametric analysis of different hybrid beams with span range from 20 to 40 m and with different reinforcment ratio is performed to get knowledge on the influence of (1) concrete cracking and (2) rheology of concrete on the redistribution of internal forces. Results are analysed and conclusions are presented. As a final step, a general method for computer aided modelling of hybrid beams (hybrid beam concept) is proposed, which is based on the uncracked analysis. Such an analysis is designer-friendly and while appropriate benchmarked (as in this paper) can spare a lot of time needed for detailed iterative cracked analysis. [ABSTRACT FROM AUTHOR]

This paper deals with an approximate solution of Saint-Venant torsion problem of orthotropic bar with solid cross section. The boundary collocation is used to get the approximate analytical solution of the torsion problem. Examples illustrate the applications of the presented numerical solution. [ABSTRACT FROM AUTHOR]

A fault tolerant control method has been proposed based on the steer-by-wire system with dual steering actuator motors as presented in this paper. The paper built a real-time fault diagnosis mechanism based on the motor model and adaptive fading Kalman filter firstly. Then the diagnosis results were used to judge whether the angle feedback control and the torque feedback control need to be amended to realize fault tolerant control. Finally, hardware-in-the-loop test bench of this steer-by-wire system has been built for experiments and the results demonstrated that the fault tolerant control method was feasible and accurate. [ABSTRACT FROM AUTHOR]

The unrestrained torsional analysis of bars is an important theme in elasticity theory, first solved by Saint-Venant using semi-inverse methods. It has been considered and solved by several others using analytical methods and numerical procedures due to the importance in the design of machine parts under torsional moments. In this paper, the Saint Venant torsion problem is solved for rectangular prismatic bars using Galerkin-Kantorovich variational method (GKVM). The work presents a detailed theoretical framework of the problem, deriving using first principles considerations the stress compatibility equation in terms of the Prandtl stress function ϕ(x, y). The derived domain equation which is required to be satisfied over the rectangular cross-sectional domain is a partial differential equation of the Poisson type. GKVM is adopted as the solution method for finding the solution to the domain equation. The unknown Prandtl stress function ϕ(x, y) is assumed, following Kantorovich method to be a product of an unknown function for f(x) sought to minimize the Galerkin-Kantorovich variational functional (integral) (GKVF) and a known function (y2 - n2) which satisfies the boundary conditions at all boundary points in the y-direction, that is, at y = ±b. The resulting GKVF is a simplified functional whose integral is a second order inhomogeneous ordinary differential equation (ODE) in f(x). The integrand is solved to find f(x) leading in a full determination of the Prandtl stress function. The expression for stresses, torsional moments and torsional parameters are then found and they satisfy the boundary conditions and the domain equation. The results for the torsional moments and torsional parameters are identical to previous results obtained using double finite sine transform method (DFSTM), and analytical methods. The merit of GKVM is that it has led to the exact solution of the unrestrained torsion problems. [ABSTRACT FROM AUTHOR]

While the effects of axial compression on beams have long been known, the effect of tensile axial loads on one-sided transversely cracked beams is less known. The crack namely shifts the position of the resultant of the axial normal stresses deeper into the uncracked part of the cross-section, and the crack tends to open, causing a transverse displacement. Therefore, this paper focuses on empirical modeling of the considered phenomenon for slender prismatic beams in order to establish a suitable 1D computational model based on detailed 3D FE mesh results. This goal can be achieved through the already established simplified model, where the crack is represented by an internal hinge endowed with a rotational spring. Several analyses of various beams differing in geometry, crack locations, and boundary conditions were executed by implementing 3D FE meshes to establish the appropriate model's bending governing differential equation. After that, the corresponding parameter definitions were calibrated from the database of 3D FE models. By redefining the model's input parameters, a suitable solution is achieved, offering a good balance between the results' accuracy and the required computational effort. The functionality of the newly obtained solutions was verified through some comparative case studies that supplement the derivations. [ABSTRACT FROM AUTHOR]

This paper studies the chatter stability of composite cutter bar milling system in rotating coordinate frame. The main contribution of this paper is establishing a continuous distributed chatter analysis model for a composite cutter bar milling system in rotating coordinate frame. The stability of the milling system with a rotary symmetric dynamic cutter bar is predicted using the semi‐discrete time domain method. The effects such as internal damping, external damping, and symmetrical and asymmetric laminates on the stability of the milling system were analysed, and the results were compared between rotating and fixed coordinate frames. The results are consistent for symmetrical cutter bars in both the rotating and fixed coordinate frames. A new chatter instability zone appears at high rotating speeds due to the material internal damping of the rotating composite cutter bar. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the transient response of Lorentz force at finite magnetic Reynolds numbers Rm on an electrically conducting rectangular bar that is strongly accelerated in the presence of a localized magnetic field. This is done through numerical simulations utilizing a coupled finite-difference boundary element approach. The results show good qualitative agreement with existing experiments with a circular cylinder. The Lorentz force rise time is seen to be a linear function of Rm . The linear dependence of Lorentz force on Rm is found to be valid only for low values of Rm , after which the slope decays leading to an apparent saturation in the Lorentz force at sufficiently large values of Rm . Our results provide important information for the development of Lorentz force flow meters for transient flow applications. [ABSTRACT FROM PUBLISHER]

In this paper, a new possibility of fabricating a metal lattice structure with a continuous rod is demonstrated. A multi-layer, periodic, and aperiodic lattice structure can be manufactured with a continuous thin rod by bending it with a repetitive pattern. However, joining their nodes are challenging and an important problem to solve. This paper is investigating the joining of nodes in a loose lattice structure by delivering materials through the dipping process. Both liquid state (epoxy) and solid-state (inorganic particles) joining agents are considered for polymer–metal and metal–metal bonding, respectively. Liquid Carrier Systems (LCS) are designed considering their rheological behavior. We found 40% solid loading with the liquid carrier system provides sufficient solid particles transfer at dipping and join the lattice node using transient liquid phase bonding (TLP). 3D metal lattice structures are constructed, and their mechanical properties are investigated. The lattice structure shows comparable strength even with smaller relative density (< 10%). The strength and elastic modulus of all the fabricated samples decreases with the increase in cell size, which is consistent with the traditional wisdom. [ABSTRACT FROM AUTHOR]

In steel-concrete composite girders, composite dowel rib shear connectors can be used to transfer shear forces between the concrete slab and the steel section. In regions with negative bending moment, where concrete cracking occurs, the shear capacity of composite dowel connectors may be affected by transverse concrete cracks. So far, the internal shear-carrying mechanisms of composite dowel connectors in cracked concrete are not clarified, and existing shear capacity models do not account for concrete cracking. Hence, the present paper summarizes the results of 38 shear tests, providing novel insights regarding the pryout failure in cracked concrete. The tests were performed in an innovative test setup allowing the investigation of the impact of crack spacing and crack width. Using the test results, the present paper analyzes the phenomenology of pryout failure in cracked concrete. [ABSTRACT FROM AUTHOR]

Thin sheets assembled into three dimensional folding origami can have various applications from reconfigurable architectural structures to metamaterials with tunable properties. Simulating the elastic stiffness and estimating deformed shapes of these systems is important for conceptualizing and designing practical engineering structures. In this paper, we improve, verify, and test a simplified bar and hinge model that can simulate essential behaviors of origami. The model simulates three distinct behaviors: stretching and shearing of thin sheet panels; bending of the initially flat panels; and bending along prescribed fold lines. The model is simple and efficient, yet it can provide realistic representation of stiffness characteristics and deformed shapes of origami structures. The simplicity of this model makes it well suited for the origami engineering community, and its efficiency makes it suitable for design problems such as optimization and parameterization of geometric origami variations. [ABSTRACT FROM AUTHOR]

This paper presents a 2-D static analytical method in the frequency domain for the calculation of magnetic field distribution, eddy-currents, circuit model parameters, and steady-state performances in multiphase/multipole cage rotor induction motors with integer and fractional stator winding. The complex model allows to study the healthy, defective, and broken bars conditions in these electrical machines. The proposed static analytical model considers stator and rotor slotting with tooth-tips. The method is based on the resolution of Poisson’s, Laplace’s, and Helmholtz’s equations in stator slots, air-gap, and rotor bars regions, respectively. The electromagnetic torque is obtained from both the electrical equivalent circuit and Maxwell stress tensor that is given by the magnetic field calculation. The analytical results are validated by those issued from time harmonic finite-element method. [ABSTRACT FROM PUBLISHER]

This paper presents two types of new deployable mechanisms based on the motion characteristics of the four-bar slider–crank mechanism (FBSCM): the prism mechanism with constant cross-section and the round deployable mechanism. A new basic planar deployable unit based on the path-generating characteristics of the FBSCM is proposed. The method of building a deployable mast unit with one DOF from the new planar deployable mechanism is given. The prism mechanism with constant cross-section of one DOF is constructed, and the magnification ratio is analyzed. Moreover, the deployable unit with a negative Poisson's ratio for building the round deployable mechanism based on the properties of functional output of the FBSCM is proposed. The structure of the round deployable mechanism is described, and the parameter model with multilevel deployment is calculated and validated with cases given; the DOF of the round deployable mechanism is one. Last, the static analysis of the round deployable mechanism is studied by simulation; by locking 6 guide rails, the structure is found to have a balanced bearing capacity, and the bearing performance is improved compared with locking only one guide rail. [ABSTRACT FROM AUTHOR]

It is necessary to generate the yield position away from the column face to minimize damage to the beam-column joint during a large earthquake in a reinforced concrete building. The same efficacy can be realized using partially high strengthened rebar. The number of longitudinal bars can be calculated for a bending moment smaller than the column face, reducing their number compared to the conventional bar-arrangement method. This paper describes reinforced concrete an interior beamcolumn subassemblage tests using this rebar as the longitudinal bars of beams and a column. The beam yield hinge was formed at a position apart from the column face, and the damage to the beam-column joint was less than the conventional bar-arrangement method. Additionally, the good performance was obtained if the bending strength of the column was large, even if the shear capacity margin of the beam-column joint was small. The column-beam flexural strength ratio and shear capacity margin at the beam-column joint need to be set with consideration of their relationship. [ABSTRACT FROM AUTHOR]

The compression load of straight bars, for which the cross-sections are smaller compared to their length, causes a phenomenon of bending along the longitudinal axis. Upon reaching a certain level, called the critical level of the stresses, the bending deformations begin to increase beyond the bearing limit of the bar. It yields instantly, due to an unstable elastic deformation state, although the material's resistance limit has not been exceeded. The irreversibility of the phenomenon is dangerous especially for the railway tracks and is not fully mastered by calculation methods. They can eventually establish the level of the critical demand, which has values specific to each rail configuration. It is accepted that for loads lower than this level, buckling of the respective rail does not occur. The longitudinal tension in the railway tracks occurs due to the expansion caused by their heating under the action of the sun's rays, but also due to the friction between the rails and the train wheels. This paper proposes the realization of a study model of the buckling of the railway tracks. This model is represented by an assembly, built in the SOLIDWORKS application for which a Buckling simulation was made. The imposition of two distinct temperatures on the rails and crossties is the source of the model's request. The increase in the temperature of the component parts of the assembly causes their expansion, so implicitly the appearance of some longitudinal deforming forces, specific to the buckling phenomenon. [ABSTRACT FROM AUTHOR]

The planar mechanisms with articulated bars and gears (which we will simply note MeBaRd) are part of the general planar mechanics category. Although structural structural studies have been carried out [7], the structural synthesis of bars and wheels can be approached as a distinct problem. Some papers refer directly to a certain class of mechanisms, such as planetary mechanisms [1], [2], others stop on subsystems with zero mobility, called structural groups with toothed elements [6], [8]. In this paper, developing some ideas presented in [3], [5], a general algorithm for unitary structural synthesis of MeBaRd was developed and developed, having the input parameters: M - the degree of mobility and N - the number of contours. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo 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.)

Copyright of Journal of Engineering Sciences is the property of Faculty of Engineering - Assiut University 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.)

The objective of this paper is to use µ-X-ray fluorescence (XRF) analysis to evaluate the fineness and components of European Medieval Silver Bars samples. Conductivity measurements were used to assess the fineness and localization of the faults found in the samples. Because unevenness causes a change in conductivity, the tests were performed on the flattest areas of the Bars. Some rods, such as B3 and B9, have greater conductivity than others. All bars were subjected to the segregation test. In the instance of certain bars, it was not always practicable to categorically state that segregation had happened. There is no diminishing conductivity curve as one moves away from the zero height, as there is for bars B1, B8, and B9. As a result, there may be no solidification on these bars from Obverse to Reverse. A scanning electron microscope was used to record the following bars at various positions on the bars, and quantitative determinations were achieved using energy-dispersed XRF analysis through intensity measurements of the element-specific wavelength. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the wave propagation in a generalized piezothermoelastic rotating bar of circular cross-section using three-dimensional linear theory of elasticity. Design/methodology/approach – A mathematical model is developed to study the wave propagation in a generalized piezothermelastic rotating bar of circular cross-section by using Lord-Shulman (LS) and Green-Lindsay (GL) theory of thermoelasticity. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been derived by using the thermally insulated/isothermal and electrically shorted/charge free boundary conditions prevailing at the surface of the circular cross-sectional bar. The roots of the frequency equation are obtained by using the secant method, applicable for complex roots. Findings – In order to include the time requirement for the acceleration of the heat flow and the coupling between the temperature and strain fields, the analytical terms have been derived for the non-classical thermo-elastic theories, LS and GL theory. The computed physical quantities such as thermo-mechanical coupling, electro-mechanical coupling, frequency shift, specific loss and frequency have been presented in the form of dispersion curves. From the graphical patterns of the structure, the effect of thermal relaxation times and the rotational speed as well as the anisotropy of the of the material on the various considered wave characteristics is more significant and dominant in the flexural modes of vibration. The effect of such physical quantities provides the foundation for the construction of temperature sensors, acoustic sensor and rotating gyroscope. Originality/value – In this paper, the influence of thermal relaxation times and rotational speed on the wave number with thermo-mechanical coupling, electro-mechanical coupling, frequency shift, specific loss and frequency has been observed and are presented as dispersion curves. The effect of thermal relaxation time and rotational speed on wave number for the case of generalized piezothermoelastic material of circular cross-section was never reported in the literature. These results are new and original. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Polytechnic Institute of Iasi - Construction & Architecture Section is the property of Sciendo 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.)

The phenomenon of the lateral instability of the vehicle when the steering is one of the extremely serious and dangerous problems. To improve safety and stability, vehicles often are equipped with stabilizer bars at the front and rear axles. However, the passive stabilizer bar cannot guarantee safe and stable performance in dangerous cases. Therefore, the active stabilizer bar is used to replace the passive stabilizer bar. The active stabilizer can automatically generate an anti-roll moment depending on the condition of the vehicle at each time. In dangerous cases, the anti-roll moment of the active stabilizer bar is much greater than the passive stabilizer bar. This research focused on the problem of establishing a spatial dynamics model in combination with a nonlinear double-track dynamic model to describe the state of oscillation of the vehicle when steering. The PID control method is used to control the hydraulic stabilizer bar. The results of the research indicated that when the vehicle was equipped with the hydraulic stabilizer bar, the values of the roll angle, the displacement of the un-sprung mass, the vertical force at the wheel, ... were significantly reduced. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum: Architectura is the property of Wydawnictwo SGGW 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.)

This paper presents cyclic responses of five exterior beam-column joints made with 100 ksi (690 MPa) longitudinal bars, 115 ksi (790 MPa) transverse reinforcement, and 10 ksi (70 MPa) concrete. The test joints satisfied the existing ACI 318 design provisions for special moment frames, except for the joint shear demands, the anchorage limitations of the maximum bar yield strength, the maximum concrete strength, and the minimum clear spacing between headed bars. The test results show that the minimum development length can be used for anchorage of closely spaced headed bars in well-confined joints. It is found that the deformation capacity of beam-column joints could be increased by reducing the joint shear demand or increasing the joint transverse reinforcement ratio. The presented test results were assembled with previous research data for assessing the design provisions. This paper proposes several modifications to the existing design provisions for beam-column joints using high-strength reinforcement and concrete. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study on the anchorage strength of conventional and high-strength steel hooked bars. Three hundred and thirty-seven exterior beam-column joint specimens were tested with compressive strengths ranging from 4300 to 16,500 psi (30 to 114 MPa). Parameters investigated included the number of hooked bars per specimen, bar diameter, side cover, amount of confining reinforcement, hooked bar spacing, hook bend angle, hook placement, and embedment length. Bar stresses at failure ranged from 22,800 to 144,100 psi (157 and 994 MPa). The majority of the hooked bars failed by a combination of front and side failure, with front failure being the dominant failure mode. Test results show that development lengths of hooked bars calculated based on ACI 318-14 are very conservative for No. 5 (No. 16) bars and become progressively less conservative with increasing bar size and concrete compressive strength. [ABSTRACT FROM AUTHOR]

The aim of this paper is to find a computationally efficient and predictive model for the class of systems that we call 'pantographic structures'. The interest in these materials was increased by the possibilities opened by the diffusion of technology of three-dimensional printing. They can be regarded, once choosing a suitable length scale, as families of beams (also called fibres) interconnected to each other by pivots and undergoing large displacements and large deformations. There are, however, relatively few 'ready-to-use' results in the literature of nonlinear beam theory. In this paper, we consider a discrete spring model for extensible beams and propose a heuristic homogenization technique of the kind first used by Piola to formulate a continuum fully nonlinear beam model. The homogenized energy which we obtain has some peculiar and interesting features which we start to describe by solving numerically some exemplary deformation problems. Furthermore, we consider pantographic structures, find the corresponding homogenized second gradient deformation energies and study some planar problems. Numerical solutions for these two-dimensional problems are obtained via minimization of energy and are compared with some experimental measurements, in which elongation phenomena cannot be neglected. [ABSTRACT FROM AUTHOR]

This paper presents an efficient model-updating method suitable for complex finite element model with shell and solid elements utilising static inspection data. Based on the standard parameter estimation procedure, a simplified parameterisation procedure based on engineering experience and static inspection was used. Moreover, the parameter estimation was conducted by stages according to the sensitivity level of parameters. To verify the effectiveness of the algorithm, a curvilinear steel box girder bridge is taken as a research case study. General damage detection and corresponding rehabilitation are conducted. It indicates that the parameterisation procedure can meet the practical engineering demands. The multistage model-updating method is more effective and efficient than direct model updating, especially when low sensitivity level parameters are removed from the parameter groups. The updated model can contribute to reveal the behaviour of the structure and can be used for related safety assessment and rehabilitation according to the case study. It is proved that the method shown in this paper works well for existing complex structures. It is sufficient for practical engineering demand and can provide useful reference for similar projects. [ABSTRACT FROM PUBLISHER]

Conventional reinforced concrete shear walls are vulnerable to strong earthquakes with significant residual deformations, which substantially affect structural service and can even lead to structural collapse. Superelastic shape memory alloys (SMAs) are advanced materials that can realize strain recovery upon unloading. If SMAs can be used as reinforcing bars in structures, they can undergo large deformation without permanent deformation. This study presents a complementary and synergistic material system that integrates SMA with damage-tolerant engineered cementitious composites (ECCs) to minimize residual displacement and mitigate concrete damage. This study explored the seismic performance of shear walls using SMA and ECC in the plastic hinge region. Reverse cyclic loading tests were performed on four specimens to demonstrate the feasibility of this method. The specimens included a conventional steel-reinforced concrete shear wall (SW-R-C), steel-reinforced ECC shear wall (SW-R-ECC), SMA-reinforced concrete shear wall (SW-SMA-C), and SMA-reinforced ECC shear wall (SW-SMA-ECC). The results show that the SW-SMA-C specimen exhibited remarkable self-centering capability of more than 85% even after a large deformation, compared to SW-R-C. Furthermore, reduced damage and better ductility were observed in the SW-SMA-ECC specimen in addition to reduced residual displacement. The proposed approach indicated that SMA combined with ECC is more effective in mitigating plastic hinge damage and minimizing residual displacements, which could improve the seismic performance of shear walls. [ABSTRACT FROM AUTHOR]

Abstract The use of glass fibre reinforced polymer (GFRP) bars as internal reinforcement of concrete structures has been growing, mainly due to the advantages they present over steel reinforcement, namely their low weight, high strength and corrosion resistance. However, at moderately elevated temperatures, especially when approaching the glass transition temperature (T g) of the polymeric matrix (usually between 65 and 150 °C), the stiffness, strength and bond properties of these rebars are known to be significantly degraded. The first part of this paper presents an experimental investigation comprising tensile and pull-out tests on sand coated GFRP rebars at elevated temperatures under steady-state conditions; the tensile tests were carried out up to 300 °C, whereas the pull-out tests were performed up to 140 °C (measured at the GFRP-concrete interface); two embedment lengths of the rebars were considered. The obtained results confirmed that the stiffness and strength of the GFRP-concrete interface are significantly reduced with temperature increase, especially when the T g of the GFRP rebars is approached and exceeded. In the second part of the paper, analytical bond vs. slip relations for the GFRP-concrete interface are proposed for each of the tested temperatures; the defining parameters of these local laws were calibrated with the experimental data from the pull-out tests. Moreover, the accuracy of two empirical (relaxation) models in predicting the GFRP-concrete bond strength reduction with temperature was also assessed. [ABSTRACT FROM AUTHOR]

Abstract This research is motivated by the problem of regenerative chatter vibration, which is a pronounced problem in machining. The problem of chatter vibration is especially critical in the internal turning process, where the material is removed from the inner part of a rotating workpiece using a slender bar. Active mechatronic solutions to the problem of regenerative chatter vibration in internal turning are mostly given by means of piezoelectric actuators embedded into the boring bar. However, due to the volume needed for accommodation of the actuators, it is difficult to apply these solutions to narrow bars. This paper presents a novel actuation approach with a potential application for active control of regenerative chatter vibration in internal turning. This approach involves a bar whose clamping has an ability to move perpendicularly to the bar axis. In addition, it involves two actuators: one of them is placed near the bar clamping, and another one is placed at the bar clamping. The presented actuation approach is compared to the related approaches in the literature. Additionally, this paper presents a method for robustness analysis of the actively controlled cutting process, which is based on the structured singular value methodology. Experiments performed on a specially designed testbed imitating the internal turning process demonstrate the potential applicability of the introduced actuation approach, as well as the utility of presented robustness analysis method. [ABSTRACT FROM AUTHOR]

The present paper provides a collision model for Cosserat rods, able to represent a very general collision response, including frictional effects as well as multiple simultaneous collisions of a large number of rods. The proposed collision model falls into the category of constraint-based collision models. This concept is extended to a general class of objects sharing properties of rigid and deformable bodies, here undertaken for viscoelastic Cosserat rods. The collision constraints are imposed by collision impulses added to the external loads of the equations of motion of the colliding objects. No iterations between the equations of motion and the collision model are required. Both parts are executed in a staggered manner, so that the collision model is well separated from the equations of motion. Hence, existing solvers for Cosserat rods or similar objects can easily be extended, so that the range of application is significantly enlarged to the collisional regime. Extensive validations are presented using various test cases, ranging from a collision of a single rod with a wall to more realistic configurations with multiple simultaneous collisions of numerous rods. [ABSTRACT FROM AUTHOR]

Materials and structures are exposed to simultaneous fluctuations in temperature, pressure, and moisture in the environment, which result in additional stresses and strains in addition to mechanical loadings. This paper develops the effective coefficient of thermal expansion (CTE), coefficient of moisture expansion (CME), and compressibility for the interconnected array of ring and sliding rod structures made from conventional materials, wherein conditions that lead to negative thermal expansion (NTE), negative moisture expansion (NME) and negative compressibility (NC) -- and hence the negative environmental expansion (NEE) -- are established. The above-mentioned coefficients shift toward negative values as the ratio of ring-to-rod expansivity increases. The established effective CTE, CME, and compressibility not only permit the requirements for NTE, NME, and NC to be ascertained, but also allow the less restrictive condition of zero environmental expansion to be implemented in the design of materials and structures, without requiring zero CTE, CME, and compressibility. [ABSTRACT FROM AUTHOR]

Conventional sensors for debris flow monitoring suffer from several drawbacks including low service life, low reliability in long-distance data transfer, and stability in severe weather conditions. Recently, fiber Bragg grating (FBG)-based sensors have been developed to monitor debris flows. However, they can be easily damaged by the impact forces of boulders within debris flow. This paper presents a new FBG-based device to measure the strain induced by the impact force of debris flow with high reliability and effectiveness. The effects of the impact forces of debris flows have been investigated. Then, the relationship between the strain and the debris flow energy correlating with the damage to building structures has been established. It is shown that this new FBG-based device is capable of monitoring and warning about debris flows. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation of torsional strength and behavior of full-scale concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars and stirrups. The beams measured 4000 mm (157.5 in.) long, 250 mm (9.8 in.) wide, and 600 mm deep (23.6 in.) and were tested under pure torsion loading. The test specimens included four beams reinforced with GFRP bars and stirrups and one control beam reinforced with conventional steel reinforcement. The test variables were the type and ratio of torsional reinforcement. As designed, all specimens failed due to diagonal torsional cracking with GFRP stirrup rupture. The test results indicated that the GFRP-reinforced concrete (RC) beam exhibited similar strength and cracking behavior with lower post-peak torsional stiffness compared to the counterpart steel RC beam. In addition, it was found that the closer the spacing of the GFRP stirrups, the higher the enhancement of the torsional strength with improvement in the post-peak stiffness. Finally, the paper examines the validity of the new design provisions in CAN/CSA S806-12 in predicting the nominal torsional strength of GFRP RC beams. [ABSTRACT FROM AUTHOR]

In this paper an analytical, exact procedure for the reconstruction of simply supported bending vibrating beams having given values of the first N natural frequencies is presented. The results hold for beams in which the product between the bending stiffness and the linear mass density is constant. The analysis is based on the fact that this class of beams is spectrally equivalent to a family of strings fixed at the ends, and uses recent results on the exact construction of second-order Sturm–Liouville operators with prescribed natural frequencies. The analysis can be adapted to beams with pinned–sliding and sliding–sliding ends. [ABSTRACT FROM PUBLISHER]

Copyright of Bulletin of the Polytechnic Institute of Iasi - Construction & Architecture Section is the property of Sciendo 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.)

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo 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.)

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The paper proposes an implementation of creep analysis of reinforced concrete structures which utilizes the B3 model and the direct stiffness method for reinforced concrete frames. The analysis is based on a numerical integration and it is implemented in an algorithmic programming language. There is presented a solution with the mentioned approaches which is compared with solution based on the EN 1992-1-1 technical standard. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a new approach to detect the location of multiple broken rotor bars (MBRBs) in induction motor (IM) drive, running under no load and full load conditions using direct in and variable frequency drives. This technique is based on earlier work of location detection of one broken rotor bar. The techniques are tested for various fault severity levels so the detection of the exact location of the fault at early stage helps to reach sufficient time maintenance. In this paper, the authors used Hilbert Transform to extract the fault signature from the stator current envelope which is the low frequency component. Then statistical analysis is applied which produce a formula that is used to get the exact location of the fault in IM rotor. Highlights • Novel approach for detecting the location of multiple broken bar in a three-phase induction motor squirrel cage rotor. • Hilbert transform is applied to obtain the envelope of the signal. • Statistical analysis is used in extracting the fault location by analyzing the envelope of the signal. • The proposed technique offers fast computational and accurate location diagnostic process. • The diagnostic technique is considered for detecting two and three broken rotor bars. [ABSTRACT FROM AUTHOR]

This paper presents results of an investigation on the development of headed bars extending from a column into the slab of a reinforced concrete slab bridge. Three full-scale slab-column specimens were tested under quasi-static cyclic lateral loading to determine the minimum embedment length required for the headed bars to develop their full tensile capacity, and the reinforcement details needed in the slab-column joint region to prevent premature anchorage failure, when a plastic hinge forms at the top of the column. The experimental results showed that for 5000 psi (34.5 MPa) concrete and Grade 60 steel, a development length equal to 11 times the bar diameter is adequate for headed bars in slab-column joints designed according to Caltrans specifications with a minimum of 2 in. (50.8 mm) of clear concrete cover. Specimens with shorter embedment lengths were able to develop the moment capacity of the columns and showed significant ductility, but exhibited moderate to severe punching cracks in the cover concrete of the slabs. Finite element analyses of slab-column assemblies showed that punching damage can be eliminated by increasing the concrete cover above the bar heads. [ABSTRACT FROM AUTHOR]

In deep hole boring process, long and flexible boring bars are often used. Due to the large length-to-diameter ratio, the stiffness of the boring bars is inevitably reduced, where the boring bars’ vibration effects will occur. The influences of vibration will significantly degrade the accuracy and the surface quality, or even lead failure of the production. Therefore, it is of significant importance to develop techniques to reduce vibration in deep hole boring. In this paper, a new boring bar with a variable stiffness dynamic vibration absorber (VSDVA) is presented, where the basic parameters of the proposed boring bar are measured. Based on the proposed dynamic model, the vibration characteristics of the proposed boring bar are analyzed, and the change laws of the vibration reduction performance are obtained under different excitation frequencies. A new vibration reduction method is proposed, where best vibration reduction performance can be achieved by adjusting the stiffness of the VSDVA. Finally, the vibration reduction performance of the proposed boring bar is validated and evaluated by boring experiments. These works could provide guidance for designing new types of boring bars, selecting cutting parameters, and adjusting the vibration reduction performance of the proposed boring bar, and as a result, it provides a new design idea for the design of boring bar. [ABSTRACT FROM AUTHOR]