CFRP Cables Research Articles

A novel anchor method for large tonnage CFRP cable: Anchorage design and full-scale experiment

This study introduces a novel three-segment CFRP cable anchorage to address stress concentration challenges in CFRP cable anchors. The anchorage features a continuously varying inner cone angle along the anchor length to prevent excessive radial stress on the CFRP cable. The radial stress distribution is theoretically analyzed, followed by a numerical simulation design using the Tsai-Wu failure criterion and the anchor system's equivalent stiffness as evaluation indices. The results demonstrate a 47.06 % and 45.73 % reduction in the radial stress peak of the novel anchorage compared to the inner cone and inner cone + straight cylinder anchorage, respectively. Importantly, beyond an anchor length 23 times the equivalent diameter of the CFRP tendon, increasing length has a marginal impact on anchor efficiency but diminishes equivalent stiffness. Positive effects are observed by increasing the inner cone segment proportion and adjusting the inner cone angle within the 2° to 4° range. Conversely, increasing the bonding medium thickness reduces anchor efficiency and equivalent stiffness. Experimental verification indicates the anchor system achieving 99.83 % anchor efficiency. Moreover, the axial strain of CFRP tendons in the anchor zone exhibits a linear trend along the anchor length, with test stresses at corresponding positions consistent with FE calculation results.

A New Technique for Calculating the Effective Length Factor of the Tower in Cable-Stayed Bridge

The stability issues of the tower column (hereinafter referred to as ‘tower’) in the cable-stayed bridge are studied in this paper. Two types of cable-stayed bridges are considered, namely inclined tower cable-stayed bridges without backstays and floating single-tower cable-stayed bridges. Based on the structure feature of the inclined tower cable-stayed bridge without backstays, a novel double-beam model with discrete springs is established to facilitate the linear elastic buckling analysis of the tower. To solve the model, the transfer matrix method is applied, and the stability characteristic equation of the system is derived by considering the boundary and continuity conditions. In this way, the effective length factors for the longitudinal stability of the tower are obtained. At the same time, the finite element method is utilized to verify the results obtained by the proposed model and method. Then, the parametric analysis is conducted to explore the effects of some structure parameters on the effective length factor of the tower. In addition, the influence on the effective length factor of the tower is investigated in detail when the steel cables are replaced with CFRP cables for an inclined tower cable-stayed bridge without backstays. Finally, the same processing method is extended to derive the effective length factor of the tower in the floating single-tower cable-stayed bridge. The comparison with the results of the finite element method confirms the feasibility of the present method again.

Finite element analysis of edge gripper processing of carbon fiber composite cables

Light-weighted and high-strength CFRP cables are increasingly being used to increase the transmission capacity and improve the sag of suspended transmission line. CFRP cables are covered with aluminum and steel layers in sequence and compressed with a dies when the conductor is connected to the lattice tower. In the process, a mechanism that transmits a tensile load from the metal part to CFRP was implemented by utilizing the plastic deformation of aluminum and steel and the elastic deformation of CFRP. In this study, damage to CFRP cables that occurs during the processing of an edge gripper was simulated by a finite element analysis (FEA). A three-dimensional (3D) matrix of Hashin’s theory was coded, and a 3D damage analysis using Abaqus, a generic FEA software suite, was conducted. The analysis was carried out with a model that uses the dimensions of each material as parameters to discuss the relationship between the damage on the CFRP cable that may occur during the edge gripper processing and the gripping force generated.

Vehicle-Induced Vibration of Suspension Bridge with CFRP Cables Based on Different Cable Replacement Criteria

Vehicle-Induced Vibration of Suspension Bridge with CFRP Cables Based on Different Cable Replacement Criteria

SUSPEN DOME: AN EVALUATION WITH CFRP CABLES

This study investigated the feasibility of using CFRP cable as tension cables in suspen domes in view of the fact that suspen domes have been made with steel cables as its cable-strut system for centuries due to its availability. Indisputably, CFRP cables have become the material of choice in the 21st century for its efficiency and innovative design in bridge works. However, the application of CFRP cables to other cable structures has been limited. The need for its application to other cable structures is required in order to acquire more knowledge about its behavioral patterns. This paper gives preliminary findings of a successfully designed and constructed suspen dome prototype which comprehensively deepens the understanding of CFRP cable performance as a cable-strut system in a suspen dome. Results show that with its high stiffness, low weight and high strength, CFRP has proven to be a technically efficient and adequately strengthening material for structurally improving the adequacy of a suspen dome.

Novel self-anchored CFRP cable system: Concept and anchorage behavior

CFRP cables are promising to be utilized in bridge engineering, but their effective anchorage remains a challenge for engineers. To solve this problem, novel self-anchored CFRP cables with different anchorage configurations were designed and tested, with main variables including the radius, thickness, and slope of the CFRP loop at the anchorages. The results indicate that the mechanical behavior of the self-anchored cables is mainly determined by the thickness and radius of the CFRP loop and by increasing these characteristics, the cable’s material strength can be fully exploited. With optimized anchorage configurations, the anchor efficiency of the proposed self-anchor CFRP cable system can reach 95% or larger. Additionally, finite element analysis was conducted, with good agreement between the numerical and experimental results. Finally, the influence of the radius and thickness of the CFRP loop on the anchoring capacity and the nominal anchor efficiency was further discussed based on an orthotropic thick-walled cylinder model.

Bending behavior of CFRP cables in the nonlinear displacement range

The tensile behavior of cables and wire ropes has been widely explored in the literature, with many analytical, numerical and experimental results available. However, their bending behavior is still not yet fully comprehended, especially when dealing with cables made of non-isotropic materials. When these materials are bended over small diameter sheaves or drums, they may experience large strains, causing nonlinearities that are not captured by any known analytical model. The aim of the present work is to numerically verify through finite-element method the tensile and bending behavior of composite CFRP cables. The numerical results were compared with experimental data. Good correlation between them was found in a four-point bending test configuration, even at large displacements and with a nonlinear response. Hybrid cable constructions (using aramid and glass rods) were also numerically analyzed relative to their tensile and bending behavior, achieving satisfactory results.

Modeling and Parametric Analysis of In-Plane Free Vibration of a Floating Cable-Stayed Bridge with Transfer Matrix Method

As a classic bridge type, cable-stayed bridge is widely used because of its superior spanning capacity. Based on the mechanical characteristics of stay cable supporting deck, we propose a novel mechanical model aiming to evaluate the vertical bending stiffness of a floating cable-stayed bridge, namely, multi-beam model with discrete springs. First, a single-tower cable-stayed bridge is modeled as a triple-beam model with discrete springs in order to introduce the novel method easily. In this model, the stay cables are simplified as springs without mass and the single tower is regarded as an Euler–Bernoulli beam with consideration of the effect of axial force. At the same time, the bridge deck has been cut into two Euler–Bernoulli beams at the intersection of a deck and a tower. Then equations governing vibrations of the beam and tower are derived according to Hamilton’s principle for dynamic problems in elastic body under equilibrium state. The program is established by transfer matrix method to solve the eigenvalues of the system along with its boundary and matching conditions. Thus, the vertical bending stiffness of the floating cable-stayed bridge can be evaluated based on the frequency. In addition, the influences of the cables’ material, location, stiffness and number on vertical bending stiffness are analyzed in detail when the steel cables are replaced with CFRP cables. Lastly, the same method is directly extended to modeling the floating multi-tower cable-stayed bridge. The results, which are validated by commercial finite element software, demonstrate that the proposed mechanical model and method are both valuable and significant not only in theoretical research and calculation but also in design of engineering.

Effects of Cross-Sectional Size and Shape on the Longitudinal Tensile and Anchoring Properties of CFRP Cables

AbstractCarbon fiber–reinforced polymer (CFRP) is very suitable for use as a prestressed cable and can replace conventional steel cables in cable roofs. In engineering practice, the anchoring lengt...

A novel anchorage system for CFRP cable: Experimental and numerical investigation

In this paper, a novel bonding anchorage system characterized by the diverged arrangement of CFRP bars inside socket with resin-based adhesive was proposed for CFRP cable. The anchorage system was experimentally tested to verify its performance and numerical simulations were conducted to investigate the influential factors in proposed anchorage to cable bearing capacity and failure mode. In the anchorage system, the bonding capacity with the selected high-efficient adhesives and the bonding length in socket determined by the simulated bonding behaviors was verified experimentally. Besides, the effect of the adhesive stiffness on the uniformity of the tensile stress distribution of CFRP bars in cable, as well as the effects of the adhesive wedge action on the cable fracture mode were investigated with the finite element simulation. The experimental tests and numerical simulations reveal the influences of resin-based adhesive and adhesive wedge action on anchorage performance.

Experimental Investigations on Impact Behavior of CFRP Cables under Pretension

AbstractCarbon fiber–reinforced polymer/plastic (CFRP) used in bridge cables may be subjected to lateral impacts caused by vehicle collisions when in service. However, to date, few studies have been conducted on the impact behavior of CFRP cables and their anchor systems. In this paper, the impact behavior of CFRP cables was investigated through drop-weight tests of eight CFRP cable specimens. A seven-wire CFRP strand was used as the tendon, and reactive powder concrete (RPC) was used as the filling grout for anchors at both ends of each specimen. The results show that a bond length of no less than 36 times the diameter of the wire of the CFRP strand in 128 MPa RPC grout can provide a CFRP strand with reliable anchorage under impact. The average transverse impact resistance of the specimens was approximately 16 kN and was not significantly influenced by pretension. The specimens fractured at a cable tension of 30% of the static tensile breaking load under transverse impact. In addition, the energy dissipa...

REVIEW ON NONLINEAR VIBRATION AND MODELING OF LARGE SPAN CABLE-STAYED BRIDGE

As a hot research topic, the nonlinear dynamics of cable-stayed bridge has been highlighted in the field of mechanics, structure and bridge. With the development of new materials, such as CFRP cable, and new construction technology, the main span of cable-stayed bridge has been enlarged, which make this kind of bridge more competitive in bridge engineering. However, the increase of its span and the application of new materials make the bridge structure become lighter and more flexible, so that the nonlinear vibration of the structure becomes more prominent than ever, which may endanger the safety of the bridge. Based on our research of the nonlinear dynamics of cable-stayed bridge in recent years, the research progress in recent 10 years on the nonlinear dynamics and modeling of large span cable-stayed bridge is reviewed in detail. The nonlinear dynamic models, theories and modeling and solving methods for cable, beam, cable-beam and cable-stayed bridges are discussed. The results show that the cable stayed bridge has rich nonlinear dynamic behavior due to the coupling problem of the multi flexible cable, the large span beam, and the complexity of the environmental load. At the same time, due to the bottleneck problem of high dimensional nonlinear system, the study on the nonlinear dynamic behavior of the whole cable-stayed bridge becomes very complicated. Finally, based on the future development trend of cable-stayed bridge, some new ideas on nonlinear dynamics of cable-stayed bridge is proposed and future research directions are discussed.

Application study on the first cable-stayed bridge with CFRP cables in China

In order to push forward the development of CFRP cable-stayed bridge and accumulate experiences, the study on the application of the first cable-stayed bridge with CFRP cables in China was carried out. The design essentials of main components of the bridge were introduced and its integral performances, including static properties, dynamic properties and seismic response were analyzed using finite element method. A new bond-type anchorage was developed and the processes of fabricating and installing CFRP cables were elaborated. Based on the results of construction simulation, a tension scheme for bridge was propound. During constructing, the stresses and displacement of girder and pylon, as well as the forces and stresses of cables, were tested. The results indicate that all sections of the bridge could meet the requirements of the ultimate bearing capacity and normal service; the performance of the anchorage is good and the stresses in each cable system are similar; the tested values accord well with the calculated values. Further, creep deformation of the resin in anchorages under service load is not obvious. All these results demonstrate that the first application of CFRP cables in the cable-stayed bridge in China is successful.

Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables.

In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

The Static Test Study on Anchors of CFRP Cables

The axial performance of CFRP is excellent, while the lateral compression strength and shear strength are low, thus they can’t be anchored by traditional anchors. A new type of adhesive anchor was designed and five experimental cables were fabricated and the static tests were carried out. In the tests, the tensile capacity, bond strength and pullout behavior of CFRP cables anchors filled with resin were discussed. The efficiency coefficients and the load-slip behaviors of the bond-type anchors and the uniformities of the stresses in the tendons were studied. Several conclusions are drawn which have become powerful evidences for using the bond-type anchors in the first cable stayed bridge with CFRP cables in China.

Special Issue: Recent Advances in Structural Engineering

Papers were presented by the international and regional scholars in the area of Structural Engineering. The Special Issue is a collection of the peer adjudged 18 papers from the Conference, including 4 keynote papers. Exciting new developments in the world of computational mechanics and materials are leading the way to advances in Structural Engineering. Computational modeling developments are the catalyst for a new wave of research into problems addressing nanoand micromechanical behavior, in addition to provide improved constitutive models for monotonic, cyclic and dynamic loading of structures. Innovations in materials engineering include the use of nano-technology in the production of superior concretes and adhesives, smart materials and their use in retrofitting of damaged structures, and use of new superplasticizers and mineral admixtures in the production of ultra-high strength concrete. Such developments in the world of structural mechanics and materials make demands on structural engineering researchers to match the advances, and to conceive and design structures that would take full advantage of the innovations. The use of these models and the new generation of materials by structural engineers in traditional and innovative structures are now allowing the buildings to reach higher into the skies, for bridges to traverse distances and terrain not dreamt of before and to provide for safe and stable foundations for such structures. The structural engineer has to interface with the geotechnical engineer and be cognizant of developments in geotechnical engineering. The 18 papers in the Special Issue address subjects in various broad groups, including three papers in concrete materials and durability modeling (including two keynote papers, one on nano-concrete and another on improvement of durability of post-tensioned reinforced concrete bridges), five papers in precast and prestressed concrete and bridges (including a keynote presentation on the challenge of using CFRP cables in ultra-long span suspension bridges), and two papers including a keynote address on ferrocement and fiber reinforced concrete. Considering the recent natural disasters that have occurred around the world, two papers on earthquake engineering, including a theme presentation addressing this very important topic in the regional context, have been included. Three papers on the use of FRP’s in retrofitting and repair of reinforced concrete structures, two papers on composites including a theme presentation on the design of composite columns, and one paper addressing soil–structure interaction complete the list of eighteen papers selected for inclusion. It is hoped that this Special Issue will provide researchers and practicing professionals in the Gulf region with valuable information which can be incorporated in the design of new structures and stimulate further research in structural design, constitutive modeling and computational mechanics, and concrete materials. The team of Technical Editors would like to express their deepest gratitude and appreciation first to KFUPM for hosting the 11th ASEC Conference, allowing regional and international scholars to share their experiences with the engineering community in the Kingdom. The Editors also offer thanks to the authors who responded spontaneously to the invitation to submit enhanced versions of their 11th ASEC papers for review for possible inclusion in this Special Issue. Special thanks are due to the referees for their meticulous reviews, and for their role in improving the presentations and the discussions in the papers.

Comparative Study of Natural Frequencies of Super-Long Steel and CFRP Cables

By using FEM method, the natural frequencies of the super-long steel and CFRP cables with possible engineering parameters have been comprehensively studied. The error and limitations of cables’ natural frequencies theoretical calculation formula have also been analyzed. The results show that: Theoretical formula results are more approximate to out-plane frequencies of the cables. In a symmetric mode, out-plane frequency is lower than in-plane frequency, whereas in an asymmetric mode the situation is reversed. The difference between out and in-plane frequencies appear most in the first-order mode. The difference between out and in-plane frequencies is more obvious for cables with low stress, small inclined angle, long length with big sag and strong nonlinearities. The nonlinearities of CFRP cable is relatively slight for its lightweight and high strength. Out and in-plane frequencies are almost identical, and the theoretical formula is applicable to CFRP cables.

Evaluation of FRP and hybrid FRP cables for super long-span cable-stayed bridges

Abstract This paper evaluates the safety factors, the applicable lengths, and relative cost of FRP (fiber reinforced polymer) and hybrid FRP cables that are potentially suitable for cable-stayed bridges with a super long-span of between 1000 m and 10,000 m. Following previous studies on 1000-m scale cable-stayed bridges with FRP cables, two kinds of hybrid FRP cables – the previously discussed hybrid basalt and carbon FRP (B/CFRP) cable and the newly-developed basalt and steel-wire FRP (B/SFRP) cable – as well as conventional steel cable, CFRP cable, and BFRP cable are further investigated focusing on their promise in meeting potential requirements for super long-span bridges. Some major results are as follows: (1) a three-stage model for determining safety factors of cables with different kinds and lengths is proposed; (2) a threshold of λ2 is suggested to achieve both high material and stiffness utilization efficiency, based on which the applicable lengths for different kinds of cables were evaluated; and (3) hybrid B/SFRP cables and BFRP cables are comparable in cost to steel cables within a 3000 m span, while hybrid B/CFRP cables and CFRP cables demonstrate a superior performance/cost ratio over a longer span.

Mechanics feasibility of using CFRP cables in super long-span cable-stayed bridges

To gain understanding of the applicability of CFRP cables in super long-span cable-stayed bridges, by taking a 1400 m cable-stayed bridge as example, mechanics performance including the static behavior under service load, dynamic behavior, wind stability and seismic behavior of the bridge using either steel or CFRP cables are investigated numerically and compared. The results show that viewed from the aspect of mechanics performance, the use of CFRP cables in super long-span cable-stayed bridges is feasible, and the cross-sectional areas of CFRP cables should be determined by the principle of equivalent axial stiffness.

Research and Application Review on CFRP Cables for Cable-stayed Bridges

AbstractFor its excellent characteristics, such as light weight, high strength, good corrosion resistance and outstanding fatigue resistance, the CFRP cables will find wide application for future cable-stayed bridges. The state of arts of the research and application of CFRP cables is presented. A few pioneer cable-stayed bridges with CFRP cables are listed and the first cable-stayed bridge with CFRP cables is briefly introduced. The properties and advantages of CFRP cables are expounded. Some existing problems of CFRP cables, especially anchorage, are discussed. In the end, the prospects of some essential areas to be researched on CFRP cables are previewed.