Spacer Cable Research Articles

Study on Deflection-Span Ratio of Cable-Stayed Suspension Cooperative System with Single-Tower Space Cable

This study uses the wind–vehicle–bridge coupling vibration analysis method to investigate the bridge stiffness problem of a large-span cable-stayed-suspension cooperative system. On the basis of the particle-damping-spring vehicle model, the TMeasy surface contact tire model is introduced, and a set of universal wind–vehicle–bridge coupling analysis algorithm is built in the framework of the whole process iterative method. Based on the Latin supercube sampling principle, random traffic flow is generated and loaded onto bridge structures with different stiffness conditions to analyze the driving comfort and safety under each stiffness condition. Combining the specification requirements, engineering experience, and research results, the vertical stiffness limit applicable to the bridge of the highway cable-stayed-suspension collaborative system is proposed. Existing engineering experience shows that the vertical deflection-to-span ratio of a cable-stayed bridge under live load is distributed between 1/400 and 1/1600, and the vertical deflection span ratio under the action of lane load is recommended based on numerical analysis.

Radiometric Partial Discharge Detection: A Review

One of the most common failures or breakdowns that can occur in high-voltage (HV) equipment is due to partial discharges (PDs). This occurs as a result of inadequate insulation, aging, harsh environmental effects, or manufacturing flaws. PD detection and recognition methods have gained growing attention and have seen great progress in the past decades. Radiometric methods are one of the most investigated detection approaches due to their immunity to electromagnetic interference (EMI) and their capabilities to detect and locate PD activities in different applications such as transformers, cables, etc. Several review articles have been published to classify and categorize these works. Nonetheless, some concepts are missing, and some improvement techniques, such as PD detection at high-frequency (HF) and very high-frequency (VHF), have been overlooked. We present in this paper an exhaustive review study of state-of-the-art PD detection based on radiometric methods at different usable radiofrequency bands (i.e., HF, VHF, and UHF). Accordingly, we propose a new generic categorization approach based on the detected electromagnetic wave component (magnetic or electric fields) and pick-up location, either from free space or ground cable.

Design of the Hanging-Mesh Hyperbolic Paraboloid Space Cable Pedestrian Suspension Bridge in a River Canyon

Design of the Hanging-Mesh Hyperbolic Paraboloid Space Cable Pedestrian Suspension Bridge in a River Canyon

Design of 800-m Hillside-Anchored Pedestrian Suspension Bridge with Univalent Hyperboloid Space Cable Net

Design of 800-m Hillside-Anchored Pedestrian Suspension Bridge with Univalent Hyperboloid Space Cable Net

Research on Static and Dynamic Load Test of Suspension Bridge with Univalent Hyperboloid Space Cable System

In this paper, a new model of univalent hyperboloid space cable system suspension bridge is proposed, and a comparative test model of 15 m space suspension bridge and parallel suspension bridge is made. Vertical load test, horizontal load test, partial load test and moving load test were carried out. The results show that compared with the parallel and space cable suspension bridge, the vertical stiffness of the suspension bridge increases slightly, the lateral stiffness is greatly improved and the torsional rigidity is tremendously improved. The space suspension bridge has good wind resisting stability.

Design of Flying-Bird Type Cable Stayed Arch Bridge with Three-Leaf Rose Shaped CFST Arch Rib

According to the geometric figure of three-leaf rose curve, this paper puts forward a flying-bird type cable-stayed arch bridge with three-leaf rose curve shaped CFST arch rib, which has beautiful appearance and one bridge leads to three banks.The space cables are set between the three-leaf rose linear space arch ribs to resist negative bending moment, and the tie cables are set between the arch feet to resist positive bending moment. On the inclined pylon at the tail of the flying-bird type cable-stayed arch bridge, the stay-cables are arranged to balance the arch thrust, and the suspension-cables are arranged on the three leaf rose linear spatial arch ribs to hang the three fork bridge deck.The flying-bird type cable-stayed arch bridge with three-leaf rose linear CFST arch rib adopts spatial cable structure system, which has good structural stability.Combined with the actual project, the engineering parameters are designed, the Midas finite element analysis model is established, the internal force analysis and modal analysis are carried out, and the rationality of flying-bird type cable-stayed arch bridge with three-leaf rose linear CFST arch rib is verified.

Design of Pedestrian Landscape Flying-Bird Arch Bridge with Cable-Stayed Cable and Lissajous Curved Arch Rib

In view of the demand of super long span pedestrian landscape bridge with curved deck, this paper proposes a kind of cable-stayed and flying-brid arch bridge with Lissajous curved arch rib and double curved bridge deck. Its plane positive projection is Lissajous curve figure, the side elevation of the arch rib is the shape of the cable-stayed and flying-brid arch, and the arch foot cable and the upper space cable between the arch ribs are installed on the Lissajous spatial curved arch rib with concrete-filled steel tube to form a self balanced structure system, which floats and drags across the river. The main arch sling and the tail cable are installed, the double curved bridge deck and the central circular sightseeing platform are suspended, and multiple groups of spatial cables work well together to complement each other, with having complementary advantages. Combined with the actual project, the parameter design is carried out, the Midas finite element model is established, the internal force of the structure is calculated, the structural dynamic mode and stability analysis are carried out, the rationality of its structural performance is verified by analysis and research.

Realistic Virtual Cables in a 2D Environment Representing a 3D Virtual Reality

A new method for the realistic visualization of virtual cables in a 2D environment, which is representing a 3D virtual reality, is presented in this paper. They are described with two consecutive cubic Bezier curves, whose common point is movable. Experiment was carried out and the optimal proportions for the parameters of the curves were obtained in order to achieve a realistic representation of cables. The suggested method has been developed for and implemented in the Engine for Virtual Electrical Engineering Equipment. The obtained results show that it is easy to manipulate the route of the virtual cables in 2D space and that they look realistic for any position of the control point.

3-D NUMIT: A General 3-D Internal Charging Code

A general 3-D internal charge analysis method, 3-D NUMIT, was developed by combining a Monte Carlo radiation transport simulation tool such as MCNPX or GEANT4 and a commercial finite-element analysis software such as COMSOL. The method was validated in 1-D cases with the analytical solution and NUMIT 2.0 and in a 3-D case with previously developed CB_IESD. The internal charging behavior of a semi-rigid coax cable in space was successfully analyzed using this 3-D NUMIT method.

Bridge Deck Transverse Stress Analysis of Arch Tower Cable-Stayed Bridge with Steel Box Girder

In the engineering background of zhijang bridge, shell finite element model of steel box girder segment was established by the ABAQUS finite element program. The transverse stress of the bridge deck was analyzed by two cases of body cable and external cable, and the transverse stress of the bridge deck caused with deadweight and vehicle load was been compared. Conclusions obtained mainly include: the transverse stress of the bridge deck induced by the four cases were not large, if lateral inclination of stay cable was not particularly large, the transverse stress of the bridge deck caused by space cable can not be given special consideration.

Stability of the space cable

The space cable consists of evacuated tubes supported by fast-moving objects, called bolts, travelling inside them. The bolts are connected to the tubes via permanent magnets stabilized electronically for minimal power consumption. Version 1 was designed to replace the role of a first-stage rocket by lifting space vehicles from the ground to 50 km at 5800 km/h. Version 2 rises to 140 km and has wider applications. Comparable proposals include the space fountain and the launch loop. In the long term, such a fixed infrastructure is more economical than rockets. A key issue with these dynamically supported structures is lateral stability, particularly in the presence of varying cross winds in the stratosphere. The relevant partial differential equations are derived below with a set of solutions. A proposal is presented for providing stability by means of tethers, pipes, and a support structure at each end. Each support is a miniature space cable rising to 15 km, and it bears the load of the tethers and pipes that would otherwise have to be carried by the main structure.

Arc Tracking between Space Cables due to Electrostatic Discharge

Discharge mechanism in a space-used cable is needed to clarify the arc tracking formation process on the cable under different environments, against the background of the accident of ADEOS2. The experiment was performed in the vacuum chamber that simulated LEO environment. Three types of sample cables were prepared under different environments (Cut, Heat and UV). Arc tracking formation process has been studied by repetition of sustained arc (SA) inception. With the repetition of SA inception lowering of the resistance between the cables was observed. Only the arcs tracking which occurred below the resistance of about 10kΩ were studied. As a result, there was no difference observed between the cables prepared under different environments. Arc tracking formation process does not depend on the state of deterioration of cable.

Parametric vibration and vibration reduction of cables in cable-stayed space latticed structure

Mechanical model and vibration equation of a cable in cable-stayed space latticed structure (CSLS) under external axial excitation were founded. Determination of the mass lumps and natural frequencies supplied by the space latticed structure (SLS) was analyzed. Multiple scales method (MSM) was introduced to analyze the characteristics of cable’s parametric vibration, and the precise time-integration method (PTIM) was used to solve vibration equation. The vibration behavior of a cable is closely relative to the frequency ratio of the cable and SLS. The cable’s parametric vibration caused by the external axial excitation easily occurs if the frequency ratio of the cable and SLS is in a certain range, and the cable’s vibration amplitude varies greatly even if the initial disturbance supplied by SLS changes a little. Furthermore, the mechanical model and vibration equation of the composite cable system consisting of main cables and assistant cables were studied. The parametric analysis such as the pre-tension level and arrangement of the assistant cables was carried out. Due to the assistant cables, the single-cable vibration mode can be transferred to the global vibration mode, and the stiffness and damping of the cable system are enhanced. The natural frequencies of the composite cable system with the curve line arrangement of assistant cables are higher than those with the straight-line arrangement and the former is more effective than the latter on the cable’s vibration suppression.

Installation of Cable System for Single Tower Space Cable Structure Self anchored Suspension Bridge

Installation of Cable System for Single Tower Space Cable Structure Self anchored Suspension Bridge

Production of Main Cable Saddle and Loose Cable Sleeve for Single Tower Space Cable Surface Self anchored Suspension Bridge

Production of Main Cable Saddle and Loose Cable Sleeve for Single Tower Space Cable Surface Self anchored Suspension Bridge

Application of the Pseudo-Excitation Method with Spatial Coherence in Random Vibration Analysis of Long-Span Space Structures

The pseudo-excitation method is applied for the random seismic response analysis of long-span space structures in this paper. The differences and their orderliness of the structural responses are studied generally under multiple support excitation and simple support excitation from two aspects, i.e. the displacement response variance and the acceleration power spectrum, for four types of structures, such as space truss, shell, cable net and cable dome. Furthermore, the effects of pseudo static response on the above structures are discussed. Some important conclusions are drawn which present the theoretical foundation on aseismatic projects for long span space structures. On the other hand, it shows the pseudo excitation method is efficient and precise and is applicable to the random seismic response analysis of the complicated structure under multiple support excitations, such as long span space truss, shell and cable.

Spacer-Cable Lightning-Induced Overvoltages Computed Using Measured Ground Resistances

Spacer cable provides compact distribution of three-phase power. However, the close proximity of the phases to each other and the neutral carrier wire results in very high fields under lightning conditions. The concept of spacer cable is based on the assumption that the neutral carrier wire is grounded at each pole with an earth resistance no greater than 25 Omega. In many areas, this assumption is far from met. In this paper, we compute lightning-induced overvoltages for long lengths of spacer cable including the effect of every lightning arrester, transformer, etc., on the line and using measured ground resistances, for a range of lightning currents and rise times

Modelling torsion in an elastic cable in space

When an imperfectly flexible, elastic cable is suspended in a vertical plane under the sole influence of gravity and boundary conditions involving axial twist are then applied to the endpoints of the cable, its shape extends from the original vertical plane to a three-dimensional configuration in space. The aim of this paper is to develop a mathematical model (consisting of differential equations) for the configuration of and tension in such a twisted cable. The model is solved numerically for different boundary conditions. Although the final model delivers satisfactory results for small amounts of twist (inside the elastic deformation domain of the cable), realistic bounds for the amount of twist that may be applied (before plastic deformation of the cable causes model inaccuracies) are yet unknown. However, the effect of an increase in the amount of torsion applied at the endpoints of the cable is investigated numerically. The model seems capable of capturing first points of twisting bifurcation, when so much twist is applied at the endpoints that the cable jumps from un unstable equilibrium configuration to a more stable one.

New Technologies, Standards, and Maintenance Methods in Spacer Cable Systems

The overhead distribution lines with bare conductors for medium-and low-voltage circuits are being substituted due to their failure rate and security level, particularly in adverse areas i.e., heavy trees and high isokeraunic levels. The failure rate in CEMIG's medium-voltage overhead distribution lines, in urban areas, is 0.9 failure/km-year. More and more customers ask for better services and lower costs. These types of systems are greatly influenced by external causes such as lightning, rain, trees, collision, and vandalism. In Brazil, based on U.S. experience, the Aerial Spacer Cable System has been shown as the best system to improve its reliability. The low-maintenance cost, easy operation, high security level, and the attractive cost benefits have justified its use, mainly in urban areas, by CEMIG, a Brazilian utility. In the MV Spacer Cable System were included other technologies, such as the CSP transformer, SF6 switch, medium-and low-voltage polymeric arresters, low-voltage multiplex cable, and wedge and piercing connectors. The CEMIG's Spacer Cable System has been performing at an average failure rate of 0.04 failure/km-year. This paper describes the line design, equipment, standards, and maintenance methods in live-line and field experiences of Spacer Cable System in our company, with the technical support of Hendrix Wire & Cable, USA, and Wirex Cable, Brazil. Other utilities in Brazil are now using this system, to meet one of the government's requirements of improved reliability. It is a great alternative for companies searching for high reliability for their distribution electrical system.

Comment on 'Equilibrium configurations and energies of the rotating elastic cable in space'

I N Ref. 1, it is suggested that a thin elastic rod rotating in space can have stable equilibrium configurations that contain intersections or loops. The conditions for stability, which are neglected by Wang, are given here together with a derivation of a simplified version of the energy equation. Unfortunately, these results cannot be used to demonstrate the stability of Wang's looped configurations because they are found to be unstable. For the rod to be stable, the configuration must be at a local energy minimum for any small perturbation of the shape that maintains the angular momentum. The angular momentum is given in a nondimensional form by