Top Beam Research Articles

Seismic performance of semi-rigid steel frame infilled with prefabricated damping wall panels

In this research, two innovative semi-rigid steel frames infilled with prefabricated damping wall panels in different types of connection are proposed. Working principles and main features of the developed infill system with both uncoupling mechanism and sliding joints are defined. A quasi-static test was conducted to explore the seismic response of the two systems, as compared with a bare steel frame. Test results confirm that the detrimental infill-frame interaction is prevented by the proposed wall panels. Both specimens infilled with prefabricated damping wall panels characterize a considerably large deformation capacity up to 3.33% drift, while significant crack or corner crushing in the wall panels is not observed, contributed to the configurations of the prefabricated damping wall panels. The infilled steel frames have stable seismic behavior similar to the bare steel frame without infill, indicating that the prefabricated damping wall panels can be designated as an additional safety stock with damping for the steel frame rather than the major component of strength, stiffness, and brittleness. Specifically, thanks to satisfactory energy dissipation capacity of the damping layers, dissipated energy of steel frame infilled with the prefabricated damping wall panels is about 23.3% larger than the bare steel frame after yielding. Moreover, it would be a more effective and controllable configuration that the lateral displacement of the upper wall panel is directly enforced by the top beam.

A Refined Theory for Bending Vibratory Analysis of Thick Functionally Graded Beams

A refined beam theory that takes the thickness-stretching into account is presented in this study for the bending vibratory behavior analysis of thick functionally graded (FG) beams. In this theory, the number of unknowns is reduced to four instead of five in the other approaches. Transverse displacement is expressed through a hyperbolic function and subdivided into bending, shear, and thickness-stretching components. The number of unknowns is reduced, which involves a decrease in the number of the governing equation. The boundary conditions at the top and bottom FG beam faces are satisfied without any shear correction factor. According to a distribution law, effective characteristics of FG beam material change continuously in the thickness direction depending on the constituent’s volume proportion. Equations of motion are obtained from Hamilton’s principle and are solved by assuming the Navier’s solution type, for the case of a supported FG beam that is transversely loaded. The numerical results obtained are exposed and analyzed in detail to verify the validity of the current theory and prove the influence of the material composition, geometry, and shear deformation on the vibratory responses of FG beams, showing the impact of normal deformation on these responses which is neglected in most of the beam theories. The obtained results are compared with those predicted by other beam theories. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and free vibration responses of FG beams.

Structural Design Optimization of the Top Beam of a Propeller Processing Machine Tool Using FEA Analysis

Aiming to reduce the weight under its rigidity and strength restrictions of a propeller processing machine tool, structural design optimization of the top beam of the machine tool is carried out using FEA analysis approach. Based on static and modal analysis, both the thickness and the width of the rib are optimized and light-weighted, followed FEA analysis results demonstrate that although the maximum stress and deformation of the optimized structure go up slightly, but are still allowable. After optimization, the weight of the top beam is reduced by approximately 8.03% and the dynamic characteristics of the top beam are also enhanced, which is beneficial to the noise reduction of the machine tool.

Experimental and numerical investigation of energy harvesting from double cantilever beams with internal resonance

Conventional harvester systems usually have linear behavior. One of the great matters in these systems is that energy is harvested in a low frequency bandwidth. In this study, double cantilever beams connected at the end through a linear spring are used for energy harvesting. The bimorph piezoelectric patches are attached to the top beam by using double-sided tapes for energy harvesting. A pair of magnets is utilized for adding a nonlinear effect to the system. One of the magnets is mounted at the end of the bottom beam, and the other one is placed on the system’s base. The whole system is designed based on the internal resonance phenomenon. The system’s vibration equations are derived by using the assumed modes method and solved with the numerical solution. Two cases are investigated, including the absence and the presence of the magnetic force. When the magnetic force exists, the effects of nonlinearity and internal resonance on the energy harvesting are investigated and the results are compared to the case when the magnetic force does not exist, which has a linear behavior. To validate the results, a test rig has been designed and fabricated for experimental studies. Experimental results show that the simulation results are in good agreement with the experimental data. The obtained results show that energy is usually harvested in a broader frequency bandwidth when the magnetic force exists compared to when it does not exist. However, when the magnetic force exists, peak voltage can be higher or lower than the case that the magnetic force does not exist. It depends on the system’s parameters.

Effects of the crack location on the dynamic response of multi-storey frame subjected to the passage of a high-speed train

The high-speed railways require more viaduct than a conventional railway. When the viaduct is subjected to high-amplitude vibrations for a long time, the fatigue-induced crack formation can occur . The presence of a crack changes the stiffness of the structure. Depending on the location of the crack, the reduction effect in stiffness varies. In this study, the presence of a single crack in a multi-storey frame structure, which is considered as a viaduct model, has been investigated. Effects of crack location on the dynamic response are investigated via 3D velocity-crack location-dynamic magnification factor (or maximum displacement) graphs. The train is modelled as a four-axle two-bogie multi-body system with 10 DOF and moving at a constant speed. The finite element method, based on Euler–Bernoulli beam theory, is used to simulate the vibrations of the coupled vehicle-structure system. Wilson-theta time integration scheme is used to solve the equation of motion. It has been determined that when the crack is located at the midpoint of the top beam, the highest effect on the dynamic response is observed.

Study on Prefabricated Firewall with Truss Load

In this paper, a prefabricated structure is used to study the main transformer firewall with truss structure of the substation. The beams, columns and wall panels of the firewall are prefabricated components, and the cast-in-place structure is used only at the top beam and column joints.

Macro-Scale Numerical Modeling of Unreinforced Brick Masonry Squat Pier Under In-Plane Shear

Numerical modeling of brick masonry behaviour under different performance conditions has always remained a challenging task. Several modeling strategies have been developed for masonry, in general, through the course of time that have been simplified to speed up modeling and analysis duration. This ranges from a simplified strut model to a highly discontinuous micro-scale nonlinear model. With the current advent of high-speed computing and modeling tools, more realistic numerical modeling of masonry is now possible. In this paper, the strategy adopted is based on macro-scale modeling, where isotropic material properties are considered for the homogenous continuum. ABAQUS is used as a state-of-the-art finite element-based analysis and modeling tool. The Concrete Damage Plasticity (CDP) model is used for simulating inelastic material behaviour of brick and mortar, which is available in the ABAQUS library. This material model can be used in both implicit and explicit schemes of integration but the explicit procedure is highly preferred as it overcomes the convergence issues. Various parameters required for CDP modeling of brick and mortar are adapted from literature. The model is assembled in two parts, first part is modeled for masonry with both elastic and plastic properties, while the other part simulates a rigid beam at the top of the masonry part to create a uniform in-plane shear loading effect. The masonry part has been fixed at the bottom with free vertical ends, while horizontal in-plane displacement was applied to the top rigid beam. The load-displacement curves were generated from these models for monotonic push, to compare them with the envelopes of experimental results, loaded similarly. Since brick masonry is a highly disjointed material, it is a complicated procedure to develop an exact model and predict its exact behaviour. However, the overall representative load-displacement curve developed numerically was in good agreement with the ones produced experimentally.

Thermo-mechanical modeling and experimental validation for multilayered metallic microstructures

This paper presents thermo-mechanical modeling on multilayered metallic microstructures consisting of two bilayers that enable 3D deployment once being Joule heated. A representative design of such microstructures, as well as their working principle is introduced. A mathematical model is derived using Euler–Bernoulli beam theory, and analytical solutions describing out-of-plane displacement of the multilayered microstructures when uniformly heated, which is validated by finite element analysis. Parametric analysis on thermal load and dimensional change of beam shows a good agreement between the analytical solutions and results given by finite element analysis. The phases of the near-equiatomic NiTi layer are analyzed by EDS and XRD, which prove to be austenite during the Joule heating process. The mechanical properties of austenite NiTi are incorporated into the analytical solutions that provides a good estimation of 3D deployment of microstructures made of NiTi and aluminum. The experimental results provide an approximately 7 µm out-of-plane deployment by applying a uniform temperature increase of 132 K, and parametric analysis on the dimension of top aluminum beam offers another promising approach to larger 3D deployment. The proposed mathematical model provides an efficient tool for predicting the out-of-plane deployment of such multilayered microstructures.

AVA Biochem teams with Michelin Group

In this paper, the buckling of cross-ply and angle-ply composite beams under hygro-thermo-mechanical loading is presented by the analytical approach. This approach is based on theory of hyperbolic refined shear deformation. This approach which has strong resemblance with beam theory of Euler Bernoulli in various aspects, accounts for a second-degree variation of the transverse shear strains through the thickness and verified the zero traction of boundary conditions on the bottom and top beam surfaces sans employing shear correction factors. The effects of temperature and moisture concentration, thus the effect of the ratios of modulus, length to thickness and coefficient of thermal expansion respectively on hygro-thermo-mechanical buckling of cross-ply and angle-ply laminated beams are studied.

Hygro-thermo-mechanical buckling of laminated beam using hyperbolic refined shear deformation theory

In this paper, the buckling of cross-ply and angle-ply composite beams under hygro-thermo-mechanical loading is presented by the analytical approach. This approach is based on theory of hyperbolic refined shear deformation. This approach which has strong resemblance with beam theory of Euler Bernoulli in various aspects, accounts for a second-degree variation of the transverse shear strains through the thickness and verified the zero traction of boundary conditions on the bottom and top beam surfaces sans employing shear correction factors. The effects of temperature and moisture concentration, thus the effect of the ratios of modulus, length to thickness and coefficient of thermal expansion respectively on hygro-thermo-mechanical buckling of cross-ply and angle-ply laminated beams are studied.

Mechanical analysis of the structure of longwall mining hydraulic support.

Existing studies of the structural strength of longwall mining hydraulic support are mainly focused on the force acting on individual supports instead of the general mechanical characteristics of the support group in a fully mechanized coal seam working face. This study combines theoretical analyses and experiments to investigate the mechanical characteristics of a longwall mining hydraulic support group and the stiffness of key support components under different working conditions. The theory of a beam on an elastic foundation was applied to construct a mechanical model for the hydraulic support group. The location and the size of loads on the top beam were determined. Field tests yielded data on the deflection of the roof and loading on the support group along the working face, where the stiffness of end supports varies. The transverse load distribution of the top beam and the offset loading coefficient at different locations along the working-face direction were obtained. A three-dimensional model was constructed for the support group while assembling virtual hydraulic supports using modern virtual modeling theories and methods. Finite element analysis was used to analyze the strength of the hydraulic support. The weakest areas of key components were found to be pinholes connecting the column cylinder to the base and roof of the mine. These results can be applied to achieve secure and stable operations of hydraulic supports in the working face of a thin coal seam, thereby improving the safety and production efficiency of mining operations.

Moment–rotation response of post-tensioned self-centring beam–column connection

In order to overcome common problems such as low stiffness, insufficient ductility and enormous residual displacements in beam–column connections, a steel beam–column connection equipped with high-strength strands was developed. These so-called post-tensioned (PT) steel connections consist of high-resistance strands passing parallel to the beam web and through drilled holes in the column flange and the top and bottom beam angles, which act as energy dissipation elements. The displacement and rotation of connections in earthquake events is a problem that can be avoided by a self-centring feature of steel PT connections. In this research, the cyclic response of PT beam–column steel connections with stiffeners connected to the top and bottom beam angles was investigated. Different stiffener geometries and thicknesses were examined and numerical models were simulated using Abaqus software. The results showed that installation of stiffeners on the top and bottom beam angles had a direct effect on the gap opening of the beam–column interface and reduced the relative rotation. Under large applied drifts, primary elements of the connection experienced large deformation and failure. Thus, by equipping angles with stiffeners, all of the induced stresses and damage will be concentrated in the stiffeners. In all the models equipped with stiffeners, the behaviour of beam reached the plastic phase and the minimum value of Mmax/Mpn was almost 1·1. Failure of the angles was also delayed and the primary elements of the connection (beam and column) remained undamaged.

Establishment and simulation of dynamic model of backfilling hydraulic support with six pillars

A backfilling hydraulic support with six pillars used for working face roof support and goaf backfilling in coal mine is designed, and the structure and working principle of the backfilling hydraulic support are described. In order to improve the working stability of backfilling hydraulic support, the differential equations of motion and the state space model of backfilling hydraulic support are established based on Lagrange method and space coordinate system. According to the support structure and related parameters, the differential equation of motion of the system is solved by MATLAB. The influence law of disturbance frequency and amplitude on the top beam vertical vibration, roll and pitch vibration is obtained. The results show that the vertical vibration and roll vibration of the top beam are more severe in the low frequency range. And the degree of vibration gradually decreases as the disturbance frequency increases. As the disturbance amplitude increases, the vibration of the top beam is more severe. The vibration of the backfilling hydraulic support and the deformation distribution nephogram of the top beam are obtained by the finite element analysis, the validity of the dynamic model is verified by finite element simulation. The results provide the basis for the optimization design and the stability evaluation of backfilling hydraulic support.

Influence of fetal gender on overall perinatal outcome: a prospective observational study.

Fetal gender is considered as one of significant predictors of pregnancy and perinatal outcome. Aim - To assess impact of fetal gender on perinatal outcome. Present observational study was conducted in Obstetrics and Gynecology department of rural tertiary center of Northern India over one year (January-December 2018) on all randomly selected antenatal women at gestation ≥28 weeks, delivering by any route (Cesarean/Vaginal) and fulfilling inclusion criteria were enrolled. Immediately after delivery, neonatal birth weight was measured using table top beam weighing scale. Apgar scores at 1- and 5-minutes, Neonatal Intensive Care Unit admission, neonatal complications were assessed by pediatrician. Adverse perinatal outcome including neonatal morbidities (prematurity, neonatal intensive care unit admission, neonatal complications) and perinatal mortality were compared between two genders. Statistical analysis was done using SPSS 22 version software. Of 3,085 delivered neonates, 1,450(47%) were females, 1,633(52.9%) males and two (0.06%) had ambiguous genitalia, hence excluded. Mean±SD for neonatal birth weight for males was 2.77±0.540 Kg and females 2.65±0.506 Kg (p=.0000). 1- and 5-minutes Apgar scores for male neonate were 6.81±1.565, 8.51±1.841and for females 6.98±1.184, 8.70±1.383 respectively (p=0.001). NICU admission rate, need for oxygen and intubation, complications were significantly higher for male neonates (p<0.05) whereas females had higher incidence of intra-uterine growth restriction (p=0.000). Intra-uterine deaths were also more common with male gender (p=0.007). No significant difference was observed between two genders in relation to gestation at birth (p>0.05). Male neonates had higher birth weight, but adverse perinatal outcome as compared to females.

Wideband beam-forming metasurface with simultaneous phase and amplitude modulation

Achieving simultaneous controls of the amplitude and phase for electromagnetic waves is essential when shaping a complete wave-front aimed at forming an arbitrary beam. Here a strategy of manipulating the reflected amplitude and phase is proposed using a bi-layered metasurface element. The metasurface unit cell, consisting of a modified I-shape particle and one all-metal ground, achieves broadband phase- and amplitude control by tuning the gap size and rotating the modified I-shape particle, respectively. As a proof of concept, we design a fan-shaped beam metasurface antenna using the genetic algorithm to obtain the optimal phase and amplitude distributions. A Vivaldi antenna with less blockage effect is chosen to illuminate the metasurface, and then the amplitude and phase are compensated by the elements to achieve the optimized distributions. Finally, the beam-forming metasurface antenna is simulated, fabricated, and measured. The results show that the metasurface can generate a flat top beam under rectangular coordinate within the frequency range of 9–12 GHz. Our findings not only provide a universal way for generating beams with arbitrary shapes using metasurfaces but also offer an economical and simple alternative for a beam-forming array antenna.

Linearity performance analysis of the differential wavefront sensing for the Taiji programme

ABSTRACTThe Taiji programme is a Chinese space-based laser interferometer gravitational wave detection mission and the differential wavefront sensing (DWS) technique is introduced to reduce the effect of the laser pointing noise. As the distance between two adjacent satellites is about , the wavefront of the receiving beam is a flat top beam. In this paper, we construct an analytical model of the DWS signal under the circumstances of Gaussian beam-flat top beam interference and study the linearity performance. The position offset of the beams is found to greatly affect the linearity range. A numerical method is used to simulate the linearity range of the DWS signal under various operating conditions. The linearity range decrease with the increase of the offset angle of the Gaussian beam and the offset length of the flat top beam. The offset range of the beams based on the requirement of the Taiji is given at last.

Seismic response of soil slope reinforced by compression anchor and frame beam based on shaking table test

Compression anchor is a good anchorage structure in the slope and landslide project. Compared with tension anchor, it is a relatively new retaining structure, and the studies on compression anchor under seismic loadings are very limited. To investigate the seismic behavior of compression anchor under earthquake and get it to work much better in an earthquake-prone area, based on the shaking table test, a soil model slope reinforced with compression anchor and frame beam was carried out. In the test, the smooth steel bar and Q235 steel plate ring were used to simulate the anchor tendon and bearing plate of the compression anchor. The testing results indicate that the anchoring slope shows an obvious amplification effect on input seismic waves in both time domain and frequency domain, and the amplification effect of the acceleration response increases along the slope height. The axial force of the compression anchor is relatively uniform along the length of the anchor. As for different anchors in the same column, at 0.05~0.2 g, the axial forces of all anchors show tiny values, and the axial force of the bottom anchor is slightly greater than that of other anchors. The axial force of the bottom anchor is about 2.1~2.8 times that of the other anchors. At 0.3~0.6 g, the axial forces of the upper two anchors and the bottom anchor increase rapidly, while the axial forces of the other two middle anchors increase a little. The axial force ratio of the five rows of anchors from the bottom to the top at 0.3 g, 0.4 g, and 0.6 g is 4.2:1:1:2.1:2.9, 4.2:1:0.9:3.1:3.4, and 3.6:1:0.8:3.2:3.8, respectively. As for different beams, at 0.05~0.2 g, the bending moments of all beams show tiny values, and the bending moment of the bottom beam is slightly greater than that of other four beams. At 0.3~0.6 g, the bending moment of the top beam plays a more and more vital role, while the bending moment of the other four beams shows little variation.

FEM analysis of induced ground settlement of tunneling side-crossing high-voltage rod foundation considering reinforcement measures

Taking the actual working conditions of the Wuhan Guanggu 1st/Gaoxin 4th drainage channel project as the research object, Finite Element Method (FEM) is used to analyse the effectiveness of reinforcement measures to control surface settlement deformation around poles during tunnel propulsion. Calculations prove that as the tunnel advances, the displacement around the high-voltage rod gradually increases and tends to stabilize; The numerical simulation study of the combined engineering conditions of different reinforcement measures shows that the pile foundation reinforcement and the pile top beam reinforcement both can effectively reduce the surface settlement, and the reinforcement effect in pile top beam is far greater than that in pile foundation; The numerical results of both the two reinforcement measures involved are compared with the actual monitoring data, and the results are in good agreement. Then the correctness of the numerical model is verified. Therefore, the two reinforcement measures in this area show great effectiveness by studying the four different engineering conditions. The reinforcement measures have certain reference value for related engineering design in this area.

High-dimensional quantum frequency converter

In high dimensional quantum communication networks, quantum frequency convertor (QFC) is indispensable as an interface in the frequency domain. For example, many QFCs have been built to link atomic memories and fiber channels. However, almost all of QFCs work in a two-dimensional space. It is still a pivotal challenge to construct a high-quality QFC for some complex quantum states, e.g., a high dimensional single-photon state that refers to a qudit. Here, we firstly propose a high-dimensional QFC for an orbital angular momentum qudit via sum frequency conversion with a flat top beam pump. As a proof-of-principle demonstration, we realize quantum frequency conversions for a qudit from infrared to visible range. Based on the qudit quantum state tomography, the fidelities of converted state are 98.29(95.02)\%, 97.42(91.74)\%, and 86.75(67.04)\% for a qudit without (with) dark counts in 2,3, and 5 dimensions, respectively. The demonstration is very promising for constructing a high capacity quantum communication network.

Out-of-plane capacity equations for masonry infill walls accounting for openings and boundary conditions

A large part of 20th and 21st centuries’ residential buildings is characterised by reinforced concrete, or less frequently steel, frames filled with masonry walls. Recent seismic events have shown that failure of infills may occur under moderate earthquakes, inducing a risk to life and limb of occupants, as well as to construction cost of the building. For this reason, researches have been devoted to the capacity of infill walls carrying out both analytical and experimental tests, also in the out-of-plane direction. These studies have identified the main parameters affecting the out-of-plane response of infill, such as the boundary conditions and the slenderness of the infill.In this study, a large data set of experimental tests is collected with the aim of investigating the influence of the main factors relevant for the infill response and to assess the suitability of different formulations proposed in the literature. It is found that, for the most part, such formulations underestimate the out-of-plane strength. Afterwards, numerical analyses are performed to investigate those situations that were scarcely considered in experimental campaigns, namely the presence of an opening (window or door) and of a gap between the infill and the top beam. Finally, taking into account all the considered parameters, a formula to predict the out-of-plane strength capacity of an infill is proposed.