Parallel Steel Research Articles

Seismic design parameters (R, Cd, and Ω0) for uncoupled composite plate shear walls−concrete filled (C‐PSW/CF)

AbstractComposite Plate Shear Walls−Concrete Filled (C‐PSW/CF) are an innovative seismic force resisting system recently adapted for building applications. The walls consist of parallel steel faceplates connected with tie bars and filled with concrete. This paper summarizes the results of a recent FEMA P695 study completed to verify seismic design parameters for uncoupled C‐PSW/CFs with rectangular flange plate boundary elements. Seven archetype structures were: (i) designed, (ii) modeled using a benchmarked fiber‐based finite element analysis approach, (iii) subjected to nonlinear pushover analysis, (iv) and to incremental nonlinear dynamic analysis to failure for 22‐sets of scaled ground motions, and (v) the results were statistically analyzed to assess performance. These structures ranged from three (3) to twenty‐two (22) stories and included both planar and C‐shaped configurations. As part of this design process, recommendations for stiffness approximations for linear analysis of C‐PSW/CFs were developed. Additionally, these nonlinear incremental dynamic analysis results were post‐processed to determine the rotation and strain demands at the base of these structures at the design basis, maximum considered, and failure level earthquakes. These results showed that the rotation and strain demand at failure level earthquakes were comparable regardless of the ground motion. Ultimately, this FEMA P695 approach verified the R factor of 6.5, Cd factor of 5.5, and Ω0 of 2.5 for C‐PSW/CFs with boundary elements.

Tribo-corrosion interaction of the parallel steel wires in the suspension bridges

AbstractThe effect of contact load and relative displacement on tribo-corrosion interaction of parallel steel wires of main cable in the suspension bridge was investigated in this study. A self-made tribo-corrosion test bench was employed to conduct tribo-corrosion tests of parallel steel wires in 3.5% (wt%) NaCl solution and deionized water under different contact loads and different relative displacements. The friction coefficient and wear coefficient of wires were presented. Electrochemical corrosion behavior (Tafel polarization curves, Nyquist diagram, and equivalent circuit diagram) was characterized by electrochemical analyzer. Wear morphology was observed by scanning electron microscope. Wear volume loss and corrosion-wear interaction were quantitatively demonstrated by high-precision weighing balance. The results show that the electrochemical corrosion ability of the steel wires increases with the increase of the contact load or relative displacement. The increased contact load or relative displacement increases the volume loss of corrosion-wear and pure wear, but decreases the wear coefficient. The wear mechanisms in 3.5% NaCl solution are adhesive wear, abrasive wear, and corrosive wear as compared to adhesive wear and abrasive wear in deionized water under different contact loads. The wear mechanisms of parallel steel wires are slightly different under different relative displacements. But the main wear mechanisms are similar to that under different contact loads. The interaction effects of corrosion and wear produced by the contact load and relative displacement are all the synergistic effects.

Real-Time Damage Self-Diagnosis and Self-Localization Brillouin Distributed Optical Fiber–Fiber-Reinforced Polymer Composite Smart Cables

Cables are important components of long-span space structures, cable-supported bridges, slopes, and so on. However, they often suffer from damage such as wire breakage, corrosion, and anchor head loosening, which threatens structural safety seriously. Therefore, it is very important to diagnose and localize their damage. To address this problem, a real-time damage self-diagnosis and self-localization smart cable is proposed. It is made of a polyethylene cover pipe and some parallel intelligent steel strands with the Brillouin distributed monitoring capability. Fiber-reinforced polymer (FRP) and optical fiber are put together in the thermosetting molding process to form the intelligent central wire of each intelligent steel strand. When the side wire of the steel strand reaches the ultimate load, the intelligent central wire only reaches about 50% of its ultimate load, so it can be used in the real-time monitoring of side wires. Numerical models of seven-wire steel strands with different lengths were established, and the broken wire damage was simulated by changing coupling conditions in single and multiple damage cases. To further verify the proposed smart cable, experiments were carried out based on two intelligent steel strands with the length of 34.5 m. Experimental damage cases were simulated by cutting side wires at different positions under different loads. Both numerical and experimental results show that the change in the tension strain of the intelligent central wire can indicate the damaged location of the broken side wire. For a healthy steel strand, the tension strain of the central wire is a constant value; for a damaged steel strand, damage can be localized according to the strain waveform of the intelligent central wire and its ratio of peak strain to stable strain. The proposed smart cable has functions of real-time stress self-sensing, damage self-diagnosis, damage self-localization, damage self-warning of any side wire, and its central wire has excellent corrosion resistance; it can be well used in life-cycle real-time structural health monitoring of cable structures/substructures, which dramatically reduces the probability of cable accidents, and lays a good foundation for smart civil structures.

Seismic behavior of steel-plate encased concrete shear wall with paralleled circular CFST columns: Laboratory test and numerical simulation

Aiming to improve the structural behavior of high-rise buildings, a steel-plate encased concrete shear wall with parallel circular concrete-filled steel tube columns (P-CFST-SCSW) is proposed and investigated by experiments and numerical studies in this study. All seven specimens were conducted and tested under reversed cyclic force to explore the influences of different design parameters, including axial compression ratios, steel tube thicknesses, spacing-thickness ratios, and shear span ratios. The failure modes, hysteresis behavior, strength and stiffness degradation, energy dissipation were thoroughly recorded and compared in detail. Results indicated that all specimens have experienced the failure process of boundary steel tubes buckling, steel plates buckling and concrete crushing. Results also showed that the bearing capacity and deformation capacity of proposed composite walls was excellent. The peak force and initial stiffness of P-CFST-SCSWs were improved by reducing the shear span ratio and increasing the axial compression ratio, while the stiffness degradation and ductility quickly deteriorated. The increased thickness of circular steel tubes considerably improves the seismic behavior of P-CFST-SCSWs. Finally, the numerical model was established to further investigate the effect of the concrete strength, steel yielding strength, and circular CFST columns number on lateral behavior of P-CFST-SCSWs.

Analysis of Double Inverted Flag Energy Harvesting System in Pipe Flow

This technical note numerically and experimentally studies a vibration energy harvester (VEH) consisting of a set of two parallel elastic steel sheets (ESSs) and piezoelectric patches (PZTs) in pipe flow. The roots of the elastic steel sheets are fixed on the base with the PZTs to form a double inverted flag vibration energy harvesting system (DIF-VEHS). In this note, a semi-circular receiving device (receiver) was added to the free end of the elastic steel, and a cylinder was installed upstream to generate a periodic oscillating flow field in the pipeline to obtain better electric energy generation efficiency. This study reveals the effect of different factors on the energy harvesting system, such as the distance between the ESSs, the diameter of the cylinder, etc. This study uses ANSYS software to simulate the fluid–structure interaction vibration of ESSs to determine the feasibility of this design. An experimental setup is then implemented to find the most effective combination of factors for the system. The results of this study show that with all parameters configured properly, the electric energy generation reaches a maximum average value of 1.6657 V per minute. In the future, such devices could be installed in sewers, pipes or rivers, allowing the flow energy of the fluid to be recycled to generate more energy.

A multi-dimensional evaluation of wire breakage in bridge cable based on self-magnetic flux leakage signals

The wire breakage of bridge cable may result in potential bridge safety and durability problems. Therefore, it is urgent to develop an effective testing method for quantitatively evaluating wire breakage. In this paper, based on magnetic dipole theory, the dual defects magnetic dipole model of bridge cables was established to quantify the width of breakage. Then, the multi-dimensional self-magnetic flux leakage (SMFL) detection experiments were carried out for different wire breakage states of parallel steel wire bundles. The experimental results show that the distribution law of the theoretical model is consistent with the experimental results. Finally, a method was proposed to quantitatively characterize the axial wire breakage width of the cable using the Boltzmann fitting curve. In addition, a three-dimensional (3D) line graph was proposed to qualitatively evaluate the relative magnitude of the radial wire breakage depth. This study provides a theoretical basis for quantitatively evaluating bridge cables using the SMFL signals.

Reliability assessment of parallel wire suspender components considering interlayer corrosion variance

The suspenders bear the repeated stress caused by various cyclic actions during the bridge operation while the stress amplitude under dynamic load is smaller than under dead load. The steel wire degradation process is a typical corrosion fatigue degradation, in which the initial defects caused by surface corrosion are the main source of fatigue cracks and the crack development under operating load leads to the failure of the steel wire. The steel wires of the suspender are considered as a co-deformed parallel structural system. The corrosion process of steel wires in different layers are different for the diffusion paths of corrosion medium, which makes the bearing capacity of steel wires differs from each other. The suspender strength depends on the wire of lowest strength due to the Daniels effect, interlayer corrosion variance should be considered in the evaluation of suspender reliability. This paper investigates the interlayer corrosion variance of parallel steel wire suspenders on the basis of neutral salt spray test. It proposes a corrosion variance coefficient, and considers the stochastic degradation process of suspender. Combined with the daily traffic model, it establishes a sophisticated reliability evaluation method of suspender. The results are shown: The steel wires in each layer of test specimens are all severely corroded when the corrosion time reaches a certain degree. For the specimens with different damage types, the overall corrosion condition of the annular damaged specimen is the most severe; whereas that of the vertical damaged specimen is the least. Under experimental environment, the corrosion variance coefficients of sheath damaged specimens follow normal distribution. In the application of suspender evaluation, the service lifespan of wires varies obviously with the corrosion variance coefficient. The distribution of steel wire lifespan under different corrosion variance coefficients also follows normal distribution. The service lifespan of outer layer wires is longer than inner layer wires, and the overall reliability lies between the reliability of outer and inner layers.

Effect of temperature on tribo-corrosion behaviors of parallel steel wires of main cable in the suspension bridge

The effect of temperature on tribo-corrosion behaviors of parallel steel wires of main cable in the suspension bridge was investigated in the present study. The self-made tribo-corrosion test rig was employed to conduct tribo-corrosion tests of parallel steel wires in 3.5% (wt%) NaCl solution and deionized water with distinct temperature. The coefficient of friction, wear loss and wear coefficient of steel wires were presented. Morphologies and chemical elements of wear scars of steel wires were measured by the scanning electron microscope and electron spectrometer, respectively, in order to explore wear mechanisms of steel wires. Tafel polarization curves, Nyquist diagram and equivalent circuit diagram were obtained by the electrochemical analyzer to investigate electrochemical corrosion behaviors of steel wires. Finally, the interaction between corrosion and wear of steel wires were quantitatively demonstrated. The results show that the coefficient of friction, wear volume and wear coefficient of parallel steel wires all increase with increasing temperature in cases of deionized water and 3.5% NaCl solution. Wear mechanisms of parallel steel wires are adhesive wear, abrasive wear and corrosive wear in the 3.5% NaCl solution as compared to adhesive wear and abrasive wear in the deionized water. An increase of temperature reduces the corrosion resistance of parallel steel wires in the 3.5% NaCl solution, while the interaction of corrosion and wear increases with increasing temperature indicating the synergistic effect. The results are of important fundamental significance to the load-bearing safety of main cable and improvement of service stability of suspension bridge.

Calibrating geometrical acoustics models of non-diffuse rooms

A case study is presented for the challenging case in which a conference room with a strongly non-diffuse impulse response is measured, and geometrical acoustics models are built and calibrated using two separate software packages simultaneously. Both software packages are able to reproduce the measured flutter echoes, although with surprising input scattering coefficients, particularly for parallel stainless steel wall finishes. Caution is advised concerning common assumptions about scattering coefficients for operable partitions. Furthermore, the authors suggest that benchmarking for acoustics simulation software be performed in strongly non-diffuse rooms, in addition to the existing round robin studies that have traditionally been held using more normal or diffuse rooms.

P20. Evaluation of interbody design parameters on graft subsidence in the 3D-printed era: separating fact from fiction

<h3>BACKGROUND CONTEXT</h3> Cage subsidence is a known complication of spinal interbody fusion and is associated with poor clinical outcomes. Three-dimensional-printed titanium interbodies are becoming increasingly popular and their unique manufacturing allows for alteration of several features including stiffness and porosity. Though there are many claims made regarding the influence of these features on interbody subsidence, there is a lack of rigorous scientific evaluation. <h3>PURPOSE</h3> The purpose of this study is to determine how changes in implant parameters biomechanically affect subsidence using an in-vitro sawbone model. <h3>STUDY DESIGN/SETTING</h3> In vtiro biomechanical saw bone model. <h3>OUTCOME MEASURES</h3> Subsidence measured as relative displacement of the interbody and foam block using digital imaging correlation. Stiffness measured using thethe linear portion of the load displacement curve. <h3>METHODS</h3> Eight groups were tested (n = 8/group) including seven 3D-printed titanium (Seaspine, Inc.) varying in surface area (aperture: standard, small and none), porosity (high vs low) and surface topography (nonporous vs porous) as well as one standard PEEK and one solid titanium. Subsidence testing was performed in a standardized foam block model compressed to 150 N, cycled between 50-250N for 5000 cycles at a rate of 1 Hz. Digital imaging correlation was used to determine relative displacement of the interbody and foam block. Stiffness testing was performed by compressing implants between parallel steel blocks by 500 N at a rate of 50N/sec for three cycles and measuring the linear portion of the load displacement curve. <h3>RESULTS</h3> Subsidence was decreased as the surface area of contact with the sawbone was increased (all p 0.353) or based on material property (all p>.192). Apparent stiffness of the implant was affected by porosity (p 0.146). The PEEK cage had similar stiffness to porous Ti (p= 0.959). A nonporous surface led to greater stiffness compared to the standard porous interbody (p= 0.010). Surface area was negatively correlated with subsidence (r= -0.808, p=0.0284), but was not correlated with stiffness (r= 0.568, p=0.183). <h3>CONCLUSIONS</h3> Implant surface area and surface topography have the greatest influence on interbody subsidence. Apparent stiffness, implant porosity, as well as material property do not affect subsidence in an in vitro model. Biologic response in the in vivo setting likely also influences clinical subsidence, which is a topic of future study. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Investigation of wave propagation path and damage source 3D localization in parallel steel wire bundle

Investigation of wave propagation path and damage source 3D localization in parallel steel wire bundle

A Position Sensor With Novel Configuration of Linear Variable Differential Transformer

This paper presents a position sensor based on a novel configuration of linear variable differential transformer. Design and optimization of the position sensor using finite element method are presented. The measurements are also conducted to validate experimentally the sensor performance. The sensor has short air core coils and long magnetic armatures. The axis of the rectangular excitation coil and two antiserially connected rectangular pick up coils is perpendicular to the motion direction of the position sensor. The coils are located between two parallel silicon steel laminations serving as the armatures. The position sensor is optimized with compromise between minimization of nonlinearity error and maximum sensitivity. The main advantage of the proposed position sensor is the small ratio of coils dimensions to the working range. The position sensor is operated for excitation frequencies of 500 Hz, 1000 Hz, and 2000 Hz. The maximum nonlinearity error is less than 1.5% for the theoretical results and it is less than 2% for the measured results in ±90 mm position range.

Probabilistic Models for Fatigue Resistance of Seven-Wire Prestressing Strands and Stay Cables

Parallel seven-wire steel prestressing strands are the dominant form of the main tension elements (MTE) used in stay cables. In this paper, probabilistic models for fatigue resistance of seven-wire prestressing strands that are not embedded in concrete and are subjected to axial stresses are developed. Available test data from seven-wire strand fatigue tests were collected and analyzed to develop probabilistic models and nonlinear S–N curves using survival analysis techniques. Results indicate that the fatigue resistance of classic stress-relieved strands produced before early 1980s is higher than the modern low-relaxation strands that have been manufactured since then. Neither the conventional classic nor the modern strands have a good chance of passing the fatigue qualification tests required by the latest design standards for use in stay cables. Only the cable-quality (CQ) strands can pass the latest fatigue qualification tests with a less than 2.5% probability of failure. Nonlinear S–N equations for all three strand types and stay cables made with CQ strands are proposed using a log-logistic parametric survival model.

EXPERIMENTAL INVESTIGATION ON THE CREEP RESPONSE AND THERMAL EXPANSION OF PARALLEL STEEL WIRES AT ELEVATED TEMPERATURES

The thermal expansion at 15 different temperatures and the high temperature creep at multiple stress levels of 1670 MPa parallel steel wires, which are widely used in practical engineering, were experimentally investigated by a charge-coupled device camera (CCDC) system. The tensile strength of the specimens which experienced 2-hour’s high temperature creep investigation was measured at the ambient temperature. The curves of thermal expansion strain and high temperature creep strain of the parallel steel wires were obtained. The test results show that the thermal expansion strain of the parallel steel wires increased nonlinearly with the increase of the temperature and the microstructure changed at 750 ℃. Both the heating temperature and the stress level significantly affected the high temperature creep strain. At a higher temperature, the effect of the stress level on the residual tensile strength of the parallel steel wires was more significant. Compared with the 1860 MPa pre-stressed twisted steel wires, the 1670 MPa parallel steel wires had a lower creep strain at a high temperature. Based on the test data, the function of the thermal expansion coefficient of parallel steel wires with respect to the temperature and the high temperature creep model are proposed. The thermal expansion coefficient and the high temperature creep model proposed in this paper can benefit the mechanical response analysis of pre-stressed steel structures at elevated temperatures.

Study on Construction Technology of Parallel Steel Wire Stay Cable of Long-span Cable-stayed Bridge —— Taking the D1 Cable-stayed Bridge Project of Coastal Avenue in Malaysia as an Example

Study on Construction Technology of Parallel Steel Wire Stay Cable of Long-span Cable-stayed Bridge —— Taking the D1 Cable-stayed Bridge Project of Coastal Avenue in Malaysia as an Example

Underwater anechoic layer with parallel metallic plate insertions: theoretical modelling

A novel underwater composite anechoic layer is proposed by inserting periodically placed longitudinal parallel steel plates into a viscoelastic rubber matrix. Built upon the complex viscosity model of viscoelastic materials, a theoretical model is established to evaluate the sound absorption performance of the proposed anechoic layer. For validation, finite element simulations are carried out, and good agreements are achieved between theory and simulation. Compared with the reference structure purely made of rubber, the new anechoic layer exhibits greatly improved sound absorption performance. It is demonstrated that the steel plate insertions significantly enlarge the shear deformation of rubber at plate–rubber interfaces, causing greatly improved viscous dissipation of acoustic energy. Systematic variations of material properties and geometrical parameters reveal the dominant roles of rubber viscosity and plate spacing. Further, a theoretical model is developed to study the effect of non-tight connection at rubber–plate interfaces. This study broadens the application scope of the complex viscosity model and provides useful guidance for designing novel anechoic layers with tailored underwater acoustic performances.

Non-contact harmonic magnetic field detection for parallel steel pipeline localization and defects recognition

A novel detection method and targets signal extraction algorithm for parallel steel pipeline localization and defects recognition based on harmonic magnetic field are proposed. An orthogonal vector differential focusing array detector was designed, which radiates high-frequency (HF) and ultra-low-frequency (ULF) electromagnetic waves to pipeline based on the principle of Frequency Modulated Continuous Wave (FMCW), and records the signals in parallel using high-sensitivity Tunnel Magneto Resistance (TMR) array sensors. The joint signal pre-processing algorithm of Combination Morphological Pulse Elimination (CMPE) and Quantum Genetic Gaussian Potential Stochastic Resonance (QGGPSR) is proposed to improve signal quality by adaptively eliminating random pulse and noise. The time–frequency analysis algorithm Complementary Ensemble Local Mean Decomposition (CELMD) is used to decompose the pipeline defects signal in detail, and the appropriate components are selected and fused into a correlation array signal cluster. Finally, the targets signal are separated by Limited-memory BFGS Independent Component Analysis (L-BFGS-ICA) based on machine learning optimization to enhance their legibility. The magnetic dipole harmonic simulation model and the 20# steel parallel pipeline experimental platform are established, and compared with the passive detection method to verify the effectiveness and practicality of the proposed method. The results show that this method can accurately locate parallel pipelines and detect different kinds of defects in noisy environment, which is of great significance for the application of non-contact Non-Destructive Testing (NDT) in practical engineering.

Fault Current Characteristics of Parallel Stainless Steel &amp; REBCO Tapes and a 6 kV/400 V HTS Transformer

In order to improve the ability of superconducting transformer on limiting fault current, the parallel stainless steel & REBCO tapes are used as the winding materials. Firstly, the critical current of an individual REBCO tape and the parallel stainless steel & REBCO tapes under fault current are measured experimentally to compare their ability of limiting fault current. Then the current distribution in the parallel stainless steel & REBCO tapes under different fault currents are simulated. Lastly, a 6 kV/400 V (120kVA) HTS transformer is designed, and the fault current characteristics of wingdings are simulated based on finite element method (FEM). Experimental and simulation results show that the parallel stainless steel tape can improve the current limiting performance of the windings, which is of important referential value for the design of HTS transformer.

Research on Dynamic Contact and Slip Mechanisms of Parallel Steel Wires in the Main Cable of Suspension Bridge

Research on Dynamic Contact and Slip Mechanisms of Parallel Steel Wires in the Main Cable of Suspension Bridge

Wire breaking localization of parallel steel wire bundle using acoustic emission tests and finite element analysis

The precise localization of cable damage is a major issue in bridge engineering. The acoustic emission (AE) method has been applied to detect defects for cable structures in bridges. In this paper, an AE localization method is proposed to localize both lateral and longitudinal positions of defects in a parallel steel wire bundle composed of seven steel wires. The proposed method is verified numerically and experimentally. Tension failure test of the parallel steel wire bundle composed of seven wires was carried out, and the precise localization of defects was realized by through modal AE techniques and the analysis of the characteristics of AE signal. A Multiphysics model based on COMSOL was established to facilitate the visualization of stimulated AE propagated in the parallel wire bundle. The propagation mechanism of AE signal was studied, and the feasibility of localization method was verified.