Bridge Section Research Articles

Adaptive h-finite element modeling of wind flow around bridges

Design of suspension bridge span is known to be very challenging, particularly considering its stability against wind flow. Traditionally, analysis of bridge section is done using wind tunnel and is very time consuming, with normal experimentation and modeling works requiring minimum 6–8weeks. To reduce cost and time requirements of wind tunnel experiments, as an alternate approach, wind flow around bridges are investigated by application of computer modeling. One challenging aspect of computational approach is to solve the Navier–Stokes (NS) equations accurately. In the present work, automatic mesh generation technique is used to transfer the continuous fluid flow into discrete numerical data, followed by use of h-adaptive technique. The adaptive simulation is carried out using two posteriori error estimations, which are based on the velocity gradient and vorticity. The current study uses the wind flow over the Great Belt East Bridge (GBEB) as a case study.

Analysis for the Effect of Wind Barrier on Reducing Wind Velocity across a Bridge

A bridge, which is located in the route of typhoon, is considered how to assure normal traffic use against strong winds. As one of the measures, wind barrier is proposed to be set on both sides of the bridge section for reducing wind velocity across it. In this study, an analysis by using CFX, a computational fluid dynamics program, is carried out to investigate the effects of wind barrier. The speed of wind is assumed as 60m/s. To find out an efficient design of the boards, different porosity ratios(r) of the boards is assumed for comparison. The result shows that wind barrier could reduce the wind speed across the bridge effectively.

Fine Analysis for Bursting Damage of Bottom Plates in Closure Section of Continuous Rigid Frame Bridge

The author took Chuanlingdong Bridge in Fujian Province for example. Applying general FEM software ANSYS and sub modeling technique, 3D model of the whole bridge was built firstly, and then closure section and nearby sections in mid-span were built to sub model. In the sub model, initial mesh was refined, weaken effects of corrugated pipes were considered and plain bars also were built. Based on the fine sub model, original design and construction tolerances are analyzed respectively. At last spatial stresses of closure section were cleared and key influencing factors were concluded. This research showed construction tolerances had a great influence on bursting damage when the design was at a disadvantage.

Settlement Control and Impact Analysis of the Subway Shield Under-Passing Beijing-Shanghai High Speed Railway Bridge

When the shield tunnel go through the bridge structure of high speed railway, it will affect the high speed railway bridge structure, thus influence to the bridge of track structure and ballastless track. Based on the Beijing subway tunnel go through the Beijing-Shanghai railway bridge section engineering examples, for the first time to shield under through the high speed railway caused the bridge pier settlements are analyzed. Combined with the actual monitoring data, the isolation pile during the period of construction bridge pier and Shield during through bridge pier during the period of settlement regularity of construction bridge pier, settlement regularity of Isolation pile as well as settlement regularity of the surface land are summarized analysis. During the construction of high-speed rail bridges and the soil to produce a certain degree of deformation, Shield Zone just above the soil settlement with a large deformation, both sides of the deformation gradually decreases, but the deformation is controlled. The use of the isolation pile reinforcement measures significantly reduced the influence by the Shield Construction and it can satisfy the requirement of high speed railway control standards

The Analysis of Impact Coefficient on Reinforced-Concrete Bridge

In order to discuss the displacement impact coefficient of the simply supported beam bridge, reinforced-concrete simply supported beam models with different span and different section stiffness are set up using the finite element method in the paper. The maximum dynamic displacement of beam models under the running vehicle is calculated. Combined with the maximum static displacement, the corresponding impact coefficients of models are calculated. At the same time, the modal analysis of beams is conducted to calculate the impact coefficient based on the base frequency. From comparing with the displacement impact coefficient, the bridge spans and section stiffness influence on impact coefficient is analyzed. Results show that the influence of section stiffness on impact coefficient can be ignored, but the influence of the change of span cannot be ignored. It will provide a reference for designing and detection technology of reinforced-concrete simply supported beam.

Mathematical Logarithmic Model for Predicting Noise of Simply-Supported PC-Box Girder in High-Speed Railway

When a train runs across a bridge, vibration energy is transmitted from the track structure into the bridge deck and other components which act as different size of ‘sounding boards’. These ‘sounding boards’ also radiate noise, namely, re-radiated noise, which results in ‘hot spots’ in noise maps for bridge sections. Based on the field tests on the noise of 32m double line simply-supported PC-box girder serviced in Chengdu-Dujiangyan High-speed Railway (CDHR) in China, mathematical logarithmic equation for predicting the equivalent A-weighed noise level (LA,eq) is proposed. Predicted results are compared with field ones and the non-parametric tests including two-related samples Wilcoxon and two-independent samples Kolmogorov–Smirnov are carried out, indicating satisfactory results and verifying the reliability of theoretical model. Analysis shows that equivalent A-weighed noise level detects no significant difference between the model predictions and the field measurements at the confidence level of 95%.

A New Approach for Including Cage Flexibility in Dynamic Bearing Models by Using Combined Explicit Finite and Discrete Element Methods

In this investigation, a new approach was developed to study the influence of cage flexibility on the dynamics of inner and outer races and balls in a bearing. A 3D explicit finite element model (EFEM) of the cage was developed and combined with an existing discrete element dynamic bearing model (DBM) with six degrees of freedom. The EFEM was used to determine the cage dynamics, deformation, and resulting stresses in a ball bearing under various operating conditions. A novel algorithm was developed to determine the contact forces between the rigid balls and the flexible (deformable) cage. In this new flexible cage dynamic bearing model, the discrete and finite element models interact at each time step to determine the position, velocity, acceleration, and forces of all bearing components. The combined model was applied to investigate the influence of cage flexibility on ball-cage interactions and the resulting ball motion, cage whirl, and the effects of shaft misalignment. The model demonstrates that cage flexibility (deflection) has a significant influence on the ball-cage interaction. The results from this investigation demonstrate that the magnitude of ball-cage impacts and the ball sliding reduced in the presence of a flexible cage; however, as expected, the cage overall motion and angular velocity were largely unaffected by the cage flexibility. During high-speed operation, centrifugal forces contribute substantially to the total cage deformation and resulting stresses. When shaft misalignment is considered, stress cycles are experienced in the bridge and rail sections of the cage where fatigue failures have been observed in practice and in experimental studies.

Istanbul Metrobüs: first intercontinental bus rapid transit

Whilst debate comparing the technologies of bus-based transit ways with rail systems continues, the comparative cost advantages and capability of responding to rapidly changing mobility needs offered by Bus Rapid Transit (BRT) systems are well acknowledged. Istanbul has recently developed its 42km BRT network with further extensions currently being constructed. The Istanbul BRT system (Metrobüs) consists of three main sections. The first section (2007) was initially built on the European side of the city through a high demand arterial and its extension as the section was completed in 2008. It received criticism for having been preferred over rail alternatives. The third section (2009) runs over one of the two Istanbul Strait (Bosporus Strait) Bridges connecting Asia and Europe, by which Metrobüs has uniquely acquired the distinction of crossing a major water barrier and connecting two continents. Istanbul Strait is a major transportation bottleneck and source of congestion and Metrobüs is the only transit system for crossings. Shortly after the opening of the bridge section, the whole system has recorded a directional capacity of 24,000passengers/h and patronage of 620,000 daily ridership. The number of passengers attracted from car users and intermediate forms of public transportation is also notable. This paper first contributes to the BRT literature by introducing this special and recent BRT system with all its planning and operational aspects. Furthermore, for policy guidance, Metrobüs is evaluated as to whether it has made effective inputs for sustainable development and mobility aims in Istanbul.

Reconstruction of a flash flood with large wood transport and its influence on hazard patterns in an ungauged mountain basin

AbstractThe reconstruction of past flash floods in ungauged basins leads to a high level of uncertainty, which increases if other processes are involved such as the transport of large wood material. An important flash flood occurred in 1997 in Venero Claro (Central Spain), causing significant economic losses. The wood material clogged bridge sections, raising the water level upstream. The aim of this study was to reconstruct this event, analysing the influence of woody debris transport on the flood hazard pattern. Because the reach in question was affected by backwater effects due to bridge clogging, using only high water mark or palaeostage indicators may overestimate discharges, and so other methods are required to estimate peak flows. Therefore, the peak discharge was estimated (123 ± 18 m3 s–1) using indirect methods, but one‐dimensional hydraulic simulation was also used to validate these indirect estimates through an iterative process (127 ± 33 m3 s–1) and reconstruct the bridge obstruction to obtain the blockage ratio during the 1997 event (~48%) and the bridge clogging curves. Rainfall–Runoff modelling with stochastic simulation of different rainfall field configurations also helped to confirm that a peak discharge greater than 150 m3 s–1 is very unlikely to occur and that the estimated discharge range is consistent with the estimated rainfall amount (233 ± 27 mm).It was observed that the backwater effect due to the obstruction (water level ~7 m) made the 1997 flood (~35‐year return period) equivalent to the 50‐year flood. This allowed the equivalent return period to be defined as the recurrence interval of an event of specified magnitude, which, where large woody debris is present, is equivalent in water depth and extent of flooded area to a more extreme event of greater magnitude. These results highlight the need to include obstruction phenomena in flood hazard analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Fuzzy regression decision systems for assessment of the potential vulnerability of bridge to earthquakes

This paper presents an innovative fuzzy regression approach for the assessment of the potential vulnerability of bridge to earthquakes. Taking the Mao-Luo-Hsi Bridge in Nantou County of Taiwan as an example, structural models representing vulnerable sections of the bridge are established and updated by ambient vibration tests. Because of uncertainties in the structural models and ambient vibration data preprocessed by wavelet filtering, the fuzzy regression approach is adopted to synthesize the maximum displacements of the bridge sections so as to develop a bridge alert–action principle. The fuzzy regression model can be achieved by the fuzzy blending of each individual input–output realization for the critical sections D, E, and F of the bridge subjected to various earthquake intensity scales ranging from one to seven. Verification of the resulting fuzzy regression models along the longitudinal and transverse directions of the bridge reflects on the high R 2 values of the models being 0.7317 and 0.8401, respectively. The developed decision systems suggest that the action value can be determined for the location of the bridge site when the earthquake intensity reaches scale 6 corresponding to the maximum slopes of the resulting fuzzy regression curves, and the next one lower scale 5 refers the alert value.

Wireless Mobile Sensor Network for the System Identification of a Space Frame Bridge

This research investigates the field performance of flexure-based mobile sensing nodes (FMSNs) developed for system identification and condition monitoring of civil structures. Each FMSN consists of a tetherless magnetic wall-climbing robot capable of navigating on steel structures, measuring structural vibrations, processing measurement data, and wirelessly communicating information. The flexible body design of the FMSN allows it to negotiate with sharp corners on a structure, and attach/detach an accelerometer onto/from structural surface. Our previous research investigated the performance of the FMSNs through laboratory experiments. The FMSNs were deployed to identify minor structural damage, illustrating a high sensitivity in damage detection enabled by flexible mobile deployment. This paper investigates the field performance of the FMSNs with a pedestrian bridge on the Georgia Tech campus. Multiple FMSNs navigate to different sections of the steel bridge and measure structural vibrations at high spatial resolution. Using data collected by a small number of FMSNs, detailed modal characteristics of the bridge are identified. A finite element (FE) model for the bridge is constructed. The FE model is updated based on the modal characteristics extracted from the FMSN data.

Reinforced concrete bridges: effects due to corrosion and concrete young modulus variation

Most of the Brazilian bridges of federal road network are made of reinforced concrete and are more than 30 years old, with little information about the mechanical properties of their constitutive materials. Along the service life of these bridges much modification occurred on vehicles load and geometry and in design standard. Many of them show signs of concrete and steel deterioration and their stability conditions are unknown. With the aim of contributing to the structural evaluation of reinforced concrete bridges it was decided to analyze the stresses in reinforced concrete bridge sections to verify the effects due to reinforcement corrosion and variation of the concrete Young modulus on the stress distribution regarding several load patterns and cracking effects in a representative bridge of the Brazilian road network with different longitudinal reinforcement taxes and two concrete Young modulus, Ec and 0.5Ec, and with different percentage of reinforcement corrosion. The analysis considered two finite element models: frame and shell elements as well as solid elements. The results indicate that these variation effects are more significant in reinforcement bars than in concrete.

Human papillomavirus type 16 E6 protein inhibits DNA fragmentation via interaction with DNA fragmentation factor 40

The E6 oncoprotein of human papillomavirus (HPV) is critical in cervical cancer development. Using the yeast two-hybrid assay, we showed that HPV-16 E6 (16E6) interacts with one of the DNA fragmentation factors (DFFs), DFF40, which mediates DNA degradation during apoptosis. Furthermore, 16E6 interacts with DFF40 through its zinc finger motif 2 and a bridge section linking the two zinc finger motifs. DNA fragmentation assays disclosed that 16E6 binding to DFF40 leads to blockage of DNA cleavage. Our data collectively suggest that suppression of DNA fragmentation through 16E6–DFF40 interaction is a central event promoting tumorigenesis.

Wind-induced performance of long-span bridge with modified cross-section profiles by stochastic traffic

The presence of traffic on a slender long-span bridge (SLB) deck has two types of primary impacts: (1) modification of the bridge cross-section profiles, which may influence the flutter derivatives and in turn, wind-induced aeroelastic loads acting on the bridge and (2) additional dynamic loads acting on the bridge including dynamic interactions from the vehicles. As compared to the investigations on the impact of traffic as external dynamic loads, those on the impact from the modification of bridge cross-section profiles are rather rare. A scaled bridge section model with vehicle models distributed on the bridge deck has been tested in the wind tunnel laboratory following the simulated stochastic traffic flow. With the flutter derivatives obtained from the wind tunnel experiments of various modified bridge cross-section profiles by traffic, the present study is to numerically evaluate the impact on the wind-induced performance of the long-span bridge, such as the aeroelastic performance, buffeting response and potential fatigue accumulation.

Wind tunnel measurements of crosswind loads on high sided vehicles over long span bridges

This paper presents the results obtained from a series of wind tunnel experiments undertaken in order to assess (and improve) the operation of a generic long span bridge subjected to strong winds (the operation of the bridge is evaluated in terms of the aerodynamic loads on a number of vehicles—in all cases the mean crosswind is greater than or equal to 10m/s). The aerodynamic loads, in terms of mean and peak side and lift force coefficients and rolling moment coefficient are presented for three 1:40 scale model vehicles placed on the bridge: a Van, a Bus and a Lorry. These vehicles were tested under static conditions (i.e., the motion between the vehicle and the bridge deck was not simulated), and subjected to a uniform turbulent crosswind at different incoming directions. Two separate bridge deck scenarios were examined—an ‘Ideal’ and a ‘Typical’ deck shape. The data show a good agreement with the findings of previous research with respect to the ‘Ideal’ bridge geometry. The Typical bridge section enables the differences between the idealised bridge and a more realistic deck geometry to be explored. The work indicates that the Lorry, rather than the Van or the Bus, is the critical vehicle in terms of overturning stability (as characterized by the highest magnitudes of the rolling moment coefficient). An approximately linear decrease of the side force and rolling moment coefficients is found on the Typical deck when the vehicle is positioned at a progressively larger distance from the windward edge. The research provides novel data and interpretation on the aerodynamic loads experienced by road vehicles.

Comparative Study on Seismic Performance of Prestressed Concrete Box-Girder Bridges with Corrugated Steel Webs

Prestressed concrete (PC) box-girders with corrugated steel webs are one of the promising steel concrete composite structures applied to highway bridges. Although the basic structural characteristics including bending, shearing and torsion, etc., have been paid much attention, few researches on the seismic performance of this type of bridges are found, especially when the span of this type of bridges becomes larger and larger. In this paper, the seismic performance of one long-span PC box-girder bridge with corrugated steel webs is studied and compared with a conventional box-girder bridge with concrete webs, based on response spectrum analysis using ANSYS. The results show that, the vertical and transverse displacements of the box-girder with corrugated steel webs are slightly less than those of the box-girder with concrete webs, but the longitudinal displacement reverses, under the same earthquake excitation. The bending moments of representative sections of the box-girder bridge with corrugated steel webs are only about 70% ~ 90% of those of the corresponding conventional PC girder bridge. The results indicate that the box-girder bridge will have better seismic performance if the corrugated steel webs are adopted instead of the concrete webs, but it could also fulfill the tasks such as displacement control which resulted from stiffness reduction.

Pier Form Selection and Parameter Analysis of Reinforced Concrete Thin-Wall High Pier

Two forms of reinforced concrete pier were compared by internal force analysis and nonlinear stability analysis. According to the restriction of the stability and intensity, size optimization of the high piers’ section is calculated by means of differential coefficient. The results of the calculation and analysis indicate that the parameter optimization of the piers’ section of Long-span continuous rigid frame bridges is feasible by using the optimization model, and the results are provided to the optional design of Long-span continuous rigid frame bridges.

Optimization Analysis of Thin-Walled High Pier

According to the restriction of the stability and intensity, size optimization of the high piers’ section is calculated by using the current FEM software ANSYS, by means of differential coefficient. The results of the calculation and analysis indicate that the parameter optimization of the piers’ section of Long-span continuous rigid frame bridges is feasible by using the optimization model together with the finite element method, and the results are provided reference for optional design of similar bridge

Experimental Study on Static Mechanical Behavior of Steel-Concrete Joint Section of Hybrid Girder Cable-Stayed Bridge

According to the structural characteristics of steel-concrete joint section of WuSu Bridge, a 1:3 reduced scale test model was designed to study the static mechanical behavior of the steel-concrete joint section. The test model is loaded according to the serviceability limit state and ultimate limit state separately, the stress of each members of the control sections of the test model is obtained. As shown in the results, the load from steel is smoothly delivered to concrete through the steel-concrete joint section, the stress values of the test model are generally less than the permissible value of the material given by the standard. The load-stress curve shows that the structural materials are in the elastic stage when being loading. All these show the steel-concrete joint section of WUSU Bridge has sufficient security reserve, the design of the steel-concrete joint section meets the security requirements. of the bridge is 140m+140m. The girder is consolidated with tower and pier. The main beam of the bridge is steel box beam with long cantilever while the beam at the tower root is made of concrete with two steel-concrete joint sections set up on both sides of main tower. Axial force, bending moment and torque from steel box beam are delivered to concrete beam through the bearing plate and the shear studs in steel-concrete joint section. The layout of the steel-concrete joint section of WuSu Bridge is shown in Fig. 1.

Characteristics of Settlement and Assessment Methods of Engineered Structures under Certain High-Speed Railway Tracks in China

The assessment of settlement deformation of engineered structures under high-speed railway tracks is an important control link in high-speed railway line construction. This paper discusses characteristics of settlement deformation of sections of subgrade, bridges and tunnels, and analyzes the suitability of predictive methods in currently available technical codes and standards based on measured data of settlement deformation. Currently available assessment analysis methods have good applicability for subgrade sections but are not suitable for sections of bridges and tunnels. Suitable assessment analysis methods are proposed and have been successfully applied to settlement deformation of engineered structures under the tracks of high-speed railway lines. The methods suit the characteristics of “small magnitude and large fluctuation” changes of measured settlement deformations taking account of the construction process of the engineered project.