Stanislav Kmet

Computer modelling of wire strands and ropes part II: Finite element-based applications

In the comparison with the theoretical analyses of wire strands reported in the literature where obviously single-layered strands with a construction of the 1+6 wires were modelled and analysed, this paper is focused on a multi-layered strand with a construction of the 1+6+12+18 wires. The geometric parametric equations developed in the first part of this paper [1] are implemented in CATIA V5 software code for geometric modelling of the multi-layered strand. The methodology of their implementation and the approach for the generation of the strand geometric model are demonstrated. To predict the behaviour of the multi-layered strand under tensile loads, the mathematical geometric model is further implemented in a finite element program. For this purpose ABAQUS/Explicit software is used. The derived 3D geometric models of the multi-layered strands and the results of the finite element elastic behaviour analyses of the strand under tension loads are validated through comparisons with experimental and theoretical data available. The results obtained confirm the correctness of the derived parametric equations and mathematical and physical importance of the finite element model developed.

Computer modelling of wire strands and ropes Part I: Theory and computer implementation

In this paper the mathematical geometric models of the single-lay wire strands and double-lay wire ropes with defined initial parameters are presented. The present geometric models fully consider the single-helix configuration of individual wires in the strand and the double-helix configuration of individual wires within the wound strands of the ropes. The mathematical representation of the single and double helixes is in form of parametric equations with variable input parameters which determine the centreline of an arbitrary circular wire of the right hand lay and left hand lay strands and ropes of the Lang lay and regular lay construction. The concrete forms of the parametric equations are derived and presented. The application of the derived geometric analytical model is illustrated by numerical examples. Techniques for the implementation of the derived mathematical models in CATIA V5 software and procedures for the generation of the rope model are briefly presented. Correctness of the derived parametric equations and a performance of the generated rope model are controlled by visualizations. The application of the derived mathematical model and the development of a finite element model for the numerical simulation of the multi-layered strand under tension tests are treated in the second part of the paper [1].

Finite element analysis of spiral strands with different shapes subjected to axial loads

A new mathematical geometric model of spiral oval wire strands is proposed.Concrete forms of derived parametric geometric equations are presented.Results of FE analyses of four spiral strands with different shapes are presented.Responses of round, triangular and oval strands under axial loads are compared.Result ant stress and/or deformation behaviours are discussed. In this paper a new mathematical geometric model of spiral one or two-layered oval wire strands are proposed and an accurate computational two-layered oval strand 3D solid model, which is used for a finite element analysis, is presented. The three dimensional curve geometry of wires axes in the individual layers of the oval strand consists of straight linear and helical segments. The present geometric model fully considers the spatial configuration of individual wires in the right and left hand lay strand. Derived geometric equations were used for the generation of accurate 3D geometric and computational models for different types of strands. This study develops 3D finite element models of two-layer spiral round, triangular and oval strands subjected to axial loads using ABAQUS/Explicit software. Accurate modelling and understanding of their mechanical behaviour is complicated due to the complex contact interactions and conditions that exist between individual spirally wound wires. Comparisons of predicted responses for the strands with different shapes and constructions are presented. Resultant stress and/or deformation behaviours are discussed.

Time-dependent analysis and simulation-based reliability assessment of suspended cables with rheological properties

The intention of the paper is to illustrate the ability of the probabilistic time-dependent reliability assessment procedure applied to non-linear suspended cable structure with rheological properties, when a rope made from the high strength synthetic fibres is used in order to demonstrate the new qualitatively different concept. Attention is turned to the individual main steps in the assessment procedure, i.e. to the selection of an appropriate method of structural analysis and to derivation of an appropriate closed-form and discrete analytical models, analysis of random variables representing individual actions (four basic random variables, such as structural geometry, cables modulus of elasticity and creep strain increments and loading, are considered), evaluation of the structural response with respect to the interaction of the random variables considering a history of the time-dependent action effects and to the definition of the limiting values considering serviceability of cable structure. The potential of the method using direct Monte Carlo technique as one of the possible alternatives for simulation-based time-dependent reliability assessment as a powerful tool is emphasized. The influence of an excessive deflection of suspended cable (caused by creep of cable and rheologic changes) on its serviceability in required time is investigated and illustrative examples are performed.

Vibrations of an aramid anchor cable subjected to turbulent wind

Abstract The vibration response of an initially pre-stressed anchor cable made of parallel-lay aramid fibres excited by a measured and artificially simulated spatial turbulent wind field is presented in the paper. Results of the analyses of in situ measured wind records are described. For selected data set statistical characteristics and power spectral density functions of the measured wind velocity components are calculated. The wind stochastic velocity fluctuation is modelled as a one-variate bi-dimensional random field. Cross-power spectral density functions, at different point locations are introduced. The combination of the weighted amplitude wave superposition method (WAWS) with the Shinozuka–Deodatis method is used for the analyzed problem. A time-dependent behaviour of the synthetic cable is investigated which is subjected to turbulent wind with large expected oscillations that arise as a result of slackening due to the relaxation effects. A nonlinear transient dynamic analysis is used in conjunction with the finite element method to determine the dynamic response of the cable subjected to turbulent wind at its initially prestressed state and in the selected times after the relaxation effect. The constitutive equation of the relaxation of the aramid cable follows an experimentally obtained law of the logarithmic type. To monitor the dependences of the individual quantities of cable vibration in the phase space, attractors and Poincare maps are created by sampling the cable’s displacement and velocity at periods of relevant frequencies. Interesting findings based on the response of the cable with rheological properties to turbulent wind are presented.

Time-Dependent Analysis of Prestressed Cable Nets

AbstractIn this paper, time-dependent nonlinear numerical and analytical computational models suitable for rheological analysis of prestressed cable nets subjected to creep effects are presented. The principal aim of this contribution is to describe a developed design computational tool for a theoretical simulation of the time-dependent behavior of cable nets and predict their rheological characteristics. For this purpose, a modified finite-element method for the time-dependent analysis of materially linear and geometrically nonlinear cable nets is proposed. Creep constitutive equations in the logarithmic form are incorporated into the finite-element model to express the current lengths of cables as the functions of creep strain increments. As an extension of the Irvine approach, a geometrically nonlinear time-dependent analytical static solution of taut flat cable nets over an orthogonal square plan is presented. The cable net is replaced by an equivalent membrane. Creep strain is incorporated into the c...

Analysis of wind-induced vibrations of an anchor cable using a simplified fluid-structure interaction method

Wind-induced vibrations of an anchor cable using a simplified FSI method are studied.Simulations of spatially correlated in situ measured wind histories are presented.Vortex-shedding phenomena around the cross-section of the cable are obtained.The FE method is applied in the nonlinear dynamic analysis of the cable (CSD).Responses obtained by the FSI and CSD models are compared and discussed. Wind-induced vibrations of a pre-stressed aramid anchor cable using a simplified fluid-structure interaction (FSI) method are presented in the paper. Navier-Stokes equations for incompressible flow are solved in nine two-dimensional transverse planes located perpendicularly to the longitudinal axis of the cable. Based on in situ measured wind records statistical and spectral characteristics of the simulated turbulent wind fields were assigned to the investigated cable. The Shinozuka-Deodatis method is used to generate wind velocity histories. Spatially correlated wind velocity components in the longitudinal and lateral direction were considered as an inflow condition in nine created parallel plane fluid flow models. In order to generate an appropriate computational fluid dynamics model (CFD) of sufficient accuracy the verification and validation of the most critical issues were performed. The turbulent hybrid Spalart-Allmaras Detached Eddy Simulation (SA-DES) model was assumed accurate enough and applied in the plane fluid flow models of the dynamic analyses. The finite element method is applied to simulate the aeroelastic behaviour of the cable subjected to turbulent wind effects. Aeroelastic response characterised by wind velocity fields and vortex-shedding phenomena around the cross-section of the cable are presented. Results obtained from the simplified FSI analysis were used for the calculation of the Rayleigh Beta damping coefficient and applied in the nonlinear dynamic analysis of the anchor cable (CSD model). Responses obtained by FSI and CSD models are compared.

Analysis of Tensegrity Structures

This paper describes experimental and theoretical analyses of a newly developed adaptive tensegrity module which has the ability to alter its geometrical form and pre-stress properties in order to adapt its behaviour to current loading conditions. This tensegrity system contains sensors that sense forces from the environment and an actuator that adjusts its shape accordingly, making the structure more rigid or flexible depending upon the load applied.

Analysis of Cable Domes

This paper describes a newly developed adaptive cable dome in the Levi form which has the ability to alter its geometrical form and stress properties in order to adapt its behaviour to current loading conditions. This cable dome contains the sensors and active member that sense forces from the system and adjust its shape and stress state, making the structure more rigid or flexible depending upon the actual load. This system consists of forty-two tensioned cables, six compressed struts and a central strut which is designed to function as an actuator. Results of the experimental and theoretical analyses are presented.

Reconstruction of an Ice Hockey Hall in Kosice, Slovakia

The reconstruction of the ice hockey hall in Kosice, Slovakia, is a one of the most significant construction projects currently underway in Slovakia. The old ice hockey hall, with seating for 5000 spectators, was built sixty years ago. Morevoer, the new technical requirements for ice hockey halls and the participation of the ice hockey team in international competitions stimulated the need for reconstruction of the hall. The basic purpose of the reconstruction was to increase the seating capacity to 10 000 and to create a multi-purpose hall suitable for various activities.