Concrete Bridge Piers Research Articles

Yield displacement charts for performance-based seismic design

A new tool for seismic design is presented, called Yield Displacement Charts (YDC). As with its predecessors, the Yield Point Spectra (YPS) and the Yield Frequency Spectra (YFS), the YDC concept takes advantage of the simple features of yield displacement (uy), to use uy in a performance-based design instead of a force-based period-dependent approach. A self-contained and comprehensive approach to YPS and YFS is presented, enabling the novel aspect of YDC to be introduced: a tool for a multi-performance objective design that only depends on the location of the structure to be designed. Once the yield displacement chart has been calculated for a particular place, it can be used for the preliminary design of any structure. For a given value of yield displacement, the YFS are obtained from the Yield Displacement Chart. The suitability of the methodology proposed is illustrated by means of a simple case study of a concrete bridge pier.

Seismic response prediction of RC bridge piers through stacked long short-term memory network

This paper aims at addressing the prediction of the displacement time histories and subsequently hysteresis curves of reinforced concrete bridge piers using a real-time hybrid simulation. A deep recursive long short-term memory (LSTM) network combined with a bidirectional LSTM, as a powerful deep learning algorithm, is utilized to achieve this goal. The designed stacked LSTM network includes multiple uncertain input variables, horizontal and vertical ground motions, horizontal and vertical actuator loads, the effective height of the bridge pier, the moment of inertia, and the mass assumed for hybrid simulation. The functional application programming interface in the Keras Python library is utilized to develop a complex model with these multiple inputs. Considering all these variables helps to predict the hysteresis curves of reinforced concrete bridge piers more accurately. The database for the training, validation, and unseen dataset of the proposed LSTM network during the prediction process comprises 12 experimental hybrid simulation tests on the bridge piers considering various aforementioned characteristics. The results reveal that the mean square error, as a loss function, is monotonically decreased to zero for both the training and validation datasets after 5000 epochs, and a high level of correlation is observed between the predicted and the reference values of the displacement time series for all the datasets. The Box-Whisker plot and Gaussian distribution of normalized error are also investigated for all the predictions to have more confidence in the estimations. It can be concluded that the maximum mean of the normalized error is about 0.05 for unseen data. Finally, it brings to an end that the LSTM method implemented in this study can successfully reduce the time and experimental costs to conduct new experimental hybrid simulation tests in the future.

Field test and probabilistic vulnerability assessment of a reinforced concrete bridge pier subjected to blast loads

Bridge piers have a high risk of being attacked in wartime, which has the potential to trigger progressive bridge collapse. This study aims to predict the failure probability of reinforced concrete (RC) piers exposed to military attack scenarios. Field explosion test and axial compression test were conducted to investigate the damage and post-blast performance of the RC pier first. Then, the uncertainties sourcing from the weapon accuracy were investigated. A performance-based (PB) vulnerability probabilistic assessment framework is developed which combines the Monte Carlo simulation (MCS) with a full-scale finite element (FE) model which was verified with test results. A probabilistic vulnerability assessment of a typical RC pier subjected to stochastic blast loading is conducted, and the vulnerability curve corresponding to three performance levels is developed. In addition, the damage modes and post-blast performance of the RC pier under blast loading are analyzed. Results show that the blast-induced damage to an RC pier had a significant influence on the axial bearing capacity, and the pier presents different damage modes at different scaled distances, which has a critical value of 0.65 m/kg1/3 between local and global damage modes. The failure probability of the pier corresponding to different performance levels increased with an increase in the TNT charge. The pier’s probability of collapse is less than 20 % when the TNT charge weight does not exceed 500 kg.

Parametric experimental investigation of unbonded post‐tensioned reinforced concrete bridge piers under cyclic loading

AbstractThe present paper investigates the cyclic performance of unbonded post‐tensioned reinforced concrete (PRC) rocking piers by a parametric experimental campaign. PRC rocking specimens are assembled by hybrid connections, containing an ungrouted post‐tensioned (PT) bar and grouted mild steel bars, that is, energy‐dissipation (ED) components. The properties of a benchmark PRC pier were defined according to a design procedure to control its strength, ductility, energy dissipation capacity, and self‐centering behavior. Five additional PRC piers with different ED bars amounts, initial PT force, and ED bars unbonded lengths were also tested to investigate the influence of these parameters on the cyclic performance. The test results show the superior cyclic performance of the PRC pier in limiting both damage and residual deformations. The parametric analysis highlighted that decreasing the initial PT force and/or ED bars amount enhances the PRC's ED capacity at the expense of the lateral force resistance and self‐centering behavior. Moreover, it has been observed that the influence of ED bars’ unbonded length only minimally affects the PRC pier's cyclic performance due to ED bars’ bond‐slip and concrete cover spalling of the pier shaft. Analytical models describing the PRC piers’ lateral force‐drift cyclic behavior were formulated and calibrated, showing a good agreement with test results for all specimens. The results and findings provide a valuable reference and solution for tailoring an efficient parameter recommendation of PRC rocking piers.

Performance of precast concrete bridge piers with grouted sleeve connections against vehicle impact

The bridge failure caused by vehicle impact is a great potential traffic danger. According to the new trend of bridge industrialization construction, this study aims to explore the dynamic behavior and failure modes of precast concrete (PC) piers with grouted sleeve connections against vehicle impact. Finite element (FE) models of PC components under impact loadings are developed and calibrated against experimental tests. Then, the calibrated simulation method of grouted sleeve connection is utilized to establish the numerical model of PC piers subjected to vehicle impact, and a comparative analysis is conducted to distinguish the impact responses of PC piers and reinforced concrete (RC) piers. A curvature-based method is proposed for the damage evaluation of the impacted PC piers. Further, intensive numerical simulations are performed to identify the effectiveness of sleeve location, interface shear strength, tensile strength of grouted sleeve, and axial force on the dynamic behavior of PC piers. The results show that the impact forces of RC and PC piers are almost identical, but the resistance mechanism of PC piers at the base varies from the shear-flexural mechanism to the truss-arch mechanism in the impact process. The proposed curvature-based method could intuitively describe damage details of PC piers, especially local damage. The grouted sleeve enhances the stiffness and capacity of the pier column in the sleeve region, and sleeve defects shall be avoided in the construction stage. The grouted layer would weaken the pier integrity, and thus obvious cracking and sliding are likely to appear at the interface. To some extent, increasing the axial force could improve the impact capacity of PC piers.

Repair and Retrofit of RC Bridge Piers with Steel-Reinforced Grout Jackets: An Experimental Investigation

Many concrete bridges around the world have passed their service life and are at high risk of collapse, especially in active seismic regions. This is particularly true in many developing and underdeveloped countries, where deficient construction and underpreparedness would result in a major catastrophe should a major seismic event occur. Thus, there lies a need to introduce an efficient, cost-effective, and readily available method of bridge rehabilitation. In this study, steel-reinforced grout (SRG) jacketing is used as a seismic strengthening technique for reinforced concrete bridge piers. Two bridge piers, one seismically damaged and one seismically deficient, were jacketed with SRG and then tested to observe their seismic response. The findings from the experimental program revealed that SRG jacketing can rehabilitate/repair a damaged bridge pier, and restore its flexural capacity, energy dissipation capacity, and ductility. While strengthening a seismically deficient pier, results showed that the flexural capacity and energy dissipation capacity could be improved, and ductility could be enhanced.

Vehicular impacts on precast concrete bridge piers with grouted sleeve connections

The grouted sleeve connection has been demonstrated to be robust enough to maintain its integrity under earthquake loads. However, no research to date has examined the connection behaviour under direct shear, resulting in a high risk of failure of the pier subject to a vehicle collision. In this regard, this research first carried out static and impact loading tests on grouted sleeve specimens to characterize their direct shear damage mechanisms. Next, a simplified finite element (FE) modelling method was proposed to simulate connection behaviour, and its accuracy was verified using the test results. Based on the proposed connection modelling approach, truck-bridge collision analysis was performed on a prototype highway bridge that uses grouted sleeves in the pier. From the analysis results, increasing the number of column segments can lead to higher stiffness of the pier when resisting the vehicular impact. The friction property at the connection interface plays an essential role in avoiding unacceptably large rebar shear stress due to excessive sliding and developing the diagonal compression strut to resist the impact load. Finally, feasible retrofit techniques were explored for the precast concrete piers that showed inadequate impact resistance.

Seismic performance of concrete bridge piers reinforced by stainless steel bars: A quasi-static experimental study

This paper presents a set of large-scale quasi-static tests on 6 bridge piers reinforced by stainless steel bars and 4 bridge piers reinforced by conventional carbon steel bars as control specimens to investigate the seismic behaviour of stainless steel reinforced concrete bridge piers. Different reinforcement ratios and axial loads are applied on the columns. The damage progression of the columns during the test is recorded. The experimental result is analysed in terms of force–displacement relation, energy dissipation capacity and ductility to evaluate the seismic performance of bridge piers reinforced by stainless steel bars. It is found that concrete columns with stainless steel reinforcement have similar lateral strength and larger deformation capacities compared to the conventional RC column. However, the application of stainless steel may reduce the energy dissipation capacity of RC columns. Dual-wave buckling of stainless reinforcement and severer concrete cover spalling of columns reinforced by stainless bars are observed in this work.

Post-earthquake seismic capacity estimation of reinforced concrete bridge piers using Machine learning techniques

This study analytically explored a parameterized set of 20 reinforced concrete bridge piers which share several geometrical and material properties commonly found in Canadian bridges. A nonlinear fiber-based modelling approach with a proposed material strength degradation scheme is developed using the OpenSEES platform. A multiple conditional mean spectra approach is used to select a suite of 50 mainshock-aftershock (MS-AS) ground motion records for the selected site in Vancouver, British Columbia. Nonlinear time history analysis is performed for mainshock-only and mainshock-aftershock excitations, and static pushover analysis is also performed in lateral and axial directions for the intact columns, as well as in their respective post-MS and post-AS damaged states. Using the resulting data, a framework for post-earthquake seismic capacity estimation of the bridge piers is developed using machine learning regression methods, where several candidate models are tuned using an exhaustive grid search algorithm approach and k-fold crossvalidation. The tuned models are fitted and evaluated against a test set of data to determine a single best performing model using a multiple scorer performance index as the metric. The resulting performance index suggests that the decision tree model is the most suitable regressor for capacity estimation due to this model exhibiting the highest accuracy as well as lowest residual error.

Laser-scan based pose monitoring for guiding erection of precast concrete bridge piers

Precast construction creates cost-effective structures by rapidly assembling prefabricated components. The emerging trend in increasing weights and scales of precast members, poses new challenges on installation quality. This study proposes an efficient and accurate pose measurement technique for guiding the erection of precast bridge piers using terrestrial laser scanning techniques. An arbitrary position of the scanner is allowed which is pre-calibrated by a single scan before the erection. For data analysis, a novel coarse-to-fine registration method is proposed to automatically align the scan model with the design model. A feature descriptor based on two-dimensional local kernel density map is used for fast coarse registration. An objected-oriented iterative closest point (ICP) registration based on virtual scan generator and nearest neighbour search is adopted for accurate fine registration. The proposed system was evaluated in the construction of an expressway viaduct and shows the potential for improving the installation efficiency and accuracy.

Dynamic mechanical responses of reinforced concrete pier to debris avalanche impact based on the DEM-FEM coupled method

Engineering accidents of bridge pier damage and collapse incurred by debris avalanches frequently occur in mountainous areas. This paper presented a three-dimensional DEM-FEM coupled numerical model with the aim of exploring the dynamic mechanical characteristics of a reinforced concrete (RC) bridge pier subjected to a debris avalanche. It allows for considering the debris avalanche particles' discreteness and the continuous medium's structural dynamic responses. Moreover, a steel-sand composite structure was introduced to shield the pier from the impacting damage. The coupled model, constructed in the LS-DYNA software, was described in detail as well as its validation. The complicated interaction mechanism between the debris avalanche and the RC pier was interpreted. The critical dynamic responses of the RC pier throughout the collision process were also analyzed. A detailed discussion of influential parameters indicates that the debris avalanche's dry density has the most significant effect on dynamic mechanical characteristics of the bridge pier. Moreover, the numerical simulation of the RC pier with a steel-sand composite protective structure impacted by the debris avalanche was performed, and the results indicate that the composite shield could provide superior anti-collision performances.

Curvature response of bridge pier subjected to earthquake action in a saline soil environment

The curvature of bridge piers can be described in terms of their syntagmatic deformation in the cross-sectional tensile and compressive zones. In the present study, 12 reinforced concrete bridge piers were designed and cast. Two of them were control specimens without corrosion, while the other 10 were corroded by immersion in a saline solution through the application of an electrical current; pseudo-static tests were conducted on the bridge piers after corrosion. The failure modes, corrosion ratios of the rebars, and load–curvature backbone curves were obtained and discussed. The evolution in curvature, in relation to different axial forces and corrosion ratios, was compared and analysed. It was found that the effective diameter of the rebars was reduced by corrosion, resulting in considerable reductions in the expected deformability (curvature) of the bridge pier cross-section. A robust load–curvature model was derived based on classical lamination theory and by dividing the bridge pier cross-section into concrete and steel reinforcement bar layers. The modelled curvature values match the results of the pseudo-static tests well. The experimental data and model can help lay out improved guidelines for bridge design, particularly for the seismic design of bridge piers in saline soil environments.

Machine learning driven seismic performance limit state identification for performance-based seismic design of bridge piers

Performance-based earthquake engineering requires the identification of different damage states in structural components. Bridge piers are one of the most critical components in the bridge system that dictate the overall performance of bridges under seismic loading. The ability to predict different damage states of a bridge pier following an earthquake can be useful in restoring service or prescribing appropriate remediation. Machine learning techniques are becoming attractive in earthquake engineering for predicting failure modes of buildings and bridges. This study implements several machine learning techniques to capture different performance limit states such as spalling, core crushing, and bar buckling of reinforced concrete bridge piers under seismic loading. Using experimental data from the large scale testing of bridge piers, this study compares different machine learning techniques for predicting drift capacity performance limit states of circular and rectangular bridge piers. Model tuning using grid search algorithm and 5-fold crossvalidation is performed to optimize model predictions over a wide tuning parameter search space. The efficiency of different methods is compared using a reserved 20% testing dataset to determine the optimal machine learning regression method for each limit state. This study compares the respective bar buckling and concrete spalling drift limit state models against existing physics-based empirical models, where the machine learning models are found to have significantly improved accuracy and precision.

Reliability assessment and sensitivity analysis of vehicle impacted reinforced concrete circular bridge piers

Impact collisions of vehicles with reinforced concrete (RC) bridge piers are an increasingly common event. The collision creates a dynamic effect on the concrete pier not generally considered in design practices, making the piers vulnerable to extensive damage. Not all bridge piers collapse upon impact, and some are kept in service without adequate investigations as to their continued structural viability. Unfortunately, little attention has been provided to investigate the justification of damaged piers kept in service post-impact. A limit state model to identify the probability of failure in the damaged pier is developed and alternative approaches for solving the limit state models are analyzed. In addition, reliability indices and probabilities of failure to quantify damage incurred from vehicular impact are determined. Deterministic analyses do not capture the uncertainties involved in assessing the non-linear dynamic behavior of RC piers under impact loading. To limit the uncertainty associated with determining RC pier’s performance under vehicular impact, sensitivity analyses of the variables controlling impact performance are scrutinized, and a sensitivity ranking to outline the relative importance of the variables to the pier’s performance is developed. The proposed process for determining the reliability of damaged RC piers provides an additional design tool for structural designers, forensic structural engineers, and practitioners for use in analyzing the impact performance of RC bridge piers in a useful, convincing, and economical way.

Influence of ground motion type on nonlinear seismic behaviour and fragility of corrosion-damaged reinforced concrete bridge piers

Two identical reinforced concrete (RC) bridge piers including a rectangular and a circular section are considered. The influence of corrosion damage, non-stationary characteristics of ground motions, and cross-sectional shape on nonlinear dynamic behaviour, failure mechanism and failure probability of these piers is investigated. An advanced modelling technique, capable of modelling coupled influence of inelastic buckling and low-cycle fatigue degradation of reinforcement, is employed to simulate the nonlinear structural behaviour of the piers. The considered bridge piers with various mass loss ratios (as a measure of corrosion) are subjected to a series of static pushover analyses and incremental dynamic analyses under three different suites of ground motions such as, Far-Field (FF), Near-Field With Pulse (NFWP), and Near-Field with No Pulse (NFNP). Furthermore, an advanced matching algorithm is used to investigate the effect of non-stationary content of near-field earthquake records including the presence of large pulses in ground motion time series on the nonlinear dynamic behaviour of the corrosion-damaged RC bridge piers. Finally, fragility curves are developed for each corroded bridge pier with different corrosion ratios subjected to each ground motion suite. Analyses results show that the failure mechanism of the corrosion-damaged bridge piers significantly depends on the cross-sectional shape and ground motion type. It is concluded that while both of the piers with slight corrosion levels are much more vulnerable under NFWP ground motions than those under FF and NFNP ground motions; the probability of failure of the extremely corroded bridge piers is approximately the same regardless of ground motion type.

First order basis splines to perform isogeometric topology optimisation to design the outline of bridge pier and analyse using idea statica®

Now-a-days managing the traffic in major cities is a challenging task. One of the ways is to construct flyovers over intersections and to ensure smooth signal less traffic flow. The design philosophy has now become the design norm for most of the structural systems. To provide Reinforced Concrete Flyover Bridge is very essential in all major cities like Hyderabad, Chennai, and Mumbai etc. Our study is mainly focused on design and analysis of concrete bridge pier. The present study focuses on pier of an elevated bridge which is conventionally based on force based approach. The main focus of the present study is to perform an optimal design of a reinforced concrete pier which carries the deck of the flyover. The traffic flow is taken for 2 lane flyover on each side of the median. An Isogeometric topology optimization algorithm is used to determine the outline of the bridge pier. The bridge pier is then modeled in AutoCAD and imported to IDEA StatiCa® software. The reinforcement is calculated using Indian Standard (IS) code with all the necessary checks. The distribution of material within the given domain is determined. Shear strength, bending strength and crushing strength are calculated manually for checking strength compatibility. The static analysis and buckling analysis is performed using Idea Statica® software and the results are obtained.

Damage assessment of circular bridge pier incorporating high-strength steel reinforcement under near-fault ground motions

Bridge piers are typically the most vulnerable to damage during an earthquake, and the entire seismic performances of the bridge is determined to some extent by the hysteretic energy of its piers. It was discovered that partially embedding high-strength reinforcements in bridge piers is a reliable and efficient method to increase the ductility performance. The term “high-strength reinforcement” refers to reinforcement with a yield strength of (500 MPa) or above. The use of certain high-performance materials can help to enhance bridge pier seismic performance. Because of their strong and impulsive impact on structures, near-fault ground vibrations deserve special attention. These features are distinct from far-field ground vibrations, which are the basis of practically all seismic design requirements. The goal of this study is to evaluate the effects of near-fault ground vibrations on reinforced concrete bridge piers, as well as to develop a framework for evaluating bridge columns near active faults. The impact of Forward-directivity pulses effect on the behavior of a continuous steel box girder bridge pier is investigated in this work using fragility analysis. Damage measures such as pier displacement ductility and rotational ductility of pier are used to generate fragility curves and Probabilistic seismic demand model for bridge pier using high strength reinforcement bars under the ensemble of near-field forward- directivity earthquakes. The damage model presented may be assumed to be a well-versed model which may address the variability in earthquake ground motion while performing the bridges pier seismic vulnerability evaluation. Two sets of near-field forward-directivity records with peak ground velocity to peak ground acceleration ratio (high PGV: PGA > 150 cm/s/g and low PGV: PGA < 150 cm/s/g) are employed to carry out incremental dynamic analysis. The findings show that even at low PGA levels, near-field directivity pulses result in a substantial chance of pier damage exceedance.

Seismic Performance of Offshore Piers under Wave Impact and Chloride Ion Corrosion Environment

Offshore bridges may suffer from chloride ion corrosion, tsunami wave impact, and earthquake. However, the coupling effects of multiple factors have not been fully considered. This paper studied multiple degradation effects on the seismic performance of offshore piers considering tsunami wave impact, chloride ion corrosion, and their interaction. Firstly, through the scale model test of tsunami wave flume, the wave force of box girder structures and piers under different tsunami wave conditions is measured. Then, according to the corrosion characteristics of coastal chloride salts on reinforced concrete bridge piers, the corrosion parameters is selected by Latin hypercube sampling, and the influence of corrosion expansion and cracking of bridge pier cover on the chloride ion corrosion process is considered to modify the degradation model of corroded reinforced concrete materials. Finally, the wave load measured by the test is converted by the similarity criterion of the fluid mechanic test and loaded into the ABAQUS full-bridge model, and the pier after the tsunami wave is evaluated by the pushover analysis. The bearing capacity and lateral stiffness of the corroded pier before and after different tsunami waves are compared. The results show that the lateral bearing capacity and stiffness of bridge piers are, respectively, decreased by 27.6% and 6.2% after 30 years of service. Without corrosion, the lateral bearing capacity and stiffness of piers were, respectively, reduced by 11.45% and 10.6% after HXB-5 wave impact. After 30 years of service, the lateral bearing capacity and stiffness of bridge piers are, respectively, reduced by 41.8% and 22.5% under the combined action of corrosion and HXB-5 wave impact. It is found that the coupling effects of multiple degradation factors were more significant than the simple superposition ones. Therefore, the coupling effect of multiple factors should be considered in practical engineering.

Shaking table test on single segment prefabricated concrete bridge pier connected by grouting sleeve

PurposePrefabricated pier technology has the advantages of quick construction time, relatively little traffic interference and relatively small environmental impact. However, its applicability under earthquake conditions is not yet fully understood. The seismic performance and influence parameters of a prefabricated concrete pier connected by embedded grouting sleeve (GS) in a pile cap are investigated in this study.Design/methodology/approachTwo prefabricated pier scale model specimens with different reinforcement anchorage lengths and two comparative cast-in-place (CIP) pier model specimens are designed and manufactured for a seismic simulation shaking table. With the continuous increase of input ground motion strength, the changes in basic dynamic characteristics, damage development, acceleration and displacement variation laws, and pier bottom strain responses are compared among the specimen. The finite element software ABAQUS is used to simulate the test pier.FindingsThe crack location of the two prefabricated pier specimens is almost the same as that of the CIP pier specimens; CIP pier specimens show more penetrated cracks than prefabricated pier specimens, as well as an earlier crack penetration time. The acceleration, displacement and strain response of the CIP pier specimens are more affected by earthquake activity than those of the prefabricated pier specimens. The acceleration, displacement and strain responses of the two prefabricated piers are nearly identical. The finite element results are in close agreement with the acceleration and displacement response data collected from the test, which verifies the feasibility of the finite element model established in ABAQUS.Originality/valueA GS connection method is adopted for the prefabricated pier, and on the premise of meeting the minimum reinforcement anchorage length required by the code, this study explores the influences of different reinforcement anchorage lengths on the seismic performance of prefabricated piers in high-intensity areas. A shaking table loading test is used to simulate the real changes of the structure under the earthquake. This work may provide a valuable reference for the design and seismic performance analysis of prefabricated pier, particularly in terms of seismic stability.

Improvement of energy damage index bounds for circular reinforced concrete bridge piers under dynamic analysis

AbstractAn improvement of energy damage index bounds for circular reinforced concrete (RC) bridge piers under dynamic time history analysis is presented in this study. The energy‐based damage model has been defined as a ratio of hysteresis dissipation energy to input energy for performance evaluation of circular RC bridge pier systems. Based on the energy balance equation, the mentioned damage model can consider all energy aspects, including kinematic energy, strain energy, hysteresis energy, damping energy, and input energy. Additionally, the effect of ground motion duration, amplitude, and frequency content is appropriately considered in this damage model. For this purpose, the damage limit state bounds for two empirical RC bridge piers are statistically evaluated under the 22 far‐field ground motion sets of FEMA‐P695 for simulation of strong‐earthquake motion and consideration of record‐to‐record variability. First of all, appropriate validation between empirical and numerical fiber element models is implemented to estimate accurate results. Then, damage data at each performance level through strain limit states are collected by developing energy incremental dynamic analysis curves. Statistical results on collected damage data are presented in all performance levels to determine damage index bounds by the convolution of fragility curve distribution. Hence, five damage index bounds at five performance‐level are suggested, including very slight, slight, moderate, extensive, and complete damage. Finally, the effect of the other damping ratios on the modified energy damage model is carried out by using the beta coefficient in the formula. In the end, the modified energy damage model is compared with other damage indices to investigate the efficiency of the proposed damage model.