Auxiliary Cables Research Articles

Research on fatigue failure and structural measures of suspenders in the Jinsha River railway suspension bridge

In consideration of the significant impact of train loads on the fatigue of suspenders in railway bridges, this paper focuses on the first railway suspension bridge in China − the Jinsha River Railway Suspension Bridge. The study analyzes the force characteristics and bending failure features of the steel wire ropes in railway suspension bridges, aiming to provide insights into the design of such structures. Firstly, a finite element model of the Jinsha River Railway Suspension Bridge is established in this paper. The natural frequencies are analyzed and compared with on-site measurements to validate the accuracy of the finite element model. Secondly, the tension force amplitude and angular displacement amplitude of the suspenders are analyzed under design loads, and the failure characteristics of the cables are experimentally examined. Subsequently, a wear fatigue test for steel wire rope is designed, evaluating the fatigue life of the suspender in the bridge. The computational results are compared with experimental data to validate their accuracy. Finally, structural measures to reduce the bending fatigue of railway suspension bridge suspenders are proposed to ensure their safety during the service life. The study reveals that the presence of bending stress exacerbates the fatigue failure of suspension cables in railway suspension bridges, with the failure mode identified as fatigue failure due to the tension-bending-wear coupling effect. Furthermore, our findings indicate that the implementation of auxiliary cables can reduce the displacement differential at both ends of the suspension cables by approximately 4/5, and decrease the axial tensile stress amplitude by about 3/4. Consequently, this significantly enhances the fatigue life of the suspension cables.

Defect location of power cables by frequency domain reflectometry with auxiliary cables

When there is a slight water invasion on a power cable, the change of the cable impedance is not large enough and leads to a challenge for water invasion detection. Thus, in this work, a small auxiliary cable is proposed to be buried in a traditional cable, and used to detect the water invasion defects with frequency-domain reflection cascaded with discrete Fourier transform (DFT). In order to enhance the positioning resolution, Kaiser window is adopted during DFT. The experiment results show slight water invasion can be detected by using the auxiliary cable. Besides, during the defect detection, the terminals of the power cable are not required to be used to inject test signal. Thus, the proposed method can be carried out on-line without power outage.

Dynamic Analysis and Experiment of Underactuated Double-Pendulum Anti-Swing Device for Ship-Mounted Jib Cranes

Abstract This paper proposes a three degrees of freedom parallel anti-swing method by the main and auxiliary cables to address the problems related to underactuated double-pendulum anti-swing for a ship-mounted jib crane. By analysing the dynamic coupling relationship between the swing of the hook and the payload, it seeks to establish an accurate dynamic model of the anti-swing device under the ship’s rolling and pitching conditions, and discusses the influence of ship excitation, the crane state, load posture and anti-swing parameters on the in-plane and out-of-plane swing angles. The analysis shows that the primary pendulum reduces the in-plane angle by 90% and the out-of-plane angle by 80%, the in-plane angle of the secondary pendulum is reduced by 90%, and the out-of-plane angle is reduced by 80%. The reliability of the simulation data is verified through experiments.

Approximate calculation of the static analysis of a lifted stay cable in super-long span cable-stayed bridges

The sag effect of long stay cables is one of the key factors restricting further increase in the span of cable-stayed bridges. Based on the formerly proposed concept of long stay cables lifted by an auxiliary suspension cable in cross-strait cable-stayed bridges, corresponding static approximate calculations and analytical theory based on catenary and parabolic cable configurations are established. Taking a main span 1400 m cable-stayed bridge as the research object, three typical lifting conditions and the whole process of auxiliary cable lifting are analyzed and discussed. The results show that the sag effect is effectively reduced. The support efficiency is only improved when the cables are lifted above the original cable chord. Reduction of the horizontal component force of the cable is limited. The equivalent elastic modulus and the vertical support stiffness of the lifted cables are significantly increased with increased horizontal projection length and not sensitive to the change of the lifting point position. The scheme of lifting the cable to the chord midpoint is more economical because of the less steel required for the auxiliary suspension cable, but its effect on improving the vertical support efficiency is limited. The support efficiency is better when the cable is lifted to the cable end tangential to the original cable chord, but the lifting force and the cross-sectional area of the auxiliary suspension cable are doubled. The approximate calculation results of the lifted cables are very close to the numerical analysis results, which verifies the applicability of the approximation method proposed in this study. The results of parabolic approximation calculations are approximately equal to that of catenary cable geometry. As the parabolic approximation analysis theory of lifted cables is more convenient in mathematical processing, it is feasible to use parabolic approximation analysis theory as the analytical method for the conceptual design of lifted cables of super-long span cable-stayed bridges.

Improving temporal modulation sensitivity in cochlear implant users

The present study investigated the limitations of temporal modulation sensitivity in cochlear implant (CI) users. Adult users of Cochlear Nucleus devices were tested by presenting sounds through their clinical processors using an auxiliary cable and using direct electrical stimulation provided through a custom research processor. Threshold and comfort current levels were determined by adjusting the phase duration of 10 Hz amplitude modulated pulse trains of 400 ms duration at a given stimulation rate. After mapping the participants, modulation detection thresholds were measured by means of a 3 alternative forced choice procedure which adaptively adjusted the modulation depth to determine the threshold in dB relative to full modulation. Participants completed the task using a graphical user interface to indicate which interval was different. Modulation frequencies from 10 to 800 Hz were tested at various stimulation rates on basal and apical electrodes in both psuedomonopolar and bipolar modes of stimulation. Preliminary findings indicate that modulation sensitivity drops off with increases in modulation frequency. Performance was significantly better with direct stimulation as compared to through the clinical processor and better at higher modulation frequencies than previous findings from CI users. Outcomes will have implications for the development of next generation CI devices.

A 5 Gb/s Voltage-Mode Transmitter Using Adaptive Time-Based De-Emphasis

A 5-Gb/s voltage-mode (VM) transmitter using adaptive time-based de-emphasis is presented. The duty cycle of the pulse-width modulation data is adjusted by the spectrum-balancing technique. This adaptive VM transmitter does not need an auxiliary cable. It can adaptively compensate the loss of the channels with different lengths. This transmitter and a receiver are fabricated in a 40-nm CMOS process. The active areas of the transmitter and the receiver are 0.075 mm2 and 0.105 mm2, respectively. For a 1.1 V supply voltage, the power of the transmitter is 9.3 mW and the total power of the transceiver is 17.5 mW. For a 5-Gb/s PRBS of 27-1 passing through a 9-m coaxial cable with a 15.35-dB loss, the measured root-mean-square and peak-to-peak jitters of the recovered data are 12.25 and 64.44 ps, respectively. The settling time for adaptive time-based de-emphasis is 2.048 $\mu \text{s}$ . The measured bit error rate is less than 10−12.

Optioneering analysis for connecting Dogger Bank offshore wind farms to the GB electricity network

This paper outlines possibilities for connecting 2.4 GW of power from two separate wind farms at Dogger Bank in the North Sea to the GB transmission system in Great Britain. Three options based on HVDC with Voltage Source Converters (VSC HVDC) are investigated: two separate point-to-point connections, a four-terminal multi-terminal network and a four-terminal network with the addition of an AC auxiliary cable between the two wind farms. Each option is investigated in terms of investment cost, controllability and reliability against expected fault scenarios. The paper concludes that a VSC-HVDC point-to-point connection is the cheapest option in terms of capital cost and has the additional advantage that it uses technology that is commercially available. However, while multi-terminal connections are more expensive to build it is found that they can offer significant advantages over point to point systems in terms of security of supply and so could offer better value for money overall. A multi-terminal option with an auxiliary AC connection between wind farms is found to be lower cost than a full multi-terminal DC grid option although the latter network would offer ability to operate at greater connection distances between substations.

Dongping Channel Bridge: Long-Span Steel Arch Bridge in High-Speed Railway, China

Dongping Channel Bridge, a significant project of the new Guangzhou station, is the longest arch bridge on the Wuhan-Guangzhou high-speed railway. A half-through continuous steel-truss arch bridge was chosen, with a total length of 442 m and deck width of 28 m. Several highlighted features in this bridge design are new three main trusses system, integrated structural joint, orthotropic-plate ballast deck, integral pile caps, and drilled piles. Cantilever erection method was applied in the construction, assisted by temporary piers in the side span and auxiliary cables attached to towers on the main piers. In this paper, the structural system, design features, as well as construction were introduced, and structural behavior, ultimate load-carrying capacity, joint analysis, and seismic behavior of this long-span bridge were analyzed and investigated.

Experimental Investigation into Aerodynamic Stability of Narrow Steel Truss Girder Suspension Bridge

A narrow steel truss girder suspension bridge was designed for pedestrian and livestock in pasture in Xinjiang Province, China. For the complex wind climate at bridge site, the cautious designers resorted to wind tunnel test to confirm the aerodynamic stability of the bridge. The analysis and results from wind tunnel test conducted in Chang’an Wind Tunnel Laboratory indicated the original scheme must be changed considerably to improve the aerodynamic stability under action of wind. Considering the shape feature of Siudirgol Bridge and its geographical location, section model with such mitigation measures as auxiliary cables and central buckles were re-tested in wind tunnel joint with analysis. The auxiliary cables and central buckles can increase considerably the fundamental frequency of the bridge and hence the critical wind speed of flutter.

Spatial Arch Bridges Over the Galindo and Bidasoa Rivers

This paper presents two examples of spatial curved-arch bridges recently built in Spain: the bridge over the Galindo River in Vizcaya and the Endarlatsa Bridge over the Bidasoa River.Both bridges have curved decks supported by arches (an upper solution in the Galindo river bridge and a lower arch in the Endarlatsa bridge), but the solution used moves away from the classic planar arches normally employed in these decks: their arch centreline follows in plan the curved deck alignement, resulting in a warped geometry. For that reason, they are in the strict sense spatial arches, curved both in plan and in elevation.Different solutions were used in each of them to resist the out-of-plane forces that appear in warped arches. In the Galindo bridge with active forces introduced with auxiliary cables. In the Endarlatsa bridge with an adequate distribution of the transverse stiffness of the arch and the support conditions of the deck over it.This approach is quite innovative in arch bridges—they are unique examples of this kind of structures—;and creates interesting solutions both from the structural and the aesthetic points of view.

Dashengguan Bridge—The Largest Span Steel Arch Bridge for High-Speed Railway

The Nanjing Dashengguan Bridge is a key project on the Beijing–Shanghai high-speed railway; it is designed to handle a speed of 300 km/h. The main bridge has a large-span continuous steel arch truss structure with a total length of 1615 m. The two main spans over the main navigation channels of the Yangtze River are steel arch trusses, each of which is 336 m long. The arches comprise three truss planes above the orthotropic deck. Erection of the steel arch truss adopted the double cantilever method with auxiliary cables supported by towers on piers.

Model-based PID control of a crane spreader by four auxiliary cables

This article presents the anti-sway and anti-skew control of a container crane that is widely used in cargo terminals. A four-cable suspended spreader is used to load and unload the container. In such a loading/unloading process, the spreader has usually residual oscillation, the sway and skew, due to the motion of the trolley and the gantry or an external disturbance such as wind. Thus, it is difficult to locate the container at the desired position quickly and precisely. In order to suppress the residual oscillation, this article proposes the use of four auxiliary cables added to four main cables. Using null space, the tension of the redundant auxiliary cables, i.e. the optimal tension distribution among four auxiliary cables, is achieved. The inverse dynamic control and a model-based proportional and integral and derivative (PID) control is applied to derive the control law. The effectiveness of the proposed tension assignment for the auxiliary cables and the model-based PID control algorithm are verified by computer simulations.

An underwater towed electromagnetic source for geophysical exploration

Low-frequency electromagnetic methods are used in geophysical exploration to detect the magnetic field distortion between a transmitter and receiver produced by locally conductive bodies. Both ground and airborne systems are in current use. It is possible to similarly conduct underwater geophysical exploration by using an underwater towed source of electromagnetic radiation and a receiving magnetic or electric field detector. The receiver can be towed on an auxiliary cable, mounted on a boom on the towing platform, or land based. An underwater towed electromagnetic source suitable for ocean-bottom exploration has been constructed, and its underwater propagation characteristics at low frequency have been studied. This underwater calibrated source (UCS) is 4 m long, weighs 383 kg in air, and can produce vertical and horizontal magnetic dipoles and a horizontal electric dipole. Powered by a current-feedback-controlled, high-power, modified sonar amplifier, the UCS can produce 9710 ampereturn.m2 of magnetic dipole or 200 A.m of electric dipole at 50 A at frequencies up to 200 Hz without significant attenuation from coil inductance. This paper concentrates on the mechanical, hydrodynamic, and magnetic design details of the UCS and the electrical system, consisting of the high-current drive power system and the shipboard monitoring system for attitude and depth detectors.

Heat-shrinkable plastics for termination and jointing of power and auxiliary cables

The nature and properties of crosslinked materials are discussed and a number of applications described for which a background of experience has already been obtained. The advantages of using these materials for medium-voltage applications are considered and an attempt made at forecasting their long-term performance for the termination of 11 and 33kV cables.

Screening Factor of Pipe-Type Cable Systems

After reviewing the background of zero sequence impedance of pipe-type cables, the paper describes in general the longitudinal voltages induced in adjacent auxiliary cables due to a fault in power transmission systems. The magnitude of the induced voltage is influenced by the screening effect of the power cables. The screening factor and the impedance of the steel pipe have been measured in the laboratory by short-circuit tests on a 275-kV cable sample with a simulated ground return path. The results are used to illustrate the application in induced voltage calculations in a typical example.

Difference voltages and circulating currents in pairs of cores in auxiliary multicore cables

At power-system frequencies there may be sufficient imbalance in two cores of an auxiliary cable so that, when used as a pair, current circulates which impairs the functioning of terminal equipment. It is shown that the technique of calculating voltages induced longitudinally in auxiliary cables can be extended to determine the difference quantities in cores. Simple expressions are developed to determine difference voltages and circulating currents, and these are shown to give results very close to measured values. Factors which modify these quantities in practice are indicated.

Auxiliary cables for generating stations

THERE ARE THREE general characteristics of steam generating station design that distinguish this particular cable application problem from others. Maximum reliability is one characteristic. The failure of a power or control cable may cause the shutdown of a great part or all of the power station. The total cost of the cable system in an average power system will be about 1 or 2 per cent of the total station cost. Increasing the cost of the cable system would not be out of order if an appreciable increase in reliability could be obtained. In the case of a utility distribution system, an increase of 1/64 inch of insulation applies to hundreds of miles of cable and represents a major item of cost, while in a central station, it is a relatively minor item and therefore, the use of insulation classes well above operating voltage may be fully justified.

Auxiliary Power and Control Cables for Steam Electric Generating Stations [includes discussion

Auxiliary Power and Control Cables for Steam Electric Generating Stations [includes discussion

Steel tower economics

Partly from theoretical considerations, but mainly from practical data, an empirical formula is derived giving the approximate weight of any tower in terms of its height and maximum working overturning moment at the base. The tower weight above ground line is shown to be satisfactorily represented by kH√M tons, where H is the overall tower height above ground line, in feet; M is the overturning moment at ground line, in thousand lb-ft; and k is a “constant” which varies within an extreme range of about 0.0014 to 0.0029 throughout the whole series of towers; most towers have k values well within this range.The towers investigated covered ranges of about 16 to 1 in height, 3 000 to 1 in overturning moment, and 1 200 to 1 in tower weight.Design factors which explain variations in the “constant” k are discussed at some length on a qualitative basis.It is shown that an economic value for the base width of any tower is in the neighbourhood of 0.5√M ft.On the assumption that, for any given general type of tower, the total erected cost may be regarded as proportional to the aboveground weight, the tower-weight formula, kH√M, can be used with convenience and reasonable accuracy for a wide field of cost estimations, especially those involving comparisons of a number of alternatives of a generally similar nature.Such investigations include the following:Ordinary transmission lines: (a) Economic span lengths. (b) Relative costs of lines for different voltages, conductor sizes and conductor materials. (c) Number of circuits. (d) Number and height of earth conductors. (e) Abnormal wind and ice loading assumptions and/or actors of safety. (f) Different clearances between conductors and ground. (g) Suspended auxiliary cables. (h) Hypothetical “dogleg” lines. (j) Hypothetical “super e.h.v.” lines.Navigable river crossings: (a) General layout. (b) Clearance to high water; Air Ministry height restrictions. (c) Span lengths and river bank configuration. (d) Foundation conditions. (e) Number of circuits. (f) Long spans; economic conductor. (g) Narrow waterways; economic number of towers. (h) Terminal-type crossing towers; economic conductor tension.