An Improved Analytical Algorithm on Main Cable System of Suspension Bridge

Li, Chuanxi; He, Jun; Zhang, Zhe; Liu, Yang; Ke, Hongjun; Chen, Dong; Liu, Hongli

doi:10.3390/app8081358

Cited by 26 publications

(14 citation statements)

References 31 publications

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“…Orthotropic steel decks (OSDs) are widely used in cable supported bridges and girder bridges due to their light weight and the short onsite construction time [1][2][3]. However, several types of fatigue cracks occur at the edges of added holes and at welded joints in OSD bridges [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Retrofit Fatigue Cracked Diaphragm Cutouts Using Improved Geometry in Orthotropic Steel Decks

Chen

et al. 2020

Applied Sciences

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Diaphragm cutouts are set to release redundant constraints and hence reduce weld fatigue at the connection of U-ribs to diaphragms in orthotropic steel decks. However, most fatigue cracks which originate from the edge of cutouts are in fact detected in the diaphragms. Therefore, a retrofit technology on cracked cutouts at the diaphragm is proposed and applied to the orthotropic steel box girder of a suspension bridge. Firstly, the stress concentration on the cutout is analyzed through refined finite element analyses. Furthermore, the fatigue cracked cutouts are retrofitted by changing their geometrical parameters. Thereafter, an optimized geometry and the size of diaphragm cutouts were confirmed and applied in the rehabilitation of a suspension bridge. On-site wheel load tests were carried out before and after retrofitting of the diaphragm cutout. The stress distributions along the edges of the cutouts and at the side of a diaphragm were measured under a moving vehicle. The stress spectra at two critical locations on the edge of a cutout was obtained under longitudinally and laterally moving vehicles. Finally, the fatigue life of the cutouts is assessed by the modified nominal stress method. The analytical and test results indicate that the wheel loads on the deck transmit stress to the diaphragms through the U-ribs, during the load transmission process, the stress flow is obstructed by diaphragm cutouts, resulting in local stress concentrations around the cutouts. In addition, the overall size of the cutouts should be small, but the radius of the transition arc should be large, thus the stress flow will not be obviously obstructed. After the retrofitting of the cutouts by improved geometry, the maximum stress decreases by 87.6 MPa, which is about 40% of the original stress. The equivalent constant amplitude stress is reduced by 55.2% when the lateral position of the wheel loads is taken into consideration. Based on the stresses obtained by finite element analysis (FEA) and experimental tests, the fatigue lives of the original cutouts are 1.7 and 4.9 years, respectively, which increase to 78.1 and 155.5 years, respectively, after the cutouts were retrofitted, which indicates that the improved geometry and retrofit technology can enhance the fatigue performance and extend the fatigue life of diaphragm cutouts with fatigue cracks.

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Section: Introductionmentioning

confidence: 99%

Retrofit Fatigue Cracked Diaphragm Cutouts Using Improved Geometry in Orthotropic Steel Decks

Chen

et al. 2020

Applied Sciences

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“…Although the accuracy of this method is high, the cutting affects the performance of the prestressed steel strand. Nondestructive testing methods include ultrasonic guided wave method [7,8], stress wave method [9], fiber grating sensor method [10,11], acoustic emission method [12,13] and shape memory alloy method [14]. The ultrasonic guided wave method determines the stress by analyzing the vibration and transmission speed of the elastic wave in the steel strand.…”

Section: Introductionmentioning

confidence: 99%

Stress Monitoring of Prestressed Steel Strand Based on Magnetoelastic Effect Under Weak Magnetic Field Considering Material Strain

Liu¹,

Zhang²,

Qu³

et al. 2020

PIER C

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Prestressed steel strands are critical components of prestressed structures, which determine the bearing capacity of the structures. The prestress loss of steel strands causes the bearing capacity to decline. To monitor the stress of prestressed steel strands, a stress monitoring method based on the magnetoelastic effect was proposed. The influence of the material strain was considered to improve monitoring accuracy. To do the monitoring, a coil-based sensor, using a small excitation current to generate a necessary magnetic field, was employed. The sensor converted the stress into inductance. An experimental system was set up, and two batches of specimens were tested. The experimental results showed that the measured inductance was stable and repeatable. There was a nonlinear relationship between the inductance and the stress. Strands of different batches need to be calibrated separately to obtain the inductance-stress equation. Based on the calibration equation and measured inductance, the stress of strands could be calculated. The difference between the calculated stress and the actual stress was small. Besides, to improve the accuracy and ease of the construction, the self-induction coil of the senor should be one layer and with moderate turns.

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“…e initial shape is determined to satisfy the equilibrium condition between dead loads and internal member forces including cable tensions in the preliminary design stage, because cable members display strongly geometric nonlinear behaviors and the configuration of a cable system cannot be defined in the stress-free state. e process determining the initial state of cable structures is referred to as "shape finding," "form finding," or "initial shape or initial configuration'' [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…. When the value of [Δ(ΔS)] adopts an acceptable value satisfying engineering accuracy, the length adjustment of datum strand cable at side span can be calculated by equation (13) and the calculated value by the second item in equation (13) will be smaller or larger than the value of [Δ(ΔS)]; therefore, the length adjustment of datum strand cable at side span should be calculated considering the influence of elastic elongation.…”

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confidence: 99%

A Simplified Calculation Method of Length Adjustment of Datum Strand for the Main Cable with Small Sag

et al. 2019

Advances in Civil Engineering

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In order to overcome the complicated iterative process of the cable length adjustment based on catenary theory and large error of length adjustment for cable with a small sag based on the parabola theory, this paper firstly develops a direct and simply calculation method based on parabola theory, considering the influence of elastic elongation on the cable unstressed length, which can apply for datum strand of the main cable and catwalk bearing rope with a small sag to improve the construction accuracy of the datum strand of suspension bridges. Then, the applicability of the proposed cable length adjustment formula under different conditions of the sag-span ratio is analyzed and compared with other calculation methods based on the theory of catenary or parabola. Finally, numerical examples are presented and discussed to illustrate the accuracy and efficiency of the proposed analytical method.

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An Improved Analytical Algorithm on Main Cable System of Suspension Bridge

Cited by 26 publications

References 31 publications

Retrofit Fatigue Cracked Diaphragm Cutouts Using Improved Geometry in Orthotropic Steel Decks

Retrofit Fatigue Cracked Diaphragm Cutouts Using Improved Geometry in Orthotropic Steel Decks

Stress Monitoring of Prestressed Steel Strand Based on Magnetoelastic Effect Under Weak Magnetic Field Considering Material Strain

A Simplified Calculation Method of Length Adjustment of Datum Strand for the Main Cable with Small Sag

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