Pier Height Research Articles

Application of Digital Image Correlation to Field Monitoring of Masonry Arch Bridges

Many masonry bridges constructed in Europe during the Industrial Revolution are still in service. For over a century, continuous operation and weathering effects have contributed to material degradation in the main bridge components. To ensure that old masonry bridges remain safe even under increasing traffic loading, it is crucial to identify potential deterioration in bridge performance before the onset of critical irreversible damage. This task can be accomplished via periodic monitoring of the bridge response under traffic loading. Digital Image Correlation (DIC) is an effective non-contact method to measure displacements and strains. Most DIC applications have been in laboratory settings, and DIC techniques have yet to be extensively applied in the field. This paper showcases the potential of DIC monitoring for serviceability assessment of masonry bridges. Some results of an extensive monitoring program on railway viaducts in the UK are presented. Structures with different geometrical characteristics, including pier heights, span lengths, and span-to-rise ratios, have been investigated. The results obtained using specific targets attached to the monitored structures or using the actual masonry texture as natural targets have been compared; consideration is also given to the influence of camera characteristics and settings. A significant impact of the camera depth of field has been established, especially when measuring deflections at different locations on the intrados of the arch barrel.

Seismic Risk Analysis of Existing Link Slab Bridges Using Novel Fragility Functions

In this paper, a comprehensive probabilistic framework is proposed and adopted to perform seismic reliability and risk analysis of existing link slab (LS) bridges, representing a widely diffused structural typology within the infrastructural networks of many countries worldwide. Unlike classic risk analysis methods, innovative fragility functions are used in this work to retrieve more specific and detailed information on the possible failure modes, without limiting the analysis to the global failure conditions but also considering several intermediate damage scenarios (including one or more damage mechanisms), and providing insights on the numerosity of elements involved within a given damage scenario. Reliability analyses are performed on a set of LS bridges with different geometries (total lengths and pier heights) designed according to the Italian codes enforced in the 1970s. Accurate numerical models are developed in OpenSees and Multiple-Stripe nonlinear time–history analyses are carried out to build proper demand models, from which fragility functions are determined according to two limit states: damage onset and near-collapse. Mean annual rates of exceeding are thus estimated through the convolution between the hazard and the fragility. The results shed light on the main failure mechanisms characterizing this bridge typology, highlighting how different levels of risk (hence safety margins) can be associated with failure scenarios that differ in terms of elements/mechanisms involved and damage extension. Such a higher level of detail in the risk analysis may be useful to better quantify post-earthquake consequences (e.g., costs and losses) and define more tailored retrofit interventions. A comparison of the reliability levels associated with bridges of the same class with different geometries is finally presented.

Investigating earthquake-induced irregularity based on post-earthquake running performance analysis of track-bridge system

In evaluating post-earthquake damage to track-bridge systems, this study conducts nonlinear time history analysis on the CRTS II ballastless track simply-supported beam system subjected to transverse earthquake loading and explores the characteristics of residual displacement and stiffness degradation of the track-bridge system under transverse earthquakes. The effect of the earthquake-induced stiffness degradation of track-bridge systems on the dynamic performance of high-speed trains is investigated, and earthquake-induced dynamic irregularities are constructed to quantify the overall stiffness degradation degree of the track-bridge system. Furthermore, a reconstruction method for the earthquake-induced dynamic irregularity characteristic curve is proposed, considering probability guarantee rates. The research results indicate that the earthquake-induced dynamic irregularity can effectively quantify the running performance degree of high-speed trains under earthquake-induced stiffness degradation conditions. The transverse acceleration and derailment coefficient of high-speed trains increase as the ground motion intensity rises. The amplitude of the characteristic curve grows significantly with the increase in pier height.

Influence of Variable Height of Piers on the Dynamic Characteristics of High-Speed Train–Track–Bridge Coupled Systems in Mountainous Areas

With the increase in the occupancy ratio of bridges and the speed of trains, the probability of trains being located on bridges during earthquakes increases, and the risk of derailment increases. To investigate the influence of unequal-height piers on the dynamic response of high-speed railway train bridge systems, a seismic action model of high-speed train–track–bridge dynamic systems was established based on the in-house code using the finite element method and multi-body dynamics method. It is found that (1) compared to equal-height piers, the peak lateral dynamic response of unequal-height piers (with gradually increasing pier heights) decreases, while the peak vertical dynamic response increases; (2) the peak lateral dynamic response of unequal-height piers (with a steep increase in pier height) increases sharply, while the peak vertical dynamic response decreases; and (3) the safety indicators of equal-height piers are significantly superior to the two unequal-height pier operating conditions.

Safety of an express freight train running over a bridge in crosswind

Owing to the blunt car body and high design speed of express freight trains, the running safety is significantly affected by crosswinds when the train runs over a bridge; moreover, severe accidents, such as derailment or overturning may occur. Therefore, adequate measures should be adopted to avoid the occurrence of such accidents. In this study, a finite element model of the train, ballastless track, and parameterized 5-span simply supported girder bridge along with modal superposition method are adopted to establish the train-track-bridge coupling dynamic system. Numerical simulation of stochastic wind speed, wind tunnel tests, and computational fluid dynamics (CFD) simulation of vehicle-bridge scale model were conducted to calculate the wind load acting on the train and bridge. The dynamic responses of the bridge and train were evaluated to present the diagrams of wind and train speed limits for safe operation. The results indicated that the running safety of the vehicle declined with the wind and train speeds, and the wheel unloading rate was the most sensitive to wind speed. For safe operation, the train speed must be restricted if the mean wind speed is greater than 22.7 m/s, and an extreme scenario of derailment may occur for a mean wind speed of 34.0 m/s. In addition, the wind speed limit should be appropriately adjusted and improved according to the pier height of the bridge and terrain category. This research provides a theoretical basis and data support for the assessment of safety of express freight trains in actual operation.

Study on the pier bottom self-centering seismic isolation structure of the high-pier continuous rigid frame bridges

Four seismic isolation specimens were designed, fabricated, and subjected to physical loading tests to enhance the seismic performance of a high-pier continuous rigid-frame bridge. A finite element model of the seismic isolation structure of the high-pier was established using numerical simulation software. The entire bridge model was established based on the multi-scale modeling method to investigate the seismic response of the high-pier continuous rigid frame bridge under different seismic waves. The results indicate that the seismic isolation pier has self-centering and energy dissipation capabilities. The seismic isolation pier has satisfactory energy dissipation capacity and ductility when the ratio of the long-axis and short-axis radii is 1.5. The results of the finite-element simulation corresponded well with the experimental results. Significant damage occurred to the concrete at the bottom and corner of the pier, and the reinforcement did not reach its yield strength throughout the loading process. Therefore, measures must be implemented to ensure the seismic performance of the structure. The pier bottom self-centering seismic isolation structure effectively absorbs shocks, as evidenced by reduced absolute acceleration and relative displacement at the pier top, decreased shear force and bending moment at the pier bottom, and minimized girder displacement. It was recommended that the ratio of the long-axis and short-axis radii be adopted as 1.5–2.0 and that the pier height be selected as 60 m–100 m. These results provide a reference for the research and applications of this type of structure.

Multivariable probabilistic seismic demand models for parametric fragility prediction of isolated bridges portfolios under pulse-like GMs

The wide application of friction isolation bearings has led to a rapid increase in the number of frictional isolated bridges. Therefore, the traditional method of seismic fragility analysis based on nonlinear time-history analysis (NLTHA) may not suitable for bridge portfolios. For this purpose, this study developed a multivariable probabilistic seismic demand model (MV-PSDM) for friction isolation bearings conditioned on the earthquake parameters (peak pulse velocity, pulse period), bearing parameters (effective radius) and pier parameters (bending stiffness, pier numbers, pier height), in which a novel formula is adopted to calculate the seismic demand and the dispersion is also estimated. This MV-PSDM can be applied to investigate the influence of various parameters (earthquake parameters, friction bearing parameters, pier parameters) on the seismic demand, sensitivity and the vulnerable range of the bearing. Finally, an efficient parametric fragility prediction method for friction isolation bearing is proposed based on the MV-PSDM, and the flow chart is also provided. In this method, only earthquake parameters, bearing parameters and pier parameters are required to obtain the seismic fragility of friction isolation bearings, which avoids the FE modeling and NLTHA.

Design loads and integrated performance metrics for highway bridges impacted by heavy vehicles

Current prescriptive design provisions adopt a constant impact design load to address vehicular collisions to bridge piers. This practice can account for neither the vehicle characteristics nor the pier’s structural properties, which may render the existing highway bridges vulnerable to accidental heavy vehicle collisions. To address this limitation, the first objective of this article is to develop a predictive model to efficiently link the impact design load with influential structural and vehicular parameters. An essential step to achieve this objective is to use validated finite element modelling approaches to obtain the impact force-time history response for vehicle-bridge collision events with varying structural and vehicular characteristics. Statistical techniques are employed for optimal model determination. As an alternative to the prescriptive design, the performance-based approach features the ability to explicitly define structural collision safety and deliver efficient design solutions. Two complementary performance metrics (percentage loss of axial capacity and the ratio of the maximum relative displacement at the impact location to the pier height) are proposed to characterize collision-induced damage in an objective manner. The integration of these two metrics into collision performance assessment makes it possible to quantify the capacity of a bridge to resume its normal operation after collision incidents.

Reduction of the Longitudinal Seismic Response of High-Speed Railway Multi-Span Simply-Supported Bridges by the Track Constraint

ABSTRACT The longitudinal seismic response reduction in railway bridges is worthy of attention because it relates to the engineering cost. It is difficult to further explore the reduction effect because the complexity of traditional analysis model leads to the low efficiency in parametric analysis. In this paper, the track structure was simplified, and a simplified calculation model was established. The parametric analysis considering the span number and pier height on the simplified model seismic responses was carried out. The results showed that the reduction effect was extensive and there was a great internal force transferred to the subgrade-track structure.

Study on Seismic Performance Optimization of Assembly Concrete-Filled Steel Tubular (CFST)-Laced Piers

This study aims to investigate the seismic behavior of concrete-filled steel tubular (CFST)-laced piers; after verifying the model through engineering tests, the simplified finite element models (S-FEM) and refined ones (R-FEM) with CFST-laced piers are developed in this manuscript, respectively. Through comparison, it is found that the S-FEM can effectively improve analyzing efficiency while meeting the requirements of engineering analysis accuracy. In addition, the seismic response of assembled flange-connected CFST-laced piers bridge was studied based on the S-FEM, and different structural parameters, including pier height, axial compression ratios, steel ratios of CFST columns, steel lacing tube arrangement, and longitudinal slope, are considered to optimize the bridge design scheme. Results indicate that the parameters of 0.1 axial pressure ratios and 1:30 longitudinal slope show superior seismic performance. Meanwhile, the peak axial force and peak bending moment of CFST column limbs occur at the pier bottom, and the flanges, which are subject to larger bending moments, are generally located at the two connection positions above the pier bottom.

Safety analysis of train-track-bridge coupled braking system under earthquake

Bridges represent a significant proportion of high-speed railway (HSR) lines in China, and high-speed trains operate on these structures for prolonged periods. Consequently, the occurrence of an earthquake during a train crossing is a probable event. With the support of the existing communication technology, the train will receive a warning in advance and brake urgently when the earthquake hits the train. However, research on the response of high-speed trains traversing bridges during an earthquake is scarce. To address this research gap, a three-dimensional train-track-bridge coupled braking system (TTBCBS) is developed using the finite element method and multibody dynamics, and the system’s motion equation is derived. Furthermore, the system is then programmed using mathematical software, and dynamic analysis is performed using different parameters such as friction coefficient and pier height under train braking and earthquake. Finally, the calculated train and bridge responses are evaluated based on safety indices, which provide evaluation standards for train running safety (TRS). However, it is found that the response of both the train and the bridge is smaller when the train is braking under earthquake, which is advantageous for the response of the TBCBCS system.

Field and laboratory experiments on performance of double-pile substructure of bridge along slope strike

This study aims to investigate the performance of the double-pile substructure of the bridge along the slope strike utilizing field and laboratory experiments. In the field experiments, the bending moment profiles of piles increase from negative to positive and then decrease to zero as the depth increases, significantly differing from those of portal anti-slide piles in slope engineering and monopiles in bridge engineering. Furthermore, the profiles of front and rear piles differ in magnitude and the locations of maximums, and it is mainly caused by the load redistribution at the tie beam and different extra earth pressures. After the field experiments, the laboratory model experiments were conducted to investigate the effects of slope angles, pier heights, and loading patterns (i.e. vertical load, lateral load, and surcharge) on the performance of the double-pile substructure. These experimental results were employed to present some fitting formulas for predicting the bending moment profiles and validate two simplified theoretical methods, however, these formulas and methods have their limitations and thus preferable methods are required in the subsequent work.

Seismic Resilience Assessment of Curved Reinforced Concrete Bridge Piers through Seismic Fragility Curves Considering Short- and Long-Period Earthquakes

Curved bridges are commonly used for logistics and emergencies in urban areas such as highway interchange bridges. These types of bridges have complicated dynamic behaviors and also are vulnerable to earthquakes, so their functionality is a critical parameter for decision makers. For this purpose, this study aims to evaluate the bridge seismic resilience under the effects of changes in deck radius (50, 100, 150 m, and infinity), pier height irregularity (Regular and Irregular), and incident seismic wave angle (0°, 45°, and 90°) under short- and long-period records. In the first step, fragility curves are calculated based on the incremental dynamic analysis and probabilistic seismic demand models. Finally, seismic resilience curves/surfaces are constructed and their interpolated values of the log-normal distribution function presented for assessing system resilience. It is found that when long-period records are applied in one given direction, the angle of incidence has the most significant effect on seismic resilience, and bridges are most vulnerable when the angle of incidence tends to 0°. The effect of deck radius on seismic resilience became more remarkable as the angle of incidence increased. Additionally, results indicate that the bridge vulnerability in long-period records is more significant than that under short-period records.

Numerical investigation on the dynamic behavior of UHPFRC strengthened rocking concrete bridge piers subjected to vehicle collision

The nonlinear dynamic responses of UHPFRC-strengthened monolithic and rocking concrete bridge piers with different configurations including the rocking monolithic pier (RMono), rocking segmental piers with four (RSeg4), and eight (RSeg8) are numerically investigated in this study. Different rocking piers subjected to vehicle collisions with variations of the UHPFRC cover thickness (tU), length (LU), and its strengthening scheme are investigated using finite element (FE) simulations in LS-DYNA. From the evaluation of the piers constructed with normal concrete (NC) under different Vimp, it was found that the segmental piers experience higher recoverability and lower peak impact and internal forces compared to the Mono and RMono piers, however, they suffered more severe concrete spalling at the corners and edges of the segments due to the segment’s slippage. Also, the RMono pier demonstrates better impact resistance with a displacement recoverability of 55% against a high-velocity vehicle impact with Vimp = 140 km/h and withstands collapse compared to the total collapse of the Mono and segmental piers. In addition, it is found that the increase of tU from 80 mm to 160 mm had a more positive effect on the impact resistance and damage mitigation of the Mono and the RMono piers than its effect on the performances of segmental piers. As a result, the residual displacement of the RMono pier decreased by 60% while enhancing its residual shear force by 33%, and the residual bending moment by 64%. Also, the residual displacements of the RSeg4 and RSeg8 piers decreased by 75% and 80%. The Mono pier with Scheme-2 and a UHFRC cover of 80 mm resulted in lower impact force by 42%, lateral displacement by 43%, peak shear force by 22.5%, and bending moment by 31% than those of Scheme-1. Besides, the use of UHPFRC cover for the column-footing and column cap-beam connections in addition to the whole height of the RMono pier (Scheme-3) significantly reduces the concrete spalling damage level at the column base. Moreover, it is found that the use of UHPFRC for all the edges of the column segments in addition to the bottom zone of the RSeg4 and RSeg8 piers (Scheme-4) considerably mitigates the spalling damages and enhances the recoverability of the segmental piers by 67% and 63%, respectively compared to performances of these piers when using Scheme-1 and Scheme-2.

An Analytical Algorithm for Determining Optimal Thin-Walled Hollow Pier Configuration with Sunlight Temperature Differences

Formulas for computing the line shape of a thin-walled hollow pier body based on structural characteristics and measured sunlight temperature difference are derived using an analytical algorithm. In a case study of the No. 5 pier of a newly constructed continuous beam bridge on a mountainous expressway of Guizhou Province in China, the pier top’s displacement calculated by the analytical algorithm, currently accepted code, and a FEM program were each compared to its measured values. Furthermore, the effects of sunlight temperature difference, pier height, and wall thickness on the line shape of the pier body were explored, and the results show that the calculation values from these formulas were closer to the measured values than the currently accepted code, with a maximum error of 0.507 mm, demonstrating that the formulas have a more dependable result, higher precision, and more specific applicability. Thus, the algorithm provides a better method for the line shape calculation and construction control of thin-walled hollow piers because it can accurately account for sunlight temperature differences and pier height.

Comparative Analysis of Isolation Effects of Laminated Rubber Bearing and Composite Rubber Bearing Used in Bridges with Different Pier Heights

In order to reveal the vibration isolation performance of new composite rubber bearings (CRBs), this paper establishes a numerical model of composite rubber bearings based on SAP2000, and studies the seismic response of bridges supported by LNB and CRB at different pier heights. The results show that compared with LNB, CRB can effectively reduce the shear force and bending moment of the pier without increasing the structural displacement.Compared with LNB, the advantages of CRB in isolation performance vary little with pier height, which indicates that CRB has broad application prospects..

Residual Deformation-Based Performance Evaluation Method for CFST Piers Subjected to Vehicle Collision

Concrete-filled steel tubular (CFST) piers have been applied in bridge structures due to their high bearing capacity, good ductility, and light weight. During their service life, CFST piers may suffer vehicle collision. Nevertheless, there is still a lack of a performance evaluation method for CFST piers subjected to vehicle impact. Therefore, this paper presents a residual deformation-based method to evaluate the performance of CFST piers under truck impact. Before that, a numerical model was developed to simulate responses of CFST piers under truck collision and validated by reported impact tests. Then, the performance levels of 6- and 12-m high CFST piers under 20 and 40 ton and 60, 100, and 140 km/h truck collisions were numerically investigated. Afterwards, a residual deformation-based performance evaluation method was proposed based on the numerical investigations. In this method, the ratio of the residual lateral deflection at the mid-height to half of the pier height was first selected as the evaluation index. Then, threshold values of the evaluation index at different performance levels were determined. Finally, an analytical model for the evaluation index was developed. Comparisons indicate that the analytical performance levels are in good agreement with the numerical results. The proposed residual deformation-based performance evaluation method can be used for design and accident analysis of CFST piers subjected to truck collision.

Preliminary results of parametric study of structural behaviour of Persian brick masonry groined multipartite (Tarkin) vaults

In this paper, the structural behaviour of Persian brick masonry groined quadripartite, sexpartite and octopartite vaults is studied. Three different spans, three different pier heights and three different pier widths adopted from real structures are considered. Seven different cross-sectional shapes are selected for the vaults and the supporting arches. Vaults are subjected to four cases of pier settlement and seven cases of pier rotation. Three-dimensional non-linear finite element has been used for analysis. Results show that the load bearing capacity is sensitive to the type of the vault and the shape of the arches, to the type of pier settlement and pier rotation. Ranges for the pier height to the pier width ratio for the highest resistance of the vaults are proposed for pier settlement and rotation.

Regularity classification and corresponding analysis method requirements of horizontally curved bridges with unequal pier heights

Regularity classification and corresponding analysis method requirements of horizontally curved bridges with unequal pier heights

Seismic Fragility of a Single Pillar-Column Under Near and Far Fault Soil Motion with Consideration of Soil-Pile Interaction

The soil-structure interaction is a significant challenge faced by civil engineers due to the complexity potential in terms of seismic fragility evaluation. This paper presents a seismic fragility estimation of a single pier considering seismic ground motion types. Furthermore, sand type, pile diameter, pier height, and mass variation were considered to estimate their effect on the seismic fragility of the concrete pier. Incremental dynamic analysis was performed using a beam on a nonlinear Winkler foundation model. The analysis model condition compared near- and far-ground motion effects. Dynamic analysis and fragility assessment of the single-pier structure showed that low mass center produced less vulnerability of the concrete pier in the two cases of the sand type under near- and far-ground motions. The near and far earthquake simulations at complete failure probability had a difference of less than 5% when 0.65s<T1<1s and 2.4<T1/T2, but the opposite was shown when T1<0.5s and 3<T1/T2 were present together.