Span Suspension Bridge Research Articles

Micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables

The outstanding combination of high strength and ductility of bridge cable steel wire is attributed to the cold drawing process with intermediate equivalent strain. However, the micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables is not well understood. In this study, defects-controlled deformation in nano-scale interfaces between ferrite and cementite phases with heavily cold drawing process was investigated using high-resolution transmission electron microscopy and molecular dynamics simulation. The excessive thinning of the cementite lamellar thickness observed from the morphology suggested the evolution of the Fe3C/Fe interface in the cold-drawn wires, namely, the partial cementite deformation during the drawing process. Drawing strain played a major role in the occurrence of partial cementite nano-crystallisation. This was because the change in cementite morphology was the primary cause of cementite free energy increase, which ultimately led to cementite phase instability. The decrease of yield strength during the drawing process of the bridge cable steel wire was caused by the inverse Hall-Petch effect resulted from the nodule rotation. When the nodule morphology became flat, the inverse Hall-Petch effect was suppressed. At this time, the strengthening mechanism caused by cementite nano-crystallisation ensured the improvement of tensile strength of steel wire when the dislocation density was close to saturation.

Main cable structure analysis and construction control of short span suspension bridge within three-tower

The Feng Chu suspension bridge in Xiangyang holds the distinction of having one of the shortest span lengths among global suspension bridges, measuring less than half the length of conventional designs. This paper focuses on the engineering background of the bridge and delves into the analysis of the main cable structure and construction control methods for short-span suspension bridges with three towers. The study examines the impact of elastic modulus deviation in the main cable and the dead-load error of the stiffening beam on key parameters such as the unstressed length of the main cable, pre-deflection of the cable saddle, and mid-span elevation of the empty cable. Additionally, the effects of temperature, span, and cable length on the sag of the empty cable during the erection process are analyzed. Findings reveal that the elastic modulus and dead-load error significantly influence the unstressed length of the main cable, pre-deflection of the saddle, and the shape of the empty cable. This study establishes a relationship between changes in cable length and mid-span sag, providing valuable theoretical guidance for aligning and adjusting the main cable strands. Furthermore, synchronized alignment adjustments for the two mid-span sections are proposed to prevent main cable strand sliding, which may occur due to significant differences in sag between the sections.

Structural Analysis and Application of Long Span Suspension Bridge

Structural Analysis and Application of Long Span Suspension Bridge

Twinning of the Egongyan Bridge

The First Egongyan Bridge in Chongqing, China was opened to traffic on December 27, 2000. It carries six-lanes of city traffic and two pedestrian paths, one on each side. It is a 600 m span suspension bridge. It was planned that the two pedestrian paths might eventually be converted to transit tracks in the future. However, with the rapid increase in urban traffic, the deck was transformed into an 8-lane bridge instead. Therefore, a new bridge parallel and adjacent to the old bridge was built for the rail transit. For aesthetic reasons, the city decided that the new bridge should also be a suspension bridge, with the same span length and tower height as the first bridge. The First Egongyan Bridge was a true suspension bridge with main cables anchored to ground anchors. However, the new bridge bridge’s proximity to the first bridge necessitated the construction of a self-anchored suspension bridge that did away with a second set of ground anchors. This 600 m span happened to be the world’s longest span for a self-anchored suspension bridge.

Seismic Reduction Analysis of Super-Long Span Suspension Bridge with Lattice Composite Tower and Damping System: A Case of Study for Qiongzhou Strait Bridge

In this paper, we proposed a lattice composite tower damping system to reduce the seismic response of super-long-span suspension bridges. Taking the QiongZhou strait bridge as a case study, we evaluated seismic performances through a finite element analysis (FEA) and shaking-table tests. First, the seismic responses of a super-long-span suspension bridge with or without a lattice composite tower to far-fault and near-fault earthquakes were analyzed and compared. The influence of the lattice composite tower on the dynamic characteristics and seismic performance was then investigated using shaking-table tests. Finally, the influences of different damping systems on the seismic response were evaluated, considering factors such as the damper type, damper arrangement scheme and design parameters. The results indicated that lattice composite tower could significantly increase the seismic performance of super-long span suspension bridge, while the optimal damping system could markedly improve the energy dissipation ability of whole system. Subsequently, this could provide references to enhance the seismic safety of the super-long span suspension bridge under strong earthquakes.

Establishment and effect analysis of traffic load for long-span bridge via fusion of parameter correlation

Traffic flow is the main driver behind the dynamic response in operation of long-span bridges. To further improve the effectiveness of safety analysis for long span bridges, the bridge dynamic response should be analyzed under traffic flow. This paper investigated the simulation method of traffic flow and the bridge dynamic response under it. Firstly, the potential parameter correlation in the traffic flow was analyzed based on WIM data. Secondly, a refined simulation method of stochastic traffic flow that considers the correlation in vehicle arriving sequence and axle weight (AW) was proposed and validated. The Markov Chain Monte Carlo (MCMC) method and the correlation random sampling Monte Carlo simulation (CMCS) method were used to simulate the correlation of vehicle arriving sequence and axle weight, respectively. Finally, the constructed stochastic traffic flow is used to evaluate the influence of parameter correlation of traffic flow on dynamic response for long span suspension bridges. Results highlight the correlation of traffic flow. For the vehicle arriving sequence, those vehicles with a small quality rarely follow those with a large quality. The vehicles of different types follow certain transfer relationship. The correlation of vehicle arriving sequence can be effectively simulated that the vehicle type distribution and transition probability of the samples are both close to the WIM data. Meanwhile, the correlation of vehicle AW is mainly observed among multi-axle vehicles, and that in two- and three-axle vehicles is not significant. In the bridge application, the proposed method outperforms the MC method in the simulation of multi-axle vehicles. The parameter correlation of traffic flow has obvious influence on the response of the girder of long-span suspension bridge. The distribution of vertical displacement and bending moment of SC is closer to WIM data, and due to the small ratio of live load to dead load, some indexes such as the suspender force are less affected. The consideration of parameter correlation brings the load effect closer to the WIM data, the parameter correlation should be considered in the evaluation of the fatigue life of components, which can positively contribute to the long-term evaluation of bridge response under traffic flow.

Buckling behavior of orthotropic steel deck stiffened by slender bulb flats for large span bridges

Slender bulb flat stiffeners with a large height-to-thickness ratio were proposed for the orthotropic steel decks (OSDs) in a large span suspension bridge. The buckling behavior of the panels stiffened with bulb stiffeners under pure compression was experimentally and numerically studied in this paper. Four specimens consisting of four longitudinal stiffeners and a top deck plate were fabricated and subjected to axial compression loading tests. Finite element models were established and validated by the result tests. A parametric analysis was conducted to study the effects of residual stresses and geometric imperfections on buckling behavior. A buckling failure of overall stiffener buckling before the yielding and ductile post-buckling behavior were observed in the tests. A buckling strength of 311∼337 MPa was obtained in the tests. The ratio of buckling stress to yield strength ranging from 0.80 to 0.86 was slightly lower than that of closed ribs, which shows a potential use of the slender bulb flat in large span suspension bridges. The numerical results showed that the residual stresses can decrease the load-bearing capacity by 10%. The residual stresses have a higher influence on the resistance than the regular geometrical imperfections. The standard vehicle load has negligible influence on the buckling resistance, but overload may cause a certain decrease.

Influence Analysis of Traveling Wave Effect on Rail Interaction of Long-Span Suspension Bridge

At present, there are few research results on the seismic response of the track system on railway suspension bridges, and relevant research has not yet formed a certain standard. In order to provide a certain reference for the development of industry standards and the design of seamless lines on railway suspension bridges, based on the large-mass method based on multi-point excitation, taking China’s longest high-speed railway suspension bridge-Wufengshan Yangtze River Bridge as the engineering background, a beam–rail integrated dynamic calculation space model was established with ANSYS, and the influence of traveling wave effect on the beam-rail interaction of large span suspension bridges was studied. The study shows that: the traveling wave effect will increase the relative displacement of the beam and rail, and then increase the stress of the rail; the traveling wave effect will cause the stress of the rail far from the source measurement to lag behind the stress of the rail near the source side, and the lag phenomenon gradually disappears with the increase of the apparent wave speed; the traveling wave effect has a greater effect on the displacement of the main bridge end than that of the approach bridge end; the longitudinal displacement of the main bridge end on the north and south side keeps changing synchronously under high apparent wave speed and consistent excitation, and no longer keeps changing synchronously under low apparent wave speed. The longitudinal displacement of the north-south side of the main bridge end keeps changing synchronously at high apparent wave speed and consistent excitation, but no longer at low apparent wave speed.

Experimental study on buckling behavior of orthotropic steel deck with slender open ribs for large span suspension bridges

This paper presents an experimental and numerical study of the buckling behavior of the orthotropic steel deck with slender open ribs for the Zhangjinggao Yangtze River Bridge. Eight specimens consisting of four longitudinal stiffeners and a top deck plate were fabricated and subjected to axial compression loading tests. Finite element simulations and a parametric discussion were carried out using ANSYS software. Experimental results demonstrated that the axial buckling failure mode was characterized by stiffener tripping before the yielding of ribs. The post-buckling stage showed a certain ductility when the ribs did not collapse simultaneously. A buckling strength of 323 MPa was obtained from the tests, which reflected a sufficient safety margin compared to the working stresses in the real bridge. The numerical results agreed reasonably well with the tests. The study showed that the ratio of buckling stress to yield strength ranged from 0.72 to 0.84. Besides, geometric imperfections, residual stresses, and vehicle loads merely degrade the buckling strength to a small extent according to the parametric discussion.

An anomaly pattern detection for bridge structural response considering time-varying temperature coefficients

To improve the detection rate in the bridge anomaly detection, this study proposes an anomaly pattern detection method based on the time-varying temperature–displacement relationship. First, the empirical wavelet transform method is used to extract thermal-induced displacement components. Then, based on the daily variation of solar radiation, a pattern is defined as three groups of regression parameters associated with the temperature–displacement relationships. To measure the uncertainty in the anomaly detection, distributions of the parameters in the defined pattern are determined by Bayesian estimation. To overcome occasionality, a new index — weekly mean detection rate is defined. The effectiveness of the proposed temperature-driven anomaly pattern detection method is validated by using actual girder end displacements from a large span suspension bridge in China. As a result, the anomalous boundary condition is detected with a weekly mean detection rate of 0.91. Whilst, the weekly mean detection rate is 0.67 when applying the conventional anomaly detection method without considering the time-varying factor. Finally, the detection rate and the false detection rate of the proposed method are compared with those of cointegration and moving principle component analysis methods. The proposed method has a higher detection rate and a lower false detection rate for the anomalous boundary condition.

Unified method for fully automated modal identification and tracking with consideration of sensor deployment

Automated modal identification and tracking provides the key technique for modal parameters based structural condition evaluation. However, the existing automated modal identification and tracking methods have limitations for situation with very few sensors deployed and require manual intervention. This paper proposes a unified fully automated modal identification and tracking method that can be used for structures with many or very few sensors deployed, for closely spaced modes with severe spatial aliasing and for structures with high flexibility or rigidity. A new index, which is called Modified Modal Observability Correlation, is proposed to estimate the similarity of two modes. New spurious mode elimination method and fully automated mode separation and tracking methods are proposed to realize the automated modal identification and tracking. The feasibility and novelty of the proposed method are validated using in-field monitoring data from a long span suspension bridge with high flexibility and a short span bridge with high rigidity and closely spaced modes. Automated modal identification and tracking for situations with many and very few sensors deployed for the two bridges are conducted, and extreme situation of closely spaced modes with spatial aliasing in mode shape is also considered to prove the novelty of the proposed method. Comparisons with existing mainstream methods are also conducted. The results show that the proposed method yields the right identification and tracking results in all situations, showing novelty in automated modal identification and tracking for structures with closely spaced modes having severe spatial aliasing when only very few sensors are deployed.

Nonlinear torsional primary resonance analysis of suspension bridge with generalized configuration using mathematical model

Torsional vibration of long span suspension bridge can be commonly induced by various sources, and detailed investigation is required from both design and safety point of view. This study proposes a continuum model of the generalized suspension bridge using the Hamilton principle. This model can consider any inclination angle of main cables. The horizontal and vertical motions of main cables, and torsional motion of deck are considered individually in this model. The proposed model is verified by comparing its modal properties with those from a finite element model. The nonlinear primary resonances of the two lowest torsional modes are studied through multiple-scale method (MSM) under harmonic excitation. The effects of system parameters, such as inclination angle of hangers, sag-to-span ratio, tensile stiffness of main cable and torsional stiffness of deck, on the resonance responses are investigated in this study. Results show that, increasing inclination angle of main cable and torsional stiffness of deck can intensify the softening feature of the system. In contrast, increasing the sag-to-span ratio and tensile stiffness of main cable can strengthen the hardening feature.

Structural health monitoring on Yangluo Yangtze River Bridge: Implementation and demonstration

Long-span cable-supported bridge is one of crucial transportation infrastructures. Structural health monitoring (SHM) system that is used to assess structural service conditions and detect early damage has drawn a growing attention in engineering structural society. It provides a real-time monitoring of various structural changes under operational and extreme conditions. Yangluo Bridge over Yangtze River in Wuhan city of China is a 1280 m central span suspension bridge with an orthotropic steel box girder. Taking the SHM system of Yangluo Yangtze River Bridge as an example, this paper presents an implementation of SHM system on the bridge in terms of sensor layout, data acquisition strategy, data transmission, data processing, and abnormal alarm framework. With such an SHM system, the typical monitoring results are demonstrated such as operational environments, loadings, structural deformation, strains, dynamic properties, and structural responses. The SHM system of Yangluo Yangtze River Bridge is continuously gathering data and monitoring structural behavior. It is anticipated that it will provide either scientific or technological supports to the service comfort and safety of the bridge.

The influence of gap- and chord-widths for multi-box girders: Superposition of flat plate flutter derivatives and section model tests

A two dimensional model based on the superposition of Theodorsen’s flat plate theory generalized to approximate the aeroelastic effects on an arbitrary multi-box bridge girder is developed. The model is compared with wind tunnel test results of a single box girder and two triple-box girders having different gap-widths between the center box and the external boxes. Reasonable agreement between the flutter derivatives obtained from single degree of freedom harmonic forced motion tests and superposition of flat plate flutter derivatives is obtained. For vertical motion, the aerodynamic damping is correlated with the sum of chord-widths of the interconnected boxes. The aerodynamic damping during harmonic torsional motion is correlated with the distance from the elastic axis of the section to the mid-chords of the external boxes. The torsional aerodynamic damping agrees with the superposition of flat plate derivatives while the torsional aerodynamic stiffness disagrees. This means that the flat plate model overestimates the critical flutter wind speed for the present sections, but it can be used to approximate the flutter derivatives: H1, H2, H3 and A2. Empirical results are used to tune the superposed flat plate model, which is then used to approximate the critical flutter wind speed for a 2200 m single span suspension bridge featuring a light-weight triple-box girder. The wind tunnel tests indicate that the light-weight triple-box girder is aerodynamically stable up to at least 70 m/s even though the torsional frequency is lower than the vertical.

Mechanical Properties and Structural Optimization of Continuous Welded Rail on Super-Long-Span Suspension Bridges for High-Speed Railway

In order to ensure driving safety and comfort, it is necessary to figure out the complex interaction between continuous welded rail (CWR) and suspension bridges for high-speed railway. A spatial finite element model for a 1092 m main span suspension bridge was established based on the bridge-track interaction theory. A specific correction method was put forward to keep the rail in a zero-stress state when just laid. Three rail expansion joint (REJ) layout schemes were proposed according to practical engineering experience. Both static and dynamic analysis methods were used to evaluate the feasibility of these schemes. The results show that the REJ should be laid at the position with a distance away from the primary beam end, and the beam with more substantial integral stiffness should be preferentially selected. For the recommended scheme, the REJ expansion reaches more than 380 mm under expansion load. The factors affecting the REJ expansion from major to minor are temperature, earthquake, rail fracture, braking, and bending load. The superposition effect of the above factors is suggested to be considered in the selection of REJ range.

Cable structure design of suspension bridges through strand reduction method

AbstractCable structures hold a special place for the cost of suspension bridges. Considerable development of the structural cable material leads to design and construction of long‐span suspension bridges. Thus, designing cable structures that are cost‐effective and reliable is significant for these mega structures. The overall layout of a main cable is consistent with constant number of elements per span since the design of the first suspension bridge. However, the reduction of main cable area in regard to design loads could play an important role in saving cost of long span suspension bridges. This paper presents the strand reduction approach for the cable structure design of suspension bridges. The proposed approach has been implemented by releasing the required number of parallel wire strands in main cable of the suspension bridge at specific locations in accordance with axial loads on main and hanger cables where released strands are transformed into a hanger cable with special types of clamps. The strand reduction approach is named as “saddle‐clamp system” and has been compared with the current design of 1915 Canakkale Bridge. The results indicate that the strand reduction method provides 7.6% to 34.1% material quantity deduction for the cable structures of the suspension bridge.

Flutter Analysis of The Sunda Strait Suspension Bridge

Economic movements in Indonesia and the logistics and distribution systems that accompany them are highly dependent on road transportation modes. On the other hand, the islands of Sumatra and Java are the centers of concentration for the Indonesian economy where the number of people inhabiting the two islands reaches 80% of the total population of Indonesia. In order to accelerate development and increase the economic integration of Java and Sumatra, it is necessary to build the Sunda Strait Bridge. The main bridge considered incudes the long span suspension bridge. At present, the planning and construction of the long bridge including suspension bridge was greatly affected by the failure of the Taccoma Narrow Bridge on 7 November 1944. Due to the wind load, the bridge structure shook until it finally collapsed. Although the cause of the collapse was not immediately known, it is currently concluded that it was caused by a single degree of freedom torsional flutter caused by self-excited wind load. This phenomenon is classified as an aerodynamic phenomenon on long span bridges. The flutter analysis performed on the Sunda Strait Suspension Bridge using the Direct Flutter Analysis method will be presented in this paper.

Flutter Control of Long Span Suspension Bridges in Time Domain Using Optimized TMD

Suspension bridges due to their long span are susceptible against dynamic events, like air flow which can cause considerable problems for them. Flutter, as an aerodynamic phenomenon, makes bridges vibrate, whereas their amplitude gradually diverges, needed the vibration control strategies. Tuned mass damper or in brief TMD, as the simplest passive device, can be used for this purpose. The performance of it can be enhanced when it’s parameters are adjusted to their optimum values. In this paper, the TMD was optimized by meta-heuristic optimization algorithms to control the flutter of long span suspension bridges. In this regard, the Golden Gate suspension bridge and Car tracking algorithm were selected for case study and optimization process, respectively. Firstly, the flutter analysis of bridge was done by multi-mode method in the time domain, and at second part, the TMD’s parameters were simultaneously optimized for maximum increase of flutter velocity of all the vulnerable modes. The results indicated that TMD was perfectly suitable device to control the flutter of long span bridges.

Monitoring-based evaluation of dynamic characteristics of a long span suspension bridge under typhoons

The Xihoumen Bridge, with a main span of 1650 m and two side spans of 578 m and 485 m, respectively, is a long-span suspension bridge spanning the Jintang and Cezi islands in Zhejiang Province, China. In order to establish a reference baseline for vibration mitigation and condition assessment of the bridge under typhoons, the wind field properties, vibration energy distribution, and modal parameters of the bridge are identified through in-situ monitoring. Dynamic responses at different locations on main span and wind speeds at 1/2 main span of the bridge under 10 typhoons and under normal wind were collected for this study. Vibration energy distribution is estimated using wavelet packet transform. Modal parameters are identified by the peak-picking (PP) and data-driven stochastic subspace identification (SSI-DATA) methods. The results indicate that in the low-frequency range, the fluctuating wind energy of typhoons changes more significantly than that of normal wind. More than 80% of the vibration energy is concentrated in the frequency band (0–1.5625 Hz) under typhoons, while nearly 90% of the vibration energy under normal winds is evenly distributed in three frequency bands (0–1.5625 Hz, 1.5625–3.125 Hz, and 3.125–4.6875 Hz). When using typhoon-induced dynamic responses as input, the SSI-DATA method performs better than the PP method in the identification of modal parameters. The results obtained in this study can be used as a baseline for future structural condition assessment of the bridge after typhoon events.

Research of Damper Parameters of Large span Suspension Bridge

This paper research the parameter selection range of large span suspension bridge dampers. The finite element model of the Puli Bridge was established by using ANSYS software. Under consideration of the pile-soil interaction, the cross analysis of 16 dampers with different parameters under the action of longitudinal + vertical earthquake was carried out. The bending moment and shear force at the bottom of the tower, the relative displacement of the tower and the girder, the maximum speed and the maximum damping force of the dampers under different working conditions are analyzed. Therefore, the suggested range of each parameter of a single damper is proposed.