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[Objective] It is aimed to provide advice for via- duct noise control in city rail transit and application of noise reduction measures. [Method] Based on theories of vehicle- track dynamics, wheel-rail vibration radiation, and viaduct structure vibration radiation, a prediction model for viaduct noise in city rail transit is established. The influence of factors such as train speed, distance from viaduct structure, viaduct type, and noise barriers on city rail transit viaduct noise is analyzed. [Result & Conclusion] When train speed exceeds 100 km/h, the viaduct noise increases by 1.8-5.5 dB (A) compared to train speeds below 100km/h. For single-cell single-box girders, single-cell double-box girders, and U-shaped girders, the peak frequency range of viaduct noise is 50-80 Hz, with a peak frequency at 63 Hz. At a distance of 7.5 m from the track centerline, the single-cell double-box girder demonstrates the lowest noise levels at all heights, whereas noise levels at the girder sides of single-cell single-box girders and U-shaped girders are higher by 1.0-4.1 dB(A) and 5.2-10.6 dB (A), respectively, compared to single-cell double-box girders. Near-track noise barriers with heights of 0.90 m or more above the track surface ensure a noise reduction effect of 7.0 dB (A) at 500 Hz frequency band, with noticeable noise reduction effects maintained across frequencies above 630 Hz. [ABSTRACT FROM AUTHOR]

[Objective] To reduce the impact of elevated lines in urban rapid rail transit on environmental noise, multiple noise-reduction measures such as near-track sound barriers and ballast bed sound-absorbing panels are adopted. On-site measurements and analyses should combine with on-site operating conditions to verify the effectiveness of trackside noise reIn the case study of the already operating Line S1 of Wenzhou Urban Rapid Rail Transit, the environmental noise in the viaduct section of this line is measured on site. The noise reducduction measures in reducing environmental noise. [Method] tion effects of near-track sound barriers and ballast bed soundabsorbing panels for the environmental noise under different train running speeds are compared and analyzed, and the influence characteristics of different noise reduction measures on the viaduct section noise are explored. [Result & Conclusion] The near-track sound barrier reduces the maximum instantaneous A-weighted time-domain sound pressure level (hereinafter abbreviated as "A-weighted level") on the viaduct inner and outer sides by approximately 20 to 21 dB(A). At the position 7.5 meters away from the track center line and 7.5 meters above the rail surface, the A-weighted level in the 500 Hz and 800-1 000 Hz frequency bands are respectively reduced by 6 to 11 dB(A) and 17 to 21 dB (A). The ballast bed sound-absorbing panels can further reduce the trackside noise on and outside the viaduct. Compared with the working conditions where only the near-track sound barriers are installed, when using the sound-absorbing panels, the maximum instantaneous A-weighted level on the viaduct is further reduced by 14 to 17 dB(A) with the same train running speed, and the A-weighted level is reduced by to 8 dB (A) and 5 to 7 dB(A) respectively for the noise in the 500 Hz and 800-1000 Hz frequency bands at the same measuring point outside the viaduct. [ABSTRACT FROM AUTHOR]

The creep-slip and dislocation of urban active faults poses a potential safety threat to municipal construction. Different from abrupt earthquake disasters, the creep-slip dislocation of fault is a slowdeforming disaster with controllability. In order to reveal the influence of creep-slip dislocation on metro viaducts, this paper takes the Xi'an Metro Line 10 viaduct crossing the Weihe fault(F1) and Jingyang-Weinan Fault ( F3) as the engineering background, a strata-fault zone-viaduct calculation model is established with finite numerical software, and the deformation characteristics of the metro box girder viaduct with different spans and pile lengths under the creep-slip dislocation of the fault are analyzed. The results show that the strata deformation in the viaduct site is approximately "V" shaped under the fault dislocation, and the influence range in the hanging wall is greater than that in the footwall of active fault. Under the creep-slip dislocation of active fault, the deformation of the bridge structure crossing active fault and the ground surface decreases with the increase of viaduct pile length, and when the span of the bridge is 40 m and the pile length is 60 m, the surface settlement and the deformation of box girder and pier of viaduct are the smallest. The deformation of the bridge structure is related to its angle across the fault zone. When crossing the fault zone at a small angle, the deformation of the bridge structure is greater than that of the orthogonal and large angle crossing conditions. When the viaduct crosses the fault zone at large angle obliquely or orthogonally, the optimal span of viaduct is about 40 m and the optimal pile length for bridge piles adjacent to the fault zone is about 55 m. When the viaduct crosses the fault zone at a smaller angle, the optimal span of viaduct is about 50 m and the optimal pile length of the bridge pile adjacent to the fault zone is about 60 m. The impact of fault dislocation of metro viaduct on the bridge can be reduced by adopting large angle intersection, appropriate pile length and bridge span length. [ABSTRACT FROM AUTHOR]

With the large-scale construction of urban rail transit viaducts in China, the noise problem caused by trains traversing these sections has become increasingly prominent and a key technical challenge that restricts the sustainable development of rail transit. There are two main noise sources when trains pass on rail transit viaducts, namely, wheel-rail noise (WRN) and bridge-borne noise (BBN). However, most of the existing rail transit viaduct noise prediction models consider only a single noise source. In this study, a total noise prediction model incorporating both WRN and BBN was established using the finite element method (FEM), the boundary element method (BEM), and statistical energy analysis (SEA). The viaducts of Wuhan Metro Line 2 were selected as the research object, and noise tests of trains passing on the viaducts were carried out to validate the total noise prediction model. Based on the validated model, the spatial distribution characteristics and attenuation laws of the total noise were investigated, along with the influence of train speed on the total noise. The results show that the prediction model accurately simulated the total noise caused by trains passing on viaducts. When a train passed on the viaduct at a speed of 60 km/h, the total noise near the viaduct reached 88 dB(A) and decreased with the increase in the distance; at 120 m from the track centerline, the total noise decreased to less than 57 dB(A). As the distance increased, the total noise diminished across the entire frequency spectrum. Notably, low-frequency noise decayed at a slower rate than high-frequency noise. As the distance from the track centerline doubled, the total noise decreased by about 4.23 dB(A). The total noise increased with train speed. When the train speed doubled, the total noise at 30 m and 120 m from the track centerline increased by 6.32 dB(A) and 5.96 dB(A), respectively. The reason for this phenomenon is that the wheel-rail forces increase with the increase in train speed. This study will have important guiding significance and scientific value for the sustainable development of urban rail transit. [ABSTRACT FROM AUTHOR]

[Objective] When a train running on the viaduct track, the rail vibration caused by the vehicle-track interaction will be transmitted to the bridge, piers, and pile foundations through the track structure, thereby triggering ground vibration around the bridge. Therefore, it is necessary to study the impact of elevated section rail and track bed vibration reduction on the environment for elevated rail transit. [Method] Based on the vehicle-track multi-body dynamics theory and the finite element method, a vehicle-track-U beam bridge-soil vibration model is established to solve the vibration response of the ground source intensity near the viaduct when rail transit vehicles passing through. [Result & Conclusion] The peak frequency band of the ground source intensity vertical vibration frequency for elevated section is distributed in 40~60 Hz. Vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates and steel spring floating plates all have a reduction effect on the ground source intensity vibration, and their contribution is mainly reflected in the vibration frequency range of 25 100 Hz. Under the conditions of using vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates, and steel spring floating plates, when the vibration frequency is 40 50 Hz, the ground source intensity vibration acceleration levels are reduced by about 4.2~4.4 dB, 6.5~6.9 dB, 7.8 8.1 dB and 10.0~10.7 dB respectively. When the fastener stiffness is < 15 kN/mm, the rail vertical displacement and vertical acceleration peak value increase significantly. When the fastener stiffness decreases from 60 kN/mm to 10 kN/mm, the rail vertical displacement and acceleration peak value increase by about 5 times and 18.26% respectively. In the peak frequency band of 40 50 Hz, the vertical vibration acceleration level at the ground source intensity decreases by about 4.5 4.9 dB. [ABSTRACT FROM AUTHOR]

To assess the impact of different heights of the viaduct on air pollutant dispersion and the prediction accuracy of pollutant concentration in urban street canyons, simulation results based on LES and RANS models are analyzed. The presence of a viaduct generated a poorly ventilated region underneath it, and RANS significantly underestimated the wind speed and grossly overestimated the pollutant concentration. LES gives better results for the flow pattern, distribution of turbulent kinetic energy and mean pollutant concentration. With a fluctuation of less than 15% of the pollutant concentration, both RANS and LES cases show that an increase in the viaduct height has a weak impact on the concentration of pollutants in most areas of the canyon except windward, and cases with a viaduct height of 0.75H had the lowest predicted pollutant concentration relative to other cases with a viaduct as a result of better ventilation. In addition, LES found a subregion of pollutant accumulation above the ground, but RANS did not. [ABSTRACT FROM AUTHOR]

［Objective］ It is aimed to provide advice for viaduct noise control in city rail transit and application of noise reduction measures. ［Method］ Based on theories of vehicle-track dynamics, wheel-rail vibration radiation, and viaduct structure vibration radiation, a prediction model for viaduct noise in city rail transit is established. The influence of factors such as train speed, distance from viaduct structure, viaduct type, and noise barriers on city rail transit viaduct noise is analyzed. ［Result & Conclusion］ When train speed exceeds 100 km/h, the viaduct noise increases by 1.8-5.5 dB(A) compared to train speeds below 100km/h. For single-cell single-box girders, single-cell double-box girders, and U-shaped girders, the peak frequency range of viaduct noise is 50-80 Hz, with a peak frequency at 63 Hz. At a distance of 7.5 m from the track centerline, the single-cell double-box girder demonstrates the lowest noise levels at all heights, whereas noise levels at the girder sides of single-cell single-box girders and U-shaped girders are higher by 1.0-4.1 dB(A) and 5.2-10.6 dB(A), respectively, compared to single-cell double-box girders. Near-track noise barriers with heights of 0.90 m or more above the track surface ensure a noise reduction effect of 7.0 dB(A) at 500 Hz frequency band, with noticeable noise reduction effects maintained across frequencies above 630 Hz.

［Objective］ To reduce the impact of elevated lines in urban rapid rail transit on environmental noise, multiple noise-reduction measures such as near-track sound barriers and ballast bed sound-absorbing panels are adopted. On-site measurements and analyses should combine with on-site operating conditions to verify the effectiveness of trackside noise reduction measures in reducing environmental noise. ［Method］ In the case study of the already operating Line S1 of Wenzhou Urban Rapid Rail Transit, the environmental noise in the viaduct section of this line is measured on site. The noise reduction effects of near-track sound barriers and ballast bed sound-absorbing panels for the environmental noise under different train running speeds are compared and analyzed, and the influence characteristics of different noise reduction measures on the viaduct section noise are explored. ［Result & Conclusion］ The near-track sound barrier reduces the maximum instantaneous A-weighted time-domain sound pressure level (hereinafter abbreviated as “A-weighted level”) on the viaduct inner and outer sides by approximately 20 to 21 dB(A). At the position 7.5 meters away from the track center line and 7.5 meters above the rail surface, the A-weighted level in the 500 Hz and 800-1 000 Hz frequency bands are respectively reduced by 6 to 11 dB(A) and 17 to 21 dB(A). The ballast bed sound-absorbing panels can further reduce the trackside noise on and outside the viaduct. Compared with the working conditions where only the near-track sound barriers are installed, when using the sound-absorbing panels, the maximum instantaneous A-weighted level on the viaduct is further reduced by 14 to 17 dB(A) with the same train running speed, and the A-weighted level is reduced by 7 to 8 dB(A) and 5 to 7 dB(A) respectively for the noise in the 500 Hz and 800 - 1 000 Hz frequency bands at the same measuring point outside the viaduct.

［Objective］When a train running on the viaduct track, the rail vibration caused by the vehicle-track interaction will be transmitted to the bridge, piers, and pile foundations through the track structure, thereby triggering ground vibration around the bridge. Therefore, it is necessary to study the impact of elevated section rail and track bed vibration reduction on the environment for elevated rail transit. ［Method］Based on the vehicle-track multi-body dynamics theory and the finite element method, a vehicle-track-U beam bridge-soil vibration model is established to solve the vibration response of the ground source intensity near the viaduct when rail transit veh-icles passing through. ［Result & Conclusion］The peak frequency band of the ground source intensity vertical vibration frequency for elevated section is distributed in 40 ~ 60 Hz. Vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates and steel spring floating plates all have a reduction effect on the ground source intensity vibration, and their contribution is mainly reflected in the vibration frequency range of 25 ~ 100 Hz. Under the conditions of using vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates, and steel spring floating plates, when the vibration frequency is 40 ~ 50 Hz, the ground source intensity vibration acceleration levels are reduced by about 4.2 ~ 4.4 dB, 6.5 ~ 6.9 dB, 7.8 ~ 8.1 dB and 10.0~10.7 dB respectively. When the fastener stiffness is ≤15 kN/mm, the rail vertical displacement and vertical acceleration peak value increase significantly. When the fastener stiffness decreases from 60 kN/mm to 10 kN/mm, the rail vertical displacement and acceleration peak value increase by about 5 times and 18.26% respectively. In the peak frequency band of 40 ~ 50 Hz, the vertical vibration acceleration level at the ground source intensity decreases by about 4.5 ~ 4.9 dB.

To assess the impact of different heights of the viaduct on air pollutant dispersion and the prediction accuracy of pollutant concentration in urban street canyons, simulation results based on LES and RANS models are analyzed. The presence of a viaduct generated a poorly ventilated region underneath it, and RANS significantly underestimated the wind speed and grossly overestimated the pollutant concentration. LES gives better results for the flow pattern, distribution of turbulent kinetic energy and mean pollutant concentration. With a fluctuation of less than 15% of the pollutant concentration, both RANS and LES cases show that an increase in the viaduct height has a weak impact on the concentration of pollutants in most areas of the canyon except windward, and cases with a viaduct height of 0.75H had the lowest predicted pollutant concentration relative to other cases with a viaduct as a result of better ventilation. In addition, LES found a subregion of pollutant accumulation above the ground, but RANS did not.

To investigate the effects of a trapezoidal sleeper track (TST) on the vibration and noise of rail transit viaducts, the wheel–rail interaction model was first built according to the vehicle–track coupling dynamics theory. Subsequently, the vibration responses of the viaduct were analyzed using the beam–slab finite element method, and its radiated noise was calculated using the acoustic boundary element method. The modeling method was verified based on the test data of a 3 × 40 m continuous rigid frame bridge. Taking the Jialing River Bridge of Chongqing Rail Transit Line 9 as the background, the control effects of the TST on the vibration and noise of the viaduct and the effective laws of different track parameters on the bridge noise were analyzed. Results show that the simulated and measured values are in good agreement; for example, the modeling methods are reliable; the radiated noise of the viaduct is influenced by the vibration responses under the action of train load, which are jointly determined by dynamic wheel–rail force (external excitation) and displacement admittance (self-vibration characteristics); compared with embedded sleeper track (EST), the TST can reduce the overall vibration acceleration level and sound pressure level of the box girder web plate by 13.9 dB and 7.8 dB, respectively; the stiffness of the damping path is the primary factor influencing the noise of the elevated box girder, followed by the sleeper thickness and the fastener stiffness; taking the bottom plate as an example, the stiffness of the damping pad is reduced by 1 and the overall sound pressure level can be reduced by approximately 3 dB; the sleeper thickness is increased by 1, and the overall sound pressure level can be reduced by 1–2 dB; and the fastener stiffness is reduced by 1, and the noise reduction is within 1 dB. [ABSTRACT FROM AUTHOR]

In urban metro construction, shield tunneling often needs to pass through building and bridge pile foundations, potentially affecting the stability of existing structures. Therefore, accurately assessing the impact of shield tunneling on bridges and buildings is crucial. This study presents a comprehensive prediction method combining numerical simulation and empirical formulas, taking the underpass project of the Shijiazhuang–Wuhan High-Speed Railway Bridge by Zhengzhou Metro Line 5 as a case study. Three-dimensional numerical model calculations were performed using finite element software to analyze the displacement and stress changes of buildings and tunnel structures at different construction stages, revealing the deformation patterns of buildings adjacent to the tunnel during shield tunneling. In particular, the ground settlement caused by twin-tunnel excavation was compared with Peck's empirical formula to verify the reliability of the numerical simulation. The results show that twin-tunnel excavation exacerbates the horizontal displacement, uplift, and settlement of the ground, with maximum deformation rates increasing by 7.10%, 20%, and 11.4%, respectively. Comparing the ground deformation results of Peck's empirical formulas with numerical calculations revealed similar trends in the settlement curves, with a maximum deviation of 6.67%. It can be concluded that using Peck's empirical formula to calculate ground deformation characteristics complements the limitations of numerical simulations, making the assessment results more reliable. The findings of this study demonstrate that integrating numerical simulation with empirical formulas significantly enhances the reliability of deformation predictions in complex tunneling scenarios. This research not only offers a comprehensive safety assessment method for shield tunneling construction but also provides valuable guidance for the design and construction of similar projects, serving as a theoretical reference for future engineering endeavors. [ABSTRACT FROM AUTHOR]

The newly proposed high‐speed rail in Czech Republic creates a set of new challenges for engineers in design overall. In this case, the most significant challenge was to design a viaduct over several obstacles due to the crossing of Special Area of Conservation (SAC), part of Natura 2000. This aims to limit impacts in short‐term, during construction and more importantly in the long term. Construction of the viaduct will mitigate an impact to the natural surrounding area, whilst allowing immigration of its natural habitats. Nevertheless, the viaduct design and operational speeds will reach 320 km/h with possible raising to 350 km/h limit, with minimal impact within the area. Initial length of the viaduct was over 1 300 m and the main requirement given by an infrastructure manager was to design a viaduct without railway expansion joints. Due to such a long distance, the viaduct had to be separated into several dilatation segments in order to avoid the use of rail expansion joint. The most susceptible parts of SAC were in proximity of the river Šatava and surrounding wetlands. This area created an obstacle, which had to be crossed by a long span avoiding the implementation of bridge piers. Poor geological conditions close to the watercourse had to be taken into consideration for design of pier foundation, therefore the span had to be shortened to a compromised length. The final design of the viaduct consists of 16 segments, of which 14 are continuous segments and 4 are single spans. Overall, there are 29 spans over the length of the viaduct. Construction method of incremental launching had been chosen to reduce the short‐term impact in the SAC. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the application of the Multiple Objective Particle Swarm Optimization (MOPSO) method, enhanced with specifically tuned parameters using the Taguchi method, for optimizing bridge and viaduct designs. Unlike conventional approaches, the optimization in this study encompasses the entire structure rather than focusing solely on the deck. This approach is illustrated through case studies on two viaducts located in Atalaia and Mandaguaçu along the BR-376 highway in Paraná, Brazil. In Atalaia, the optimized solutions achieved reductions in construction costs by 10.5% to 22.7%, CO2 emissions by 8.9% to 21.2%, and extended the design service life by 24.0% to 540.7%. Similarly, in Mandaguaçu, the optimizations resulted in cost reductions ranging from 9.1% to 23.2%, decreases in CO2 emissions from 12.7% to 23.5%, and increases in the design service life by up to 540.7%. The study also revealed consistent patterns between the degrees of freedom and objective functions; specifically, larger cross-sectional dimensions tended to lower costs, while smaller dimensions were associated with reduced CO2 emissions. These findings illustrate the real-world performance improvements afforded by the optimization process, which not only reduces the global cost per year of service compared to the original designs but also enhances economic and environmental performance, thereby demonstrating the effectiveness of MOPSO in structural optimization for sustainable infrastructure development.

With the development of urban rail transportation, the environmental vibration problem caused by the running of metro vehicles has received attention. In order to reduce ground vibration near buildings caused by metro vehicles running on viaducts, this paper establishes the train–track–viaduct rigid–flexible coupling dynamics model and pier–soil–building finite element model and carries out the simulation calculation and analysis of ground vibration. The influence of train speed and fastener stiffness on ground vibration is explored, and the vibration reduction effect of the track vibration reduction pad and continuous support vibration reduction structure is studied. The results show that the ground vibration near the building caused by the train running on the viaduct decreases with the reduction in speed, when the speed is reduced to 40 km/h, the vibration attenuation is slower as the speed continues to be reduced; the reduction in the vertical stiffness of fasteners can reduce ground vibration; the arrangement of the vibration damping pad can effectively reduce ground vibration, and after installing a vibration damping pad, 0–23 Hz and 50–80 Hz ground vibration speeds are effectively suppressed. In order to meet the environmental requirements for ground vibration, the vehicle speed can be reduced to less than 35 km/h or vibration damping mats can be installed. [ABSTRACT FROM AUTHOR]

This paper focuses on the application of pile foundation underpinning technology in a deep foundation pit of a subway Viaduct Project in Beijing. The study aims to address the engineering characteristics of the project, including a large number of new piles, a wide span of underpinning abutment, a long length of deep foundation pit, and a wide range of influences. This research utilizes field monitoring and numerical simulation methods to investigate the pile foundation underpinnings. The impact and management of road-deep foundation pit construction are considered, as well as their combined effect on subway viaducts and track structures. The primary accomplishments are as follows: (1) By analyzing the data from on-site deformation monitoring, it is evident that the pier exhibits maximum vertical deformation and maximum transverse deformation at the same location. The measuring locations are specifically situated on Pier 7# at the pile foundation underpinning. The maximum vertical and transverse deformations of the track are directly proportional to the maximum deformation of the pier. (2) By comparing the numerical simulation results with the field monitoring data, it is observed that although there is some discrepancy between the two, the deformation trend is largely consistent. This suggests that the numerical simulation analysis method is effective in reflecting the deformation of the bridge and track. (3) Through the numerical model and changing the values of the retaining structure parameters, the sensitivity of the pier deformation near the road foundation pit to the retaining structure parameters is systematically analyzed. The sensitivity of the pier deformation to the foundation pit parameters is as follows: the embedded depth insertion ratio of the retaining pile > the diameter of the retaining pile > the pile spacing. [ABSTRACT FROM AUTHOR]

The viaduct is an important infrastructure for urban sustainable development, but it will inevitably pass through a coal mining subsidence area in coal resource-based cities, which poses a threat to the construction and operation of the viaduct. However, there is a lack of research on long time-series monitoring and assessing the safety of elevated bridges above subsidence areas, both domestically and internationally. In this study, a resource-based city viaduct in Shandong, China, was selected as the research object, utilizing SBAS-InSAR technology for deformation monitoring during bridge construction and post-opening phases. The viaduct based on the goaf was analyzed by the key settlement subsection. Before completing construction (March 2019 to December 2020), research revealed that the cumulative maximum deformation in the bridge area was 44mm and the maximum uplift was 22 mm, with overall stability in the underlying subsidence area. After completion (January 2021 to July 2023), the cumulative maximum deformation value in the elevated bridge area was 10mm and the maximum uplift was 6 mm, indicating minimal fluctuations over three years, maintaining overall stability. This stable condition ensures the safety of construction and operation of regional elevated bridges. These findings not only support the safe operation of bridges in underlying subsidence areas but also provide a new approach to sustainable areas globally, especially in coal resource-based urban areas. [ABSTRACT FROM AUTHOR]

Rapid transit or mass rapid transit (MRT) is a high-capacity public transport designed to carry a large number of passengers, especially during the peak hours. They are becoming very popular in major cities and some deem the presence of the rapid transit system in a city as a symbol of modern development and essential feature of urban life. As the rapid transit system expands, the traveling time on a rapid transit train may increase due to longer journey and cabin noise has become an environmental concern for the passengers. In the present study, we would attempt to do a more detailed study of the effect of viaduct height, in particular viaducts of different heights on the cabin noise of various rapid transit systems. The present study examined and benchmarked the cabin noise in terms of both dB(A) and dB(C) for four different rapid transit systems, namely part of the East-West line including the Tuas-West extension on elevated tracks with very high viaduct of the Singapore MRT System; part of Paris Line 2 from Anvers to Belleville station including a stretch of elevated track on viaduct; part of the Piccadilly line of London from Heathrow Airport to Green Park station with a stretch on surface ground; and finally part of Chongqing Line 3 from Gongmao to Lianglukou station across the Yangtze river. It was found that the cabin noise would be dominated by low-frequency content and would be better reflected if the measurements were presented in dB(C), especially for trains running on elevated tracks of greater height.

It is necessary to evaluate the construction effect of viaducts and identify the viaducts that play a key role in road networks. Based on the node deletion method, this article proposes a method to identify the importance of viaducts in road networks. After applying this method to simulate the importance of viaducts in the highway networks in Yunnan and Guizhou Provinces from 2001 to 2020, the results show the following: (1) The viaducts with high importance were mainly built in 2002, 2009, 2015, and 2016. They are mainly distributed on expressways such as the HUKUN Expressway, HANGRUI Expressway, and YINBAI Expressway. Among the viaducts, the Mengzhai Bridge and Beipanjiang Bridge Hukun are the most important. (2) The importance of viaducts will increase, decrease, or increase first and then decrease. Among the years studied, 2012 and 2016 are important time nodes for change. The trend of changes is affected by the construction of highways and viaducts in other locations. In this road network, there are strong coupling relationships between nodes. (3) The importance of some viaducts is not prominent in the whole region, but that does not mean their construction value is low. They may have a high connectivity effect on specific regions from a local perspective.

Technical rehabilitation and strengthening of the Chemnitz viaduct The Chemnitz viaduct, which was built between 1901 and 1909 for a four‐track operation, is being technically refurbished and reinforced for modern use in accordance with the requirements of the historical monument preservation. The two inner tracks will be used for future railway traffic, while the outer bridge structures will accommodate inspection, maintenance and emergency routes as well as technical equipment. The approx. 275 m long and 17.50 m wide bridge structure consists of two arch and ten beam segments. During the technical repair, the inner beam segments were renewed and constructed as a steel‐concrete composite structure. The other structures were repaired, strengthened and supplemented with a reinforced concrete structure above the hump plates. This article begins with an overview of the existing structure and its prospective use. This is followed by explanations of the planning, tendering and execution of the construction work. Subsequently, various measures for technical repair and reinforcement are described. The article concludes with a brief summary of the experience gained with the Chemnitz viaduct in terms of refurbishment and monument protection. [ABSTRACT FROM AUTHOR]

With the development of urban rail transportation, the environmental vibration problem caused by the running of metro vehicles has received attention. In order to reduce ground vibration near buildings caused by metro vehicles running on viaducts, this paper establishes the train–track–viaduct rigid–flexible coupling dynamics model and pier–soil–building finite element model and carries out the simulation calculation and analysis of ground vibration. The influence of train speed and fastener stiffness on ground vibration is explored, and the vibration reduction effect of the track vibration reduction pad and continuous support vibration reduction structure is studied. The results show that the ground vibration near the building caused by the train running on the viaduct decreases with the reduction in speed, when the speed is reduced to 40 km/h, the vibration attenuation is slower as the speed continues to be reduced; the reduction in the vertical stiffness of fasteners can reduce ground vibration; the arrangement of the vibration damping pad can effectively reduce ground vibration, and after installing a vibration damping pad, 0–23 Hz and 50–80 Hz ground vibration speeds are effectively suppressed. In order to meet the environmental requirements for ground vibration, the vehicle speed can be reduced to less than 35 km/h or vibration damping mats can be installed.

This paper focuses on the application of pile foundation underpinning technology in a deep foundation pit of a subway Viaduct Project in Beijing. The study aims to address the engineering characteristics of the project, including a large number of new piles, a wide span of underpinning abutment, a long length of deep foundation pit, and a wide range of influences. This research utilizes field monitoring and numerical simulation methods to investigate the pile foundation underpinnings. The impact and management of road-deep foundation pit construction are considered, as well as their combined effect on subway viaducts and track structures. The primary accomplishments are as follows: (1) By analyzing the data from on-site deformation monitoring, it is evident that the pier exhibits maximum vertical deformation and maximum transverse deformation at the same location. The measuring locations are specifically situated on Pier 7# at the pile foundation underpinning. The maximum vertical and transverse deformations of the track are directly proportional to the maximum deformation of the pier. (2) By comparing the numerical simulation results with the field monitoring data, it is observed that although there is some discrepancy between the two, the deformation trend is largely consistent. This suggests that the numerical simulation analysis method is effective in reflecting the deformation of the bridge and track. (3) Through the numerical model and changing the values of the retaining structure parameters, the sensitivity of the pier deformation near the road foundation pit to the retaining structure parameters is systematically analyzed. The sensitivity of the pier deformation to the foundation pit parameters is as follows: the embedded depth insertion ratio of the retaining pile > the diameter of the retaining pile > the pile spacing.

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The new Urban Viaducts at the Section 1 of the "Tren Maya" railway are located in southern Mexico, at the municipalities of Tenosique (State of Tabasco) and Candelaria and Escárcega (State of Campeche). The structural solution for the urban viaducts' deck is made of a reinforced concrete slab with a pair of "I" main steel girders. The girders have vertical bracing trusses, in order to reduce the distortion of the cross‐section, and a lower horizontal bracing truss, to close the torsional circuit. Steel diaphragms are located at the supports to transfer vertical and horizontals forces to the column. Viaducts consist of a succession of simply supported 40 m spans. The lengths of the viaducts are: 2920 m Tenosique, 990 m Candelaria and 1080 m Escárcega. The viaducts are located in a zone of high seismicity hazard, so the columns' design has been developed by a displacement‐capacity analysis. As a result, they consist of a single shaft on which rests a pier cap, both of reinforced concrete. This typology has been chosen because of the benefits of its construction process, which allows the execution of the spans to be independent. The steel structure of the deck also allows to reduce its mass, what helps to reduce the dimensions of the substructure. [ABSTRACT FROM AUTHOR]

Sudden failure of reinforced concrete (RC) or prestressed concrete (PC) Gerber saddles of bridges and viaducts has occurred all around in the word in the last few years due to corrosion of steel bars. The danger of sudden and brittle failure is often due to general and pitting corrosion of steel bars, concrete crushing, and loss of bond in steel bars. In this paper, the flexural response of reinforced concrete Gerber supports under their self-weight with or without service loads was investigated through determination of the load-deflection response of beams, with the focus on the consequences of pitting corrosion and loss of bond in steel bars. A simplified strut-and-tie model was developed to predict the flexural response of Gerber supports in terms of load-deflection curves, deduced analytically in a closed form. The model includes the effects of corrosion of steel bars, loss of bond, and concrete crushing due to the biaxial state of stresses. Several experimental laboratory studies regarding the flexural behavior of RC beams with Gerber supports were collected to validate the proposed model. In addition, numerical analyses were performed through a nonlinear finite-element code for comparison with the experimental and analytical results. [ABSTRACT FROM AUTHOR]

Finite element (FE) model updating of bridges is based on the measured modal parameters and less frequently on the measured structural response under a known load. Until recently, the FE model updating did not consider strain measurements from sensors installed for weighing vehicles with bridge weigh-in-motion (B-WIM) systems. A 50-year-old multi-span concrete highway viaduct, renovated between 2017 and 2019, was equipped with continuous monitoring system with over 200 sensors, and a B-WIM system. In the most heavily instrumented span, the maximum measured longitudinal strains induced by the full-speed calibration vehicle passages were compared with the modelled strains. Based on the sensitivity study results, three variables that affected its overall stiffness were updated: Young's modulus adjustment factor of all structural elements, and two anchorage reduction factors that considered the interaction between the superstructure and non-structural elements. The analysis confirmed the importance of the initial manual FE model updating to correctly reflect the non-structural elements during the automatic nonlinear optimisation. It also demonstrated a successful use of pseudo-static B-WIM loading data during the model updating process and the potential to extend the proposed approach to using random B-WIM-weighed vehicles for FE model updating and long-term monitoring of structural parameters and load-dependent phenomena. [ABSTRACT FROM AUTHOR]

The deconstruction of post-tensioned viaducts with a movable scaffolding system is an established method where conventional and blasting deconstruction cannot be applied. The report describes the components of the deconstruction MSS, the special features of this deconstruction method and the boundary conditions for the use of movable scaffolding systems against and in the direction of construction of the structure to be demolished, as well as the possibility of reusing the movable scaffold for the new construction. Interfaces to the bridge structure are defined and advices are given on the planning of such dismantling projects. Using the example of the Onsbach viaduct, a description of the dismantling procedure is given. [ABSTRACT FROM AUTHOR]

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In this work, we numerically investigate the process of atmospheric air pollution in idealized urban canyons along the road in the presence of a viaduct, taking into account different height of barriers. To solve this problem, the 3D Reynolds-averaged Navier–Stokes equations (RANS) were used. The closure of this system of equations was achieved by using various turbulent models. The verification of the mathematical model and the numerical algorithm was carried out using a test problem. The obtained results using various turbulent models were compared with experimental data and calculated results of other authors. The main problem considered in this work is characterized as follows: assessment of emissions of pollutants between buildings using barriers of various types in the presence of a viaduct. Computational results have shown that the barrier viaduct plays a large role in improving air quality in urban canyons. So, for example, a barrier erected on a viaduct with a height of 2 m reduces the concentration value to a cross-section x = 84 by more than 2 times in comparison with the case of a complete absence of protective barriers. A similar situation was observed with barriers erected above the earth’s surface: located along the road, they also significantly reduce the value of the concentration of pollutants. Thus, the presence of barriers in both cases is necessary to prevent the dispersion and deposition of pollutants. [ABSTRACT FROM AUTHOR]

In recent years, the urgent need to increase the safety standards of viaducts and bridges—under static and dynamic loading conditions—has required the development of advanced modeling approaches able to accurately predict the expected behavior of such infrastructures in a reliable manner. This paper presents a comparison between the adoption of a simplified modeling approach, widely used in the current practice, where the response of the structural system neglects the effects of the soil-structure interaction (SSI) phenomenon (considering the base of the structure fixed at the ground surface) and a rigorous modeling approach that considers the full 3D problem with all the components of the system (superstructure, foundation, and soil), through a finite element model. The pier of a real-world viaduct in central Italy was considered, with the aim of starting from a specific case study with foundation characteristics that are frequently found in viaducts in Italy, to obtain results that can be generalized to a wide range of similar types. Its behavior was evaluated both in the dynamic range of small oscillations and in the field of the seismic response to low and strong motion events. The results show that, in terms of seismic demand, the fixed-based model appears more conservative, but it significantly underestimates both elastic and residual displacements and rotations [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Shanghai University / Shanghai Daxue Xuebao is the property of Journal of Shanghai University (Natural Sciences) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Incorporating MIMO technology with 3D geometry-based stochastic models (GBSM) is a promising channel modeling technique for 5G and beyond. These models could be extended to high-speed train (HST) environments at mmWave bands. In this paper, the proposed 3D MIMO model is composed of the line of sight component (LOS), the non-line of sight component (NLOS) from one sphere, and multiple stochastic confocal elliptic cylinders. The model is applied in the viaduct and cutting environments with a time-varying Rician K-factor. The local channel statistical properties such as the auto correlation function, stationarity distance, and the level crossing rate (LCR) are derived and thoroughly investigated at the 41GHz frequency. These properties are compared with the corresponding measured results at the same wave frequency for an HST wireless channel. There is a strong correlation between the results from the derived model and the measured results. Therefore, this model can be extended to be used for viaduct and cutting channel modeling at the mmWave band. [ABSTRACT FROM AUTHOR]

In this paper, the influences of the ambient wind speed and the height and width of a viaduct in a 2-dimensional street canyon on the diffusion of reactive pollutants emitted by motor vehicles were investigated using computational fluid dynamics (CFD) method. Pollutants were treated as reactive by including a NO-NO2-O3 photochemical reaction mechanism in the simulation. The Reynolds-averaged Navier-Stokes (RANS) k–ε turbulence model and the discrete phase model were used to simulate the airflow movement and the concentration distribution, respectively, of the reactive pollutants in the street canyon. Three indices, i.e., the chemical reaction contribution of NO (CRCNO), the chemical reaction contribution of NO2 ( CRC NO 2 ) , and the O3 depletion rate, were used to evaluate the relative importance of the photochemical reactions. It was found that the presence of a viaduct changed the flow field structure in the street canyon. The CRCNO and CRC NO 2 decreased from the windward side to the leeward side of the canyon. The maximum values of the CRCNO and CRC NO 2 were observed at the pollution source (x = 245 m) due to the influence of a clockwise vortex in the street canyon. As the height and width of the viaduct increased, concentration of the ground pollutants and the O3 depletion rate increased. The O3 depletion rate was much higher on the leeward side (90%) than on the windward side. The pollutant concentrations after the reaction were twice as high with the viaduct as without the viaduct when the viaduct height was the same as the building height. The viaduct had a significantly larger influence on the concentration of the reactive pollutants than the chemical reactions. The O3 depletion rate in the canyon and the pollutant concentrations decreased as the ambient wind speed increased, whereas the CRC NO 2 increased. [ABSTRACT FROM AUTHOR]

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Arch bridges are built since two thousand years at least. Structural materials changed during this time. The design methods were changed also. The biggest impact was noted with development of Finite Element Method and graphical methods of preparation of technical drawings which is strictly combined with development of computers. These processes appeared also in Polish construction industry, especially from the beginning of 90-ties XX century. But in this paper we do not consider mentioned above problems. We would like to present development of arch bridges from construction technology point of view. This aspect of creation of bridge structures is not very often the subject-matter of analysis. For many investors, design engineers and contractors optimization of structures is most important issue. For most of them the reduction of volume (weight) of structural material is only solution. But sometimes it is not true – the construction technology gives much more efficient results. We present below examples of realization in Poland medium and large span arch bridges – steel, concrete and hybrid structures.

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)