Bridge Section Research Articles

Aerodynamic Characteristics Evaluation of a Cable-Stayed Bridge Section with a New-Type Hybrid Fairing

In this study, new-type hybrid faring is suggested to improve the aerodynamic performance of the long-span cable-stayed bridge. The proposed fairing is developed by applying the concept of the multibox section to the normal faring. The proposed faring has void regions inside the faring so that wind passes through the gaps in the faring. As a result, the wind flow is changed and the forces to the bridge section are reduced. The efficiency of the proposed faring was verified by a series of wind tunnel test. From the test result, it can be found that aerodynamic performances, such as drag force and flutter resistance, are enhanced.

The installation of embedded ultrasonic transducers inside a bridge to monitor temperature and load influence using coda wave interferometry technique

This article presents a unique method of installing a special type of embedded ultrasonic transducers inside a 36-m-long section of an old bridge in Germany. A small-scale load test was carried out by a 16 ton truck to study the temperature and load influence on the bridge, as well as the performance of the embedded transducers. Ultrasonic coda wave interferometry technique, which has high sensitivity in detecting subtle changes in a heterogeneous medium, was used for the data evaluation and interpretation. The separation of two main influence factors (load effect and temperature variation) is studied, and future applications of wave velocity variation rate for structural health condition estimation are discussed. As a preliminary research stage, the installation method and the performance of the ultrasonic transducer are recognized. Load- and temperature-induced weak wave velocity variations are successfully detected with a high resolution of 10−4%. The feasibility of the whole system for long-term structural health monitoring is considered, and further research is planned.

Discussion on Construction Technology of Roadbed and Pavement in Transition Section of Road and Bridge

Discussion on Construction Technology of Roadbed and Pavement in Transition Section of Road and Bridge

A comparative study of structural parameters of a RCC T-girder bridge using loading pattern from different codes

Nepal is an under-developed country; it is on the threshold of becoming a developing country. With new highways and railroad projects launching, construction of bridges is likely to increase. Bridges improve connectivity across the country and provide support to the country's overall economic growth. While designing a bridge, concrete properties, reinforcement properties, superstructure and substructure sections, traffic movements and loading conditions are specified. Bridges in Nepal are designed based on criteria enumerated by Indian Road Congress (IRC) code provisions. But, there are different bridge design codes used by different countries. Although these provisions follow the same basic principles, they may yield different results. The study on various structural parameters' variation is significant while selecting the code provision for the design and analysis of the bridge. In this study, a T-Girder Bridge is considered and is modelled and analyzed by vehicular loading patterns from IRC Codal Provision, AASHTO Codal Provision, and Chinese Codal Provision. This study uses CSiBridge computer software to perform the analysis.

Numerical and theoretical analysis of spatial shear lag effect in through wide box bowstring arch bridge main girder

The shear lag of the box girder section of a wide box bowstring arch bridge was investigated in this study. The finite element analysis software Midas Civil was used to discretize the bridge into separate entities, establish its spatial model, and analyze the law of shear lag effect in the longitudinal direction during the main construction stage and the completion stage separately. The shear lag effect is more prominent at certain key points due to the influence of the tension of the boom and the weight of the arch foot during the construction stage. After the bridge is completed, the axial pressure of the arch foot drives the shear lag effect near the midpoint of the main girder section to its maximum; the axial force is transmitted along the longitudinal bridge direction in a V shape along which it gradually decreases. Under the action of uniformly distributed load, the cross-section of the box girder near the middle fulcrum is affected by the axial force of the arch foot; there is both a positive and negative shear lag effect. Under the eccentric load, the positive and negative shear lag effects appear simultaneously at the end fulcrum. The shear lag coefficient is higher in the web on the eccentric load side than the non-load side. There is obvious and widely fluctuating positive/negative shear lag effect in the vicinity of the middle fulcrum. There is significant tensile stress on the roof under the action of the middle fulcrum. The cross-sectional stress of a single-box seven-cell box girder under compression-bending load action was analyzed according to the finite element analysis results. The stress was decomposed into a superposition of bending moment action and axial force action. The shear lag coefficient λM under the action of bending moment was also solved via energy variation method. Assuming that the axial force is only borne by the compressed area, the shear lag coefficient λN under the action of the axial force was obtained; λM and λN were superimposed to determine the comprehensive shear lag effect coefficient λ.

Life-Cycle Assessment of a Railway Electric Power Feeding Cable for Replacement Planning: A Case Study of an Electric Railway in Korea

Electric railways are subjected to preventive maintenance to maintain a stable supply of electric energy to railway vehicles. The feeder cable is the main equipment of an electric railway that supplies stable electric energy to the Overhead Contact Line. The airport railway in Korea has many bridge sections and a feeder cable is used to secure the insulation distance from the messenger wire. A bridge section is a complex structure consisting of two stories, and the railway section on the lower story consists of a structure similar to the tunnel on the upper story. However, the insulation equipment on the lower story is decontaminate from natural environment such as rain, snow, tunnel and see. The lower story is closer to exposed locations such as the sea, and the degradation rate is high due to salt damage. In this paper, we propose a method for increasing the life expectancy of insulation equipment installed in a section subject to salt damage. Therefore, the insulation performance of the feeder cable installed on a sea bridge was measured. The life-cycle assessment was shown in a health index by applying a weighted average. In addition, the life expectancy was predicted by considering the health index and the remaining life.

Sensitivity Investigation on the Pressure Coefficients Non-Dimensionalization

The scaling of large structures to investigate their aerodynamics in wind tunnels is a common and robust procedure to estimate important magnitudes, including pressure coefficients. Different aspects can affect the estimation of pressure coefficients; four examples are the non-dimensionalization, blockage, non-stationarity, and non-Gaussianity of the wind tunnel velocity. This paper shows the variability of pressure coefficients due to these four aspects for the case study of a closed box section of a suspended bridge. It was estimated that the pressure coefficients of similar pressure taps vary significantly due to different sets of wind velocity time history used to non-dimensionalize the wind tunnel pressures. In addition, the stationarity of the wind velocity process was not confirmed for all wind velocity sets and the non-Gaussianity of the wind velocity time history was confirmed.

Aerodynamic response of high-speed trains under crosswind in a bridge-tunnel section with or without a wind barrier

High-speed trains experience a sharp transition to a strong crosswind environment when running in a bridge–tunnel section due to the perennial prevailing crosswind in the canyon, and this sudden transition seriously affects train safety. In this study, a 3D computational fluid dynamics numerical model of the train–tunnel–bridge–wind barrier is established based on the delayed detached eddy simulation turbulence model and porous media theory. A dynamic analysis model of wind–train–bridge coupling is adopted. The effects of wind barrier with a height of 3 ​m and porosity of 30% on the aerodynamic coefficient, flow field structure and running safety of high-speed trains under crosswind in the bridge–tunnel section are studied. Results indicate that the sharp change effect of the aerodynamic coefficient is significantly weakened by more than 50% by the wind barrier. The aerodynamic fluctuation amplitudes in the bridge–tunnel section are 1.25–5.5 times higher than those in the bridge section. The difference in pressure distribution in the longitudinal direction is significantly reduced because of the obstruction and diversion of the wind barrier and the space limitation on the windward side. Accordingly, the change in amplitude of the aerodynamic coefficients in the bridge–tunnel section is reduced, and so is the safety of train operation. The bridge–tunnel section is the weak link of safety control. Using a wind barrier with the same parameters for the bridge and bridge–tunnel sections is unreasonable, that is, the parameters should be separately designed.

Effects of the angle of attack on the aerodynamic characteristics of a streamlined box girder

This paper presents experimental and numerical approaches to systematically investigate the aerodynamic characteristics of streamlined box girder at angles of attack (AoA) of up to 12°. The effects of AoA on the pressure characteristics and total forces are first studied through wind tunnel experiments. Based on three-dimensional large-eddy simulations (3D LES), the flow topology is investigated to study the influence mechanism of AoAs. The results show that the flow topology around the section can be divided into three types: (i) completely attached flow pattern as |α| ≤ 4°; (ii) separated-reattached flow pattern as 6°≤|α|≤8°; (iii) fully separated flow pattern as |α| ≥ 10°. The combination of experimental and numerical results presents a deep understanding of the aerodynamic characteristics of a streamlined box girder and reveals the relationships between the pressure features and flow topology. The pressure characteristics and total forces are very sensitive to the flow separation and reattachment. At small AoAs, the flow attaches to the bridge section, the mean and RMS pressure, total force, as well as streamwise correlations change slightly with AoAs. Besides, the shear layer is a laminar pattern and has less impact on the span-wise correlations. Moreover, the vortices in the wake remain successive in the span-wise direction, and the Strouhal numbers are larger. On the other hand, with the increase of AoAs, large separation bubbles can be observed around the bridge section. Especially for fully separated flow pattern as |α| ≥ 10°, the shear layer no longer attaches to the bridge section and the separation bubble is longer than the section width. Accordingly, the mean and RMS pressure, total force, as well as streamwise correlations increase significantly. Besides, the shear layer is a turbulent pattern, and the turbulent fluctuations in wake become complex and less organized in the span-wise direction, then the St is lower than others.

Viscous inertial mass damper (VIMD) for seismic responses control of the coupled adjacent buildings

Many research studies have focused on a novel kind of damper involved with an inertial/gyro mass component, called the inertial mass damper (IMD). Different realizations of the IMD share common standard features: a sizeable apparent mass and the pseudo-negative dynamic stiffness. The connected control method (CCM) has been proven effective for mitigating vibration between adjacent flexible structures. This paper explores the efficacy of using an IMD in parallel with a viscous damper (termed VIMD) configured in the sky bridge to control the vibration of two adjacent towers under random earthquake excitation. First, numerical models of two buildings are developed using a Timoshenko beam model, which can accommodate both bending and shear deformation. Key damper parameters are explored through a parametric study. Then, stochastic optimization is performed to determine optimum damper parameters and the most effective configuration. The optimization results are analyzed in detail, and guidelines for the damper configuration are recommended. By comparing the optimal control performance between the VIMD and traditional viscous damper (VD), the following conclusions can be drawn: due to its pseudo-negative stiffness characteristics and large damper force, the VIMD can achieve better control performances for a wide range of the axial stiffness of the sky bridge; the VIMD requires a smaller damping coefficient and axial stiffness, which can result in smaller damper sizes and member sections of the sky bridge. Therefore, the VIMD is demonstrated to be a useful alternative for engineering practice in CCM vibration mitigation strategies.

Flow Redistribution at Bridge Contractions in Compound Channel for Extreme Hydrological Events and Implications for Sediment Scour

This study investigates the flood flow characteristics in a compound channel subject to both lateral contraction (caused by bridge abutment/embankment) and vertical contraction (caused by bridge deck submergence) at bridge sites. Three abutment setback distances and three pressure flow types [free surface (FS), submerged orifice (SO) and overtopping (OT)] are tested. The results show that turbulence structures in the approach channel remained the same irrespective of downstream obstruction. However, lesser abutment setback from the main channel led to greater flow acceleration as the flow approached the bridge section, where SO flow had the highest flow intensity and FS flow had the lowest. At a bridge contraction, the distributions of flow velocity, turbulence intensity, and Reynolds shear stress are significantly affected by the type of pressure flow and the extent of contraction. Enclosed counterclockwise secondary circulating flows in the main channel may occur for a combination of long or medium setback abutments and a FS flow, while other conditions usually feature open-ended upward flows due to flow relief. The strong downslope flow component detected at the main channel bank has a noticeable bank erosion capability. The bed shear stress, which is an indicator of sediment scour, is highlighted by apparent peak zones at the main channel bank and abutment toe. Finally, clear relationships between turbulence intensity, unit discharge ratio, and lateral contraction length are found. In general, normalized turbulence intensities on the floodplain and in the main channel can be used to assess the contribution of macroturbulence to the final bed topography after scour.

Research of Thermal Effect of Cable‐Stayed Bridge with a Separated Side‐Box Steel‐Concrete Composite Girder under Solar Radiation

At present, there are few studies on the thermal effect of solar radiation on a separated double‐sided box steel‐concrete composite girder cable‐stayed bridge. In this paper, the beam element and mixed element models are combined with the theory of transient heat transfer analysis and meteorology; this approach is adopted to carry out a thermodynamic analysis of a related bridge project. The calculation results of the thermal field and structural thermodynamic analysis of bridge sections show that, in terms of a separated double‐sided box steel‐concrete composite girder cable‐stayed bridge, the thermal field distributions of the main girder and the pylons are extremely complex under conditions of solar radiation. Therefore, the real thermal field cannot be accurately described as a one‐dimensional temperature gradient. The traditional beam element model cannot accurately simulate the temperature effect, and it will underestimate its thermal effect. The calculated temperature stress values of the mixed element model are quite different from those of the of beam element model. The mixed element model can precisely reflect the local thermal effect of each component in this system under solar radiation. Compared with the calculation results of the beam element model, the maximum temperature stress of the bridge deck in each section of the main girder is generally 20% larger; the maximum temperature stress levels of the steel‐beam top and bottom plates are 14.7 MPa and 15.9 MPa larger, respectively. The maximum shear stress of the steel‐concrete interface is 0.2 MPa larger. The research results of the temperature effect calculated by the mixed element have an important guiding significance for the design and maintenance of bridges.

Influence of wind barrier on the transient aerodynamic performance of high-speed trains under crosswinds at tunnel–bridge sections

Porous wind barriers (PWBs) are gradually applied to tunnel–bridge–tunnel infrastructures (TBTIs) along high-speed railway lines. Due to the remarkable aerodynamic effect of high-speed trains (HSTs), the windproof performance of a PWB at tunnel–bridge section (TBS) is particularly critical when a HST passes through the TBTI under crosswind. And it seems to be easily ignored by researchers. This study aims to determine the influence mechanism of the PWB in the TBS. A CFD dynamic model of air–train–PWB was built based on porous media theory, and its reliability is verified by model and field tests. The main results are as follows: the corresponding variation amplitudes of the train’s aerodynamic load coefficients are reduced by 36–95% when a PWB is set in the TBS; adopting the same design parameters along the full-length PWB on the TBTI is unreasonable; the PWB height and porosity in the TBS must be increased and reduced more than 33%, respectively, to achieve equivalent windproof performance. The conclusions in this paper can provide a preliminary idea for the optimization design of the PWB on the TBTI.

Influence of turbulence integral length scale on aerostatic coefficients of bridge sections

This study investigates the influence of turbulence on the aerostatic coefficients of typical bridges by obtaining force measurements via the simulation of turbulence in wind tunnels. The traditional simulation method for turbulence based on spires and grilles cannot be employed for the accurate simulation of the large integral scale of turbulence in an actual wind field. Thus, in this study, the turbulence integral length scale was effectively increased using an active control grid. The wind fields of different turbulence integral scales were generated by controlling the vibration frequency of the active control grid. The aerostatic coefficients of five typical bridge sections (single-box girder, twin-box girder, truss girder, edge girder, and edge-box girder) were measured under turbulent and uniform flow. The test results were compared and analyzed, which revealed that the drag coefficients increased in accordance with a decrease in the reduced turbulence integral length scale, and they were lower under turbulent flow than under uniform flow.

Delamination detection on a concrete bridge deck using impact echo scanning

AbstractIn this large‐scale field study we use a prototype impact‐echo scanner to detect delaminations on a concrete bridge deck surveying in total over 17,000 m2. Delaminated bridge sections are known from manual sounding and coring. A large‐scale damage assessment is necessary to identify the need of repair work. Based on first results, two lanes of the bridge are repaired and in subsequent tests the bonding of fresh and old concrete is examined. It shows that delaminations found on the bridge deck surface are unevenly distributed with more defects on the southbound lanes. This indicates constructional problems during the concrete placement. The developed scanner excites stress waves by dropping steel solenoids on the surface and recording the impact‐echo frequency by air‐coupled microphone arrays. It is pushed at a speed of 600 m/h, hitting the surface 300 times per square meter. The recorded data is preprocessed on site with an automated delamination detection threshold implemented. Found delaminations are transferred to a bridge map to allow an overall damage assessment.

On the special nucleus of reticular formation at the level of the upper sections of the Varoliyev bridge

Recently, thanks to the research of Koller, mine, Mislavsky and others, in the formation of already well-known early formations (such as the upper olives, etc.), it was possible to isolate several new or little known substances in the early which, adhering to the ascending topographic location, we will call: 1) the nucleus of the anterior column described by Mislavsky or the respiratory nucleus embedded in the medulla oblongata at the level of the roots n. hypoglossi, partly inwardly, partly outwardly from the last ones: 2) the lower central nucleus of Koller'a, located in the medulla oblongata above the head or upper part of the lower olives; 3) the lamellar core of the tire described by me at the level of the bridge, located above the inner part of the loop layer; 4) the upper central nucleus described by me, lying on the sides of the suture at the level of the posterior colliculus; 5) the anonymous nucleus that I described, laid at the level of the anterior colliculus inside and at the cold of the loop layer, which is present at this level on the transverse edges in the form of a sickle-shaped bundle, and finally 6) the small conical-shaped nucleus of the transverse bundle is located even higher.

Thermal monitoring of a concrete bridge in London, UK

During bridge design and assessment, effects of thermal actions are accounted for by means of a uniform temperature variation and temperature difference components. The uniform temperature variations cause changes in length and width of the structure, whereas the temperature difference components primarily cause curvatures and internal stresses. The effects of these strains on the superstructure depend on the structure's articulation and restraint. Design profiles used to model the temperature difference components vary between design codes, which can have a significant effect on the induced curvatures. Thermal data findings obtained from a comprehensive, year-long monitoring programme on Waterloo Bridge in London are examined, which allows comparison of these various models with performance data. The design thermal model in BS EN 1991-1-5 is examined, supplemented by the models from the Aashto and New Zealand codes. The measured uniform bridge temperature generally fell within the stipulated limits of BS EN 1991-1-5; however, at low temperatures the minimum deck temperature may be lower than the design relationship provided. The resultant moments implied from the measured vertical profiles: significantly exceed the worst-case values predicted by the UK model; exceed the Aashto model at different bridge sections; and do not exceed the New Zealand model.

Effects of Wind-Barrier Layout and Wind Turbulence on Aerodynamic Stability of Cable-Supported Bridges

Wind barriers are nowadays commonly placed on bridges to protect vehicles from adverse cross-wind effects. In addition to this beneficial influence, wind barriers may adversely affect the bridge dynamic stability. This is particularly exhibited for long-span cable-supported bridges. It is therefore the scope of the present study to analyze the effects of wind barriers on aerodynamic and aeroelastic characteristics of bridge-deck sections of long-span cable-supported bridges together with the respective flow characteristics around bridge-deck sections. The focus is on various arrangements of wind barriers, i.e., (1) wind barriers placed at the windward bridge-deck edge only; (2) wind barriers placed at the leeward bridge-deck edge only; and (3) wind barriers placed at both windward and leeward bridge-deck edges. This was carried out experimentally on small-scale models in a boundary layer wind tunnel. Three typical bridge-deck section models were studied, i.e., Great Belt (Denmark), Kao-Pin Hsi (Taiwan), and Golden Gate (United States). The galloping susceptibility of the bridge-deck sections in all arrangements of wind barriers proved to be the same, as is the case for the empty bridge-deck sections without wind barriers; i.e., from this point of view, wind barriers do not adversely bridge dynamic stability. However, in configurations with the windward wind barrier only, as well as both windward and leeward wind barriers, the flutter susceptibility of the bridge-deck sections increases substantially; i.e., the critical flow velocity for the bridge flutter decreased significantly in comparison with the respective empty bridge-deck sections. For the leeward wind barrier only, the flutter susceptibility of the bridge-deck sections did not change and remained the same as it was for the empty bridge-deck sections. The empty bridge-deck sections do not exhibit any significant change concerning their susceptibility to flutter for various turbulence levels of the incoming freestream flow. The flutter susceptibility of cable-supported bridges equipped with wind barriers is lower in more turbulent incoming flows. The bridge decks with wind barriers are more resilient to flutter in more turbulent winds. Shear layers that separate from the top of the wind barrier may have an important role in the self-excited lift force and the pitch moment and, consequently, the dynamic behavior of bridge decks.

Reliability analysis on the reservoir dam spillway structure using fluid-structure interaction

This paper presents a combined reliability and flow analysis on the spillway of reservoir dam using the numerical fluid-structure interaction (FSI) approach. The spillway is an important structure to the operation of reservoir dam, as it regulates the water flow from upstream to downstream. Therefore, a rapid discharge of water from the reservoir along the spillway will causes possibly flooding at downstream and incurs high structural stress. Using the ANSYS software, the two-way FSI problem of a dam spillway is numerically simulated. Such FSI numerical study able to simultaneously simulate and obtain both the parameters on fluid flow and structural deformation. The current study shows that the downstream has the highest flow velocity; while the highest deformation of 10.7 mm being observed in the connection bridge section. As the general stress level of the overall spillway structure (max. 30.75 MPa) is less than the yield stress of corresponding materials, the spillway will not exhibit any structural failure upon the current discharge mode.

Determination of the influence area of a bridge crossing in a river stream

The object of research is the formation of the influence zone of the bridge crossing in the river flow. The method for determining the length of the zone of influence of the bridge crossing provides for the calculation of such parameters as the specific discharge of floodplains, the length of the zones of compression and spreading, and the full backwater in front of the bridge section. The proposed approach is based on changing the properties of the central stream of the river flow in the zone of artificial influence of the bridge structure. Determination of the flow depth and the inclined free surface is carried out according to the corresponding finite-difference analogs of differential equations describing the change in these quantities. All calculations are made, respectively, for each branch of a flood or flood, for a certain day. Calculations start with a full spreading alignment, where all hydraulic characteristics of the flow have natural values. The paper presents the calculation of the zone of influence of the bridge crossing on the river Seversky Donets on the T-05-14 highway within the Donetsk region (Ukraine). It has been established that the development of general channel deformations in the channel and on the floodplains occurs in a section from 1195 m to 2144 m long. The distribution of the river flow depth is obtained, which increases from 0.58 m to 2.17 m in the alignment of the bridge crossing after the flood. With an increase in the flow rate of the river flow, the parameters of the compression zone also increase from 246 m to 1382 m, and the spreading zones decrease from 949 m to 762 m. The change in the parameter of the central jet occurs in accordance with the distribution of the compression and spreading zones during the course of the flood. The obtained results are the initial conditions for conducting research on predicting eroded processes in a river flow, taking into account artificial compression in the zone of influence of the bridge crossing.