High Piers Research Articles

Research on Construction Crack Diagnosis and Treatment Technology of Double-Column Large Cantilever Pre-Stressed Bent Cap

This paper took a pre-stressed bent cap of a high pier of a bridge as the research object, expounded the crack type and construction process of the bent cap, combined with the numerical calculation and analysis of the construction process to study the crack generation mechanism and its influence during the construction period of the bent cap. Besides, it gave the repair and treatment technology of jacking and unloading combined with pressure glue, so as to provide reference for the disease diagnosis and treatment of similar bridge structures.

Mechanical Response Analysis of Double-Column High Piers Impacted by Rolling Stones under the Influence of Pier Height Differences

Mechanical Response Analysis of Double-Column High Piers Impacted by Rolling Stones under the Influence of Pier Height Differences

Safety risk assessment of cast-in-situ box girder of mountainous high-pier interchange

The safety risk events that may occur during the cast-in-situ process of a concrete box girder of an interchange bridge with high piers in mountainous areas are briefly listed. Based on the background of an interchange project in Yunnan province, China, the relative importance weights of selected safety risk events are calculated by an analytic hierarchy process, and the uncertainty and fuzziness of the analytic hierarchy process are solved using the cloud theory to improve the accuracy of the analytic hierarchy process; then the improved likelihood–exposure–criticality method is used to evaluate the risk level of safety risk events. It is verified that the use of back-propagation-neural network theory can realize the risk prediction of engineering projects based on human factors and environmental factors. At the same time, real-time risk prediction based on dimension and space dimension is necessary, and it also provides a new idea for security risk assessment.

Experiment on Seismic Behavior of Neotype Column-slab High Piers

The low-cyclic reversed loading test was carried out for a scale model of a neotype column-slab high pier. The test was designed to investigate its failure modes, hysteretic characteristics, ductility, energy dissipation, residual deformation stiffness degradation. Test results indicate that the neotype column-slab high pier has strong and stable bearing capacity, good ductility and energy dissipation capacity, small residual deformation. The destruction process of the structure components is that bending cracking of the wing slab buttom firstly, shear cracking at the juction of the web plates with the corner columns, then bending cracking at the roots of the corner columns. Cracking and energy dissipation of the slabs decrease the stiffness of the structure, which effectively protects the corner columns. The study contributes to the literature for developing future design guidelines, for the purpose of providing experimental and theoretical background of the neotype column-slab high pier.

Seismic fragility analysis of reinforced concrete piers of steel box girder bridges: A parametric study

The purpose of this paper is to investigate the influence of typical parameters on seismic fragility curves of reinforced concrete (RC) piers of continuous steel box girder bridges. Typical parameters considered include the pier heights, pier section types, and total length of bridges. Twenty recorded ground motions from historic seismic events are randomly selected for fragility analyses. The finite element analysis program, OpenSees, is employed to perform nonlinear dynamic analyses of the bridges. A set of damage states of bridge piers is proposed based on the damage index, which is based on the drift ratio of the pier. Fragility curves of piers are eventually generated using maximum likelihood estimation. The numerical analysis results show that the bridges with shorter piers are less vulnerable to earthquakes than those with higher piers. Moreover, the wall pier types have significantly improved seismic performance compared with the other types. The fragility analysis results also reveal that the total bridge length has notably affected to seismic response of bridges.

Definition of a Simplified Design Procedure of Seismic Isolation Systems for Bridges

In the recent past, numerical and experimental investigations on full-scale isolators have led to extensive improvements in seismic isolation techniques for bridge structures. Significant advances in dynamic testing techniques have been made at both software and hardware levels, and the response of an isolated bridge can be realistically simulated. In general, the response of an isolated bridge structure is strongly affected by the valley topography; therefore, high piers may not need isolation devices, since they are flexible enough to accommodate the design displacement in the elastic range. On the other hand, at those locations no hysteretic damping is provided and higher displacements can be achieved, compared to the maximum displacement allowance. In this work, a simplified procedure is proposed for the optimization of isolation systems for bridge structures. The seismic response of a designed case study structure is investigated through nonlinear time history analyses, and the effective contributions of both the nonlinear hysteretic behaviour of isolators and the elastic response of piers are considered. Regarding displacement and force responses in particular, the results show a very good agreement between mean and single-event peak responses, and the corresponding values returned by the proposed design procedure.

Improvement of design method of rock-socketed pile based on the enhancement effect of shaft resistance

Large diameter rock-socketed piles are usually used to support bridge with long-span or high piers. To research its mechanical properties in mountain area, field loading tests based on distributed fiber sensing technique were performed. The tests results indicate that shaft resistance came into play earlier than tip resistance and the upper load was borne mainly by shaft resistance. When the load-sharing ratio of tip resistance exceeded 10%, the enhancement phenomenon of shaft resistance occurred, which became more and more obvious with the increase of the ratio. The shaft resistance and tip resistance are not independent but interact of each other. The increase of tip resistance can promote the shaft resistance to play its role effectively. According to the field test results, the design method of rock-socketed piles was improved based on the enhancement phenomenon of shaft resistance. The calculation results indicate that the rock-socketed length of pile can be shorten effectively by this method which can obtain considerable economic benefits.

Influence of Actual Site Soil Layers on Pounding of a High-Pier Bridge Occurred between Deck and Abutment

This study aims to determine the pounding probability of a continuous rigid bridge with high piers and long span at the actual site soil under the action of an earthquake. Finite element models of the bridge are built to analyze separation length. The effect of the actual site soil on seismic wave propagation from the bedrock to the pier and the abutment foundation is considered using DEEPSOIL software. A pounding probability analysis method under multi-support seismic excitations with bedrock peak acceleration as the strength index is proposed. The pounding probability of the continuous rigid bridge with high piers and long span under multi-support seismic excitations is analyzed using the proposed method. Meanwhile, a comparison analysis of the pounding probability results under uniform excitations without considering the influence of the actual site soil is performed. The study indicates that the required width of the expansion joint under uniform excitation is larger than the multi-support excitation with the increase in bedrock peak acceleration. With the increase in the width of expansion joint and the acceleration peak, the probability of pounding at a single abutment and at two abutments under multi-support excitation is gradually less than uniform excitation. Therefore, the actual site soil must be considered when determining the width of the expansion joint of a continuous rigid bridge with high piers and long span.

Seismic performance of single-limb to double-limb thin-walled high pier bridge

Seismic performance of single-limb to double-limb thin-walled high pier bridge

Stability Analysis of Hollow Thin-Walled High Pier Curved Bridge Without Diaphragms

As the height of bridge increases, more and more high piers are designed with diaphragms to ensure their stability. However, the insertion of the diaphragms will have a significant impact on the speed and efficiency of the pier construction. For the stability problem of hollow thin-walled high piers, the numerical simulation of the model with or without diaphragms is carried out to compare and analyze the force mode, ultimate bearing coefficient and deformation characteristics of high pier of curved bridge from the perspectives of full bridge buckling analysis, high pier integral stability and high pier local stability in this paper. Studies have shown that the effect of installing concrete diaphragms on the stability of such single hollow thin-walled high piers is not obvious. If the wall thickness of the high pier meets the requirements for strength and stiffness and the theoretically calculated maximum allowable width-to-thickness ratio, the long-span continuous rigid frame curved bridge high piers may not be provided with diaphragms.

Study on seismic performance of high pier multi-span beam bridge

Girder bridge with high piers has obvious advantages in crossing deep gorges, and is commonly applied to highway construction in the western mountainous area of China. In Qinghai province, the earthquake response is very complicated, and the seismic design is absolutely necessary. In this paper, the seismic performance of the typical span of a high-pier-girder bridge in seismic zone of Qinghai province is analyzed by the time-history analysis method based on the existing seismic design code. The seismic response characteristics and development rules of the bridge are obtained, and the methods to effectively improve the integrating stiffness and seismic performance of the bridge are discussed. The results can provide references for the seismic design of the same kind of bridges.

Combination of LS-SVM algorithm and JC method for fragility analysis of deep-water high piers subjected to near-field ground motions

The objective of this paper is to propose a novel fragility analysis method pertinent to the combination of the least squares support vector machine (LS-SVM) algorithm and JC method for the vulnerability estimation of deep-water high piers located in reservoirs under near-field ground motions. First, the uncertainties associated with the design parameters are considered and the LS-SVM algorithm is adopted to predict the cross-sectional critical curvature values of each damage state of the example pier and determine the probability distributions. Then, a group of finite element models of the example pier is developed using the OpenSees platform for considering the uncertainties related to the design parameters and near-field seismic waves; the Morrison equation is employed to calculate the added mass to simulate the hydrodynamic pressure. Meanwhile, the dynamical responses of the example pier with seven different water depth conditions are investigated using increment dynamic nonlinear analysis along the longitudinal and transverse directions under seismic excitations. Finally, the fragility functions are derived based on the JC method to consider the probability distributions of the cross-sectional critical curvature values and dynamical responses simultaneously; these functions are applied for assessing the damage probability at different damage states of the example pier. It can be concluded that the hydrodynamic pressure plays an important role in influencing the natural vibration period and mode shape of the deep-water high pier. In the slight, moderate, and extensive damage states, the damage probability of the middle-upper and bottom areas of the example pier is relatively large under longitudinal near-field seismic excitation; nevertheless, only the bottom is easily damaged under transverse near-field seismic excitation.

The Construction Technology of High Pier Verticality Control Based on Rapid Construction of Super High Pier in Mountainous Area and Unscented Kalman Filter

Based on engineering examples, the paper carried out research on the rapid construction technology of high piers in mountainous areas, and used unscented Kalman filter technology to eliminate the influence of measurement factors, man-made construction factors, and structural nonlinearities on the pre-deflection. The research results show that this technology can significantly improve the verticality of ultra-high piers in mountainous areas and has important application value.

Highly crystalline ZnO film decorated with gold nanospheres for PIERS chemical sensing.

In this paper, we report on the study of a novel type of substrate based on a highly crystalline ZnO film photo-irradiated using UV for enhancing the Raman signal. This effect is called photo-induced enhanced Raman spectroscopy (PIERS). This PIERS substrate is composed of a photo-irradiated thin ZnO film on which gold nanoparticles are deposited and allows large photo-induced SERS enhancement to be obtained for the chemical detection of small molecules compared to normal SERS signals. This photo-induced SERS enhancement is due to increasing electron density of the gold nanoparticles and charge transfer mechanisms. Here, we achieve a high quality PIERS substrate, the signal of which exhibits weaker fluctuations and a similar or greater gain (up to 7.52) than those reported in the current literature. Henceforth, these PIERS substrates can be of great potential for industrial applications.

Dynamic Characteristics Analysis of High Pier Steel Pipe Lattice Support System in Typhoon Region

According to similar criteria, the on-site lattice support on-site in the typhoon area is 62m high and scaled down at 1: 150 to produce an aeroelastic scaled model of the lattice support. Based on the specifications and the characteristics of the wind field in the area where the project is located, a type A landform is used for wind tunnel tests. Through the measured structural dynamic characteristics combined with the help of the finite element analysis software Ansys, the dynamic characteristics of the lattice support under typhoon wind field were studied. The test results showed that under wind load, the lattice support itself is dominated by second-order low-frequency vibrations. The top end of the bracket is excited with a lower first-order frequency. The difference between the first-order and second-order natural frequencies is small. The support is about H / 3 height or more, which is greatly affected by wind load and speed, and is less affected below 30m; at each wind direction angle, the acceleration response of each measurement point of the support generally increases non-linearly with the increase of wind speed. The response of the measuring point shows a quadratic curve relationship with the wind speed. The acceleration of the measuring point gradually decreases from the top to the bottom. At the same wind speed, the closer to the top, the larger the acceleration. The positive change is more than H / 2, and the change period is unstable. Below 20m, the positive and negative acceleration changes relatively uniformly, the closer to the bottom, the smaller the acceleration period; the maximum value of the wind vibration response at each measurement point occurs under the wind angle of 0 ° and 90 °, the wind resistance generated by the box girder cross section has little effect on the support; at a wind angle of 45 °, the response value of the crosswind and windward wind vibration is similar, and the effect of the crosswind cannot be ignored.

Substructure Responses of a Concrete Bridge with Different Deck-to-Pier Connections

This paper tried to analyze the effects of deck-to-pier connections on pier design forces of a number of typical bridges. To this end, the behavior of pier connection of several 3D concrete bridge models was studied under service loads. A parametric study is conducted to investigate the different bearing types and pier height effects. The responses of models, such as superstructure displacements, forces, and displacements of deck-to-pier connections, and column forces are presented. The analysis results revealed that an increase in pier height leads to a considerable rise in the pier displacements and a decrease in transferring forces in all types of connections, and the greatest increase was found in the single elastomeric-bearing line. Therefore, rigid connections have better performance compared to other cases in high piers. Moreover, evaluating the effect of deck-to-pier connection on the pier force distribution indicated that the double elastomeric-bearing line connection increases the rigidity and transferred moment in comparison to the single line to the pier. Thus, its restraint lies between rigid and single bearing line conditions, and it should be considered in column design and can be more effective in moderate pier height. It was also revealed that the bearing location has a significant effect on the connection stiffness and transferred forces to the pier and influences its behavior and design.

Seismic damage pattern analysis of high piers of RC bridges based on the fiber model

The practical method of the seismic damage analysis of high piers of RC bridges is established using the uniaxial modified Faria-Oliver damage model for concrete and modified Menegotto-Pinto model for rebars, based on the fiber beam-column element, in the FEA software ABAQUS. Furthermore, the seismic damage analysis of short pier and high piers of different section sizes are conducted, respectively. The results indicate that for the short piers the damage zone is located at the bottom of piers. However, the high piers tend to have multi-location damage zones, and the tendency is more obvious for the high piers with a more slender shape.

Analysis on dynamic characteristics and wind-induced buffeting response of Hezhang Large-span Bridge

Hezhang Large-span Bridge is a concrete continuous rigid frame bridge with super high pier. The highest pier reaches 197m and stands the peak among the similar bridges. In order to study the wind resistance capacity of the bridge, ANSYS, a finite element software, is applied to establish models at the stage of the largest cantilever constructing and completing of the bridge. The dynamic characteristics of the models are solved by subspace iteration method and the fluctuating wind velocity time history was generated by modified Fourier spectrum method. After that, the buffeting load time history is calculated based on the theory of quasi-steady state and the buffeting time history of the stage of the largest cantilever constructing and completing of the bridge is gained respectively by time history analysis.

Geometrically Nonlinear Stability of Curved Continuous Rigid Frame Bridges with Initial High Pier Imperfections at Largest Cantilever Stage

Geometrically Nonlinear Stability of Curved Continuous Rigid Frame Bridges with Initial High Pier Imperfections at Largest Cantilever Stage

Seismic Performance Evaluation of Typical Piers of China’s High‐Speed Railway Bridge Line Using Pushover Analysis

Currently, it is a challenge to effectively assess the seismic performance of the high‐speed railway bridge line. To figure it out, this paper discussed the applicability of the Pushover analysis in the seismic fragility of the high‐speed railway bridge. As the piers are the core components to resist the earthquakes, a typical high‐speed railway bridge line consisting of 22 piers was established by the finite element software OpenSees. The influences of the different pier height and sites on the fragility analysis of the pies were investigated. From the component level, the seismic performance of the high‐speed railway bridge line was evaluated by the Pushover analysis. The results show that the seismic responses of the piers by the Pushover analysis are agreeable with those by the incremental dynamical analysis when the peak ground acceleration is less than 0.4g. The high piers have better seismic performance than the lower piers. The high‐speed railway bridge line exhibits good seismic performance under the 7‐degree design earthquake (0.15g) and the 8‐degree low‐level earthquake (0.10g) but may be severely damaged under the 9‐degree low‐level earthquake (0.40g).