Locked Coil Ropes Research Articles

Simulation of the State of Stress in Locked-Coil Ropes during Tension and Torsion

Simulation of the State of Stress in Locked-Coil Ropes during Tension and Torsion

Cover Picture: Steel Construction 1/2020

AbstractFor Schorgast Bridge Full Locked Coil Rope high strength tension components have been designed and implemented as stay cables. As part of the revision of EN 1993‐1‐11 the fatigue design rules for tension components have been modified and adjusted. An article in this edition provides insight and background information (Annan, R. et al., pp. 61–75) © FATZER AG

Metrological Assurance of Magnetic Flaw Detection of Steel Ropes

A technique for measuring losses of the cross-sectional area in the metal of hoist ropes made of ferromagnetic steel wire for the purpose of estimating their performance is considered. An analysis of the efficiency of the measurement technique using a mathematical model of a locked-coil rope is performed and the measurement errors determined. Steps to improve the measurement technique are proposed.

MRT detection of fretting fatigue cracks in a cableway locked coil rope

The Magnetic Rope Testing is a non-destructive method in use for the detection of flaws and cracks in steel wire ropes. Given the severe protocol of safety certification for in-service cableway ropes, a proper methodology operating in accordance with new European standard specifications is here presented. A relevant experience about detection of multiple cracks due to fretting fatigue on a peculiar locked coil structure rope is also shown and discussed.

Wrapping with Butyl Rubber Tapes—An Innovative Corrosion Protection for Bridge Cables

According to the codes of the German Ministry of Traffic, the surface of new and existing locked coil ropes has to be protected against corrosion by an approximate 400 μm thick layer of paint. For the preparation of the rope surface and for the application of the different paint layers by a brush, access has to be granted over the entire rope length by fixed or movable scaffoldings—what in existing bridges may lead to important traffic disturbances. If, instead, the ropes are protected against corrosion by butyl rubber tapes—as known since a long time from the protection of pipelines etc.—the requirements for the preparation of the rope surface and thereby the amount of work and equipment may be reduced substantially. Owing to the application of these tapes by automotive and automatic wrapping robots, scaffoldings and lifting equipment are not needed any more, whereby important time and cost savings are achieved and the impact on the traffic is widely reduced. General considerations with reference to this innovative, robust and economic corrosion protection system are presented; the successful applications for two cable stayed bridges—across the Rhine between Kehl (Germany) and Strasbourg (France) and across the Köhlbrand in the Port of Hamburg—are described. An outlook on further possible applications is given.

Performance comparison of track ropes in contemporary ropeway installations

Non-destructive testing is an important means for assessment of the performance of track ropes in a bi-cable zig-back ropeway installation. The visual method produces the possibility of inadequate inspection due to its subjectivity. Electromagnetic and visual wire rope inspections complement each other. Both are essential for safe operation. Periodic in-situ measurement of faults in ropes would help to determine the effects of various parameters on rope life. Track ropes are generally locked coil ropes. Full locked coil (FLC) ropes are made with a spiral strand as the main core and are finally covered with one or more layers of shaped wires. The final covering layer is made from full locked sections of wires which interlock with each other and present a smooth surface. Wire ropes wear out eventually, gradually losing work capability throughout their useful life, making periodic inspections, lubrication and tensioning necessary. Magnetic flaw detectors, which measure the loss of metallic area (LMA) and detect local faults (LF) such as broken wires and other faults, are used to determine rope wear. In this paper, an attempt has been made to describe the performance of track ropes in contemporary ropeway installations.

Spanning the Rhine River with a New Cable-Stayed Bridge

This paper reports on the design and construction of the new Rhine River bridge “Niederrheinbrücke” being built near the cities of Wesel and Büderich, Germany. The paper outlines the design and bidding process as well as the on-site construction of the new bridge, which will be the longest cable-stayed bridge in Germany. The new Rhine River crossing is only the second cable-stayed bridge in Germany to use parallel strands rather than steel wire ropes (locked coil ropes) and contributes to a new generation of cable-stayed bridges in Germany.

Spanning the River Rhine with a new cable‐stayed bridge

AbstractThis paper reports on the design and construction of the new bridge over the River Rhine being built near the cities of Wesel and Büderich, Germany, the “Niederrheinbrücke”.The paper outlines the design and bidding process as well as the construction of the new bridge, which will be the longest cable‐stayed bridge in Germany.The new Rhine crossing is only the second cable‐stayed bridge in Germany to use parallel strands (Suspa DSI) rather than steel wire ropes (locked coil ropes) and contributes to a new generation of cable‐stayed bridges in Germany.

Nondestructive Assessment of Full Locked Coil (FLC) Ropes in Cage and Skip Winders

Magnetic nondestructive evaluation is being used to assess the condition of full locked coil ropes used in cage and skip winders. Four locked coil ropes were studied for a period of 4 years. This paper focuses on the determination of the in situ condition of full locked coil ropes in cage and skip winders throughout this 4-year period.

Prediction of coupled axial/torsional stiffness coefficients of locked-coil ropes

The paucity of theoretical and/or experimental results for locked-coil ropes is emphasised. In locked-coil ropes, shaped wires of full-lock type (Z section) or half-lock are used to provide a final layer (or sometimes two or more final layers) over the basic spiral strand construction with round wires, resulting in a structure more resistant to corrosion, at the cost of a slight reduction in strength to weight ratio. Using an extended version of a previously reported orthotropic sheet theory, a model is proposed for predicting the patterns of interwire contact forces, wire kinematics, and the coupled axial/torsional stiffness coefficients in fully bedded-in locked-coil ropes experiencing either static monotonic axial/torsional loading or a mean axial load superimposed on which are external load perturbations. The theoretical model takes interwire contact deformations into account, and is capable of predicting the full-slip values of all the four stiffness coefficients in the stiffness matrix. The full-slip stiffnesses correspond to cases when large variations in axial and/or torsional loads take place, with their associated large changes in the contact forces between adjacent wires in various layers. Using theoretical parametric studies, simplified routines amenable to hand calculations, which are aimed at practising engineers, are developed for obtaining reasonable estimates of the full-slip stiffness coefficients in the 2×2 stiffness matrix defining the coupled axial/torsional behaviour of locked-coil ropes.

Bending fatigue of locked coil ropes in the proximity of cast sockets. II. influence of lubrication: Oplatka, G. and Roth, M. Wire (1995) 45 (4), 236–239

Bending fatigue of locked coil ropes in the proximity of cast sockets. II. influence of lubrication: Oplatka, G. and Roth, M. Wire (1995) 45 (4), 236–239

Bending fatigue of locked coil ropes in the proximity of their ends : Oplatka, G. and Roth, M. Wire (1995) 3, 156–159

This paper proposes a thermal method for estimating fatigue life of metallic ropes. Rotating bending fatigue tests are performed on rope specimens and their temperature evolution is monitored till specimen failure. The proposed method is justified through a theoretical framework based on thermally dissipated energy and energy spent for mechanical damage. Experimental fatigue tests are carried out in different conditions by primarily varying the bending load and the rotational speed. Experimental results are in agreement with the theoretical model allowing the estimation of damage evolution and rope life via thermal measurements.

Prediction of axial hysteresis in locked coil ropes

In published literature, the strand constructions dealt with have almost invariably involved only wires which are circular in cross-section. There are, however, instances when shaped wires are used in, for example, half-lock and full-lock coil constructions. The paper reports details of a theoretical model which enables an insight to be gained into various characteristics of axially loaded lock coil ropes. The model is based on an extension of a previously reported orthotropic sheet concept and provides a fairly simple means of estimating wire kinematics, interwire/interlayer contact forces, effective axial stiffnesses and axial hysteresis in axially preloaded locked coil ropes experiencing uniform cyclic axial load perturbations. The theory takes interwire contact deformations and friction into account. Final numerical results based on theoretical parametric studies on some substantial cables highlight the substantial role that the outermost layer(s) with shaped wires play as regards the overall axial damping capacity of fully bedded-in (old) locked coil ropes, and it is found that (for the same lay angles and outer diameters) axial hysteresis in locked coil ropes is generally higher than spiral strands which are composed of only round wires. This finding may have significant practical implications in terms of the design against dynamic instability of structures supported by such cables.

The Jackfield Bridge, Ironbridge, UK

This article briefly describes the planning, design and construction of the cable-stayed Jackfield Bridge, which is the new neighbour of the world bridge famous Iron Bridge and several other historic bridges in the Iron Bridge Gorge, Shropshire, England. The unusual and striking design is the result of national debate and a Public Inquiry. Located 1 km downstream of the Iron Bridge, it is in the centre of the Severn Gorge World Heritage Site. The Jackfield Bridge uses composite steel and concrete sections for both the tower and the deck, which is supported from the tower by high tensile locked coil ropes. Special steel casting, bearings and parapets were designed for the bridge.

Determination of flaws located at different depth levels in the cross-section of steel rope

Signals received from the magnetic testing of steel rope vary depending on the location of the defect in the rope's cross-section. Measurements of the radial and tangential components of the leakage flux performed with a single Hall-effect probe have shown significant variations of the distribution of these components around the rope. The Hall-effect sensor, built in such a way that it measures the average value of the tangential component, indicates stronger and narrower signals from defects positioned closer to the rope's surface. This effect can be used to determine the depth of the flaw's location, which is especially useful in the testing of locked-coil ropes.

ON LONG-TERM BEHAVIOR OF CABLES IN CABLE-STAYED BRIDGES

The Locked Coil Rope cables of cable-stayed bridges have reportedly undergone significant relaxation and the deflections of the girders have also increased noticeably year after year from a number of field measurements. In this paper, an attempt is made to account for such behavior analytically assuming that the cables follow the linear visco-elasticity law; whereas the girders and towers remain linearly elastic. Described herein are the determination of the visco-elastic constants, and numerical analyses performed on totally fifteen cable-stayed bridges by finite element method and the numerical Laplace inverse transformation; The results were compared with the measured data on two bridges.

Calculation of limiting moment in torsion of shaped wires for locked-coil rope

Calculation of limiting moment in torsion of shaped wires for locked-coil rope

Suspended locked-coil-rope television feeder systems

The paper deals with coaxial-line transmitting feeder systems of the type in which the whole system is suspended from the top of the transmitting tower. The inner conductor, weighted at the lower end, consists of a locked-coil winding rope of the type common in mining practice, but modified in design so as to have low electrical loss and high uniformity in diameter along its length, and thereby to reduce to negligible proportions the reflections arising in the feeder. The paper also discusses the principles and properties of locked-coil ropes, and records the results of tests, both mechanical and electrical, on ropes developed for feeder systems; indications are given, from theoretical considerations, of the tolerances in mechanical uniformity which must be satisfied in the manufacture of the rope and of the outer conductor of the feeder. Information relative to the performance of a trial system erected on the Hayes transmitting tower in May, 1949, is included, as well as a brief description, with results of some electrical measurements, of a similar system erected at the Kirk o'Shotts Television Station in August, 1951.