Railway Bridge Deck Research Articles

Simulation Based Study Of Ground Mobile Robots For Inspection And Control Of The Bridge Assembly Process

Nowadays, the inspection of bridges poses a significant challenge for safeguarding critical infrastructures. Recent advancements have seen the integration of robots to replace human personnel in hazardous tasks. These robots, whether operating autonomously or through tele-operation, play a crucial role in monitoring structures and infrastructure, ensuring secure access to areas such as manholes on decks and box girder bridges. Specifically designed for environments deemed dangerous, difficult, or inaccessible to humans, ground mobile robots equipped with appropriate sensors are increasingly deployed for inspection purposes. This paper addresses simulation tests conducted by a hybrid mobile robot. Its compact design and maneuverability enable it to navigate through obstacles, making it suitable for inspecting railway or highway bridge decks as well as confined spaces within box girder bridges. The study includes a survey of existing bridges highlighting key issues to be addressed and presents simulation results for the hybrid rover, which has been developed and equipped with sensors tailored to fulfill inspection tasks within a selected case study.

Wind field characteristics of asymmetric bridge deck for a road-rail same-story bridge

The purpose of this study is to investigate the flow field characteristics of the road-rail same-story asymmetric bridge deck and the influence of the asymmetric arrangement of the bridge deck on the flow field of the main girders. Numerical simulation tests were conducted on this bridge to analyze the distribution characteristics of the flow field near the main girder, as well as the aerodynamic characteristics of the railway bridge deck and highway bridge deck under different wind speeds and directions. The results indicate that the wind speed has less influence on the flow field distribution and aerodynamic characteristics of the road-rail same-story asymmetric bridge deck, but the incoming flow direction has a significant impact on its flow field characteristics. Compared to the railway bridge deck, during the reattachment position of the airflow, the highway bridge deck moves toward the windward side, and the volume of the separation bubble has been reduced, thus improving the effect on the negative pressure area of the railway bridge deck. The road-rail same-story asymmetric bridge deck has different aerodynamic interference characteristics for different wind speeds and different wind directions.

An efficient automatic modal identification method based on free vibration response and enhanced Empirical Fourier Decomposition technique

This paper presents an efficient yet practical approach for the automatic modal identification of structures based on their free vibration response. The proposed approach relies on the Empirical Fourier Decomposition (EFD) technique. It implements a new procedure to recognize automatically the number of modal components to be extracted from noisy data in such a way to prevent both mode-mixing and mode-splitting effects. A suitable strategy is adopted to improve the segmentation of the frequency spectrum of the free vibration response, so as to identify accurately the bounds of the frequency spectrum partition corresponding to each modal component. The related modal damping ratios are estimated by means of a robust area-based approach in order to mitigate the noise-induced disturbances whereas a time-domain method based on the phase shift of the free vibration response peaks is employed to identify the mode shapes.The proposed approach is first validated through the analysis of synthetic signals that embed closely spaced components and a lowly excited vibration mode. Finally, the proposed approach is applied to two real bridges. The first case-study deals with the identification of modal frequencies and damping ratios of the cables of a stay-cabled bridge. The second case-study involves the modal identification of a steel railway bridge deck that exhibits two closely spaced vibration modes. The outcomes obtained using the proposed approach based on EFD technique are compared with the results obtained by means of the Variational Mode Decomposition (VMD) technique as well as with those computed through classical operational modal analysis techniques. The consistent estimates produced by means of the proposed approach demonstrate its accuracy and robustness.

Railway Bridge Geometry Assessment Supported by Cutting-Edge Reality Capture Technologies and 3D As-Designed Models

Documentation of structural visual inspections is necessary for its monitoring, maintenance, and decision about its rehabilitation, and structural strengthening. In recent times, close-range photogrammetry (CRP) based on unmanned aerial vehicles (UAVs) and terrestrial laser scanners (TLS) have greatly improved the survey phase. These technologies can be used independently or in combination to provide a 3D as-is image-based model of the railway bridge. In this study, TLS captured the side and bottom sections of the deck, while the CRP-based UAV captured the side and top sections of the deck, and the track. The combination of post-processing techniques enabled the merging of TLS and CRP models, resulting in the creation of an accurate 3D representation of the complete railway bridge deck. Additionally, a 3D as-designed model was developed based on the design plans of the bridge. The as-designed model is compared to the as-is model through a 3D digital registration. The comparison allows the detection of dimensional deviation and surface alignments. The results reveal slight deviations in the structural dimension with a global average value of 9 mm.

Aerodynamics of a Train and Flat Closed-Box Bridge System with Train Model Mounted on the Upstream Track

The aerodynamic features of a train and flat closed-box bridge system may be highly sensitive to train-bridge aero interactions. For the generally utilized railway bridge-deck with two tracks (the upstream and downstream ones), the aero interactions above are occupied-track-dependent. The present paper thus aims to reveal the aero interactions stated above via a series of wind tunnel tests. The results showed that the aero interactions of the present train-bridge system display four typical behaviors, namely, the underbody flow restraining effect, bridge deck shielding effect, flow transition promoting effect, and the flow separation intensifying effect. The above four aero interactions result in obvious reductions in the aerodynamic forces of the train in wind angle of attack α of [−4°, 12°] and in the static stall angle of the bridge-deck, and leads to sensible increases in the absolute values of the bridge aerodynamic forces in α of [−4°, 12°]. Upon comparing the results with the same train and bridge system but with the train model mounted on the downstream track, the quasi-Reynolds number effect was non-detectable when the train model was moved to the upstream track. Thus, no drag crisis and other saltatory aerodynamic behaviors were observed in the present study in α of [0°, 12°].

The improvement of the dynamic behavior of railway bridge transition zone using furnace slag reinforcement: A numerical and experimental study

Transition zones between railway tracks and bridge decks can cause higher dynamic impacts. A solution is smoothly changing the track stiffness by gradually mixing steel furnace slag into the stone ballast. A nominated bridge transition zone is divided into 5 blocks of 7 meters long, with the mixing percentages of 0%, 25%, 50%, 75% and 100%. The mechanical behaviors of furnace slag-ballast combinations (FS-BCs) were studied using experiments of shear strength test, Los Angles abrasion index and plate load test. Furthermore, the dynamic behavior of bridge transition zone with FS-BCs blocks was investigated using a field validated FEM model. Results show that the 100%, 75%, 50% and 25% furnace slag by weight of ballast can increase the shear strength and ballast layer bending modulus by 13%, 12%, 9% and 7% at speed of 300 km/h compared with those of the stone ballast. The FEM study shows that rail deflections are reduced about 20%, 14%, 21% and 16% at speed of 300 km/h corresponding to 100%, 75%, 50% and 25% FS-BCs and accelerations are significantly reduced as well as increasing FS content of each block in bridge transition zone so that a smooth bridge transition zone can be achieved.

비선형해석방법을 이용한 철도교량 단부 콘크리트궤도 사용성 평가

비선형해석방법을 이용한 철도교량 단부 콘크리트궤도 사용성 평가

레일지지점 간격 및 교량받침위치에 따른 철도교량 단부의 거동분석

본 연구에서는 철도교량 단부 콘크리트궤도에서 레일지지점 간격 변화와 교량받침 위치변화가 레일체결장치에 미치는 영향에 대하여 연구를 수행하였다. 레일지지점 간격은 600mm와 750mm를 고려하였고, 교량받침위치(교량 받침축과 마지막 레일지지점과의 거리)는 750mm와 935mm로 선정하여 철도교량 단부 거동 모형시험을 수행하였다. 철도교량 단부 거동 모형시험에서 거더의 휨 변형(단부 회전)에 따른 거더 단부, 레일, 레일체결장치의 변위를 확인하기 위하여 각 위치에 변위계를 사용하여 계측하였다. 또한, 철도교량 단부 거동 모형시험은 동일조건으로 유한요소해석을 수행하였다. 유한요소해석에서는 레일체결장치의 거동을 선형과 비선형으로 각각 고려하였다. 시험결과에서 레일지지점 간격, 교량 받침축과 마지막 레일지지점과의 거리가 증가할수록 교대부 단부의 상향변위와 레일체결장치의 압상력이 증가하는 것으로 나타났다. 또한, 레일체결장치의 비선형 거동 특성을 고려한 유한요소해석 결과가 선형해석 결과보다 시험결과와 유사한 결과를 보여주었다.

Stringer Longitudinal Bending–Induced Fatigue Failure of Stringer-to-Floor Beam Welded Connections in Orthotropic Steel Railway Bridge Decks

Stringer Longitudinal Bending–Induced Fatigue Failure of Stringer-to-Floor Beam Welded Connections in Orthotropic Steel Railway Bridge Decks

Impact of track irregularities and damping on the fatigue damage of a railway bridge deck slab

The structural response of reinforced concrete slabs in railway bridges is strongly influenced by local dynamic effects and, therefore, detailed calculations of internal forces have to be performed for a realistic fatigue assessment. In this context, this paper discusses the influence of track irregularities and modal damping coefficients in the dynamic response and fatigue behaviour of a railway bridge deck slab. For that purpose, track irregularities were measured (at different instants of time) and damping coefficients were determined based on acceleration records for passing trains in a real bridge. The bridge behaviour was calculated using a train–bridge interaction methodology, considering calibrated numerical models of the viaduct and the train. The fatigue damage was quantified through the linear damage accumulation method. This methodology allowed to understand the way track irregularities and damping coefficients affect the magnitude of applied bending moments and fatigue damage in the slab.

Fatigue tests of welded connections between longitudinal stringer and deck plate in railway bridge orthotropic steel decks

This research presented the fatigue tests of longitudinal stringer-to-deck (SD) welded connections, which have been identified as the locations most sensitive to fatigue damage in the orthotropic steel decks (OSDs) of railway bridges. Four full-scale SD connections were fabricated, and two loading patches were considered. Static loading was first carried out to obtain the structural hot spot stresses at weld toes as well as stress concentration factors (SCFs), by which the hot spots providing the highest stresses were identified. Cyclic loading was then implemented next to the static loading, and the behaviors including fatigue crack initiation and propagation process, fatigue failure mode, characteristic fatigue life, as well as degradation of vertical rigidity, were all obtained from the test. The crack growing process can be totally divided into four stages, and the fatigue lives after the crack arrived at the deck edge were very short. Variations of crack dimensions were also obtained, and the simplified formulae of crack growth rate were numerically fitted so that the crack propagation lives can be predicted by using the crack dimensions. Comparisons also show that the FAT 100 curve in IIW fatigue design recommendation could overestimate the fatigue resistance of such connections where double-sided fillet welds were used to connect the stringer web and the deck plate, and therefore double-sided groove welds with partial or full penetrations are recommended for the stringer-to-deck connections in railway bridge decks.

Dynamic analysis of high-speed railway bridge decks using generalised beam theory

This paper presents the details and illustrates the application of a semi-analytical Generalised Beam Theory (GBT) formulation for the dynamic analysis of high-speed railway bridge decks. The technique, which takes into account the cross-section local/distortional and shear deformations, provides an original “doubly modal” representation of the dynamic response, which makes it possible to acquire deep insight into the mechanics of the deck structural behaviour. It is employed to investigate the dynamic behaviour of a real high-speed railway viaduct, comprising a series of identical 46m-span simply supported box girder pre-stressed concrete decks carrying two tracks – the augmented structural response associated with resonance due to the crossing of trains at high-speeds is captured. The results obtained provide evidence that local/distortional deformation can play a significant role on the dynamic response of such structures. Moreover, the GBT analyses, whose validity is confirmed through the comparison with values yielded by shell finite element analyses, are shown to provide accurate results while involving just a few degrees of freedom.

Application of welded studs for fastening of railway bridge deck

Application of welded studs for fastening of railway bridge deck

Experimental Analysis of Stiffness of the Riveted Steel Railway Bridge Deck Members’ Joints

Abstract The paper deals with the real behaviour of the riveted steel railway bridge deck members’ connections with respect to their bending stiffness. Attention is paid to the stringer-to-cross beam connection as well as the cross beam-to-main girder connection. The stiffness of the two connections is investigated on the basis of evaluation of the experimentally determined stress response of the observed structural members to the actual traffic load on an existing railway bridge.

철도교량 단부 전환부 궤도시스템의 구조적 거동특성 및 장기 내구성능 분석

철도교량 단부 전환부 궤도시스템의 구조적 거동특성 및 장기 내구성능 분석

Dynamic Response of High-Speed Railway Bridge Decks with Beams Transverse to the Direction of the Track

Railway bridge decks are frequently constructed using a concrete slab supported by transverse beams, which in turn are connected to the main longitudinal supporting elements: arches, trusses, and so on. This is a structural design whose dynamic behavior often experiences excessive accelerations. Despite the frequent occurrence of this dynamic behavior, no studies have been completed that examine this dynamic response and the variables that cause it. This study proposes that reduced longitudinal stiffness is the cause of excessive vertical accelerations often exhibited by these decks. The study further proposes that increased stiffness in this direction, achieved by incorporating longitudinal beams connected to the underside of the slab, for example, greatly improves this structural design’s dynamic behavior.

Dynamic performance of existing high-speed railway bridges under resonant conditions following a retrofit with fluid viscous dampers supported on clamped auxiliary beams

This contribution investigates the application of Passive Control techniques to reduce the severe transverse vibrations that railway bridges of moderate lengths may experience under resonant conditions. The proposed solution consists in connecting the slab to a series of auxiliary beams clamped between the bridge abutments through a set of fluid viscous dampers. A particular configuration minimising the space occupied by the devices and the auxiliary beams under the bridge deck is proposed for two typical typologies in the aforementioned lengths: slabs and girder bridges. First, the dynamic response of a double-beam analytical model is obtained in closed-form under harmonic excitation in order to detect the main governing parameters, capturing the essence of the response at resonance of the main beam fundamental mode. Then conditions are obtained for the optimal damper constants that minimise the main beam amplification. Finally the effectiveness of the solution and the adequacy of the expressions derived from the harmonic case are proven under railway traffic excitation taking into account the three-dimensional deformation of the deck. Throughout the study special attention is given to the beneficial effect arising from clamping the auxiliary beam supports when compared to the simply-supported case, analysed by the authors in previous works. Partial rotational restrictions are admitted to take into consideration the expectable deviation from ideally clamped conditions. Two case studies are presented showing that the auxiliary beams size, if partially clamped, could be significantly reduced for the same main beam vibration mitigation level. If the beams are to be installed under a railway bridge deck in a practical application, this is a crucial issue in order to minimise the free space occupied with the retrofit.

Real-time drill monitoring and control using building information models augmented with 3D imaging data

The problem of placing embeds into existing reinforced concrete structures without damaging reinforcement bars is an industry-wide challenge for the construction industry. This paper presents research that investigated real-time monitoring approaches for hazardous engineering processes. A conceptual solution for processing and incorporating point cloud data obtained from 3D imaging technologies1 into the drilling process in was developed. The 3D imaging technologies were used to map the locations of rebar within a section of a railway bridge deck. Once the point clouds were processed, zones which are safe for drilling were automatically detected and saved as a Building Information Model (BIM). The BIM was used to provide real-time feedback to the drill operator about whether it is safe to continue drilling based on the position and orientation of the drill. The results showed the feasibility of real-time feedback for improving the safety, productivity, and quality of engineering processes by helping avoid the time and cost of rework.

철도교량 단부 궤도의 사용성 향상을 위한 횡단궤도시스템 적용에 관한 실험적 연구

콘크리트궤도가 부설된 철도교량 단부의 궤도구성품(레일 및 체결구)에는 교량 단부회전에 의해 상향력 및 압축력과 같은 궤도-교량의 상호작용력이 작용하여 손상 및 성능저하가 유발된다. 이러한 교량의 휨거동에 기인한 단부 궤도의 상호작용에 따른 문제를 해결하고자 본 연구에서는 횡단궤도시스템을 개발하고 그 성능을 입증하였다. 횡단궤도시스템의 구조안정성 검토를 위해 3차원 유한요소해석을 통한 시간이력해석을 실시하고 그 결과를 독일의 성능요구조건 및 관련기준과 비교하였다. 또한, 교량-궤도 상호작용 분석을 위한 시험체를 제작하여 실내시험을 수행하고 횡단궤도시스템의 적용 효과를 평가하였다. 연구결과 횡단궤도시스템의 정, 동적 구조안정성 및 횡단궤도 적용 후 교량 단부 궤도의 상호작용력(레일변위, 레일저부응력 및 체결구 응력)이 크게 저감될 수 있음을 실험적으로 입증하였다. The components of concrete track (rail and rail fastening system) in railway bridge deck ends are damaged and deteriorated by track-bridge interaction forces such as uplift forces and compression forces owing to their structural flexural characteristics (bridge end rotation). This had led to demand for alternatives to improve structural safety and serviceability. In this study, the authors aim to develop a transition track to enhance the long term workability and durability of concrete track components in railway bridge deck ends and thereby improve the performance of concrete track. A time-history analysis and a three-dimensional finite element method analysis were performed to consider the train speed and the effect of multiple train loads and the results were compared with the performance requirements and German standard for transition track. Furthermore, two specimens, a normal concrete track and a transition track, were fabricated to evaluate the effects of application of the developed transition track, and static tests were conducted. From the results, the track-bridge interaction force acting on the track components (rail displacement, rail stress, and clip stress) of the railway bridge deck end were significantly reduced with use of the developed transition track compared with the non-transition track specimen.

철도교량 단부 회전에 따른 콘크리트 궤도의 변형특성에 관한 실험적 연구

본 연구에서는 교량 단부의 레일지지점 간격, 교량과 교대사이 거리(유간) 및 교량 단부 회전각을 고려하여 콘크리트 궤도가 부설된 교량 단부 궤도의 거동을 분석하였다. 궤도구조가 고려된 교량 및 교대 시험체를 이용한 실내시험 결과, 동일한 유간(레일지지점 간격)에서 교량 단부 회전각이 증가함에 따라 레일의 변위가 선형적으로 비례하는 것으로 나타났다. 또한 이러한 레일의 변위는 레일 및 체결구의 발생응력에 직접적인 영향을 미치는 것으로 분석되었다. 실험결과를 바탕으로 다중 회귀분석을 수행하여 레일지지점 간격 및 교량의 단부 회전각을 매개변수로 하는 철도교량 단부 궤도의 궤도-교량 상호작용력 예측식을 도출하였다. In this study, by considering the rail fastening support distance and the distance between the bridge and the abutment, the behavior of concrete track installed on a railway bridge end deck and the bridge end rotation were analyzed. In order to analyze the track-bridge interaction, bridge and abutment specimens with concrete track structures were designed and used in laboratory testing. At a constant fastening support distance, an increase in the bridge end rotation caused an increase in the displacement of the rail. Therefore, the displacement of the rail directly affects the rail and clip stress. Further, it is inferred that the results of multiple regression analysis obtained using measured data such as angle of bridge end rotation and fastening support distance can be used to predict the track-bridge interaction forces acting on concrete track installed on railway bridge deck ends.