Cable Structures in Bridge Engineering

The special collection on Cable Structures in Bridge Engineering is available in the ASCE Library (https://ascelibrary.org/page/jbenf2/cable_structures_bridge_engineering).

Cable structures are used extensively in bridge engineering, including stayed cables of cable-stayed bridges, main cable and suspenders of suspension bridges, and hangers of arch bridges. These types of cable structures can offer an elegant and economic bridge alternative. They have become a primary choice for long-span bridges throughout the world, and methods of designing and constructing them have developed rapidly during the last two decades. Accordingly, research on the design, analysis, inspection, and rehabilitation of these types of structures has become one of the most interesting and timely subjects in bridge engineering. The special issue of the Journal of Bridge Engineering is intended to promote and improve the analysis, design, inspection, and rehabilitation of cable structures. Twenty-three papers were selected for this special issue, including 15 technical papers, six case studies, and two technical notes. These papers present recent advances in the design, analysis, vibration control, damage detection, and evaluation methods of different types of cable structures, including cable-stayed, suspension, and arch bridges.

There are three papers regarding the layout and detailed design of cable structures. A paper titled “Conceptual Design of a New Three-Tower Cable-Stayed Bridge System with Unequal-size Fans” by Shao et al. (2018) presents a new type of three-tower cable-stayed bridge with unequal-size fans. Numerical analysis of conventional and proposed systems showed that this new system is an excellent alternative to conventional designs regarding the stiffness, internal forces, and cost. In addition, it is fully accepted that cable anchorages in cable bridge structures are critical, yet there are no simple design and analytical methods available. Hence, Wei et al. (2018), in their paper “Full-Scale Specimen Testing and Parametric Studies on Tensile-Plate Cable-Girder Anchorages in Cable-Stayed Bridges with Steel Girder,” present their investigations of different types of cable anchorages through test and analytical methods. Their research results are useful for bridge design and analysis as well as future research. Another paper, “Analytical Models on Frictional Resistance between Cable and Saddle Equipped with Friction Plates for Multi-Span Suspension Bridges” by Cheng et al. (2018), presents a practical method for evaluating the frictional resistance in structural designs of suspension bridges and quantifying the effects of friction plates in practice. The method was verified with experimental results. The authors also concluded that incorporating vertical or horizontal friction plates significantly increases the frictional resistance and that using one horizontal friction plate is more effective in enhancing friction resistance than using one vertical friction plate.

Accurately and efficiently estimating cable tensions in a cable structure during construction and in service is crucial. Three papers in this collection present new methods for determining cable tensions. Morgenthal et al. (2018), in a paper entitled “Determination of Stay-Cable Forces Using Highly Mobile Vibration Measurement Devices,” present some methods to facilitate cable tensile force identification using highly mobile measurement equipment: modern Microelectromechanical systems (MEMS)-based acceleration sensors connected to battery-operated microcontrollers as well as those integrated in smartphones. The proposed methodology and implementation were validated through direct force measurements in a cable-stayed bridge under construction. The proposed technology has shown potential to provide very simple, cost-effective yet accurate tension force measurements. The paper “New Method for Identifying Internal Forces of Hangers Based on Form-Finding Theory of Suspension Cable” by Huang et al. (2017) presents a novel method for identification of tensions in hangers using only the measured coordinates of the main cables of the bridge based on form-finding theory. This method is convenient and economical to implement in practice and can identify the internal forces in all hangers of the suspension bridge simultaneously. The application of this method to a real bridge demonstrated that the proposed method is accurate and efficient. Zarbaf et al. (2017), in their paper “Stay Cable Tension Estimation of Cable-Stayed Bridges Using Genetic Algorithm and Particle Swarm Optimization,” present a methodology for estimating stay cable tensions of cable-stayed bridges using the genetic algorithm (GA) and particle swarm optimization (PSO). This method can account for the effects of the bending stiffness of the cable, sag extensibility, and external attachments to the cables. The agreement between tension forces estimated using the proposed method and those measured by lift-off test demonstrated that the proposed method is well capable in estimating the cable tension force in cable-stayed bridges.

With the development of structural design and material technologies during the last few decades, much longer stayed cables have become possible. To improve their dynamic or static performance, most long-span cable-stayed and suspension bridges are equipped with lateral cables, except the main cables. There are two papers on the analytical methods of complex cable bridge structures in this special issue. In their paper entitled “Determination of the Reasonable State of Suspension Bridges with Spatial Cables,” Xiao et al. (2017) present a five-step algorithm for determining the reasonable state of suspension bridges with complex spatial cables using a general FEM analysis method with additional algebraic operation and flow control. The algorithm makes full use of the commercial bridge analysis and design software available without introducing any new theoretical concept and is efficient and convenient for the bridge designers. The proposed algorithm was verified through accurate nonlinear analysis. Another paper, “Multistep and Multiparameter Identification Method for Bridge Cable Systems” by Dan et al. (2018), presents a parameter identification scheme for complicated cable systems using the particle swarm optimization algorithm. The scheme was verified through full-scale cable–damper system tests. The authors concluded that the proposed multistep, multiparameter identification program can significantly reduce the parameter identification errors and improve the identification quality.

Cables in bridge structures are vulnerable to harsh environmental effects that inevitably result in damage accumulation and that may impair the bridge. Thus, effective damage detection methods for cables are imperative in bridge maintenance. Three papers present cable damage detection methods and evaluation. In their paper entitled “Damage Detection in the Cable Structures of a Bridge Using the Virtual Distortion Method,” Lin et al. (2017) propose two damage detection methods for hangers in arch bridges based on the virtual distortion method (VDM). The proposed methods were verified through test results and can rapidly and accurately identify the damage location and degree of damage. A paper entitled “Time-Frequency-Based Data-Driven Structural Diagnosis and Damage Detection for Cable-Stayed Bridges” Pan et al. (2018) presents time-frequency-based data-driven structural diagnosis and damage detection for large-scale cable-stayed bridges. The proposed data-driven damage detection techniques exhibit high accuracy to allow distinguishing between undamaged and damaged cases, even when there are certain noise interferences as well as operational conditions. In their paper titled “Influence Length of Wire Fracture and Wire-to-Wire Interaction in Helically Wired Strands under Axial Loads,” Qu et al. (2018) propose an empirical equation for estimating the influence length of the wire fracture based on test and analytical results. They found that the difference in strains between the seven-wire strands with one damaged wire and the intact strands was negligible at 2 ft away from the damage location, and that sudden fracture in the outer wire with 90% area reduction causes only a slight or negligible dynamic effect. Their findings are useful for capacity evaluations of cable bridge structures.

Short suspenders in suspension bridges are prone to fatigue damage under repetitive vehicle and wind loads. There are three papers on fatigue damage and fatigue life evaluations for such members. Liu et al. (2017), in their paper entitled “Fatigue Life Evaluation on Short Suspenders of Long-Span Suspension Bridge with Central Clamps,” present the influence of using rigid central clamps on the fatigue performance of short suspenders and propose a fatigue life evaluation procedure. They found that central clamps can significantly mitigate the bending stress of short suspenders by reducing the relative motion between cables and the girder, and that suspenders may have fatigue lives shorter than the design value if there are no center clamps. The paper “Failure Investigation and Replacement Implementation of Short Suspenders in a Suspension Bridge” by Sun et al. (2017b) presents the failure evaluation replacement method of short suspenders in an existing suspension bridge. The authors concluded that cylindrical bushing in the pin connections of the suspender with the main cable and the deck is often subject to frequent impact transmitted from the deck and is susceptible to premature failure. Another paper, “Experimental Study and Residual Performance Evaluation of Corroded High-Tensile Steel Wires” by Zheng et al. (2017), presents a large amount of fatigue test results on the corroded hangers made of high-strength steel wires. Their conclusions on the properties of corroded wires and the prediction of residual service are useful for bridge maintenance and rehabilitation.

The installation of dampers close to cable anchorages is a common approach for stay cable vibration mitigation. In their paper “Performance Comparison between Passive Negative-Stiffness Dampers and Active Control in Cable Vibration Mitigation,” Shi et al. (2017) present a systematic comparison of vibration mitigation performances between passive negative stiffness dampers and active control methods of linear quadratic regulator and output feedback control. Their conclusions are useful for practical bridge designers. A paper entitled “Assessment of the Structural Damping Required to Prevent Galloping of Dry HDPE Stay Cables Using the Quasi-Steady Approach” by Demartino and Ricciardelli 2018) presents the evaluation of the structural damping required to prevent galloping of dry high density polyethylene (HDPE) stay cables using the quasi-steady approach based on the mean aerodynamic force coefficients of a real HDPE plain cable cover measured in the wind tunnel. The authors concluded that the cable irregularities and detuning direction have a strong influence on aerodynamic stability, and that instability is mainly due to critical Reynolds number effects.

Wind-induced vibration is another vital problem concerning cable structures. There are three papers on wind-induced vibration. Flutter stabilization of streamlined box girders is of critical importance for ensuring the structural safety of super-long-span bridges. The paper “Flutter Characteristics of Thin Plate Sections for Aerodynamic Bridges” by Yang et al. (2018) presents new findings on flutter characteristics of thin plate sections through performing theoretical analysis and wind tunnel tests with the aim of evaluating the flutter mechanism of super-long-span bridges with streamlined box girders. They concluded that the critical flutter velocities are different due to different ways of changing the structural torsional-heaving frequency ratio. With the increase of structural frequency ratio, the participation level of the heaving motion decreases, and the coupling effect becomes weaker. Andersen and Brandt (2018), in their paper “Aerodynamic Instability Investigations of a Novel, Flexible and Lightweight Triple-Box Girder Design for Long-Span Bridges,” discuss the possibilities for avoiding classical flutter and static divergence for very-long-span suspension bridges with a novel, flexible, and lightweight triple box girder. Through a section model test with a lightweight setup corresponding to a bridge girder mass in full-scale and numerical analysis, they found that no flutter was observed for the torsional-to-vertical frequency ratios ranging from 0.97 to 1.55, and that the critical flutter wind speed was approximately 88 m/s in the full-scale analysis for a suspension bridge with a main span length of 2,125.2 m. Their research results are useful for designing long-span suspension bridges. In their paper “Wind-Tunnel Experiments on Vortex-Induced Vibration of Rough Bridge Cables,” Trush et al. (2017) present the results of wind tunnel experiments on the vortex-induced vibration of rough bridge cables with various surface roughness and different levels of atmospheric turbulence. They concluded that the roughness and turbulence of the flow have a significant influence on the dynamic response of the cables, and that the vortex-induced vibration is larger for an ice-accreted bridge cable.

There are two papers on dynamic behaviors of cable-supported bridges. “Modal Analysis of the Saint Bachi Suspension Aqueduct Bridge Considering Fluid-Structure Interaction” by Di et al. (2017) presents the free-vibration behaviors of a special aqueduct cable-stayed bridge. The effects of the amount of water in the bridge main pipe on bridge vibration modes are discussed. The conclusions reached can assist bridge design of similar bridge types. Sun et al. (2017a), in their paper “Automated Operational Modal Analysis of a Cable-Stayed Bridge,” propose automated techniques for analyzing the dynamic behavior of existing bridges based on ambient vibration data. Using the proposed procedures, the vibration parameters of frequencies, damping ratios, and mode shapes can be obtained without the need for any user interactions. The proposed automated algorithm was verified with test results. The authors recommend this method be used as an operational modal analysis framework for testing existing bridges.

The paper “Experimental and Numerical Study of Lateral Cable Rupture in Cable-Stayed Bridges” by Hoang et al. (2018) presents the impact behavior of a stay cable subjected to abrupt rupture due to lateral force using model experiments and numerical analysis. They concluded that the impact force is more affected by the tensile stress of the cable during rupture than by the initial stress mentioned in the post-tensioning institute (PTI’s) recommendations. The conclusion may benefit future design of cable-stayed bridges.

Kalhori et al. (2018), in their case study titled “Nothing-on-Road Axle Detection Strategies in Bridge-Weigh-in-Motion for a Cable-Stayed Bridge,” discuss how to arrange the sensors through which the closely spaced axles can reliably be detected regardless of the speed, traveling direction, and lateral location of the vehicle on the bridge. Their findings are useful in bridge weight-in-motion research.

Readers will find that the special issue covers a vast array of interesting topics in cable-supported bridges. We trust this special issue will promote the advancement of the state of the art of the design, analysis, construction, and maintenance of cable-supported bridges. The special issue editors extend appreciation to Dr. Anil K. Agrawal, the Chief Editor; to the reviewers; and to the ASCE staff members for the support and assistance that they provided in the preparation of this special issue.