Effects of the highway live load on the additional forces of the continuously welded rails of a long-span suspension bridge

2021 ◽  
pp. 095440972110619
Author(s):  
Xiangdong Yu ◽  
Nengyu Cheng ◽  
Haiquan Jing
Keyword(s):  
High Speed ◽  
Suspension Bridge ◽  
Additional Stress ◽  
Live Load ◽  
Analysis Model ◽  
Maximum Displacement ◽  
Obvious Effect ◽  
Long Span Bridges ◽  
Long Span ◽  
Track Bridge

High-speed running trains have higher regularity requirements for rail tracks. The track-bridge interaction of long-span bridges for high-speed railways has become a key factor for engineers and researchers in the last decade. However, studies on the track-bridge interaction of long-span bridges are rare because the bridges constructed for high-speed railways are mainly short- or moderate-span bridges, and the effects of the highway live load on the additional forces of continuously welded rails (CWRs) have not been reported. In the present study, the effects of the highway live load on the additional forces of a CWR of a long-span suspension bridge are investigated through numerical simulations. A track-bridge spatial analysis model was established using the principle of the double-layer spring model and the bilinear resistance model. The additional stress and displacement of the rail are calculated, and the effects of the highway live load are analyzed and compared with those without a highway live load. The results show that the highway live load has an obvious effect on the additional forces of a CWR. Under a temperature force, the highway live load increases the maximum tensile stress and compressive stress by 10 and 13%, respectively. Under a bending force, the highway live load increases the maximum compressive rail stress and maximum displacement by 50 and 54%, respectively. Under a rail breaking force, when the highway live load is taken into consideration, the rail displacement at both sides of the broken rail varies by 50 and 42%, respectively. The highway live load must be taken into consideration when calculating the additional forces of rails on highway-railway long-span bridges.

The development of live load for long span bridges

2010 ◽  
Vol 6 (1, 2) ◽  
pp. 73-79 ◽  
Author(s):  
A.S. Nowak ◽  
M. Lutomirska ◽  
F.I. Sheikh Ibrahim
Keyword(s):  
Live Load ◽  
Long Span Bridges ◽  
Long Span

Flutter mitigation of a superlong-span suspension bridge with a double-deck truss girder through wind tunnel tests

2020 ◽  
pp. 107754632094615
Author(s):  
Yanguo Sun ◽  
Yongfu Lei ◽  
Ming Li ◽  
Haili Liao ◽  
Mingshui Li
Keyword(s):  
Wind Tunnel ◽  
Damping Ratio ◽  
Suspension Bridge ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Upper Deck ◽  
Torsional Damping ◽  
And Control ◽  
Wind Induced Vibration

As flutter is a very dangerous wind-induced vibration phenomenon, the mitigation and control of flutter are crucial for the design of long-span bridges. In the present study, via a large number of section model wind tunnel tests, the flutter performance of a superlong-span suspension bridge with a double-deck truss girder was studied, and a series of aerodynamic and structural measures were used to mitigate and control its flutter instability. The results show that soft flutter characterized by a lack of an evident divergent point occurred for the double-deck truss girder. Upper central stabilizers on the upper deck, lower stabilizers below the lower deck, and horizontal flaps installed beside the bottoms of the sidewalks are all effective in suppressing flutter for this kind of truss girder. By combining the structural design with aerodynamic optimizations, a redesigned truss girder with widened upper carriers and sidewalks, and double lower stabilizers combined with the inspection vehicle rails is identified as the optimal flutter mitigation scheme. It was also found that the critical flutter wind speed increases with the torsional damping ratio, indicating that the dampers may be efficient in controlling soft flutter characterized by single-degree-of-freedom torsional vibration. This study aims to provide a useful reference and guidance for the flutter design optimization of long-span bridges with double-deck truss girders.

Suggestion for allowable additional compressive stress based on track conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1309-1325 ◽  
Author(s):  
Kyung-Min Yun ◽  
Beom-Ho Park ◽  
Hyun-Ung Bae ◽  
Nam-Hyoung Lim
Keyword(s):  
Compressive Stress ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Additional Stress ◽  
Analysis Model ◽  
Temperature Changes ◽  
Lateral Resistance ◽  
Ballasted Track ◽  
Continuous Welded Rail ◽  
Track Bridge

A continuous welded rail has immovable zones due to its structural characteristics. In an immovable zone, thermal expansion and contraction of rails are restricted when the temperature changes, thereby causing excessive axial force on the rail. When the immovable zone of the continuous welded rail is located on a bridge, additional stress and displacement occur through track–bridge interactions. Additional stress and displacement of the rail compared to the embankment area are restricted when constructing the bridge under the continuous welded rail track to prevent problems with the track–bridge interaction according to UIC 774-3R and Euro codes. According to the various codes, the maximum allowable additional compressive stress is 72 MPa, with the conditions of a curve with a radius (R) ≥ 1500 m, UIC 60 continuous welded rail (tensile strength of at least 900 MPa), ballasted track with concrete sleepers and 30 cm of deep for a well-consolidated ballast. However, the lateral resistance that has the greatest effect on track stability can depend on the conditions mentioned above. Therefore, an additional review of various track conditions is required. In this paper, an evaluation of the current criteria was performed using the minimum buckling strength calculation formula, and the allowable additional stress on the rail suggested by codes could only be used on tracks with a large lateral resistance above 18 kN/m/track. Thus, a three-dimensional nonlinear analysis model was developed and analyzed to calculate the allowable additional compressive stress considering various track conditions. According to the results of the analysis, the allowable additional compressive stress was reduced with a comparatively small lateral resistance. The freedom of design can be enhanced with respect to the parameters of various track and bridge conditions using this model.

Probabilistic Damage Detection of Long-Span Bridges Using Measured Modal Frequencies and Temperature

2018 ◽  
Vol 18 (10) ◽  
pp. 1850126 ◽  
Author(s):  
Yang Deng ◽  
Aiqun Li ◽  
Dongming Feng
Keyword(s):  
Damage Detection ◽  
Normal Distribution ◽  
Control Chart ◽  
Temperature Effects ◽  
Suspension Bridge ◽  
Standard Normal Distribution ◽  
Long Span Bridges ◽  
Long Span ◽  
Standard Normal ◽  
Probabilistic Monitoring

This paper aims to develop a new probabilistic monitoring-based framework for damage detection of long-span bridges, by eliminating the temperature effects from the measured modal frequencies, probabilistic modeling of modal frequencies using kernel density estimate, and detection damage using the control chart. A methodology is presented to address the issue of modal frequencies' non-normal distribution, which has been neglected in the past studies using the control chart to detect the modal frequencies' abnormality caused by structural damages. The efficiency of the proposed framework is validated through a case study of long-term monitoring data of a long-span suspension bridge. The results show that after elimination of the temperature effects, the selected modal frequencies are not normally distributed, while the Q statistics transferred from the modal frequencies follow the standard normal distribution. The abnormality of modal frequencies can be detected when the data points of the Q statistics exceed the limits of the control chart. Further, the control chart has sufficient sensitivity and thus can be used to detect minor abnormalities of the prototype bridge's modal frequencies. It is concluded that the proposed probabilistic monitoring-based framework offers an effective technique for structural health monitoring of long-span bridges.

scholarly journals Wind-driven damage localization on a suspension bridge

2016 ◽  
Vol 11 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Marco Domaneschi ◽  
Maria Pina Limongelli ◽  
Luca Martinelli
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Damage Identification ◽  
Structural Response ◽  
Suspension Bridge ◽  
Element Model ◽  
Damage Localization ◽  
Damage Scenarios ◽  
Long Span Bridges ◽  
Long Span

The paper focuses on extending a recently proposed damage localization method, previously devised for structures subjected to a known input, to ambient vibrations induced by an unknown wind excitation. Wind induced vibrations in long-span bridges can be recorded without closing the infrastructure to traffic, providing useful data for health monitoring purposes. One major problem in damage identification of large civil structures is the scarce data recorded on damaged real structures. A detailed finite element model, able to correctly and reliably reproduce the real structure behavior under ambient excitation can be an invaluable tool, enabling the simulation of several different damage scenarios to test the performance of any monitoring system. In this work a calibrated finite element model of an existing long-span suspension bridge is used to simulate the structural response to wind actions. Several damage scenarios are simulated with different location and severity of damage to check the sensitivity of the adopted identification method. The sensitivity to the length and noise disturbances of recorded data are also investigated.

scholarly journals Experimental Study on Vibration Characteristics of Unit-Plate Ballastless Track Systems Laid on Long-Span Bridges Using Full-Scale Test Rigs

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1744 ◽  
Author(s):  
Weiqi Zheng ◽  
Xingwang Sheng ◽  
Zhihui Zhu ◽  
Tianjing Luo ◽  
Zecheng Liu
Keyword(s):  
High Speed ◽  
Vibration Characteristics ◽  
Full Scale ◽  
Long Span Bridges ◽  
Isolation Layer ◽  
Long Span ◽  
Ballastless Track ◽  
Excited Vibration ◽  
Scale Test ◽  
Reduction Effect

In this work, we present a series of hammering tests on full-scale unit-plate ballastless tracks used for long-span bridges. There is no denying that it is a new attempt to pave ballastless tracks on high-speed railway long-span bridges; the related issues deserve to be studied, and especially the vibration characteristics. Hence, the vibration characteristics and transmission rules of the ballastless track with geotextile or rubber isolation layers are explored, and the vibration reduction effect of the rubber isolation layer is analyzed. The main conclusions are as follows: the isolation layers change vibration modes and transmission characteristics of ballastless tracks; the introduction of the rubber isolation layer makes the excited vibration frequency range of the ballastless track concentrated; and the vibrations of the ballastless track with the rubber isolation layers are stable. Moreover, the rubber isolation layer has an obvious attenuation effect on vibration transmission in ballastless track structures. When the vibration is transmitted from the rail to the bridge deck, the vibration level differences of the ballastless track with rubber isolation layers are 20 dB larger than that of the ballastless track with the geotextile isolation layers. The vibration attenuation rate of the rubber isolation layer is about ten times larger than that of geotextile isolation layer.

scholarly journals High-Speed Train-Track-Bridge Dynamic Interaction considering Wheel-Rail Contact Nonlinearity due to Wheel Hollow Wear

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Chao Chang ◽  
Liang Ling ◽  
Zhaoling Han ◽  
Kaiyun Wang ◽  
Wanming Zhai
Keyword(s):  
High Speed ◽  
Synthesis Method ◽  
Dynamic Interaction ◽  
High Speed Train ◽  
Train Track ◽  
High Speed Railway ◽  
Long Span ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Track Bridge

Wheel hollow wear is a common form of wheel-surface damage in high-speed trains, which is of great concern and a potential threat to the service performance and safety of the high-speed railway system. At the same time, rail corridors in high-speed railways are extensively straightened through the addition of bridges. However, only few studies paid attention to the influence of wheel-profile wear on the train-track-bridge dynamic interaction. This paper reports a study of the high-speed train-track-bridge dynamic interactions under new and hollow worn wheel profiles. A nonlinear rigid-flexible coupled model of a Chinese high-speed train travelling on nonballasted tracks supported by a long-span continuous girder bridge is formulated. This modelling is based on the train-track-bridge interaction theory, the wheel-rail nonelliptical multipoint contact theory, and the modified Craig–Bampton modal synthesis method. The effects of wheel-rail nonlinearity caused by the wheel hollow wear are fully considered. The proposed model is applied to predict the vertical and lateral dynamic responses of the high-speed train-track-bridge system under new and worn wheel profiles, in which a high-speed train passing through a long-span continuous girder bridge at a speed of 350 km/h is considered. The numerical results show that the wheel hollow wear changes the geometric parameters of the wheel-rail contact and then deteriorates the train-track-bridge interactions. The worn wheels can increase the vibration response of the high-speed railway bridges.

Performance-Based Design Research on a Long-Span High-Speed Railway Suspension Bridge

2019 ◽  
Author(s):  
Xiaoguang Liu ◽  
Hui Guo ◽  
Xinxin Zhao ◽  
Pengfei Su ◽  
Mangmang Gao
Keyword(s):  
High Speed ◽  
Rotation Angle ◽  
Suspension Bridge ◽  
Performance Based Design ◽  
Live Load ◽  
Stay Cable ◽  
Expansion Joint ◽  
High Speed Railway ◽  
Track Geometry ◽  
Study Results

<p>A performance-based design (PBD) framework for high-speed railway suspension bridge is proposed from aspects of structural, operational and public requirements. Stiffness indexes are discussed. Results show that target performance shall include stiffness, strength, fatigue, stability, track geometry, train operation performance, human safety and public loss, etc. Case study results of a high-speed railway suspension bridge show that large cable force provide gravity stiffness with the vertical deflection to main span length is 1/488 under static live load. The longitudinal displacement (LD) is restricted to a proper value by arrangement of inclined stay cable at the mid-span and the viscous dampers between pylon and stiffening girder. LD at girder end under the total live load is 261mm. And the longitudinal drift mode shape appears later than symmetrical transverse and vertical bending. The vertical rotation angle at girder end is only 0.77‰ under ZK load (0.8UIC) for passenger-dedicated line by setting auxiliary pier at side span of the bridge. Considering the operational performance, elastic deformation of wind-resistant bearings at girder end shall be restricted to decrease the transverse rotation angle which has the limit value from 1.0‰ to 2.5‰ under different train speed. And the integral design of bridge expansion joint (BEJ) and rail expansion joint (REJ) at girder end is required.</p>

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