Hollow Beam Research Articles

Structural Behavior of Reinforced Concrete Hollow Beams under Partial Uniformly Distributed Load

A Longitudinal opening is used to construct hollow core beam is a cast in site or precast or pre stressed concrete member with continuous voids provided to reduce weight, cost and, as a side benefit, to use for concealed electrical or mechanical runs. Primarily is used as floor beams or roof deck systems. This study investigate the behavior of six beams (solid or with opening) of dimension (length 1000 x height 180 x width120mm) simply support under partial uniformly distributed load, four of these beam contain long opening of varied section (40x40mm) or (80x40mm). The effect of vertical steel reinforcing, opening size and orientations are investigated to evaluate the response of beams. The experimental behavior based on load-deflection measured at central and quarter of tension zones. The experimental test result shows the presence of Hollow decrease the load carrying capacity by about (37.14% to 58.33%) and increased the deflections by about (71.6% for (Hollow ratio 7.4%) to 75.5% for (Hollow ratio 14.8%)) for same applied loadcompared with solid beams with the same properties. The increase shear steel reinforcing will decrease all the deformations at all stages of loading, but particularly after initial cracking and give enhancement in ultimate load capacity of beams by about 31.5% with increasing the amount of shear steel reinforcing by about 50%. Finally, ductility is increased in all cases under partial uniformly distributed load when hollow ratio decreased by about 50% or increased in shear steel reinforcing by about 50%

Design and dynamic analysis of a novel compound bending hollow piezoelectric beam miniature rotary actuator

In this paper, a miniature hollow piezoelectric beam rotary actuator is proposed and designed based on the compound bending vibration modes. The structure body is designed as an elastic hollow square beam with symmetrical piezoelectric patches attached at both ends, which directly eliminates the step of the frequency tuning. A conical rotor is driven by the hollow piezoelectric beam through the elliptical motions of the points on its inner surface. Based on the Timoshenko beam theory and Lagrange equation, the numerical continuum model is established to analyze the working mechanism. A prototype of the miniature rotary actuator with a size of 50 × 6 × 6 mm (2 mm through-hole) is manufactured and its performance under various excitation parameters is characterized in rotor speed experiments. The experimental results show that the maximum speed of the conical rotor is 913 rpm at the excitation voltage of 400 V. With a maximum load of 70.31 mN, the spherical rotor can achieve a speed of 450 rpm. The numerical results are in great agreement with the experimental results, so the output characteristics of the rotary actuator can be estimated. The simulation and test results demonstrate that the proposed rotary actuator has outstanding output performance and controllability. In addition, the simple structure design is easy to realize the frequency tuning and miniaturization.

Flexural strength and drift ratio of reinforced concrete beams with longitudinal square hole

The main aim of this investigation was to study the flexural strength and drift ratio of simply supported rectangular RC hollow beams (with a longitudinal square hole) subjected to gradually increased and symmetrically applied one-point load. Each hollow beam had a 300 mm2 and 900 mm2-area of a square, and the position of the center of the hole was 80 mm from the top. The cross-section of the beam, the amount of longitudinal steel, and the stirrups of the beam was kept constant. The flexural strength and deflection of these hollow beams were compared with that of a solid RC beam that had the same outer dimensions and steel reinforcements. A comparison of experimental results shows that specimens with square holes 10 x 30 achieve higher peak load, MOE, and MOR. On other hands, solid beam specimens achieve a larger drift ratio.

Shear behaviour of stiffened hollow glulam beams: Experiments, analytical model, and finite element analysis

Owing to their good mechanical properties and excellent seismic performance, among other advantages, glulam beams have widely been employed in architectural engineering. However, existing studies on the mechanical properties of glulam beams have mainly focused on their bending behaviours rather than their shear performance. Additionally, more comprehensive theoretical research on the shear performance of components with different section forms is essential. To address these issues and with the aim of investigating glulam components, this work developed a stiffened hollow glulam beam (SHGB) with a rectangular cross-section. By analysing the influences of the shear-span ratio, web thickness, and stiffening plate spacing on the shear properties of the SHGB, a theoretical calculation formula for the shear capacity and shear stiffness was established; this formula was then verified via finite element analyses. Based on the results, the SHGBs featured excellent bearing capacity and ductility, and also showed potential for reducing material consumption, while ensuring the desired mechanical properties. Notably, their stiffness increased with an increase in the web thickness or a decrease in the stiffening plate spacing. These results are expected to serve as a theoretical reference for similar components.

Controllable abnormal hollow breathers caused by deviation parameters in nonlinearity Schrödinger equation with nonlocality

The nonlinearity Schrödinger equation with nonlocality can be applied to describe the propagation of laser beams in some practical nonlocal nonlinear materials. In this paper, the propagation of controllable abnormal hollow beams with deviation parameters in nonlocal nonlinear materials is studied based on nonlinearity Schrödinger equation with nonlocality. The results show that the evolution of controllable abnormal hollow beams with deviation parameters can only exhibit as the form of generalized controllable abnormal hollow breathers with periodic changes in transverse width. The evolution characteristics of controllable abnormal hollow breathers have been analyzed in detail. The expressions of periodic transverse width, maximum and minimum values of transverse width and their positions are derived. The analytical expression of wavefront curvature is given, and the reason for the periodic change of the transverse width is analyzed by using the wavefront curvature.

Strain driven mode-switching analytical framework for estimating flexural strength of RC box girders strengthened by prestressed CFRP plates with experimental validation

This paper presents a pioneering study that developed the first analytical model to analyse and design reinforced concrete (RC) box girders strengthened by prestressed CFRP plates. The proposed analytical model considered and addressed prestress loss, shear lag effect and failure modes under different design configurations at elastic, elastoplastic and plastic stages. An experimental study was also conducted to validate the proposed analytical model. The study was motivated by the increasing demand for the structural strengthening of aged and over-used hollow RC box girders in transport and other infrastructure systems, as well as the lack of previous attempts to incorporate prestressed CFRP plate strengthening for hollow RC beams. It is very common in many developing countries, the traffic flow increased dramatically due to the economic growth. The original design underestimated the traffic loads. When demolition and re-building may not always be the best option, thus, strengthening and enhanced maintenance have become promising alternatives. But the lack of existing analytical models that can guide the engineers to analyse and design this type of structures effective, has become an urgent need from the industry. In the experimental study, eight box girders with different types, cross-section sizes, and prestress levels were prepared and tested. Two samples were preloaded to create damaged beams before strengthening to simulate the aged or over-used members. The experimental results are in good agreement with the analytical prediction. The proposed analytical framework provides a comprehensive yet practical method for designing the prestressed CFRP strengthened RC box girders in bending and laid the foundation for further studies on shear and torsion behaviours.

Behavior of hollow self-compacted concrete beams reinforced with aluminum sections

This paper presents a study on improving the flexural performance of self-compacting hollow concrete beams with embedded aluminum sections, both experimentally and numerically. The experimental program involved testing three specimens to illustrate the impact of the bare and aluminum-reinforced voids on the mechanical properties of the hollow beams relative to the solid reference beam. A three-dimensional (3D) non-linear finite element model (FEM) was initially developed using ABAQUS software and validated against experimental results. The validated model examined the effects of void area (16–49% of the beam cross-section), void configuration (square or circular), longitudinal tensile reinforcement ratio (0.41–1.19%), and shear reinforcement ratio (0–0.56%) on the failure patterns and load–displacement relationships of hollow reinforced concrete (RC) beams with or without reinforced internal aluminum sections. Results showed that the embedded aluminum reinforcement promoted a more uniform distribution of flexural cracks along the effective length of the hollow RC beams and delayed the formation of shear cracks compared to the bare specimens. Furthermore, the embedded aluminum reinforcement effectively restored the ultimate capacity of the hollow beams with a void area ranging from 16 to 36% of the beam cross-section. Despite having the same area, the ultimate load-carrying capacity of both bare and reinforced beams featuring circular voids was higher than those with square voids.

Form Factor in Transition Radiation from Hollow Beams

The form factor of a hollow electron beam for transition radiation has been calculated. It has been shown that the characteristics of coherent radiation are significantly different for conventional solid and hollow beams. Numerical estimates have been obtained for terahertz radiation frequencies and relativistic energies of el-ectrons.

A Miniature Multiaxis Force/Torque Sensor for Acupuncture

To realize the quantitative analysis and research of traditional Chinese medicine (TCM) acupuncture manipulations, miniaturized multidimensional force sensors are necessary to measure the lifting–thrusting force and twisting torque in the process of acupuncture, which records the manipulations of excellent physicians for relevant physicians to learn and improve their manipulations. A miniature multiaxis force/torque ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${F}/{T}$ </tex-math></inline-formula> ) sensor for acupuncture is developed in this article. The elastomer of the design adopts hollow thin-wall cross beam structure with inverted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}$ </tex-math></inline-formula> floating beam, which retains the space for the strain gauge to be pasted, reduces the coupling between dimensions, and improves the sensitivity and accuracy. This design has the advantages of miniaturization, lightweight, high precision, and convenient needle substitution. The elastomer is processed with polyetheretherketone (PEEK) material to reduce the mass. First, the feasibility of the hollow thin-wall cross beam structure with inverted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}$ </tex-math></inline-formula> floating beam is verified by ANSYS finite element simulation. Then, the hardware system based on STM32 is designed to realize signal acquisition, amplification, and transmission. Next, the static calibration and decoupling of the sensor are accomplished with the calibration device. The calibration results indicate that the accuracy of the sensor is high (the coupling error is less than 2%). Finally, the acupuncture force measurement system is constructed to complete the acupuncture manipulation experiment. The experimental results demonstrate that our system can accurately obtain the needle force information and can distinguish different acupuncture manipulations, which verifies the feasibility of the sensor while realizing the quantitative characterization of acupuncture manipulations.

Generation of Generalized Spiraling Bessel Beams by The Illumination A Curved Fork-Shaped Hologram with New Hollow Laser Beam

Generation of Generalized Spiraling Bessel Beams by The Illumination A Curved Fork-Shaped Hologram with New Hollow Laser Beam

Study on Lateral Distribution Coefficients of Hollow Slab Bridges After Reinforced by Pasted Steel Plates

This paper adopts a new method of pasting steel plate to restore the transverse connection of hollow slab bridge, so that the strengthened bridge can meet the requirements under the state of serviceability. The original beam of the concrete hollow slab with a span of 8m from the Suizhong to Shenyang section of Jing-Shen highway was reinforced by a method of pasting steel plates. In the test the eccentric load condition was loaded and the abaqus software was used for numerical calculation after the reinforcement. Based on the theory of load transverse distribution coefficient of bridge structure, different calculation methods were used to obtain the transverse load distribution coefficient of the strengthened test beam, and it is verified that the hinged plate method can be used to calculate the hollow slab beam strengthened with steel plate. In addition, combined with previous calculations, test results and numerical analysis, this paper discusses the restoration effect of the new type of pasted steel plate reinforcement method on the bridge lateral connection. The results show that the hinged plate method can be used to calculate the load lateral distribution coefficient of hollow slab beams strengthened by pasted steel plates. therefore, the pasted steel plate reinforcement method can effectively restore the horizontal connection between the hollow slabs and meet the use of bridge structures.

Structural Behavior of Hollow Beam Reinforced with Different types of GFRP stirrups

The structure could be impacted by concrete's steel reinforcement corroding. When exceptional corrosion resistance capabilities are required, fiber-reinforced polymer (FRP) reinforcements offer a practical choice for constructions exposed to hostile environments. However, only a small number of the building's most important structural components are currently permitted to use FRP bars as interior concrete reinforcement, leaving the rest of the building unprotected. This is due to the lack of available curved or shaped reinforcing FRP pieces, which have subpar structural performance.&#x0D; Eighteen concrete beams with dimensions (1200×225×150) mm were divided into three groups and each group had five beams with three References and five different types of stirrups in each group and tested them up to failure. The first group included longitudinal reinforcing steel bars 6Ø10mm, the second group longitudinal reinforcing GFRP bars 6Ø10mm, and the third group longitudinal reinforced with hybrid (3steel+ 3GFRP) bars 6Ø10mm. All beams are self-compacting concrete with a longitudinal hollow with dimensions (50×100) mm.&#x0D; The results showed that the ultimate load of a hollow beam reinforced with steel reinforcement is less than a solid beam reinforced with steel (reference 1) by (15%) and a hollow beam reinforcing with GFRP reinforcement is less than a solid beam reinforced with GFRP (reference 2) by (5%), and a hollow beam hybrid reinforced with (Steel+ GFRP) reinforcement is less than a solid beam reinforced with GFRP (reference 3) by (4%).

Experimental and numerical studies on seismic behavior of new cross square hollow column-truss beam connections

Five cyclic tests on the specimens were conducted to investigate seismic behavior of new cross square hollow column-truss beam connections. The variables are beam, column section size and axial force ratio. The paper reports on the failure modes, hysteretic curves, ultimate load carrying capacity, ductility, energy dissipation capacity, and stiffness degradation of the specimens. Two types of failure modes, i.e., column failure and beam failure mode, were found from the tests. The specimens experiencing the column failure mode exhibit poor seismic performance due to the overall instability induced by the occurrence of the plastic hinge of the column. While, the specimens displaying the beam failure mode exhibit well seismic behavior owing to the redistribution of the plastic stresses among the members of the truss beam. Noteworthy, the failure mode will change from column failure to beam failure when the column thickness increases and the axial force ratio decreases. Additionally, in the beam failure mode, the increase of the column thickness can improve the connection’s bearing and energy dissipation capacity, while the impact of the axial force ratio can be ignored. Based on the test results, the limit value of axial force ratio corresponding to the boundary failure mode under different column thicknesses is determined by using the nonlinear numerical model.

Static performance of steel slag concrete filled steel square hollow section members

The performance of steel slag concrete (SSC) filled steel square hollow section (SHS) stub columns and beams under short-term static loading is experimentally and numerically studied in this paper. Fifteen typical specimens, including 10 stub columns and 5 beams, were tested. The main factors investigated are: mass substitution rate of steel slag aggregate (SSA) [Rc(f)], which is equal to mass of steel slag coarse (fine) aggregate over that of total coarse (fine) aggregate, and tube width-to-thickness ratio (B/t). The failure modes, relationship between loads and deformations, axial/flexural capacity and axial compressive/flexural stiffness were recorded and analysed. The test results indicate that, the SSC filled steel SHS specimens have similar static performance as the reference composite specimens using ordinary concrete (OC). The variation in the mass substitution rate of SSA mainly leads to the difference in the mechanical factors, and simultaneously the behaviour of stub columns with a smaller B/t is better than that of the corresponding specimens with a larger B/t. A modified compressive stress-strain model of the SSC with the effect of Rc and/or Rf was developed, and finite element (FE) models were further established to investigate the static performance of the SSC filled steel SHS stub columns and beams. The FE models were validated by the experimental results in this study and the existing literature. Finally, the suitable method for the axial/flexural capacity prediction of the SSC filled steel SHS members was recommended.

Design strategies of the mantis shrimp spike: How the crustacean cuticle became a remarkable biological harpoon

AbstractSpearing mantis shrimps are aggressive crustaceans using specialized appendages with sharp spikes to capture fishes with fast movement. Each spike is a biological tool that has to combine high toughness, as required by the initial impact with the victim, with high stiffness and strength, to ensure sufficient penetration while avoid breaking. We performed a multimodal analysis to uncover the design strategies of this harpoon based on chitin. We found that the spike is a slightly hooked hollow beam with the outer surface decorated by serrations and grooves to enhance cutting and interlocking. The cuticle of the spike resembles a multilayer composite: An outer heavily mineralized, stiff, and hard region (with average indentation modulus and hardness of 68 and 3 GPa), providing high resistance to contact stresses, is combined with a less mineralized region, which occupies a large fraction of the cuticle (up to 50%) and features parallel fibers oriented longitudinally, enhancing stiffness and strength. A central finding of our work is the presence of a tiny interphase (less than 10 μm in width) based on helical fibers and showing a spatial modulation in mechanical properties, which has the critical task to integrate the stiff but brittle outer layer with the more compliant highly anisotropic parallel‐fiber region. We highlighted the remarkable ability of this helicoidal region to stop nanoindentation‐induced cracks. Using three‐dimensional multimaterial printing to prototype spike‐inspired composites, we showed how the observed construction principles can not only hamper damage propagation between highly dissimilar layers (resulting in composites with the helical interphase absorbing 50% more energy than without it) but can also enhance resistance to puncture (25% increase in the force required to penetrate the composites with a blunt tool). Such findings may provide guidelines to design lightweight harpoons relying on environmentally friendly and recyclable building blocks.Key Points The heavily mineralized biological appendages of the mantis shrimp are a constant source of inspiration for developing new engineering materials. We use characterization methods of material science to investigate a biological harpoon based on chitin. Several morphological, compositional, microstructural, and biomechanical features are highlighted, allowing the spikes of the mantis shrimp to be remarkable lightweight, tough, and stiff harpoons.

A Novel Variable Stiffness Compliant Robotic Link Based on Discrete Variable Stiffness Units for Safe Human–Robot Interaction

AbstractVariable stiffness manipulators balance the trade-off between manipulation performance needing high stiffness and safe human–robot interaction desiring low stiffness. Variable stiffness links enable this flexible manipulation function during human–robot interaction. In this paper, we propose a novel variable stiffness link based on discrete variable stiffness units (DSUs). A DSU is a parallel guided beam that can adjust stiffness discretely by changing the cross-sectional area properties of the hollow beam segments. The variable stiffness link (Tri-DSU) consists of three tandem DSUs to achieve eight stiffness modes and a stiffness ratio of 31. To optimize the design, stiffness analysis of the DSU and Tri-DSU under various configurations and forces was performed by a derived linear analytical model which applies to small/intermediate deflections. The model is derived using the approach of serially connected beams and superposition combinations. 3D-Printed prototypes were built to verify the feature and performance of the Tri-DSU in comparison with the finite element analysis and analytical model results. It’s demonstrated that our model can accurately predict the stiffnesses of the DSU and Tri-DSU within a certain range of parameters. Impact tests were also conducted to validate the performance of the Tri-DSU. The developed method and analytical model are extendable to multiple DSUs with parameter configurations to achieve modularization and customization, and also provide a tool for the design of reconfigurable collaborative robot (cobot) manipulators.

Analisa Konstruksi Mesin Bubut Duplikat Untuk Profil Kayu Dengan Ukuran Kayu Diameter 15 Cm Dan Panjang 50 Cm

In desain ing wood profile lathes, the quality and strength are calculated by analyzing various loads that occur in the lathes and choosing suitable materials to be used in the manufacture of lathes, the materials used are 40 X 40 mm hollow beam type A ISI 304 with tensile strength 6 x 108 N / m 2 , mudulus elasticity 1.9 X 1011 N / m 2 , performed to calculate the distribution of the load received by the rangkan of 757 N and done to get the results close to the original as a reference for making the lathe frame duplicate the wood profile. To do the simulation, solidwork software is needed as a means to DESAIN and DESAIN the lathe frame strength duplicate the wood profile. Manual calculation results are compared with finite element analysis (FEA) simulations. S trength analysis in the frame is obtained 3.9 X 10 7 N / mm 2 , the deflection that occurs is 0.08 mm.

Additive Manufacturing of Titanium-Based Materials Using Electron Beam Wire 3D Printing Approach: Peculiarities, Advantages, and Prospects

Potential of additive manufacturing technologies, namely, xBeam 3D Metal Printing for the fabrication of uniform Ti–6Al–4V (Ti-6-4, mas.%) material as well as layered titanium-based structures, with mechanical properties sufficient for wide practical application is demonstrated. The key distinctive features of this process are titanium alloy wire as a feedstock material and hollow conical electron beam for heating and melting of the wire. 3D printed with special ‘shift strategy’ Ti-6-4 alloy meets requirements to mechanical characteristics of corresponding conventional cast and wrought products, if microstructure features, material anisotropy and crystallographic texture are controlled with proper selection of processing parameters. Production of multilayered materials consisting of combined layers of different titanium materials, viz. commercially pure titanium (CP-Ti), Ti-6-4 and high-strength T110 alloys, as well as metal matrix composites (MMC) based on Ti-6-4 matrix reinforced by fine TiC particles is considered. Microstructural features and mechanical properties of all 3D printed materials are investigated. Terminal ballistic tests are performed with different ammunition. Described results show the promising potential of 3D printing technologies, xBeam 3D Metal Printing as an example, for manufacturing of titanium-based multilayered armour materials with reduced thickness and weight, and at the same time, sufficient protection characteristics.

All-optical edge-enhanced proton imaging driven by an intense vortex laser

An all-optical approach to edge-enhanced proton radiography is realized by using a relativistic vortex laser irradiating on nanometer-thick foil. In the proof-of-principle experiments, the hollow proton beam was successfully produced by the transparent target normal electric field sheath in the break-out after-burner acceleration mechanism, using a superintense Laguerre–Gauss laser with the highest intensity of the laser exceeded 1020 W/cm2. An insect was imaged with the proton beam; the leg structures on the edge were clearly captured. By contrast, the dot proton source produced by a Gaussian laser was almost completely blocked by the insect's body, losing most edge information. Hollow-structured proton beams driven by vortex lasers conquer the dot imaging limit for high-energy proton beams, which may benefit imaging of capsule implosions in inertial confined fusion, instability research on expanding plasma, and precise positioning in medical therapy.

Spiraling elliptic hollow beams with cross phase

We introduced a class of spiraling elliptic hollow beams with the cross phase. Due to the cross phase, the spiraling elliptic hollow beams exhibit three key characteristics, having the elliptic peak ring, carrying the orbital angular momentum (OAM), and performing rotations. We investigated both linear and nonlinear evolutions of the spiraling elliptic hollow beams, and found they can propagate stably, thanks to the cross phase. Especially, we obtained the breather states of spiraling elliptic hollow beams in nonlocally nonlinear medium, and could handily control the rotation by changing optical powers. We discussed both the OAM property and optical force property. By using the spiraling elliptic hollow beams, we can achieve a jointly multiple manipulation on particles at the same time. In one step, we can trap and simultaneously rotate the particles.