Large-span Bridge Research Articles

Vibration based damage detection of bridge structures

The task of identifying damage to the load-bearing beams of large-span bridge structures using vibration diagnostic methods has been implemented, taking into account experimental uncertainties associated with natural phenomena and technological processes. The methodology for localizing damage is based on the analysis of dynamic characteristics of the structure, such as natural frequencies and modes of vibration. The study presents research on a finite element model of a bridge structure using a method for determining a damage indicator based on normalizing the values of vibration modes with respect to the values of vibration area.

Research Progress on Fire Resistance of Steel-concrete Composite Structures

The 1930s was an important period of development in the design theory of bridge technology in Europe and the United States. Among them was the invention of welding technology, which created more favorable conditions for the development of combined structures, i.e., the connection between reinforced concrete slabs and steel girders could be welded instead of the initial connection method. In China, for more than thirty years, on the one hand, large span bridges have been able to develop rapidly and set new world records, driven by the huge technical demand seeking span breakthroughs. On the other hand, concrete bridges dominate the large number of small span bridges. In short, in China, steel-concrete (SC) structures have also developed accordingly. This paper first introduces the steel-concrete combination structure, and then analyzes the steel-ability concretes to withstand fire from both theoretical and experimental perspectives. Valid data are provided by graphs and equation analysis. Finally, a method that can measure the fire resistance of SC composite structures in fire is obtained.

Strengthening effects evaluation on fatigue damage of rib to deck joint in orthotropic steel deck

Strengthening fatigue damage of orthotropic steel decks (OSDs) needs to comprehensively consider the strengthening effect and the dead weight introduced during the strengthening process, especially for OSDs in super large-span bridges or old renovated bridges, where the dead weight cannot be significantly increased during repair and maintenance. This paper proposed a new CFRP prestressed reinforcement method, that does not significantly increase dead weight while effectively inhibiting fatigue crack growth. The strengthening effects of various strengthening methods on the fatigue crack propagation of rib to deck joint in OSDs were compared. Besides, the strengthening effects of different crack sizes were also analyzed. The results showed that the proposed method is effective in reducing fatigue damage at the rib to deck joint in OSDs.

Study on Mechanical Properties of Simply-Supported Composite Beams Considering Creep and Slip

In the current industry, steel–concrete composite beams are used in large-span bridges and super-high-rise building structures due to their excellent overall performance. Concrete’s creep and slip effects in the combined structure can adversely affect the structure, thus affecting the safe use of bridges and buildings. It is necessary to study the mechanical properties of the combined structure considering creep and slip. In order to further study the mechanical properties of steel–concrete composite beams under creep–sliding coupling, in this study, based on the energy variational method principle, the energy equation of a composite beam considering creep and slip coupling is established. The second-order differential equation of the axial force of steel–concrete composite beams is derived by introducing basic assumptions. The calculation formulas for the axial force, deflection, and slip of simply-supported composite beams under different loads are obtained using different boundary conditions. Then, the creep effect of composite beams is simulated using the creep criterion in the ANSYS finite element software when the concrete material parameters change with time. The results show that a simply-supported composite beam considering both slip and creep will have a significant effect on the structure; the more strongly the studs constrain the concrete slab, the greater the adverse effect of concrete creep on the combined beam. The formula derived in this paper is consistent with the numerical simulation solution and is suitable for different creep and slip conditions. The research results can provide a theoretical basis for the calculation of the axial force, deflection, and slip of combined beams under uniform and concentrated loads in practical engineering considering slip and creep.

Influence of spatially varying ground motions on the seismic responses of bridge structures with KDampers

KDamper has been applied to control the seismic responses of bridge structures very recently. However, previous studies considered its performance under uniform ground motions only, the influence of the inevitable spatially varying ground motions (SVGMs) is not yet explored. To address this issue, this study systematically investigates the seismic responses of a large-span bridge structure equipped with KDampers subjected to SVGMs. In particular, the analytical model of a classical bridge equipped with KDampers is developed, and the corresponding dynamic equations of motion are formulated. Subsequently, KDampers are optimized by minimizing the mean peak response of the bridge deck in the frequency domain. Finally, parametric analyses are performed to comprehensively evaluate the influence of SVGMs (including wave passage and coherency loss effects) on the seismic responses of the bridge in both the frequency and time domains. The analytical results reveal that the optimized KDampers are effective in reducing the displacement and absolute acceleration responses of the bridge. Moreover, the effectiveness of KDampers is more evident when SVGMs are considered as compared to the uniform ground motions. This research can contribute to an in-depth understanding of the control effectiveness of KDampers, especially for the cases considering SVGMs.

Justification of the parameters of regulationof forces for steel-reinforced concrete span structures from project “43282 km” by TSNIIPSK

Steel-reinforced concrete spans in road bridges have been widely used since the late 1950s, in the configuration of large-span bridges built across significant water barriers. To date, the issue of the need to reconstruct such span structures, including those designed and built according to the project “43282 km” developed by TsNIIPSK, is becoming increasingly relevant. The authors analyze the stages of the production of works of a particular object, developed for the implementation of the entire complex of works on its reconstruction using the method of force regulation. The presented order of work was successfully implemented during construction of the bridge over Kabarga River in Primorsky Krai. This made it possible to preserve the existing structure of the span (main beams and braces), replacing the worn-out reinforced concrete slab with a new - metal orthotropic one, while ensuring that the conditions of strength and stability of the flexural-torsional shape of solid-walled beams are met, in the process of dismantling the existing roadway slab and constructing a new one. Considering that steel-reinforced concrete bridges are built across large water barriers and have a very significant cost due to their large length, reconstruction using existing supports can significantly reduce the cost of construction, so, the possibility of upgrading the existing steel-reinforced concrete span structure is, undoubtedly, relevant. Based on the structural and technological measures presented by the authors, it is possible to carry out and effectively implement work on the reconstruction of the existing steel-reinforced concrete bridges that do not fully meet modern requirements for load capacity and throughput.

Numerical Analysis on Spanwise Correlation of Vortex-Induced Force of Split Double-Box Beam

The vortex-induced force of bridges is not synchronized along the span direction. The spatial correlation of vortex-induced force becomes obvious when the span of the bridge structure gradually increases, and the mass gradually decreases. Therefore, it is important to study the spanwise correlation of vortex-induced forces of long-span bridges to ensure the accuracy of the prediction of vortex-induced vibration response of bridges. The study established and improved the theory and experimental research methods for vortex-induced vibration analysis of large-span bridges by discussing the spanwise correlation during vortex-induced vibration of the split double-box beam. Taking Xihoumen Bridge as the object, two-dimensional (2D) and three-dimensional (3D) numerical models of the scaled-down sections were designed and established based on the ANSYS Fluent platform and the RANS SST turbulence model. Based on the Newmark-β algorithm, a User Defined Function (UDF) was written for vortex vibration calculation, the three-dimensional bypass of the split double-box beam in static conditions and vortex-induced vibration of the split double-box beam of which were calculated, and the spanwise correlations of the aerodynamic coefficients, the surface pressure coefficients, and the wake wind velocity of the main girder section were analyzed for the static and vibration states of the bridge. The results show that the self-excited force of the split double-box beam in vortex-induced vibration improved its spanwise correlation. Compared with those in a static state, the spanwise correlation of the lift coefficient and torque coefficient increased by 55% and 87%, respectively, and the resistance coefficient increased by more than 10 times. The correlation of the pressure coefficients increased by 153%. The correlation of wake wind velocity increased by 37% in the along-wind direction and that in the across-wind and vertical-wind direction increased by more than 10 times. The accuracy of the numerical simulation results was verified by comparing the pressure distribution and pressure spanwise correlation of the main beam with field-measured data.

The Train-Bridge Coupled Vibration Analysis of a Long-Span Prestressed Concrete Continuous Beam Bridge under Creep Deformation Effect

The track smoothness of high-speed railroads is severely limited to ensure train performance. The concrete continuous girder bridge is deformed to influence the smoothness of the bridge decks and track caused by creep bulge. There is a need to research the impact of beam creep on the dynamical response of bridge and train operation safety. This paper used Midas software to calculate the long-term deformation of large-span prestressed concrete continuous beam bridges under concrete creep and shrinkage. The train-bridge coupled system was established by adopting self-programming software. Thereafter, the large-term deformation results of the main girder are considered as track irregularity input into the vibration equation of the train-bridge system. The safety of the train operation was evaluated by calculating the dynamic response of the bridge and analyzing the criteria of train running safety. It was shown that the indicators of the large-span bridge are within the allowable code values under all working conditions. The bridge deformation under creep has an impact on the displacement and acceleration response of the bridge when a high-speed train passes through. There is no noticeable impact of creep deformation on the operational performance of trains. Nevertheless, the criteria for assessing the safety of trains’ operation, such as derailment factor, wheel load differences, lateral wheel forces, and vehicle acceleration, have been increased.

Eccentrically loaded concrete-filled steel tubes made with high strength materials

High-strength welded steel sections filled with high-strength concrete, so called high-strength concrete filled steel tubes (HSCFSTs), are widely used in multi-story buildings and large span bridges to achieve superior structural performance with optimized cost. Many experimental and numerical investigations have been conducted on the behaviour of small and large scale HSCSFTs under centric axial compression. However, very few studies have investigated the response of large scale HSCFSTs under eccentric loads. This paper presents an experimental investigation conducted on five square HSCFSTs that are 2.7 m height under eccentric axial compression. The effects of loading eccentricity and depth-to-thickness ratios on the behaviour of HSCFST columns were investigated. The experimental results reveal that the failure mode of HSCFSTs was governed by local buckling of the steel tube in all cases. A finite element model was also developed in ABAQUS and was validated against the test results. Sensitivity and parametric studies that investigate the effect of various parameters of the concrete damaged plasticity model, imperfections, concrete and steel strengths, load eccentricity and plate slenderness are also presented.

A Novel Low-Cost GNSS Solution for the Real-Time Deformation Monitoring of Cable Saddle Pushing: A Case Study of Guojiatuo Suspension Bridge

Extreme loadings, a hostile environment and dangerous operation lead to the unsafe state of bridges under construction, especially large-span bridges. Global Navigation Satellite Systems (GNSS) tend to be the best choice for real-time deformation monitoring due to the significant advantage of automation, continuation, all-weather operation and high precision. Unfortunately, the traditional geodetic GNSS instrument with its high price and large volume is limited in its applications. Hence, we design and develop low-cost GNSS equipment by simplifying the monitoring module. The performance of the proposed solution is evaluated through an experimental dynamic scenario, proving its ability to track abrupt deformation down to 3–5 mm. We take Chongqing Guojiatuo Suspension Bridge in China as a case study. We build a real-time low-cost GNSS monitoring cloud platform. The low-cost bridge GNSS monitoring stations are located at the top of the south and north towers, midspan upstream and downstream respectively and the reference station is located in the stable zone 400 m away from the bridge management buildings. We conducted a detailed experimental assessment of low-cost GNSS on 5 April and a real-time deformation detection experiment of the towers and main cables during the dynamic cable saddle pushing process on 26 February 2022. In the static experiment, the standard deviation of the residual using the multi-GNSS solution is 2 mm in the horizontal direction and 5 mm in the vertical direction. The multi-GNSS solution significantly outperforms the BDS/GPS single system. The dynamic experiment shows that, compared with the movement measured by the robotic total station, the horizontal error of the south tower and north tower measured by low-cost GNSS is below 0.005 m and 0.008 m respectively. This study highlights the potential of low-cost GNSS solutions for Structural Health Monitoring (SHM) applications.

Experimental and analytical investigation on precast concrete-encased concrete-filled steel tube column-to-column dry connections under axial tension

Precast technologies featuring rapid construction and reduced on-site manpower have been gaining widespread adoption in the construction industry, particularly in reinforced concrete (RC) structures and composite steel–concrete structures over the past few decades, due to rising labour cost. However, to date, no workable precast connections have been developed for concrete-encased concrete-filled steel tube (CECFST) columns, which are increasingly used in ultra high-rise buildings and large-span bridges owing to its superior structural performance and excellent fire resistance. In this regard, to promote applications of CECFST columns in countries with increasing labour cost, this study develops two innovative precast CECFST column-to-column dry connections (PCDCs), through which the construction of CECFST structures would minimise heavy on-site work, such as welding or grouting of joints, formwork, and propping systems. Ten laboratory tests including four component tests and six column-to-column connection tests, were conducted to investigate tensile performance of the developed PCDCs. Key test results of all the ten specimens, such as load versus deformation relationships and failure modes, showed that the PCDCs had excellent tensile resistance and ductility. Furthermore, this paper carried out a series of theoretical analyses to quantify the ductility and tensile strength of the PCDCs through proposed load transfer mechanisms and component-based models. The design method of the PCDCs was presented by a simple flowchart and a worked example. With excellent structural performance, the PCDCs developed in this paper demonstrated huge potential to replace conventional cast-in-place (CIP) connections of CECFST columns.

Gap effects on the aerodynamic characteristics around three rectangular boxes in tandem arrangement

Multiple-box structures have become increasingly important in practical engineering; for example, some recent large-span bridges were creatively designed using triple-box decks. The flow characteristics and flow-induced responses of multiple-box structures are notably complex due to the existence of gaps. Herein, we conducted a detailed investigation on the effects of gap width on the aerodynamics and flow characteristics of three boxes in a tandem arrangement, that is, a triple-box model. The test model comprised three rectangular cylinders with a side ratio of 3.7 (i.e., SR = 3.7), and it was arranged in line with the incoming airflow. The gap ratio (L/D = the ratio of the gap width L to the height of the box D) was varied from 0 to 10.260. Surface pressure measurement and smoke-wire flow visualization were conducted in the wind tunnel tests. For the pressure measurements, the Reynolds number (Re) was varied from 1.01 × 104 to 2.20 × 104. The smoke-wire flow visualization was performed at a relatively low Re of 6767. The results showed that the gap ratio significantly influenced the pressure distributions, aerodynamic forces, and surrounding flow patterns. A “dual-frequency” phenomenon was observed at low and moderate gap ratios; that is, a dominant frequency and secondary frequency were found. Moreover, the secondary frequency was closely related to the secondary vortices. Furthermore, the dual-frequency phenomenon disappeared at large gap ratios, which was different from the tandem circular cylinders. Based on the experimental results, the flow patterns around the triple-box model were categorized into four basic types, depending on the gap ratio.

Optimum design of the long‐span continuous steel truss rail beams of straddle monorails

To understand the influences of beam height and side-to-midspan ratio on the mechanical characteristics of straddle monorail large-span continuous steel truss rail beams, the first phase of Wuhu Rail Transit Line 2, a section of continuous steel truss rail beams, is taken as the engineering background. The specific numerical values of the beam heights and side-to-midspan ratios of some large-span bridges, which have been built in China and abroad, are analyzed and counted. Combined with the unique characteristics of continuous steel truss rail beams, the two design variables of side-to-midspan ratio and beam height are scientifically valued. The two-variable direct grid search method is used, and the finite element software Midas Civil is employed to calculate and analyze the mechanical properties of the selected structural system. The main beam deflection, vertical fundamental frequency, beam end corner, and six other aspects are taken as the research focus of the optimization analysis. The above six aspects coordinate bridge strength, stiffness, and stability. They also consider comprehensively and enhance the scientificity of the results. Data indicate that when the side-to-midspan ratio and beam height are small, it is beneficial to the structural stress and deformation. However, to prevent the occurrence of the reaction force of the support, the side-to-midspan ratio should be greater than 0.2; when the beam height is constant, the ratio increases from 0.56 to 0.74, and the safety factor increases by about 14%. The side-to-midspan ratio of 0.56 and the beam height of 1.86 m are the recommended solutions. The scheme features reasonable structural stress and deformation, material saving, and low cost.

Track–Bridge Interaction of CWR on Chinese Large-Span Bridge of High-Speed Railway

The track–bridge interaction is a fundamental concern in the field of railway engineering, which plays an important role in the optimization design of railway bridges, especially for heavy-haul railway and high-speed railway bridges. This paper systematically introduces the research status of the CWR track–bridge interaction for large-span bridges of high-speed railway in China. The evolution process of the track–bridge interaction model from the simplest elastic bar and linear longitudinal resistance model to the complex beam–rail interaction model considering the loading history is described. In this paper, the modeling methods of the track–bridge interaction model for five types of long-span railway bridges, namely simply supported beam bridge, continuous beam bridge, cable-stayed bridge, arch bridge, and suspension bridge, are systematically introduced, and the characteristics of longitudinal force distribution under the track–bridge interaction are analyzed. This paper discusses the practical application of the theory of the track–bridge interaction on extra-large-span bridges from the aspects of system dynamic performance evaluation and system safety evaluation. The practical application of track–bridge interaction theory under special conditions such as earthquake load, complex temperature load, shrinkage and creep load, and superposition of multiple loads is emphasized. It provides guidance for the further improvement of the track–bridge interaction model and the design of large-span high-speed railway bridges in the future.

Numerical Study on the Buckling Resistance of High Strength Steel Columns and Beam‐columns

AbstractThe rising interest in the use of high strength steel (HSS) materials is justified by several advantages that they provide. In the field of construction, their benefits range from streamlined and elegant structures to lower CO2 emissions and energy consumption. High‐rise buildings and large span bridges can be designed with smaller foundations and less structural weight, since the application of HSS makes the design with slender steel sections possible. However, special attention should be given to the stability of the compressive members since the buckling resistance generally governs their design. The existing codes to evaluate the capacity of HSS columns and beam‐columns are based on rules from experimental tests related to normal strength steel (NSS) materials, which is responsible for inconsistencies. Therefore, this current work aims to present a numerical model created and validated to evaluate the major‐ and minor‐axis flexural buckling of HSS welded I‐section columns and the combined flexural and lateral‐torsional buckling of HSS welded I‐section beam‐columns. In the following, a parametric study is also conducted, in which different cross‐sections, normalized slenderness, steel grades (from S460 up), bending moment distributions and application of restraints are considered. Finally, a comparison between the European design rules and the resistances from the Finite Element model is led, evidencing the underrating expressed by the code with a level of safety even higher when superior steel grades are evaluated.

Performance Alarming for Stay Cables Based on a Frequency–Deformation Relationship Model

Stay cables are vital load-bearing components of cable-stayed bridges that are prone to corrosion and fatigue. Damaged or deteriorated cables can endanger the safety of bridges. In this paper, a performance alarming method for stay cables based on a frequency–deformation relationship (FDR) model is proposed. First, the FDR model, which represents a normal relationship between the frequency and the deformation of a certain intact cable, was established according to the stress–strain relationship of the cable. Second, the performance alarming for a stay cable was realized by constructing a mean value control chart for the estimation error of the baseline FDR model, followed by an implementation procedure for the early warning method. Last, the long-term monitoring data of a large-span bridge are utilized to validate the effectiveness of the performance alarming method. The results demonstrate that the modeling and prediction capabilities of the proposed FDR model are satisfactory and that the performance alarming for stay cables can be carried out effectively by the proposed method.

Structural Stability Analysis of Eye of the Yellow Sea, a Large-Span Arched Pedestrian Bridge

To date, scholars’ research on the stability behavior of the arch structure mainly focuses on solid–web section arches, steel tubular truss arches and concrete-filled steel tubular arches, but the stability behavior of the novel spatial grid arch structure, which integrates the characteristics of grid structure and arch structure, is not yet clear. Based on the Eye of the Yellow Sea pedestrian bridge project in Rizhao, China, the stability behavior of this large-span spatial grid arch structure was studied, in this paper, by the project’s structure design team. The project is a glass covered steel arch pedestrian bridge with a span of 177 m, a height of 63.5 m, an elliptical section with a long axis of 18 m, and a short axis of 13.5 m. The elastic and the nonlinear elasto-plastic stability behavior considering different initial geometric imperfections, was analyzed by the ABAQUS finite element model. The buckling modes and the full-range load-displacement curve of the structure were analyzed, and the stress distribution, deformation mode and overall structural performance during the whole loading process were analyzed. The effects of initial imperfections, geometric nonlinearity and material nonlinearity on the ultimate load-carrying capacity of the structure were studied. The stability behavior of large-span spatial grid arch structure was studied in this paper, which provides an important reference for the design and analysis of such structures.

Experimental and numerical flexural buckling resistance of high strength steel columns and beam-columns

The use of high strength steel (HSS) has been consolidated around the world because of its numerous advantages mostly for high-rise buildings and large span bridges. As it provides the possibility of a design with slender sections, substantial reduction in the structure weight is expected, but special attention should be given to the stability of the HSS compression members. However, the existing design codes for HSS columns are limited and based on experimental data related to normal strength steel (NSS) materials, which is responsible for an inaccurate resistance prediction. In this sense, the present paper aimed to investigate the buckling behavior of S690 HSS welded I-section columns failing by flexural buckling around the both principal axes and beam-columns failing by lateral torsional buckling. The experimental campaign contemplated 4 pin-ended columns, in which 2 were tested about their major-axis and the other 2 about the minor-axis, and also 2 beam-columns, including supplementary experimental to measure the geometric imperfections, residual stresses and material properties of the S690 welded I-section columns and beam-columns. In the following, a numerical model was built and validated against the experimental results and afterwards employed to perform a sensitivity study considering different membrane residual stress patterns. Finally, the European [1,2], American [3], and Australian [4] codes were assessed by comparing the design resistances with the results from the experimental tests and the collected test data of relevant studies, showing in general a considerable level of conservatism.

Multi-index probabilistic anomaly detection for large span bridges using Bayesian estimation and evidential reasoning

To measure uncertainties within anomaly detection and distinguish sensor faults from anomalous events, a multi-index probabilistic anomaly detection approach is proposed for large span bridges based on Bayesian estimation and evidential reasoning. To avoid false detection raised by signal spikes, an energy index is first defined and extracted from pre-processed measurements, including missing data recovery and thermal response separation. Then, a probabilistic index, namely, certainty degree, is derived from probability density functions of detection triggers – extreme values predicted by using Bayesian estimation of the generalized Pareto distribution. To distinguish sensor faults from anomalous scenarios, evidential reasoning is applied to incorporate multiple certainty degrees into a joint one under the assumption that the probability of multi-sensor failing simultaneously is extremely low. Specifically, a large joint certainty degree indicates a high occurrence probability of anomalous scenarios, while a small one together with a large individual certainty degree depicts a high probability of sensor faults. Finally, the effectiveness of the proposed anomaly detection method is validated through structural health monitoring data from the Nanjing Dashengguan Yangtze River Bridge. Measurements from four sensors, that is, three cable forces and one deflection, are selected to detect anomalies based on their high pair-wise correlations. Two case studies are presented, namely, sensor fault detection and snow disaster detection. The sensor fault is detected through a certainty degree of almost 100% for the individual index and a joint certainty degree of nearly 0. The snowstorm is detected by a joint certainty degree of 36.82%.

Dynamic amplification factor of multi-span simply supported beam bridge under traffic flow

Simply supported bridges occupy the majority of bridges. Compared with the flexible large span bridges, Dynamic Amplification Factor (DAF) of them is relatively large and attracts lots of studies. However, most of these studies are focused on the simplified condition that a single vehicle passes through a single span bridge. In general, the bridge bears complex traffic flow rather than a single vehicle. The vehicle type and dynamic loads on the bridge are thus dispersed. It is necessary to explore the multi-vehicle effects on the DAF caused by the complex traffic flow. Also, adjacent spans of a multi-span simply supported beam bridge may have continuous dynamic effects on the vehicles. In this regard, the DAF of a simply supported bridge considering the multi-vehicle and multi-span effects are explored numerically based on the coupling dynamic analysis of traffic flow and bridge, which can also consider the acceleration and deceleration of the vehicles. Cellular Automata (CA) method is used to simulate the traffic flow. It is found that the worse the driving condition of the road roughness, the greater the DAF. When road roughness is Class C, the DAF exceeds the values of American and Chinese codes. Under the action of traffic flow, DAF of the first span of the multi-span simply supported beam is larger than that of the span under the single vehicle. Only considering the effect of a single vehicle may underestimate the dynamic impact on the bridge. Sparse traffic flow has a larger DAF than moderate traffic flow and dense traffic flow in the statistic meaning of the multi-span, because the driving speed of sparse traffic flow is closer to the resonant speed of the bridge and the vibration disharmony of multi-vehicles is smaller. The greater the deceleration of the traffic, the greater the dynamic impact on the bridge.