Rectangular Beam Research Articles

An experimental behaviour of RCC rectangular beams with U-shaped encased welded wire mesh under torsion phenomena

Concrete is one form of composite material composed of fine and coarse aggregate bonded together with cementitious paste that is durable in its hardened state over time. Although it is robust in compression, it has a brittle material property in tension. Axial and shear forces, bending moments, and torsion moments may arise in the concrete body in a reinforced concrete design depending on the loading conditions. In this sequel, the encased welded wire mesh with high yield strength is used in order to improve composite material characteristics and reduce abrupt cracking with an increase in torque carrying capacity of concrete specimens. A total of 18 beam specimens were casted and tested under pure torsion, in that six numbers were control specimens and the remaining twelve numbers were specimens with encased welded wire mesh. U-shaped wrapped WWM, both in the form of transverse strips and continuous U-shaped sheets are used to observe enhancement in the cracking and ultimate torsional strength of plain and RCC rectangular beams respectively. The curves of tested specimens containing WWM wrapping patterns showed the specimens containing WWM resist more torsional loads as compared to control specimens. The ultimate torque get increased effectively due to the introduction of U-shaped WWM wrap in fully reinforcement type means longitudinal reinforcement with closed stirrups beam specimens.

Multiple Damage Prediction in Tubular Rectangular Beam Model Using Frequency Response-Based Mode Shape Curvature with Back-Propagation Neural Network

Multiple Damage Prediction in Tubular Rectangular Beam Model Using Frequency Response-Based Mode Shape Curvature with Back-Propagation Neural Network

Analysis, Comparison and Optimization of T-type Section Beam and Rectangular Section Beam based on Engineering Training

The research on the optimization of T-beam under the condition that both T-beam and rectangular section beam meet the section bearing capacity. Through theoretical calculation, component fabrication, experiment, and data collection and analysis, fully explore the advantages of a T-beam, optimize the experimental beam transport process, and apply it to practical teaching to improve the safety and convenience of the experimental process.

Hydrodynamic effect and Fluid-Structure coupled vibration of underwater flexible caudal fin actuated by Macro fiber composites

Underwater bionic robotics or vehicles using oscillating flexible structures as power sources are attracting considerable attention. In this study, the hydrodynamic effect and fluid–structure coupled vibration of a flexible caudal fin actuated by macro fiber composites(MFC) are investigated. A fluid–structure coupled dynamic equation of the MFC-actuated caudal fin with a variable cross-section is established, and both the internal moment generated by the MFC and the complex-valued hydrodynamic forces are considered. Distributions and evolutions of the flow velocity and pressure in the vicinity of the oscillating caudal fin with different parameters are visualized through comprehensive parametric CFD simulations. Simulation results show that the presence of the gap introduces significant flow reshaping effects to the flow distribution and hydrodynamics. Distributions of the flow velocities and concentrated pressure regions depend highly on the gap width of the forked caudal fin. Then, a revised hydrodynamic function depending on three nondimensional governing parameters is developed, this is, the characteristic oscillating frequency, the width ratio, and the gap-to-width ratio. Formulas for the real and -imaginary parts of the complex-valued hydrodynamic function are developed respectively through the comprehensive CFD framework. Theoretical and experimental results show that the revised hydrodynamic function and developed model are capable of estimating the hydrodynamic effect and underwater dynamic response of the MFC-actuated caudal fin. Compared with the classical hydrodynamic function for the rectangular beam, the expression for the beam overestimates the added mass effect exerted on the caudal fin, and underestimates the hydrodynamic damping effect, thus leading to a smaller estimated resonant frequency and bandwidth, but a higher predicted response peak. These findings are useful for the robotic fish or autonomous underwater vehicles which are propelled by oscillating foils actuated by smart actuators.

Maximum steady stress of various cross-section beams under combined loadings during creep

In the simplified method based on stress classification for estimating the stress at the steady stage during creep, an empirical correction factor is needed to account for the relaxation of primary bending stress during creep. An analysis of a rectangular beam subjected to tensile loading and bending moment during creep is carried out to demonstrate the applicability of the Kt, which is the correction factor proposed by the ASME code, in this work. In view of the effects of material creep property and the primary membrane stress on the relaxation of the primary bending stress, a method for accessing the parameter Kt is proposed and validated. The results reveal that the parameter Kt will increase with the tensile loading due to the relaxation of the primary bending stress accelerated by the primary membrane stress. Good agreement between the results of inelastic analysis and the modified method is observed for the beams with different material properties, combined loadings, and cross-section shapes.

Features of the Internal Force Factors Distribution in Reinforced Concrete Piles of Complex Cross Section under the Influence of a Transverse Load

Bar reinforced concrete structures, which include piles, in real working conditions perceive a whole range of internal force factors. Axial tension-compression forces, bending moments and shear forces are the most commonly perceived internal force factors. Of particular interest is the effect on the cross section of the shear force. If a complex curly shape is replaced by elementary form, then the calculation is not difficult. However, when calculating the composite cross section, there is no unambiguous solution. In accordance with the adopted regulatory documentation, it is necessary to accept only a main part, while discarding the surrounding areas. It is important to study the configuration of the shape of a complex section for the perception of a shear force. The purpose of the work was to refine the account of the entire complex section using numerical simulation by the finite element method, analytical calculations and small-scale experiments. Determination of further practical application of the obtained results on real structures was also the goal of the study. The parameters of the distribution of shear force between the main rib and flanges were obtained by numerical analysis and small-scale experiments. Numerical models of rectangular and tee cross sections beams have been developed. Analytical dependences were studied and full-scale tests of reinforced concrete beams of various sections were carried out. It has been established that when taking into account the work of the entire cross-section, the bearing capacity of concrete for the action of a shear force is 20% greater than when calculating only the main section without taking into account the shelves.

Design of cold-formed high strength steel square and rectangular hollow section beam–columns

Cold-formed high strength steel (CFHSS) square and rectangular hollow section (SHS and RHS) beam–columns were investigated in this study with an objective to evaluate the applicability of existing design rules given in American, Australian and European codes for SHS and RHS beam–columns of S700, S900 and S1100 steel grades, and subsequently, provide economical and reliable design rule for CFHSS SHS and RHS beam–columns. A comprehensive numerical investigation was performed in this study, where the values of flat width-to-thickness ratio of the tubular sections ranged from 7.5 to 96. The constitutive model developed for CFHSS tubular members was used in the numerical investigation. Global and local geometric imperfections were also included in the numerical models. In total, 465 data were compared with the nominal capacities predicted from American, Australian and European codes, including 390 numerical data obtained in this investigation. The safety levels of design rules given in these standards were examined by performing a reliability analysis. It has been demonstrated that the current design rules given in the American, Australian and European codes provide conservative predictions. A modified design method based on the recommendations given in European code was proposed in this study. Overall, it has been proved that the proposed design rule provides accurate and reliable predictions for the design of cold-formed S700, S900 and S1100 steel grades SHS and RHS beam–columns.

SIMULATION OF TEMPERATURE EFFECTS IN MASSIVE BODIES USING THE MODIFIED METHOD OF LINES

This article presents the main ideas and possibilities of the modified straight line method for modeling temperature effects in massive bodies. The calculation model of a rectangular beam with a defined thermal state is adopted. The procedure for reducing the dimensionality of the original equations using the modified method of straight lines and the Bubnov-Galyorkin-Petrov method for boundary conditions is applied. The reduced equation of thermal conductivity and the reduced equation of heat balance are given. Conclusions are made regarding the addition of reduced second-order equations with components from the boundary conditions on the lateral surfaces, and finally reduced second-order equations in spatial variables are given.
 We are considering a beam of rectangular cross-section, the three dimensions of which are of the same order. The thermal state of such an object is three-dimensional and is therefore described systematically using three-dimensional heat conduction equations. When applying the modified method of straight lines to reduce the dimensionality of the original equations, it is convenient to use them in the form of a system of partial differential equations of the first order in spatial coordinates.
 According to the modified method of straight lines, two systems of straight lines parallel to the coordinate axes Oy and Oz are applied to the beam (a decrease in dimensionality in terms of spatial variables y and z is assumed). The choice of such straight lines is due to the fact that the reduced equations will depend on the variables x and t, that is, they will resemble the one-dimensional equations of the one-dimensional non-stationary problem of thermal conductivity, for which efficient and convenient numerical methods have been developed in the literature of mathematical physics at the moment, to which it is easy to adapt the reduced equation.

Impact of Polymer Coating on the Flexural Strength and Deflection Characteristics of Fiber-Reinforced Concrete Beams

Liquid polymers (LP) have become an important structural material used in the construction industry in the last decade. This paper investigates the viability of using commercially available LPs as a coating material to improve the flexural strength of fiber-modified concrete beams. The scope included preparing rectangular prism concrete beams with a concrete mixture including fly ash and fiber and coating them with four different liquid polymers at a uniform thickness following the curing process while one set of samples was maintained under the same conditions as a control group without coating. In addition, cylindrical samples were prepared to determine the compressive strength of the concrete mixture. Following the curing process in an unconfined open-air laboratory environment for another 28 days, concrete samples were tested to determine the flexural strength and deflection characteristics under center point loading equipment. The results revealed that all four coating types enhanced both the flexural strength and the average maximum deflection of the beams compared to the control group. While the enhancement in the flexural strength changed approximately between 5% and 36% depending on the coating type, the improvements in average maximum deflections varied between 3.7% and 28.4%.

TRANSVERSE SHEAR DEFORMATIONS FOR DEFLECTIONS OF THIN-WALLED BEAMS

The Euler-Bernoulli theory (classical theory) is mainly used when beam deflections are determined. Classical theory takes into account only pure bending while transverse shear deformations are neglected. The paper examines statically determined thin-walled beams (I-beam and thin circular ring): simply supported beams and cantilevers. The load is uniformly distributed along the length of the beam and cantilever and a concentrated force applied at the center of the simply supported beam and at the edge of the cantilever. For the specified cases, as well as for round and rectangular beams, formulas for the correction coefficient were derived. The coefficient takes into account the deformation of the transverse shear. It is shown at what relative length of the thin-wallde beams, the specified deflection exceeds the classical one by more than 5%.

Status of the engineering design of the IFMIF-DONES high energy beam transport line and beam dump system

IFMIF-DONES plant [1] (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed under the framework of a work package of the EUROfusion Consortium. It will be a facility located at the south of Spain in Granada. Its objective and main goal is the testing and qualification of fusion materials by the generation of a neutron flux with a broad energy distribution covering the typical neutron spectrum of a (D-T) fusion reactor. This is achieved by the Li (d,xn) nuclear reactions occurring in a liquid lithium target where a 40 MeV at 125 mA deuteron beam with a variable beam footprint between 200 mm × 50 mm and 100 mm × 50mm collides. The Accelerator Systems is in charge of providing such high energy deuterons to produce the required neutron flux. The High Energy Beam Transport line (HEBT) is the last subsystem of the IFMIF-DONES accelerator, and its main functions are to guide the deuteron beam towards the liquid lithium target and to shape it with the required rectangular reference beam footprints. The HEBT system includes a Beam Dump devoted to stop the beam during commissioning and start-up phases. The present work details the present status of the HEBT engineering design, including beam dynamics, vacuum configuration, radioprotection, beam diagnostics devices and remote handling analyses performed detailing the layout and integration of required components through-out the beamline.

Investigação da contribuição do engrenamento dos agregados em vigas de concreto armado e concreto reforçado com fibras de aço

Abstract Shear strength in reinforced concrete (RC) beams, especially in steel fiber reinforced concrete (SFRC) beams is a subject of great interest in structural engineering. In the case of beams without transverse reinforcement, the failure is explained based on a predefined crack pattern and kinematics, and the transfer of shear force accomplished through different mechanisms. Among these mechanisms, the aggregate interlock is present in most of the existing shear strength mechanical models in the literature, with divergences regarding its performance and preponderance. Thus, this paper focuses on evaluating the contribution of aggregate interlock throughout the critical crack formation process up to the ultimate load by performing bending tests on small-scale rectangular RC and SFRC beams without considering the effect of transverse reinforcement. The Digital Image Correlation (DIC) technique is used to track the patterns of shear cracks and their associated kinematics by measuring the relative displacements of opening (w) and sliding (δ). A detailed description of the shear behavior of these beams is provided by quantifying the aggregate interlock using the simplified Walraven model. The results help to understand the level of contribution of the aggregate interlock, and the main differences between structural elements of concrete with and without steel fibers in the scope of the shear strength.

Dynamic photoelastic study of flexure hinges produced by additive manufacturing technology

There are many challenges in compliant mechanism redesign for additive manufacturing (AM) technologies, and in order to assess their applicability and propose adequate recommendations, the behavior of compliant elements has to be examined. Plastic materials are often used in AM technologies and are well suited for large volume compliant mechanisms due to their flexibility to strength ratio. However, they also have many disadvantages, notably a low fatigue strength and complex material behavior. Therefore, in this paper a photoelastic observations of corner-filleted flexure hinges manufactured from the transparent acrylic based photopolymer using the Digital Light Processing (DLP) AM technology subjected to the dynamic loading have been conducted in order to assess the fatigue strength and potentials of the photoelastic methods for the material behavior modeling. Three-point flexural tests on rectangular beam samples with the standardized dimensions printed in vertical and in horizontal orientation have been performed and the obtained data has been used for numerical simulations of corner-filleted flexure hinges. The specimens printed in different orientations exhibit significantly different anisotropic properties; the horizontally printed samples exhibit brittle behavior, while the samples printed vertically yields and consequently have much higher deformations, the calculated flexural moduli are also very different. Corner-filleted flexure hinges printed in vertical orientation and subjected to dynamic cantilever beam bending tests at relatively high stress amplitudes proved sufficient for the low dynamic compliant mechanisms applications. The qualitative photoelastic observations have shown that the photoelasticity is applicable in dynamic tests and useful in residual stress determination and stress concentration investigations.

Design of concrete beam reinforced with GFRP bars as per ACI codal provisions

This document provides design principles for concrete beams reinforced with glass fiber reinforced polymer (GFRP) bars per the ACI 440.1R-15 regulation. One of the main advantages of using glass fiber reinforced polymer rods instead of traditional steel reinforced rods is their lighter weight and higher corrosion resistance. However, the bending failure mode of FRP reinforced concrete (FRP-RC) beams is brittle rather than ductile because the elasticity of fiber reinforced polymer (FRP) bars is linear until failure and the elongation at break is small. For FRP-RC elements, concrete crushing compression failure, which gives various warnings before failure, is the preferred failure mode. In other words, unlike the usual design practice for reinforced concrete (steel-RC) beams, for FRP-RC beams, an over-reinforced structure is preferable to an under-reinforced structure. In addition, since the FRP RC member has low rigidity of the FRP rod, it bends more and cracks larger than the steel RC member. These factors limit the field of application of FRP. Here is a design example of a rectangular beam with tension reinforcement according to ACI regulations.

Numerical analysis of mixed-mode I+II fracture behavior of automotive PVB laminated glass using a novel beam-type test specimen

Laminated glass is a composite structure consisting of a polymeric interlayer (e.g., polyvinyl butyral PVB) sandwiched between two glass plies. Due to the increasing use of laminated glass (LG) in advanced industries such as automotive sectors, it is of much importance to investigate the fracture behavior of such structures. One of the most critical steps in outlining the fracture behavior of laminated glass is the accurate determination of the fracture energy of the interlayer, usually, polyvinyl butyral (PVB), which is obtained from experimental methods. So far, various laboratory samples have been presented to measure the fracture energy of laminated glass, each of which has its advantages and limitations. In this paper, a new loading setup is proposed for the determination of mixed-mode I/II fracture energy in a rectangular-shape laboratory sample of laminated glass. The loading setup consists of a rectangular beam under a four-point bending which has been analyzed by the commercial ABAQUS software package. By utilizing this specimen, the fracture energy of the combined modes from pure mode I to pure mode II in the PVB interlayer can be measured. The proposed geometry here is simpler than other available geometries in the literature and also it does not require a complex loading mechanism. The effects of crack length ratio and also the support distance on fracture parameters such as and are well investigated.

Effect of loading type on RC T-Beam sections involving construction errors

The paper presents the effect of loading type on RC T-beam sections involving construction errors. This study involved 12 RC T- beams specimens divided into two main categories according to loading method. First category were loaded with uniformly distributed load at two-edges of slab while the second, were loaded with two-point concentrated loads at the middle length of beam specimen. The aim of this study is to evaluate, the effect of malposition of slab reinforcement, unequal configuration of slab reinforcement and change in bar diameter of slab reinforcement on the structural behavior of T-beam sections. The results indicated that malposition of slab reinforcement leads to a lower bending moment capacity of the slab. Flexural capacity of T-beams were higher than the rectangular beams where part of slab contributes to the resistance of the loads. Well-arranged distribution of reinforcement improves the ductile behavior of the slab and reduces the corresponding deflections.

A Variable Clutch Mechanism for Adjustable Stiffness Actuators Based on Bending and Torsion of Prismatic Beams

Today, a major obstacle to developing locomotion mechanisms that are as safe and energy efficient as living organisms has been overcome with the development of actuators with adjustable stiffness. This work presents an innovative clutch mechanism whose stiffness can be adjusted based on the combined bending and torsion of the prismatic beams. In this way, the stiffness of any rotary actuator can be adjusted with the help of this clutch mechanism. The adjustable clutch mechanism consists of elastic prismatic beams placed in any position in the power transmission unit. The stiffness of the clutch mechanism is controlled by varying the active clutch length of these prismatic elastic beams using an additional actuator. This work is a new version developed to solve the mechanical problems observed in our previous studies using elastic cylindrical beams. Cylindrical beams subjected to dynamic bending have a higher risk of cracking on the cylindrical surface over time. The cross-section of cylindrical beams subjected to bending is very narrow at the point furthest from the center, which bears the greatest load in bending. For this reason, it has been observed that the beams break due to micro-cracks on the surfaces of the cylindrical beams in long-term use. However, the rectangular beam proposed as a solution to this mechanical problem is subject to combined torsion and bending, complicating the analytical solution. In this study, the stiffness variation of an adjustable elastic coupling mechanism depending on the coupling length was obtained with a simplified discrete analytical approach. Torsional and bending stiffness of the prismatic beams were calculated separately, and their sum gave the angular stiffness of the actuator. The analytical results obtained using this simple approach are compared with the experimental and finite element analysis results. The results show that the current design can adjust the stiffness over a wide range and the simple analytical approach gives more accurate results as the clutch length increases.

Semi-circular bending setup for predicting fracture characteristics of high-strength fiber-reinforced concrete

Semi-Circular Bending (SCB) Setup is commonly used to investigate the fracture parameters of the road materials like asphalt mixtures. This paper examines the performance of the SCB setup in extracting the fracture characteristics of high-strength fiber-reinforced concrete (HSFRC). Monofilament and fibrillated polypropylene fibers with polyolefin coatings of 19, 30, and 50 mm length were added to a high-strength concrete mixture at three volume percentages of 0.5, 1, and 1.5 %. Standard cube and cylinder specimens were initially fabricated for conventional material properties tests. Subsequently, the three-point bending test specimens, i.e., intact rectangular beam, notched beam, and SCB, were made using the same concrete mix of different fibers lengths and percentages. A total of 36 beam and SCB tests with three replications was conducted to find the fracture energy and pick load of each specimen. Results showed that selecting the shortest fibers (19 mm) of 0.5 % and 1.5 % by volume increased the elastic modulus and the splitting tensile strength by 70.5 % and 43 %, respectively. Also, increasing the fiber length and volume enhanced the fracture energy of the notched beam and SCB specimens up to 90 times and 40 times, respectively. However, increasing the volume of the fibers was more effective than using longer fibers in fracture energy increase. For these three test setups, finite element models were generated and analyzed to develop a numerical framework capable of predicting the fracture characteristics of HSFRCs with acceptable accuracy (maximum error of 4 %). The concrete damaged plasticity (CDP) model in ABAQUS software package were adopted to simulate the damage initiation and progression in concrete using the material properties from the conventional tests. Comparing the results of beam setups with SCB tests, it was found that SCB can be a reliable and economical setup to find the fracture characteristics of the HSFRCs.

Investigation of bending performance of printed continuous carbon fiber reinforced polylactic acid using acoustic emission

AbstractIn this study, rectangular beams were fabricated by 3D printed continuous carbon fiber reinforced polylactic acid. The effects of deposited space and layer thickness on bending performance are investigated, and the failure modes are analyzed accordingly. At the same time, the acoustic emission technology was applied to test the damage process to facilitate a more in‐depth study compared with related studies, and the principal component analysis method and kmeans++ algorithm were applied to analyze the test signal. The results show that the bending strength and modulus of the printed composites decrease correspondingly with the increase of the layer thickness in the range of layer height of 0.7, 0.8, and 0.9 mm. When the fused deposited space is between 0.6 and 0.8 mm, with the increase of the deposited space, the bending strength and modulus also decrease correspondingly. By using principal component analysis, the test signal could be represented by three principal components, and by applying kmeans++ cluster algorithm analysis, the three principal component are divided into five clusters, which correspond to the material failure mode of matrix cracking, interlayer delamination, fiber, and resin debonding, fiber cracking, and fiber fracture. As a result, the bending failure process can be effectively analyzed in detail with the clustering results.

Enhanced tribological performance and nanostructuring speed on AlTiN by beamshaping technology

ABSTRACT For the first time, a dynamic beamshaping technology has been utilized for the efficient production of periodic nanostructures on top of AlTiN coating to enable dry machining without costly and environmentally hazardous cutting fluids. First, a variety of periodic nanostructures with periods in a range of 740–273 nm were produced utilizing different wavelengths. Additionally, beamshaping technology increased productivity by 4008% up to 105 cm2 min−1 by shaping the Gaussian beam into a rectangular beam of 500 × 30 µm. To simulate the application load and resulting heat production during manufacturing, friction analysis was performed at room and elevated temperature to 500°C. The analysis revealed a significant reduction in the friction coefficient – up to 27% and 19% at room temperature and 500°C, respectively. The combination of these results demonstrates that the proposed method can be scaled up for the mass production of functionalized machining tools for dry machining.