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The present work investigates the mode-I fracture of single-edge notched beams under symmetric three- and four-point bends through dual-horizon peridynamic simulations. Mode-I J-integral and crack opening displacement are computed for a wide range of initial crack length-beam width ratios. δ-Convergence is carried out. Results are discussed with analytical and finite element methods. Peridynamic simulations agree well with analytical results. [ABSTRACT FROM AUTHOR]

The accurate and precise prediction of shear and flexural strengths in reinforced concrete (RC) and fiber-reinforced concrete (FRC) beams necessitates advanced computational techniques. This study pioneers the application of an Artificial Neural Network (ANN) to model these strengths and to classify failure modes in beams. Leveraging a dataset of 116 experimental tests on ultimate strengths from extensive literature, the ANN was meticulously trained, tested, and validated, revealing that the optimal neuron count for the modeling task was 15. This configuration achieved a root mean square error (RMSE) of 0.096 MPa and a coefficient of determination (R²) of 0.95, outperforming traditional design models. The study further explored an independent variable importance analysis, revealing that the beam width and effective depth were paramount in predicting strengths, findings that are congruent with established structural engineering principles. The analysis also highlighted the significance of post-cracking resistance parameters, particularly the residual flexural strength at 2.5 mm deflection, in enhancing the predictive model. The ANN classification successfully differentiated between shear and flexural failure modes, achieving an impressive accuracy of 96.5% with 25 neurons. This dual strength to model and classify underscores the ANN's robustness, offering a comprehensive tool that surpasses conventional model codes in both accuracy and precision. The results advocate for the integration of ANN techniques in structural design, promising a future where machine learning not only informs but also transforms engineering practices. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on 18 specimens, including 15 polyvinyl chloride (PVC)‐carbon fiber‐reinforced polymer (CFRP) tube confined reinforced concrete beams with longitudinal CFRP sheets (PCT‐RCBs‐LCS) and 3 PVC‐CFRP tube confined reinforced concrete beams (PCT‐RCBs). The effects of five studied parameters, such as longitudinal reinforcement rate (ρs$$ {\rho}_{\mathrm{s}} $$), concrete strength grade (Sc$$ {S}_{\mathrm{c}} $$), width (df$$ {d}_{\mathrm{f}} $$) and number (nf$$ {n}_{\mathrm{f}} $$) of longitudinal CFRP sheet, and specimen dimensions (Ds$$ {D}_{\mathrm{s}} $$), on the failure mode and flexural capacity are investigated. The PCT‐RCBs‐LCS with lower df$$ {d}_{\mathrm{f}} $$ and nf$$ {n}_{\mathrm{f}} $$ fail by the breakage of the PVC tube and the fracture of longitudinal CFRP sheets. Conversely, the cracking of PVC tube dominates the damage of the PCT‐RCBs‐LCS with higher df$$ {d}_{\mathrm{f}} $$ and nf$$ {n}_{\mathrm{f}} $$, while the longitudinal CFRP sheets are not broken. The introduction of longitudinal CFRP sheets can significantly improve the flexural capacity. The ultimate flexural capacity of the PCT‐RCBs‐LCS increases as the ρs$$ {\rho}_{\mathrm{s}} $$, sc$$ {s}_{\mathrm{c}} $$, df$$ {d}_{\mathrm{f}} $$, nf$$ {n}_{\mathrm{f}} $$ or Ds$$ {D}_{\mathrm{s}} $$ increases. In addition. considering the influence of RC beam section shape, a model for predicting the ultimate flexural capacity of the PCT‐RCBs‐LCS is proposed based on the limit equilibrium theory and cross‐sectional strain relationship. The predicted results of the proposed model agree well with test data. [ABSTRACT FROM AUTHOR]

An investigation was conducted to assess the efficacy of using waste rubber as a substitute for a portion of an aggregate to enhance concrete's sustainability. For the purpose of accomplishing this objective, a total of 12 specimens were constructed and then subjected to a series of tests to investigate their bending behavior. The samples were constructed with the following dimensions: 1000 mm length and a 100 mm by 150 mm cross-sectional area. A few factors were selected, including the impacts of the longitudinal reinforcement ratio and the waste rubber ratio. Based on the volume of aggregates, rubber replacement rates of 0%, 5%, 10%, and 15% were investigated in this study. To assess the beam bending behavior, the stirrup width and spacing were kept constant at ∅6/10. The longitudinal reinforcement was composed of three diameters: ∅6 at the top (for all beams) and ∅8, ∅10, and ∅12 at the bottom. The experimental results demonstrated that the effects of varying amounts of waste rubber and tension reinforcement on the bending and cracking of reinforced concrete beams (RCBs) were varied. The findings indicate that the incorporation of waste rubber into concrete results in a reduction in both the load-carrying capacity and the level of deformation of the material. Additionally, it was shown that as the amount of waste rubber in the RCB increased, the energy absorption capacity and ultimate load decreased. There was a reduction in energy dissipation of 53.71%, 51.69%, and 40.55% for ∅8 when longitudinal reinforcement was applied at 5%, 10%, and 15% replacement, respectively. Additionally, there were reductions of 25.35%, 9.31%, and 58.15% for ∅10, and 38.69%, 57.79%, and 62.44% for ∅12, respectively. [ABSTRACT FROM AUTHOR]

This article discusses the software tool (Simscape—Multibody program of MATLAB) primarily intended for dynamic and kinematic processes with practical applications in static calculations. Currently, there are few published scientific works utilizing this tool for tasks like basic static calculations of truss systems. We were interested in comparing the calculation using the tools we use in our work and research activities for theoretical calculation; the potential reliance on simulations in the future could help to avoid the necessity of complex theoretical calculations, which can be time-consuming and prone to errors. Despite the fact that the structure may appear simple, in practice, there may not always be time for a verification calculation in the theoretical field (proper model creation, inclusion of all conditions, etc.). The beam system is intentionally both externally and internally statically indeterminate. For this reason, it is logically necessary to also consider deformation conditions. The achieved results were interesting in terms of accuracy compared to SOLIDWORKS, which was used for computation verification. Through very simple optimization, we were able to further increase the calculation accuracy without complicating other parameters. [ABSTRACT FROM AUTHOR]

The strengthening, rehabilitation and repair of wooden beams and beams made of wood-based materials are still important scientific and technical issues. This is reflected, among other things, in the number of scientific articles appearing and the involvement of research centres around the world. This is also related to society's growing belief in the importance of ecological and sustainable development. This article presents an overview of the latest work in this field and the results of our own research on strengthening solid wooden beams with carbon-fibre-reinforced polymer (CFRP) sheets. The tests were carried out on full-size solid beams with nominal dimensions of 70 × 170 × 3300 mm. A 0.333 mm thick CFRP sheet was used for reinforcement. The research analysed various reinforcement configurations and different reinforcement ratios. For the most effective solution, a 46% increase in load capacity, 35% stiffness and 249% ductility were achieved with a reinforcement ratio of 1.7%. Generally, the higher the reinforcement ratio and coverage of the surface of the wood, the higher the strengthening effectiveness. The brittle fracture of wood in the tensile zone for unreinforced beams and the ductile crushing of wood in the compressive zone for reinforced beams were obtained. The most important achievement of this work is the description of the static work of beams in previously unanalysed configurations of strengthening and the confirmation of their effectiveness. The described solutions should extend the life of existing wooden buildings and structures and increase the competitiveness of wooden-based structures. The results indicate that, from the point of view of optimizing the cost of reinforcement, it is crucial to develop cheaper ways of combining wood and composite than to verify different types of fibres. [ABSTRACT FROM AUTHOR]

The present manuscript delineates the derivation of strong solutions for the linear elasticity problem in a two dimensional rectangular beam. The materials under consideration can exhibit either isotropic or orthotropic properties. Additionally, the analysis is not restricted to slender beams because the ratio between the length and the height of the beam can be arbitrary. The boundary conditions fall into the Dirichlet category, implying that both horizontal and vertical displacements are specified on all four surfaces. The sole requirement is that these surface displacements are continuous functions, although they may not necessarily be smooth. Since the displacements at the surfaces can be arbitrary, there is no need to consider approximations, such as those concerning local (small) boundaries in slender beams. Nonetheless, it is demonstrated that an equivalent principle to the Saint-Venant principle exists for pure displacement boundary conditions. The partial differential equations are solved through the separation of variables method, leading to the identification of two solution types, encompassing both cosine and sine Fourier series. Particular emphasis is placed on evaluating the convergence of these solutions. For two distinct and general examples, it is confirmed that the solutions indeed exist. • Derive strong solutions for linear elasticity in a 2D rectangular beam. • The boundary conditions are of the Dirichlet category. • The surface displacements are continuous but not necessarily smooth. • Identify two type of solutions and evaluate the convergence. • Confirm existence of solutions through two distinct general examples. [ABSTRACT FROM AUTHOR]

Steel-concrete composite beams are ubiquitous in construction, especially in bridge building. This paper addresses the harvesting of energy from a beam subjected to a moving harmonic load using analytical methods. The harvesting is performed by attaching a thin piezoelectric patch directly to the bottom surface of the steel beam. Based on the assumptions of the Euler-Bernoulli beam theory for the relationship between displacement and deformation, the differential equation for the vibration of a beam is derived using Hamiltonian principles. A theoretical formulation is presented for the problem of harvesting energy from a harmonic moving load on a simply supported beam. The dynamic responses are determined in exact form using analytical methods, and the energy harvested from the piezoelectric material layer is calculated. The influence of the speed of the load on the energy harvesting of the piezoelectric material layer is investigated in detail. [ABSTRACT FROM AUTHOR]

In various electron-optical and ion-beam devices and vacuum electronics installations, emission elements and units are used to extract and form beams of charged particles. Their focusing properties significantly affect the quality parameters and technical characteristics of the analytical devices and technological installations in which they are used. Due to the specificity of the initial conditions during the formation of the beams of charged particles in the area of charged particle extraction, the methods of studying single and conventional immersion electron lenses are not suitable for the high quality theoretical and numerical studies of the properties of immersion objectives. In this paper, theoretical and numerical studies were conducted on the problems in analyzing the focusing parameters of charged particles in emission elements and units when solving problems of designing and upgrading devices and installations of vacuum electronics. As a result of the studies, a theoretical method for studying cathode lenses with a curved optical axis was developed and options for solving problems in correcting aberrations of emission elements and units were proposed. [ABSTRACT FROM AUTHOR]

Due to its higher overall performance than ordinary concrete, polymer concrete (PC) beam has been widely used in the field of structural engineering. However, it is widely recognized that PC cannot simultaneously achieve the highest mechanical strength and optimal damping performance to reduce vibration during its long‐term service lifetime. To address this contradiction, the effect of various diluents contents on the overall performance of PC was investigated first in this investigation. Experimental findings revealed that the bending strength of PC exhibits an initial increase followed by a decrease with an increment of diluents, while its damping ratio displays an inverse trend. To obtain excellent overall performance (higher flexural strength and damping ratio) of PC, gradient PC has been manufactured by horizontal partition casting process (HPCP) and stereoscopic layered casting process (SLCP). Experimental results demonstrated that the gradient PC manufactured by HPCP exhibited better overall performance compared to SLCP. Furthermore, the graphite and carbon fiber were incorporated into the above gradient PC, and experimental results revealed that the incorporated graphite and carbon fiber can further increase the overall performance of the above gradient PC. Similarly, the incorporation of glass fiber cloth and carbon fiber cloth, along with surface treatment, significantly enhanced the overall performance of PC. The significance of this study lies in enhancing the comprehensive performance of PC beam structures, thus broadening its utilization scope within structural engineering. [ABSTRACT FROM AUTHOR]

Ratcheting analysis for cantilever beams subjected to the thermomechanical loads is presented using the finite element method. The cantilever beam is constrained along the vertical direction, and plane stress conditions are assumed according to the bilinear isotropic hardening model. Two points are considered to obtain areas of ratcheting by using linear extrapolation. The results and output diagrams for ratcheting with elastic-perfect plastic behavior are illustrated. It was revealed that the beam behaves elastically after the first considerable plastic strain, which is seen in two shakedown regimes. The numerical results are verified with known and analytical results in the literature. The results indicate a strong correlation between the outcomes from the cyclic ANSYS Parametric Design Language (APDL) model and Bree's analytical predictions. This consistency between the finite element analysis and the analytical solutions underscores the potential of finite element analysis as a powerful tool for addressing complex engineering challenges, offering a reliable and robust alternative to traditional analytical methods. [ABSTRACT FROM AUTHOR]

Designing or appraising framed concrete buildings exposed to high eccentric loads requires precise reinforced concrete (RC) torsional strength estimates. Unfortunately, semi-empirical formulae still fail to adequately predict the torsional capacity of RC beams, particularly over-reinforced and strong ones. To overcome this limitation, accurate Machine Learning (ML) models might replace more sophisticated and computationally intensive models. This work evaluates and determines the most effective tree-based machine learning algorithms to estimate the torsional capacity (7) of RC beams subjected to pure torsion. The objective of the present work is to provide innovative hybrid models that combine the concepts of the Adaptive neuro fuzzy inference systems (ANFIS) model with other optimization approaches, such as the Giant trevally algorithm (GTA) and Honey badger algorithm (HBA), to accurately forecast the Tr. A total of 202 RC rays were collected to form the data set. To facilitate the application of the ANFIS models, a training set and a testing set were created from the database. Out of the 202 samples in the database, 25 percent (51) were used for evaluation and 75 percent (151) were used for learning. ANFGTA demonstrated superior performance compared to ANF - HBA, with a 50% higher performance in the learning phase and an 80% higher performance in the evaluation stage, as measured by the MedSE index values. The ANF - GTA obtained lower SMAPE index values of 5.2192 and 5.39 compared to the values of 8.0622 and 9.3783 obtained by the ANF - HBA during the learning and assessment phases, respectively. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Transactions C: Aspects is the property of International Journal of Engineering (IJE) 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.)

Abstract Amidst the global pursuit of sustainable alternatives in concrete production, this study explores the viability of incorporating by-products or waste materials as aggregates to support the concrete construction industry, with a specific emphasis on steel slag. The objective of this study is to evaluate the effectiveness of steel slag as a partial replacement for fine and coarse aggregates in concrete production. The experiment involved casting 30 cubes and 10 beams, replacing fine aggregate from 0 to 60%. Flexural and compressive strength tests at 7 and 28 days followed the ACI method. Results revealed that a 30% replacement of fine aggregate with steel slag led to higher compressive strength at both 7 and 28 days, while a 45% replacement showed superior flexural strength at 28 days. Further chemical analysis and optimization are recommended for deeper insights. The study concludes with marginal improvements in compressive and flexural strength with steel slag partial replacement, identifying 30% for fine aggregate and 45% for coarse aggregate as optimal replacements. In addition, the mineral composition of steel slag exhibits significant variability, with compounds, including silicon dioxide (SiO2), iron oxide (Fe2O3), manganese oxide (MnO), aluminum oxide (Al2O3), and calcium oxide (CaO). Chemical analysis indicates high silicate content and minimal alkali content, contributing to enhanced strength during concreting. Higher steel slag replacement reduces workability, confirmed by slump tests. However, all mixes maintain a true slump, and unit weight increases with steel slag aggregate replacement. Compressive strength improves incrementally with higher steel slag content, echoing prior research. In addition, flexural strength rises with steel slag replacing both coarse and fine aggregates, suggesting enhanced performance in reinforced concrete structures. These findings highlight steel slag’s potential as a sustainable alternative in concrete production, aiming to advance its application in the construction industry, promoting environmental sustainability and economic viability.

This study examined the vibration behavior of a beam with linear spring attachments using finite element analysis. It aims to determine the natural frequency with both consistent/coupled mass and lumped mass matrices. The natural frequencies and corresponding mode shapes were correctly determined which formed the basis of any further noise vibration and severity calculations and impact or crash analysis. In order to obtain eigenfrequencies subject to the attached spring, the characteristic equation was obtained by eigenfunctions expansion whose roots were extracted using the root-finding technique. The finite element method by coupled and lumped mass matrices was then used to determine complete mode shapes against various eigenfrequencies. The mode shapes were then analyzed subject to supports with varying stiffness thereby comparing the analytical and numerical results in case of consistent and lumped masses matrices so as to demonstrate how the present analysis could prove more valuable in mathematical and engineering contexts. Utilizing a consistent mass matrix significantly enhanced accuracy compared to a lumped mass matrix, thereby validating the preference for the former, even with a limited number of beam elements. The results indicated that substantial deflection occurred at the beam's endpoints, supporting the dynamic behavior of the spring-beam system.

The specific properties of deformation and failure of a reinforced concrete frame are investigated under sequential realization of arch and catenary action of beams after removal of the middle row column. Numerical modeling with the use of solid- and beam-type finite element models is performed for the purposes of the study. It was found that at the failure of the column of the second row the beam of the frame above the point of column removal transform to catenary structure, as evidenced by the relative deflection 1/29.8 (179 mm). The compressed concrete at the outer face of the corner column then collapsed, followed by the complete collapse of the frame. It is shown that the results of calculation performed with the use of the frame model based on solid finite elements were visually close to the results of numerical modeling with the use of bar finite element models before the onset of catenary action of the beams. For more correct modeling of reinforced concrete frame structures when catenary action of beams is realized in them. It is advisable to use specific modeling methods, such as accounting for additional rotations of sections at crack formation.

In engineering practice, dynamic vibration absorber is an effective method to control vibration of beam structure. The mathematical model of beam coupled with spring–mass systems under elastic edge constraints is established in this paper. In addition to Fourier cosine series, supplementary sine functions are introduced to represent the displacement function of the beam. The spring–mass system is considered by increasing degrees of freedom when constructing the mass matrix and stiffness matrix. The efficiency of solving equivalent mass is greatly improved in the comparison with FEM, which is important when designing dynamic vibration absorber. Subsequently, we conduct parametric analysis of the control effect about the dynamic vibration absorber based on the current mathematical model. The procedure of designing distributed dynamic vibration absorber of beam structure under various boundary condition is also presented. To verify the validity of the current mathematical model and design procedure, a cantilever beam experiment was conducted. The findings presented in the current research may be useful for researchers in the process of multi-line spectrum vibration control of beam structure. [ABSTRACT FROM AUTHOR]

Amidst the global pursuit of sustainable alternatives in concrete production, this study explores the viability of incorporating by-products or waste materials as aggregates to support the concrete construction industry, with a specific emphasis on steel slag. The objective of this study is to evaluate the effectiveness of steel slag as a partial replacement for fine and coarse aggregates in concrete production. The experiment involved casting 30 cubes and 10 beams, replacing fine aggregate from 0 to 60%. Flexural and compressive strength tests at 7 and 28 days followed the ACI method. Results revealed that a 30% replacement of fine aggregate with steel slag led to higher compressive strength at both 7 and 28 days, while a 45% replacement showed superior flexural strength at 28 days. Further chemical analysis and optimization are recommended for deeper insights. The study concludes with marginal improvements in compressive and flexural strength with steel slag partial replacement, identifying 30% for fine aggregate and 45% for coarse aggregate as optimal replacements. In addition, the mineral composition of steel slag exhibits significant variability, with compounds, including silicon dioxide (SiO2), iron oxide (Fe2O3), manganese oxide (MnO), aluminum oxide (Al2O3), and calcium oxide (CaO). Chemical analysis indicates high silicate content and minimal alkali content, contributing to enhanced strength during concreting. Higher steel slag replacement reduces workability, confirmed by slump tests. However, all mixes maintain a true slump, and unit weight increases with steel slag aggregate replacement. Compressive strength improves incrementally with higher steel slag content, echoing prior research. In addition, flexural strength rises with steel slag replacing both coarse and fine aggregates, suggesting enhanced performance in reinforced concrete structures. These findings highlight steel slag's potential as a sustainable alternative in concrete production, aiming to advance its application in the construction industry, promoting environmental sustainability and economic viability. [ABSTRACT FROM AUTHOR]

Nonlinear elastic metamaterials are attracting increasing attention owing their unusual properties of wave manipulation. However, the robustness of these benefits under varying amplitude should be increased and the challenge lies in the design. Here, we demonstrate a robust design strategy of nonlinear metamaterial via combining collision and damping. The damping will not interfere but enhance the nonlinear effects for broadband vibration reduction. The design presents low-frequency, broadband, efficient vibration reduction under varying amplitude. The effect can be activated by a small input amplitude. The performance remains high in a large amplitude range, i.e., high robustness is achieved. This property is systematically demonstrated with simulations and experiments on a nonlinear metamaterial beam. This article can offer an effective method to realize robust vibration suppression. [ABSTRACT FROM AUTHOR]

A variationally consistent analytical beam model that describes the theory in a Timoshenko-Vlasov level is developed based on Reissner's mixed variational theorem. Starting from a shell theory, all the field-governing equations (equilibrium and continuity) and the boundary conditions of the shell wall are derived in closed form, and the mixed method enables finding the explicit forms of the reactive stresses and sectional warpings which are evaluated progressively depending on the level of beam model to be analyzed. The stress recovery part is incorporated in the post-stage of the analysis to compute the layer-wise distribution of stresses over the beam cross-section. The present analysis is validated against numerous benchmark examples available in the literature, including beams with multi-layered strip section, thin-walled anisotropic box sections with elastic couplings, and two-cell airfoil section. The comparison study demonstrates excellent correlations with the results from detailed three-dimensional finite element analysis and other up-to-date beam approaches. Also presented are symbolically expressed stiffness coefficients and the sectional warping modes of coupled composite beams to demonstrate the strength of the proposed beam model. [ABSTRACT FROM AUTHOR]

Shape sensing refers to the deformation reconstruction of structures using measured surface strain. However, there is currently a lack of research on the shape sensing of large deformations, especially for beam structures. To address this issue, this paper proposes a new method called the rotation angle approximation (RAA) for reconstructing large deformations of beam structures. This method utilizes theoretical and actual curvatures to create a least-squares error functional. By minimizing this functional, the rotation angles of the corresponding beam can be obtained, avoiding the accumulation of errors that occurs when using traditional computation methods. The deformed shapes can be predicted utilizing the boundary conditions and the rotation angles along the beam. This method can reconstruct the large deformation of a beam without requiring prior knowledge about the material properties or external loads. The accuracy and effectiveness of this method were validated through numerical simulations and experiments. The results indicate that this method can accurately predict the different deformations of a beam induced by various loading conditions. [ABSTRACT FROM AUTHOR]

This study examined the vibration behavior of a beam with linear spring attachments using finite element analysis. It aims to determine the natural frequency with both consistent/coupled mass and lumped mass matrices. The natural frequencies and corresponding mode shapes were correctly determined which formed the basis of any further noise vibration and severity calculations and impact or crash analysis. In order to obtain eigenfrequencies subject to the attached spring, the characteristic equation was obtained by eigenfunctions expansion whose roots were extracted using the root-finding technique. The finite element method by coupled and lumped mass matrices was then used to determine complete mode shapes against various eigenfrequencies. The mode shapes were then analyzed subject to supports with varying stiffness thereby comparing the analytical and numerical results in case of consistent and lumped masses matrices so as to demonstrate how the present analysis could prove more valuable in mathematical and engineering contexts. Utilizing a consistent mass matrix significantly enhanced accuracy compared to a lumped mass matrix, thereby validating the preference for the former, even with a limited number of beam elements. The results indicated that substantial deflection occurred at the beam's endpoints, supporting the dynamic behavior of the spring-beam system. [ABSTRACT FROM AUTHOR]

Fixed-wing unmanned aerial vehicles (UAVs) in the modern day have widespread applications in various reconnaissance, agriculture, military, and civilian operations. Their wide domain of application has placed the development of drone technology at the forefront. The energy harvesting in UAVs seems promising since it not only has the ability to lengthen flying time but also guarantees that no appreciable weight is added. The current article explores the concept of placing piezoelectric material patches on the UAV wing in order to extract energy from the vibration of the wing. This study uses a UAV's fixed NACA 2412 wing to harvest vibration energy by finding the location and placing a piezoelectric patch where it will produce the most voltage. The mode shapes generated are used to get the appropriate location to place the piezoelectric patch. The fixed-wing of a UAV with a piezo patch placed is subjected to a harmonically varying pressure load of 213.934 Pa and the behavior of the wing and its frequency response is analyzed in terms of displacement and voltage as output. The maximum voltage produced by the single piezoelectric patch is found about 0.11 V at the first mode shape of the wing. Embedding and increasing the patch at a location of high displacements help to harvest more energy and can be utilized for other purposes. [ABSTRACT FROM AUTHOR]

Textile Composites is a resin system containing a textile fiber, yarn, or fabric system for special properties. Cord knit is a simple and economic and fast technique for producing tubular textile fabrics. This article studied the effect of some variables such as outer layer yarn count and core material of poly-amide cord knitted fabrics on its properties and applying it as a cord-knitted composite bar for reinforcing concrete. six samples with two different outer layer yarn counts (1200 and 2400 denier) and three different core materials (polyamide, fiberglass, and polyethylene 50%, and polypropylene 50%) were produced and tested, then inserted in epoxy to convert to a composite cord. The properties of composite cord knitted fabrics were tested. Then different numbers of bars were used (one bar, two bars, and three bars) from the highest properties cord knitted poly-amide composite fabrics for reinforcing concrete beams (50 cm*10cm*10cm), flexure of those beams were tested and it was found that using two bars from poly-amide composite has the highest effect on reinforcing concrete beams. [ABSTRACT FROM AUTHOR]

The combination of glass fiber–reinforced polymer (GFRP) and ultrahigh-performance concrete (UHPC) to form structural members has generated significant interest due to their excellent durability and mechanical properties. This paper presents the flexural behavior and design methodology of GFRP-reinforced UHPC beams. Eight reinforced UHPC beams were tested to failure, varying in longitudinal reinforcement type (steel and GFRP), flexural reinforcement ratio, and steel fiber volume fraction (1% and 2%). Two flexural failure modes, including crack localization followed by rupture of GFRP (tension failure) and progressive crushing of UHPC followed by rupture of GFRP (compression failure), were observed in the tested GFRP-reinforced beams. Substitution of steel bars with GFRP bars resulted in delayed crack localization and a significant improvement in flexural strength by 54.9% and ultimate displacement by 55.7%. Increasing the GFRP reinforcement ratio showed a trend of increased flexural capacity, ultimate deformation, and energy dissipation capacity. Increasing the steel fiber volume in UHPC improved the flexural capacity of the tension failure–controlled beam, but had a slight effect on the flexural capacity of the compression failure–controlled beam. In addition, two different models were used to calculate beam deflection, and were compared with experimental results at the service load levels. Considering the fiber-bridging mechanism, a flexural strength model for GFRP-reinforced UHPC beams was developed. Finally, a minimum reinforcement ratio was proposed to ensure progressive failure of GFRP-reinforced UHPC beams. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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.)

Previously, classical boundary conditions (i.e. simple, fixed and cantilevered) have been adopted for the beams under the moving loads in deriving the dynamic response. In reality, most beams cannot be simply classified as the ones with classical supports, but are elastically restrained. For theoretical completeness, a general theory will be developed in this note for the damped beams with elastic restraints modeled by vertical and rotational springs subjected to a moving damped sprung mass. Essential to the present theory is the solution of the transcendental equation for the frequency by the bi-section method. The solution obtained can also be applied to the classical boundary conditions (i.e. simple, fixed and cantilevered) under a moving sprung mass. The reliability of the present theory, along with the bi-section method for solving the frequency and mode shape, is validated by comparison with the solution obtained by the finite element method (FEM) for various damping ratios, mass ratios and running speeds of the sprung mass. [ABSTRACT FROM AUTHOR]

Within the context of composite beam structure modeling, a refined model is combined with a simpler one solely within a region of interest, aiming to enhance result accuracy. The purpose is to gain computational cost without loss of precision. For that, the Partition Unity Method (PUM) is used to ensure the continuity condition on the displacement field. A 1D refined Sinus model and a 2D approach are involved to demonstrate the capability of the method. It is assessed on different numerical examples involving both laminated and sandwich beams. The accuracy of the results is shown using reference solutions and computations using a mono-model. The interest of the method is further demonstrating by estimating the computational cost with or without the coupling. The results are rather very promising. • A kinematics coupling is considered for the modeling of 2D laminated composite and sandwich beams. • The method is based on the Partition of Unity Method. • An enriched model is only localized in the region of interest. • The possibilities, the limitations and the accuracy of the method are highlighted. • The approach can be applied to different dimensionalities and FE approximations. [ABSTRACT FROM AUTHOR]

This study evaluates the cyclic response of the Precast Hollow Core Slab (PHCS) to the beam connection by proposing a novel connection detail. The evaluation involved, three different connection details, namely, (1) Continuity rebar and U-type Core Rebar Discrete with 100 mm ledge width (CUCRD_100); (2) continuity rebar and Core Rebar Combined with 100 mm ledge width (CCRC_100); and (3) continuity rebar and Core Rebar Combined with Ties along with 100 mm ledge width (CCRCT_100) were experimentally validated. These were validated through experimental testing, comparing their performance with a reference specimen that adhered to New Zealand guidelines using Continuity rebar and Core Rebar Discrete with 100 mm ledge width (CCRD_100). Displacement controlled reverse cyclic loading, following the ACI T1.1–0.1 protocol, was applied to the end of a hollow core slab for the experimental testing. The structural performance of all four connections considered failure pattern, strength, hysteretic behaviour, energy dissipation, displacement ductility, stiffness degradation, and equivalent viscous damping. The overall seismic efficiency of the connections was assessed using ACI 374.1–05 approval criteria. The experimental results proved that the peak load-carrying capacity for CCRCT_100 specimen was observed to be greater in both directions of loading (positive and negative) when compared with the other connection detailing. The presence of transverse reinforcement enhanced the confining capacity of the concrete in the joint region which substantially increased the ductility and dissipation of energy in CCRCT_100 specimen. The seismic performance of every connection specimen was favourable, and they all met the ACI 374.1–05 approval standards. [ABSTRACT FROM AUTHOR]

The flexural behavior of hybrid timber–steel encased beams comprising coniferous radiata pine (Pinus radiata) (MGP10) and Douglas fir (Pseudotsuga menziesii) (F8) timber lamellae with bonded-in steel bars is studied. The effect of cross-section depth, steel bar size, timber species/grade, and steel bar arrangements (only bottom and top-and-bottom) on the hybrid beams' stiffness, failure mode, ductility, and load-carrying capacity were investigated. The flexural capacity and stiffness of the doubly (top-and-bottom) reinforced beams are increased by 127% and 71%, respectively. However, in the singly (bottom) reinforced beams, the flexural capacity and stiffness are increased only by 41% and 25%, respectively, highlighting the important role of the compressive bars. The failure of all beams was associated with tensile flexural failure of timber, but the steel bars improved the ductility of the beams. The maximum coefficient of variation of the peak load in hybrid beams (CoV=14.3%) is lower than that of the bare timber beams (CoV=21.7%). Two analytical models were developed based on a linear and a bilinear stress–strain relationship for timber. The analytically predicted peak load and stiffness agree well (less than 13% and 12% difference) with the experimental results. [ABSTRACT FROM AUTHOR]

Bending deformation is easy to occur under the action of cutting force during machining, due to the weak stiffness of slender beam structural parts of Ti6Al4V. This will lead to the change of the theoretical cutting position relationship between the tool and the workpiece, thus affecting the machining accuracy and quality of the parts. Aiming at the structural characteristics and machining deformation of slender beam parts with weak stiffness of Ti6Al4V, the bending deformation of slender beam structural parts under the action of static force is analyzed by theory of Euler Bernoulli beam and finite element simulation of ABAQUS. The influence of support mode on the overall static stiffness and machining deformation of the beam is discussed. It is concluded that the clamping method of fulcrum assisted support and micro-crystalline wax filling in the machining process of slender beam structural parts of Ti6Al4V cannot only effectively suppress the machining deformation of parts but also solve the problem of machining chatter of parts. The machining accuracy and quality of slender beam structural parts are effectively improved. Slender beam parts with weak stiffness of Ti6Al4V processed according to this clamping concept. The maximum deformation of the part is 0.017 mm, the maximum dimensional deviation is − 0.015 mm, and the surface roughness Ra of the part is less than 0.5 μm. [ABSTRACT FROM AUTHOR]

We explicitly characterize boundary conditions that are compatible with low order variational principles. The freedom afforded by adding in a null Lagrangian without altering the Euler–Lagrange equation significantly expands the range of variationally admissible boundary conditions, although not all possibilities are permitted. Applications to several fundamental problems arising in elastostatics, including bars, beams, and plates, are presented. [ABSTRACT FROM AUTHOR]

Reinforcing seawater sea-sand concrete (SSC) with basalt fiberreinforced polymer (BFRP) bars can adequately resolve chloride corrosion issues. However, the multiple-element ions in seawater and sea sand can increase the concrete alkalinity and accelerate the degradation of BFRP bars. This study aims to enhance the durability performance of BFRP-SSC beams by regulating concrete alkalinity. A low-alkalinity SSC (L-SSC) is designed by incorporating a high-volume content of fly ash and silica fume. A total of 16 BFRP-SSC beams were designed based on the current standards and prepared using normal SSC (N-SSC) and L-SSC. The beam flexural performances before and after long-term exposure are characterized through the four-point bending test. The test results indicate that exposure in the simulated marine environment can reduce the load-bearing capacity and change the failure mode of BFRP beams with N-SSC. After exposure at 55°C for 4 months, the load-bearing capacity of the BFRP-SSC beams was reduced by 70.0%. Moreover, a slight enhancement of load-bearing capacity and ductility of the BFRP-L-SSC beams was observed due to the enhanced interface performance with further concrete curing. Furthermore, the long-term performance of the sand-coated BFRP bars is better than that of the BFRP bars with deep thread. The load-bearing capacity of the BFRP-L-SSC beams increased by approximately 20% after 4 months of accelerated aging due to concrete strength growth, and the BFRP-L-SSC beams maintained the concrete crushing failure mode after exposure. Finally, a loadbearing capacity calculation model for the BFRP-SSC beams is proposed based on the experimental investigation, and its prediction accuracy is higher than that of the current standards. This study can serve as a valuable reference for applying BFRP-SSC structures in the marine environment. [ABSTRACT FROM AUTHOR]

Estimating the stress of reinforcing bars and its variations in service conditions can be useful to determine the reserve capacity of structures or to assess the risk of fatigue in the reinforcement. This paper investigates the use crack width measurements to estimate the stress in the bars. In existing structures, crack width formulations can be used to estimate the stress in the reinforcement from crack width measurements, profiting from additional information that can be measured in‐situ, such as the crack spacing. Recent experimental results show that the values of the mean bond stress typically considered in code formulations overestimate the actual bond stresses activated in cracked concrete specimens. This paper presents the results of an experimental program consisting of reinforced concrete ties and beams instrumented with Digital Image Correlation and fiber optical measurements. The results confirm the differences with typically assumed bond stresses. A formulation to estimate the bond stresses in service conditions is derived from the results of the numerical integration of a previously developed local bond–slip relationship. Their pertinence for the estimation of the stress in the reinforcement from the measured crack width is evaluated with satisfactory results for monotonic loading and for the maximum force in cyclic tests. [ABSTRACT FROM AUTHOR]

The United Nations Sustainable Development Goals (UN SDGs) ensure future human well-being. However, they face challenges due to the pressing need to reduce carbon emissions, with nearly 40% originating from the construction sector. With the current global environmental and energy crisis, there is a pressing need to address building carbon emissions and prioritise investments in passive strategies for improving indoor thermal comfort. Exploring fast-growing bio-based materials like bamboo, straw, hemp, and flax directly addresses these concerns, fostering environmental sustainability. Material selection in construction is crucial for advancing the SDGs, for example, promoting sustainable cities and communities (SDG11) and responsible consumption and production (SDG12). This paper proposes a comparative analysis of conventional and bio-based construction materials, focusing on their production stages through life cycle analysis. Tools such as Building Emissions Accounting for Materials (BEAM) and the Methodology for Relative Assessment of Sustainability (MARS) enable a detailed comparison. The results highlight the benefits of bio-based materials in storing carbon more rapidly and their lower environmental impact compared to conventional alternatives. Moreover, bio-based materials contribute to indoor moisture regulation and a healthier indoor environment, underscoring their potential to accelerate progress towards the UN SDGs through informed material choices in design practices. [ABSTRACT FROM AUTHOR]