Humen Bridge Research Articles

Analytical model analysis of suspension bridges with tower-girder-connected dampers

Recently the tower-girder-connected damper has been utilized to suppress multi-mode vertical vortex-induced vibration (VIV) of long-span suspension bridges. In this paper, an analytical solution is proposed for the damping ratio of vertical bending modes of a single-span suspension bridge, with a vertical or/and a rotational damper mounted near the end of the stiffening girder, which significantly simplifies the design procedure for tower-girder-connected dampers on suspension bridges. The damping effect and the accuracy of the analytical solution are validated for Humen Bridge. It is found that both the vertical and rotational damper with an appropriate parameter selected can supply significantly additional damping ratio to multiple bending modes of the suspension bridge. The rotational and vertical dampers work in a similar way and provide nearly the same maximum additional damping ratio for each mode. In particular, for the first two symmetric modes, regions of reduced motion near the ends of the stiffening girder are developed due to the effects of cable geometry and elasticity, and this reduces the effect of the tower-girder-connected damper. Excluding these modes, the damper effect on a suspension bridge is similar to that on a tension beam with the same beam stiffness and horizontal tension forces.

An algorithm for large-span flexible bridge pose estimation and multi-keypoint vibration displacement measurement

Traditional visual vibration measurement methods face limitations in dynamic outdoor environments, making accurate multi-point vibration measurements challenging for the targeted objects. In this paper, a visual vibration measurement algorithm for large-span bridges is proposed by anthropomorphizing the bridge target and introducing key point detection at the same time. Firstly, the algorithm utilizes a convolutional neural network to extract multi-scale feature information from the image sequence of the bridge model. Secondly, to enhance target detection accuracy, a coordinate attention (CA) mechanism is incorporated, and the shape intersection over union (SIoU) loss function replaces the original loss function. Finally, the algorithm integrates the density-based spatial clustering of applications with noise (DBSCAN) and tracking algorithms to achieve precise localization of bridge targets. Vibration displacement data were extracted from a large-span suspension bridge structure in an outdoor environment and analyzed quantitatively and qualitatively. The vibration displacement curves obtained in this study show the highest level of agreement with the standard displacement signals, with a mean absolute percentage error of 0.5170% for the cable-stayed bridge model, 1.3822% for the Humen Bridge, and 3.2263% and 1.6982% for the Longjiang Bridge.

Examination of occurrence probability of vortex-induced vibration of long-span bridge decks by Fokker–Planck–Kolmogorov equation

Vortex-induced vibration (VIV) is a major concern for long-span bridge decks, which may happen especially for closed-box girders under certain environmental wind conditions. Traditionally, sustained VIV is observed as long as the wind speed falls within the lock-in region in wind tunnel tests. However, structural vibration monitoring of long-span bridges has indicated that frequency of VIV events may exhibit a probabilistic pattern. This paper proposes an analytical framework to evaluate the probability of VIV occurrence. First, a nonlinear aeroelastic model with multi-stability limit cycles is used to simulate the bridge deck VIV response within the VIV-triggering wind conditions. The first structural dynamic equilibrium point is usually unstable; the bridge deck instantaneous oscillation amplitude, which is excited by external environmental loads, must exceed this fixed point to trigger the VIV event. The external environmental excitation applied on bridge can be identified from the deck vibration without VIV occurring, then the VIV occurrence probability can be evaluated by Fokker–Planck–Kolmogorov equation. This study utilizes the field measurement data from the Humen Bridge, on which VIV event occurred the first time after 23-year servicing period, because water-filled barriers were placed along the two edges of bridge deck. Afterwards, VIV occurred frequently for over one month. The bridge deck VIV occurrence probability is evaluated by combining environmental wind information, stochastic deck excitation magnitude and a nonlinear aeroelastic VIV model. The results suggest that the proposed methods can approximate the VIV occurrence probability in comparison with empirical estimations using field measurements.

Risk assessment of wind resistance safety of cable-stayed bridge based on Bayesian network

Wind-induced risk accidents of cable-stayed Bridges exist all the time. It is important to evaluate the wind-resistant risk of cable-stayed Bridges. In order to better reduce and avoid risks in cable-stayed bridge engineering, this paper collates and analyzes previous studies, combines Bayesian network model with practical engineering problems, and establishes a risk assessment model for wind resistance risk assessment of cable-stayed bridge. Taking Humen Bridge in Guangdong Province of China as an example, the paper carrying out relevant derivation and discussion.

Effect of Shear Deformation at Segmental Joints on the Short-Term Deflection of Large-Span Cantilever Cast Prestressed Concrete Box Girders

The excessive deflection of large-span cantilever cast prestressed concrete (LCCPC) box girders has always been a complex problem to be solved in bridge engineering. To analyze the effect of shear deformation at segmental joints on the deflection of LCCPC box girders, comparison tests were carried out on three prestressed concrete (PC) I-girders with joints and a PC I-girder without joints, and a finite element simulation method of segmental joints was proposed based on the tests. Subsequently, finite element analysis was conducted on a test girder and the Assistant Shipping Channel Bridge of Humen Bridge (a PC continuous rigid frame bridge with a main span of 270 m) using this method. The experimental and theoretical analysis results showed that the effect of the shear deformation at joints compared to the deformation at midspan of the girder specimens was negligible. Deformation at midspan of the specimens would not significantly increase, even if shear rigidity at the joints was significantly reduced or there were more joints in the girder specimen. The effect of shear deformation at segmental joints on the deflection of LCCPC box girders was quite small and thus insignificant.

Full-Field Mode Shape Identification Based on Subpixel Edge Detection and Tracking

Most research on computer vision (CV)-based vibration measurement is limited to the determination of discrete or coarse mode shapes of the structure. The continuous edge of the structure in images has rich optical features, and thus, by identifying and tracking the movement of the structure’s edge, it is possible to determine high-resolution full-field mode shapes of the structure without a preset target. The present study proposes a CV-based method of full-field mode shape identification using the subpixel edge detection and tracking techniques. Firstly, the Canny operator is applied on each frame of the structure vibration video to extract the pixel-level edges, and the improved Zernike orthogonal moment (ZOM) subpixel edge detection technique is adopted to relocate the precise structure edges. Then, all the detected edge points are tracked to obtain the full-field dense displacement time history that is subsequently used to determine the structure frequencies and compute full-field mode shapes by combining the covariance driven stochastic subspace identification (SSI-COV) with the hierarchical cluster analysis. Finally, the proposed method is verified on the aluminum cantilever beam in the laboratory and the Humen Bridge in the field. The results show that the proposed method is able to detect more precise structure edges and identify the full-field displacement and mode shapes of structures without the need for installing artificial targets on the structure in advance, which provides valuable information for the structural condition assessment, especially for structures with small-amplitude vibrations.

Study on Suitability of Artificially Planted Native Mangroves in Coastal Areas of Guangzhou

At present, the mangrove species planted in the coastal area of Guangzhou is relatively single, and the dominant species is mainly the non-petal Sonneratia caseolaris (alien species). From 2020 to 2021, after the observation of the growth of mangroves on the north shoreline of the Humen Bridge (Guangzhou Section) in Nansha District, Guangzhou, it is shown that the dominant local mangrove species suitable for growth in the coastal area of Guangzhou are Kandelia obovata and Aegiceras corniculatum.

Fusion attention mechanism bidirectional LSTM for short-term traffic flow prediction

Short term forecasting is essential and challenging in time series data analysis for traffic flow research. A novel deep learning architecture on short-term traffic flow prediction was presented in this work. In conventional model-driven prediction method, a critical deviation in prediction accuracy was occurred in face of large fluctuations in traffic flow, while machine and deep learning-based approaches performed well in accuracy study than conventional regression-based models. Moreover, a fusion attention mechanism bidirectional long short-term memory model (ATT-BiLSTM) was proposed due to its bidirectional LSTM (BiLSTM) and attention mechanism units. The model not only dealt with forward and backward dependencies in time series data, but also integrated the attention mechanism to improve the ability on key information representation. The BiLSTM layer was exploited to capture bidirectional temporal and spatial features dependencies from historical data. The proposed model was also trained and validated using freeway toll datasets from Humen Bridge. The results showed that compared with ARIMA and SVR models, the indicators of the proposed model have been significantly improved. The ablation experiments were conducted to evaluate the role of the attention mechanism module. Compared with BiLSTM, CNN and 1DCNN-ATT-BiLSTM models, the MAE, RMSE and MAPE indexes of proposed model were reduced by 0.6–5.9%, 1.6–4.7% and 0.6–22.8%, respectively. More accurate predictions were obtained by the proposed model. The research results are of great significance to improve the level of traffic management.

Output-only modal analysis of the Humen Bridge from video measurement

Abstract Video-based vibration testing is a promising non-contact method for structural health monitoring. This article develops an innovative methodology for estimating the structural modal parameters from videos without recovering the responses of structures. Firstly, an image processing (i.e., Gaussian smoothing) are adopted to smooth frames and alleviate the noises. Secondly, several regions of interest (ROIs) contained the projection area of structure are selected, and edge detection is performed to that to reduce the size of vision data. Then under some assumptions, the reduced vision data can be subjected to the frequency domain decomposition (FDD) similar to the structural modal analysis to identify the modal parameters of structure. Moreover, the structural mode shapes are recovering from such decomposition. The feasibility and accuracy of the proposed method were validated by a field experiment on the Humen Bridge in Guangzhou, China.

Case study of vortex-induced vibration and mitigation mechanism for a long-span suspension bridge

The wind-induced vibration of long-span bridges mainly manifests as flutter, galloping, vortex-induced vibrations (VIVs), buffeting, etc. Among these, VIVs cause vertical or torsional single-mode vibrations of the main girder; these affect the comfort of drivers or pedestrians on the bridge when vortex-induced resonance occurs. In this study, field measurements, numerical simulations, and wind tunnel tests were used to systematically investigate triggering mechanism during the sudden first and secondary VIV phenomena of Humen Bridge, along with the structural mode and damping characteristics and VIV aerodynamic mitigation effects, etc. The results show that the sudden first VIV was caused by the temporary installation of water-filled barriers, as these changed the aerodynamic configuration of the box girder; the decisive removal of these water-filled barriers can effectively suppress the VIV amplitude to some extent. The succedent secondary VIV was caused by the reduction of the structural damping; therefore, aerodynamic control and damping control measures are proposed. The aerodynamic control measures include the implementation of suppressor plates on the top of handrails and removal of the maintenance rails under the girder, whereas the structural damping control measures involve the successive installation of tuned-mass damper (TMD) to compensate for the reduced damping owing to the former large-amplitude VIV performance. After verification based on reduced-scale model wind tunnel tests, the aerodynamic control measures and structural damping control measures are successfully adopted and applied to Humen Bridge. These measures are shown to effectively suppress VIVs, as confirmed via succedent long-term on-the-spot observations.

A fast on-site measure-analyze-suppress response to control vortex-induced-vibration of a long-span bridge

Vortex-induced vibration (VIV) occurred on Humen Bridge starting from May 5th, 2020. The direct reason was that the water-filled barriers were placed along the two edges of the bridge deck upper surface, which destroyed the streamlined aerodynamic shape configuration and, therefore, vortices were generated along the bridge section. With the help of several portable monitoring devices, wind speeds, structural motion, and airflow at the wake of the bridge section can also be recorded separately. After removing the barriers, subsequent VIV was continuing due to the decreased structural damping. The amplitude was smaller than the initial case, but still exceeded the threshold defined in Chinese bridge specification. The spoiler was proposed to be installed on the handrail to mitigate vortex and suppress VIV. The Doppler LiDAR detected that the vortex frequencies had been distorted after installing the spoiler, and bridge motion also had dramatically reduced to below the threshold when the wind climate kept as a similar condition when previous VIV happened. Therefore, the bridge administrative agency and local government decided to reopen Humen Bridge after ten days of closure.

Fatigue performance evaluation for composite OSD using UHPC under dynamic vehicle loading

A novel composite orthotropic steel deck (OSD) using ultra-high performance concrete (UHPC) is comprised of an OSD and a thin UHPC layer that are connected through shear connectors. The innovative composite OSD system has been increasingly applied to long-span bridges in China to overcome the defect of conventional OSD that frequently suffers from fatigue cracking. However, the fatigue performance of the composite OSD system is usually evaluated with the deterministic analysis in previous studies, which may lead to inaccurate evaluation as many uncertainties, including the statistical properties of dynamic vehicle loadings and fatigue-prone details, have not been considered rationally. In this paper, the fatigue performance of the composite OSD using UHPC was investigated using the reliability-based fatigue analysis and compared with the fatigue performance of conventional OSD system. A three-dimensional vehicle-bridge coupled system was adopted to obtain the stress time histories of fatigue-prone details in the bridge decks under the action of dynamic vehicle loading. The vehicle model was determined based on the fatigue load pattern adopted in the AASHTO standard specifications and finite element models (FEMs) of both the conventional OSD and the composite OSD using UHPC were built based on a girder segment adopted from the HuMen Bridge in China. Four key influence factors, namely, the road surface condition (RSC), length of bridge deck FEM, vehicle speed, and overloading, were taken into consideration. The fatigue life of six typical fatigue-prone details in these two deck systems was evaluated and compared. The results show that the composite OSD using UHPC can effectively extend the fatigue life of OSD by at least 60% and even eliminate the risk of fatigue cracking for most fatigue-prone details. Compared to the reliability method, the fatigue life of OSD determined based on the deterministic method would be overestimated by 65–110% if the very poor RSC is considered. Besides, the composite OSD using UHPC exhibits a better fatigue performance than the conventional OSD system under the action of overloaded trucks. The results from the study can provide a reference for the design and maintenance of the composite OSD using UHPC.

Nizhou Bridge, China: an insight into deck erection gantries supported on main suspension cables

The Nizhou waterway bridge, part of the Second Humen Bridge over the Pearl River in China's Guangdong province, is the second longest suspension bridge in the world (1688 m main span). The reinforced concrete towers are 260 m tall and the main cable spacing is 42·1 m. The deck is an aerofoil-shaped orthotropic steel box 49·7 m wide and 4 m deep. Deck erection took place during the spring of 2018. Three 500 t safe working load deck erection gantries, supported on the main cables, lifted 175 deck segments into position in 10 weeks. Strand jacks were used for deck lifting and gantry relocation. This paper describes the deck erection gantries, from concept development, through detailed design and testing, to operation on site. It focuses on the innovative movement system specifically developed for this project to reduce operating cycle times and overcome the design constraints, particularly the large range of relative positions between the deck erection gantry and the cable bands. Cast nylon wheels and aluminium ramps were designed for the gantry to roll smoothly over cable bands. Insufficient industry guidance on the design of cast nylon wheels and their interaction with the main cables required a multidirectional approach, which involved hand calculations, finite-element analysis and testing.

The Transportation Infrastructure and Regional Economic Growth—Evidence from Dongguan Humen Bridge

Transportation infrastructure is an important factor driving regional economic growth, and scientifically evaluating the economic growth effects of key transportation infrastructure is an important theoretical issue of development economics. This paper takes the opening of Dongguan Humen Bridge as a quasi-natural experiment, and quantitatively identifies the regional growth effect it brings. This paper uses panel data from 21 prefecture-level cities in Guangdong Province from 1991 to 2007, and based on the synthetic control method, assigns different weights to the cities in the control group to construct the “counterfactual” state of Dongguan where the Humen Bridge is not opened, so as to compare the difference in economic development between “real Dongguan City” and “Synthetic Dongguan City”. The results show that the opening of the Humen Bridge in 1997 made Dongguan’s GDP and GDP per capita exceed the theoretical level that could be achieved when the Humen Bridge was not opened. The opening of the Humen Bridge significantly changed the economic growth trend of Dongguan. With the passage of time, the opening of the Humen Bridge has continuously strengthened the promotion of Dongguan’s economic growth, indicating that the transportation infrastructure has a long-term effect on the promotion of regional economic growth. This work advances the research on the relationship between transportation infrastructure and regional economic growth.

Design and construction of the Second Humen Bridge, China

Completed in 2019, the Second Humen Bridge in south China has created a much-needed additional link between Guangzhou and Dongguan in the economocially thriving Pearl River Delta region. It crosses the Nizhou and Dasha waterways with suspension main spans of 1688 m and 1200 m, respectively. The Nizhou crossing is the longest steel box girder suspension bridge in the world and, at 49·7 m wide, both crossings are the widest built. This paper describes their design and construction and the innovative techniques used.

The spatial impacts model of trans-strait fixed links: A case study of the Pearl River Delta, China

The mage trans-strait fixed links are constructed in different countries to promote regional economic and social development. This paper proposes a spatial impacts model for the trans-strait fixed links in the Pearl River Delta, China. To verify the rationality of the model, four quantitative indicators, including weighted average travel time, the economic linkage intensity, the economic linkage membership grade, and the fractal index are used to investigate the effect by construction of Humen Bridge, Hong Kong–Zhuhai–Macao Bridge and Shenzhen–Zhongshan Bridge. The results show that the Hong Kong–Zhuhai–Macao Bridge and Shenzhen–Zhongshan Bridge greatly improve the regional accessibility with a maximum decrease weighted average travel time of 1.38h and 0.4h. The central part of the Delta has greatest impacts. The links increase the economic linkage of cities of each side. The cities directly connected to the fixed links (Hong Kong, Shenzhen, Macao and Zhongshan) experience the highest increasing economic linkage. The regional spatial pattern evolves from unipolarity to multi-polarity and integrates a more advanced and sophisticated spatial network. The theoretical spatial impacts model for the trans-strait fixed links accords with the actual development in the Pearl River Delta.

Analysis of Long-Term Deflection on Large-Span Continuous Rigid Bridge

Through the long-term deflection observation results and the measured data of effective pre-stress of Humen bridge before and after reinforcement, using three-phase bridge long-term deflection calculation method, compare the measured data and the calculation conditions in three kinds. Basing on the measure value of construction degradation, presenting the long-term deflection correction coefficient of long-term deflection to predict construction deflection. Analysis results show that the calculation model considering the construction degradation is more close to the practical situation. The long-term deflection calculation method based on the coefficient of correction can be used in the prediction calculation.

Japan TAF Epoxy Asphalt Concrete Design and Steel Bridge Deck Pavement Construction Technology

The TAF epoxy asphalt concrete (EAC) is a new steel bridge deck pavement materials , the application of the TAF EAC is increasing in China. But the research for some of it's performance and construction technology is not throughly, which results in the useful life of the bridge deck paving materials greatly reducing. This paper focuses on the design and construction methods of the Japanese TAF epoxy asphalt concrete, and take the Humen bridge steel bridge deck pavement repair project in December 2011 for example.

Nonlinear parametric modeling of suspension bridges under aeroelastic forces: torsional divergence and flutter

A fully nonlinear model of suspension bridges parameterized by one single space coordinate is proposed to describe overall three-dimensional motions. The nonlinear equations of motion are obtained via a direct total Lagrangian formulation and the kinematics, for the deck-girder and the suspension cables, feature the finite displacements of the associated base lines and the flexural and torsional rotations of the deck cross-sections assumed rigid in their own planes. The strain-displacement relationships for the generalized strain parameters, the elongations in the cables, the deck elongation, and the three curvatures, retain the full geometric nonlinearities. The proposed nonlinear model with its full extensional-flexural-torsional coupling is employed to study the torsional divergence caused by the static part of the wind-induced forces. Two suspension bridges are considered as case studies: the Runyang bridge (main span 1,490 m) and the Hu Men bridge (main span 888 m) in China. The evaluation of the onset of the static instability and the post-critical behavior takes into account the prestressed condition of the bridge subject to dead loads. The dynamic bifurcation that occurs at the onset of flutter is also studied accounting for the prestressed equilibrium state about which the equations of motion are obtained via an updated Lagrangian formulation. Such a bifurcation is investigated in the context of the parametric nonlinear model considering the model parameters of the Runyang Suspension Bridge together with its aeroelastic derivatives. The calculated critical wind speeds for the onset of the static and dynamic bifurcations are compared with the results obtained via linear analysis and the main differences are highlighted. Parametric sensitivity studies are carried out to assess the influence of the design parameters on the instabilities associated with the bridge aeroelastic response.

Basic Performance of the Composite Deck System Composed of Orthotropic Steel Deck and Ultrathin RPC Layer

Fatigue damage in a conventional orthotropic steel bridge deck system poses a formidable challenge to bridge engineers all over the world because of ever-increasing heavy traffic volumes and higher wheel loads over the past decade. An effective solution may be to enhance the stiffness of the bridge deck to reduce the fatigue stress amplitude of its components. This paper proposes an innovative composite bridge deck system that consists of an orthotropic steel deck stiffened with a 45-mm reactive powder concrete (RPC) layer. Based on the analysis of HuMen Bridge in China (a suspension bridge with a conventional orthotropic steel bridge deck system with span length of 888 m) and two types of full-scale model tests, a comparison investigation is conducted between a conventional orthotropic deck system where the asphalt wearing course has been ignored and the proposed orthotropic deck system that includes an integral concrete wearing course, and the proposed composite bridge deck system proves to be considerably effective in reducing the stress range caused by service vehicle loads when applied to long-span steel suspension bridges. The thin RPC layer can be reliably integrated with the deck plate through stud shear connectors, and no shrinkage cracking occurs on the surface of the RPC layer that is cast on the deck plate. The fact that the tensile stress of the RPC layer is up to 42.7 MPa before cracking occurs demonstrates that cracking will not appear in the RPC layer under service vehicle loads. The analysis, which is investigated on the premise that the dead load weight of the bridge deck of HuMen Bridge is approximately the same for the two different deck systems, demonstrates that the stress of the orthotropic steel deck is significantly reduced with the application of the proposed composite deck system. Analysis with a three-dimensional finite-element model indicates that the transverse tensile stress of the deck plate is reduced by 71%, while that of the connection between the deck plate and the longitudinal troughs is reduced by 72%. This indicates that the risk of causing fatigue cracks in the steel bridge deck system can be considerably reduced during the entire life cycle of the bridge.