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1
Serra Lluch, Juan, Ángela García Codoñer et Jorge Llopis Verdú. « Aportaciones al colorido de la modernidad "Made in Italy" : Piero Bottoni y la gradación cromática que nunca fue ». EGA Revista de expresión gráfica arquitectónica 14, no 14 (5 mai 2009) : 180. http://dx.doi.org/10.4995/ega.2009.10254.
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Wu, Bo, et Shixiang Xu. « Experimental study on damage evaluation of stainless steel–reinforced concrete piers under lateral impact ». Advances in Mechanical Engineering 12, no 5 (mai 2020) : 168781402092488. http://dx.doi.org/10.1177/1687814020924886.
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Horizontal impact tests of stainless steel–reinforced concrete piers with different reinforcement ratios at different impact velocities were carried out by using the ultra-high drop weight impact test system. Degree of piers damage after impact was comprehensively analyzed by measuring the acceleration of the impact body, the displacement of the top of the pier specimens, the strain of the steel bars, the rotation of the pier bottom, and the crack development of concrete. The test results showed that under the same impact velocity, with the decrease in reinforcement ratio, the peak acceleration of the impact body, the displacement of the top of pier specimens, the strain of steel bars, and the pier bottom rotation all increase. To a certain extent, increasing the reinforcement ratio of bridge piers can effectively reduce impact damage.
3
Nagao, T., et Y. Kurachi. « An Experimental and Analytical Study on the Seismic Performance of Piers with Different Foundation Bottom Widths ». Engineering, Technology & ; Applied Science Research 12, no 5 (2 octobre 2022) : 9142–48. http://dx.doi.org/10.48084/etasr.5088.
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Piers can be severely damaged by earthquakes. When an action of a massive earthquake is assumed, the seismic performance of the pier can be improved by widening the foundation width. A previous horizontal loading study indicated that extending only the Foundation Bottom (FB) width, rather than the complete foundation, can boost seismic resilience while suppressing the increase in building cost. However, the research dealt with only two types of FB width, i.e. normal and widened, and the data for sufficiently assessing the inclination angle of the pier with loading were not obtained. In this study, to evaluate the seismic performance of piers with different FB widths in more detail, horizontal loading tests on piers with ordinary columnar foundations and two types of piers with widened FB were conducted, and the seismic resistance of the three pier types were compared. It was shown that horizontal displacement and inclination angle of the pier can be reduced by widening the FB. Furthermore, finite element analysis was carried out to reproduce the experimental results. The analysis results showed good agreement with the experimental results in terms of pier horizontal displacement and inclination angle.
4
Deng, Jiang Dong, Zhou Hong Zong et Zhang Hua Xia. « Study on Seismic Strengthening Demand of Damage Concrete Bridge Piers ». Applied Mechanics and Materials 178-181 (mai 2012) : 2070–74. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2070.
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Initial damage often exists in the concrete piers of bridges in service. In this paper numerical analysis was used to study the seismic strengthening behavior of concrete bridge piers with different bending damage degrees, including seismic forces, pier top displacements, steel bar strain and energy dissipation, in order to obtain the strengthening demand to repair the damage piers. The results showing that: initial bending damage reduced the seismic force, increased the pier top displacements and the steel bar strain. After strengthening the pier top displacements and steel bar strain at the pier bottom decreased, energy dissipation increased, and the anti-seismic properties of damage piers effectively recovered, but the increase of the seismic force might make new plastic-hinges out the strengthened area. At last according to the mechanics properties the strengthening demand under different bending damage degrees was given.
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Lu, Wenliang, Wen-Qiang Peng, Li Zhu, Cong Gao, Ya-Dong Tang, Yue-Wu Zhou, Wei Su et Bing Zeng. « Experimental and Numerical Study of Static Behavior of Precast Segmental Hollow Bridge Piers ». Materials 15, no 19 (9 octobre 2022) : 6991. http://dx.doi.org/10.3390/ma15196991.
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To investigate the static performance of precast segmental hollow piers, two precast segmental hollow pier specimens were designed for static loading tests on the top of piers. The finite element model of precast segmental hollow piers was established by the finite element software Abaqus and verified based on the test results. Based on the experimental and finite element models, three optimal design solutions were proposed, and the calculation results of each solution were analyzed. The results show that precast segmental hollow pier mechanical behavior is similar to that of cantilevered bending members. The specimens present brittle damage characteristics after the destruction of the structure at the bottom of the pier pressure edge as the axis of the rigid body rotation. Following the test loading process, the bonding between the segments is good, except for the pier bottom damage surface of the rest of the bonding surface, which has no relative displacement. The calculation results of the finite element model are in good agreement with the test results and can effectively predict the load–displacement response of precast piers. Three optimized design solutions are proposed. The finite element simulation proves all three optimized design solutions show better overall ductility than the original solution and can effectively improve the performance of segmental precast hollow piers.
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Luna-Bahena, Juan, Oscar Pozos-Estrada, Víctor Ortiz-Martínez et Jesús Gracia-Sánchez. « Experimental Investigation of Artificial Aeration on a Smooth Spillway with a Crest Pier ». Water 10, no 10 (3 octobre 2018) : 1383. http://dx.doi.org/10.3390/w10101383.
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Crest piers placed on overflow spillways induce standing waves at the downstream end of them and the supercritical flow expands after flowing past the rear of the pier. The expanding flow from each side of a pier will intersect and form disturbances or shock waves that travel laterally as they move downstream and eventually reach the chute sidewalls. Recently, investigations regarding crest piers are related with artificial aeration on stepped spillways to eliminate the risk of cavitation damage. However, there is a lack of studies on standing and shock waves in smooth spillways concerning the air entrainment into the flow in presence of crest piers. This paper presents the study of the combined effect on air entrainment of a crest pier and an aerator on the bottom of a smooth spillway (configuration 1). For comparison, experimental tests were developed in the spillway without pier, that is in presence of aerator only (configuration 2). The configuration 1 results show that the air concentration distribution on the spillway bottom across the width and length of the chute increases in comparison with configuration 2, reducing even more the risk of cavitation damage and enhancing the safety of the hydraulic structure.
7
Zeng, Ben, Jiahui Xu, Xiaohong Zheng et Songqi Zhang. « Research on the Seismic Performance of Prefabricated Bridge Piers Using UHPC Grout under an Eccentric Load ». Advances in Civil Engineering 2023 (1 mars 2023) : 1–11. http://dx.doi.org/10.1155/2023/9092697.
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At present, research on prefabricated piers is limited to the axial compression state. However, many piers are under small eccentric compression in practical engineering. In this article, the seismic performance of ultrahigh performance concrete (UHPC)-grouted corrugated pipe-connected piers under small eccentric compression was studied. A pseudostatic test was carried out by using a prefabricated pier column model connected with UHPC-grouted corrugated pipes. The failure mechanism of the plastic hinge area of the column base was studied, and the failure mode, energy dissipation capacity, displacement ductility, and ultimate bearing capacity were compared with those of an ordinary axially compressed pier column structure. The result shows that compared to the conventional cast-in-place(CIP) pier, the overall energy dissipation capacity and the ductility factor of assembled pier with UHPC-grouted corrugated pipe-connection were decreased approximately by 5.0% and by 10%, respectively. The pinching phenomenon of the hysteresis curve of the precast pier was more obvious. When the assembled piers were under small eccentric compression, the overall energy dissipation capacity was close to that of conventional CIP piers and the ductility factor was improved by 20%. Comparison of two precast piers using the same UHPC grout connections shows that the stiffness degradation process of precast pier under small eccentric compression was similar to that under axial compression. But the ductility coefficient of precast pier under small eccentric compression increased by about 20%. The small eccentric compression caused different damage degrees in the plastic hinge zone at the bottom of the precast column. The ultimate load in the same direction as the additional bending moment was 55% lower than that of the opposite direction.
8
Wei, Si Si. « Effects of Pier Stiffness on the Seismic Response of Continuous Bridges with Irregular Configuration ». Applied Mechanics and Materials 638-640 (septembre 2014) : 1794–802. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1794.
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The seismic response of 4-span continuous bridges with different configurations has been investigated. In the series of bridges studied, the height of the central pier varies from 5 m to 100 m, while the heights of all the other piers remain the same. Using non-linear time history analysis, the internal forces at the bottom of individual piers have been predicted for each case. The correlation between the relative stiffness of adjacent piers and the ratio between the seismic response at the bottom of adjacent piers has been studied. Based on the results, in order to guarantee approximately balanced seismic response among all piers of a given bridge, a range of the relative column stiffness of two adjacent piers has been proposed.
9
Xu, Yuan Qing, Tie Yi Zhong, Wen Gang Ji et Xu Li. « Study on the Impact of Lead-Rubber Bearing Parameters on Seismic Responses of Seismically Isolated Pier ». Applied Mechanics and Materials 50-51 (février 2011) : 105–9. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.105.
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Based on the finite element program SAP2000, 120 models of eight different piers with different lead-rubber bearings (LRB) are established. The seismic response analyses of piers isolated by LRB in axial direction of the bridge are carried out under the excitations of seven earthquake waves. The calculations of seismic responses of the piers with and without isolation are implemented by using dynamic time-history analysis method, and the comparison of the results is given out. Considering the isolation ratio of the moment at the bottom of pier as observation samples, the variances of the three LRB mechanical parameters are analyzed. Furthermore, the ability of the parameters of LRB to adjust the seismic response of different piers is discussed. The analysis results show that all the mechanical parameters of LRB have significant effect on the isolation ratio of the moment at the bottom of pier, and the parameters of LRB can adjust the seismic forces of the isolated piers whose height difference is less than 30 meters to be almost equal. This paper provides some valuable references for the further study of isolation design for railway bridges.
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Wang, Zi Jian, Li Ming Wu et Sheng Xie Xiao. « Vibration Response Analysis on Deep-Water Piers under Earthquake and Wave Coupling Motivation ». Applied Mechanics and Materials 548-549 (avril 2014) : 1607–12. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1607.
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Taking a typical cylindrical solid pier as example, this paper utilizes the way of additional mass to consider the influences of hydrodynamic pressure on piers. It establishes dynamic response comparative analysis of single pier model under different earthquakes’ motivation taking ANSYS finite element software as computing platform. This draws conclusion that hydrodynamic pressure keeps characteristics of changing the seismic response of piers in which pier top displacement and pier bottom internal force are increased. Also it acquires the conclusion that weight and cycle of structure are related to the effect of hydrodynamic pressure. Through analyzing continuous beam bridge and continuous rigid-frame bridge, it is verified that there exists close relationship between effect of hydrodynamic pressure and inherent cycle of structure in which the higher inherent cycle becomes, the lower influence hydrodynamic pressure keeps on structure.
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Li, Jie, Yuanhong Hu, Dayu Yang, Tengda Feng, Yan Liang et Chenchen Tao. « Feasibility Study of Using Engineered Cementitious Composite and High-Strength Bars in Rigid Bridge Piers Based on Seismic Vulnerability Analysis ». Shock and Vibration 2020 (27 septembre 2020) : 1–11. http://dx.doi.org/10.1155/2020/8850800.
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The main function of pier is to transmit the load from superstructure to foundation reliably. Under earthquake action, the main failure reason of bridge is the damage of bridge pier. The application of some high-performance materials is helpful to improve the seismic performance of bridge piers. Based on seismic vulnerability analysis, this paper studies the feasibility of using engineered cementitious composite (ECC) and high-strength bars in bridge piers. Taking a rigid pier as an example, a nonlinear numerical model is established by OpenSees software. The reasonable replacement height of ECC in plastic hinge regions, stirrup ratio of pier section, and replacement rate of high-strength bars are obtained through the seismic performance analysis of the pier. Then, seismic vulnerability of rigid pier with ECC and high-strength bars is analyzed. The results show that it is feasible to improve the seismic performance of the piers by using ECC and high-strength bars. Considering the economic rationality, the replacement height of ECC in plastic hinge regions can be determined according to the curvature change point. For the rigid pier, the economical and reasonable volume stirrup ratio is 0.78%. The ultimate curvature of RC/ECC pier bottom increases by 12.4% when the longitudinal bars of the pier are replaced by high-strength bars, and the energy dissipation capacity increases by 22.5% on average. Compared with the pier’s original design, the exceedance probability of each limit state of the rigid pier with ECC and high-strength bars is significantly reduced. Its seismic performance is superior, and the risk of seismic damage is significantly reduced.
12
Kim, Youngdae, Jong-Sub Lee, Il-Wha Lee et Jung-Doung Yu. « Natural Frequencies of Model Piers under Different Ground Support Conditions ». Journal of the Korean Society of Hazard Mitigation 21, no 1 (28 février 2021) : 239–49. http://dx.doi.org/10.9798/kosham.2021.21.1.239.
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The natural frequency is critical for evaluating the integrity of bridge piers. However, the natural frequency of bridge piers can vary with the support condition of the ground. The aim of this study is to investigate the natural frequency of bridge piers under different ground conditions and at different embedded depths using a small-scale concrete pier. The model piers were fixed to asphalt concrete pavement using epoxy to simulate the rock site condition. Furthermore, model piers of different embedded depths were installed in a soil chamber with dimensions of 1.0 m × 1.0 m × 0.5 m to simulate weathered soil conditions. The upper part of the model pier was hit with a hammer having a rubber tip, and the acceleration signals were measured using three accelerometers installed at the upper, middle, and bottom parts of the model pier. Fast Fourier transforms were performed to analyze the natural frequencies of the model piers. The experimental results showed that the natural frequency under the fixed condition using epoxy was significantly higher than that under the unfixed condition. In the case of weathered soil conditions, three peak points appeared in the frequency domain. The natural frequencies measured at these three points increased with the embedded depth. The increment ratio of the natural frequency with the largest amplitude was significant. This study demonstrates that ground support conditions should be considered when evaluating the integrity of bridge piers through natural frequency analysis.
13
Song, Fangyuan, Tingting Zhang et Xu Xie. « Effect of Corroded Surface Morphology on Ultra-Low Cycle Fatigue of Steel Bridge Piers ». Materials 14, no 3 (1 février 2021) : 666. http://dx.doi.org/10.3390/ma14030666.
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Corrosion is a common form of durability degradation of steel bridges. Corrosion morphology affects stress distribution under cyclic loads and causes strain concentrations in pits, thus affecting the mechanical properties of steel structures, including ultra-low cycle fatigue (ULCF). To precisely simulate corrosion morphology and investigate the ULCF failure mechanism of corroded steel piers, a sculpting method was applied to mesh units using three-dimensional surface morphology data of corroded steel specimens. Moreover, the ULCF crack-initiation life was numerically predicted using the finite element model based on the cyclic void growth model (CVGM). The cumulative equivalent plastic strain, cyclic void growth index, and critical void growth index of corroded steel piers with different corroded morphologies were compared. Results reveal that, regardless of whether the pier is corroded, fatigue cracks tend to initiate at the weld toe at corners when exposed to cyclic loads under an oblique direction at the pier top. Additionally, the ULCF crack-initiation life in a corroded pier is less than that in an uncorroded pier, and it is significantly affected by a reduction in the pier wall thickness. Corrosion pits affect the position of ULCF crack initiation in a steel pier and cracks tend to initiate at the bottom of pits with large depth-to-diameter ratios. In the case of minor corrosion, the corrosion morphology affects the seismic performance of piers to a small extent.
14
Xiao, Yun, Jun Qing Lei et Zhong San Li. « Seismic Response Analysis of Railway Frame Piers ». Key Engineering Materials 517 (juin 2012) : 824–31. http://dx.doi.org/10.4028/www.scientific.net/kem.517.824.
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By response spectrum method, superposition method based elastic time-history analysis and nonlinear time-history analysis of Newmark-β based linear increasing acceleration method, the finite element models of frame piers 21#~29# of the Ziya River Bridge on Tianjin to Baoding railway are established, and an assistant program code is generated to analyze seismic response of the frame pier. Results indicate that the vibration modes of frame piers are scattered. Only a few modes would be aroused in a narrow band spectrum. And the seismic response obtained by the response spectrum method is generally 10%~20% smaller than which obtained by the elastic time-history analysis. Under seismic excitations along the longitudinal direction, the ratio of displacement difference between two columns to the maximum value is generally liner increased with the increasing of the girder deviation from the centre of the pier beam. And the plastic hinge yielding would occur both at the bottom and the top of pier columns under excitations of the transversal direction. As a result, taking more than 30 vibration modes into account is suggested in a seismic response analysis or design calculation for frame piers. A time-history analysis is recommended as well. The evaluation of earthquake resistant capability of the transversal direction should consider both the bottom and top of the columns, and the anti-seismic capability design of the longitudinal direction is one of the key points for frame piers in the ductility design.
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Chen, Lingkun, Lizhong Jiang, Zhiping Zeng et Weiguo Long. « Numerical Modeling and Simulation on Seismic Performance of High-Speed Railway Bridge System ». Noise & ; Vibration Worldwide 42, no 10 (novembre 2011) : 15–21. http://dx.doi.org/10.1260/0957-4565.42.10.15.
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In this paper, the responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation. Elastic deformation will occur in the bridge system under low-level earthquake; however, the bridge system may enter a nonlinear stage under high-level earthquake. The whole finite element model of the bridge system was set up by means of ANSYS software and self-compiled moment-curvature relationship program, the elastic seismic responses of bridge system and the elastic-plastic deformation of piers considering different vehicle speeds are calculated respectively. The calculation results show that, the earthquake responses of bridge system are increase in general with the increase of vehicle speed and earthquake intensity, and the bottom of piers step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred at the pier bottom, the pier bottom step into the plastic stage, some measures such as lateral reinforced steel encryption should be taken into account to ensure safety.
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Jia, Yi, Hexian Su, Zhengcong Lai, Yu Bai, Fuhai Li et Zhidong Zhou. « Moment-Curvature Behavior of PP-ECC Bridge Piers under Reversed Cyclic Lateral Loading : An Experimental Study ». Applied Sciences 10, no 12 (12 juin 2020) : 4056. http://dx.doi.org/10.3390/app10124056.
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In the study, the moment–curvature relations of bridge piers constructed with polypropylene-fiber-reinforced engineered cementitious composite (PP-ECC) and reinforced concrete (RC) at the potential plastic hinge regions were performed experimentally. The bridge pier specimens were subjected to a combination of constant axial vertical loading and reversed cyclic lateral loading. The test variables include the reinforcement stirrup ratio, axial compression ratio, and height of the PP-ECC regions. Strain gauges were installed at the plastic hinge regions to determine the curvature. PP-ECC and RC bridge piers presented similar shapes of moment–curvature hysteretic curve. Regardless of the concrete type for the pier, the maximum moment and curvature were located near the bottom of the pier, which was consistent with the observed failure patterns. As greater peak moments and larger areas of hysteretic curves were observed for PP-ECC piers, this indicated that the use of PP-ECC at the potential plastic hinge regions significantly improved the deformation capacity and damage tolerance of bridge piers. Regarding the design variables, it was found that the axial loading ratio has a negative effect on enhancing the rotation capacity and plastic deformability, while the height of the PP-ECC portion and the amount of reinforcement stirrups displayed the opposite trend. Moreover, the contribution of stirrups in PP-ECC piers was more significant than that of RC ones.
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Horvath, Robert G., Daniel Schebesch et Murray Anderson. « Load–displacement behaviour of socketed piers—Hamilton General Hospital ». Canadian Geotechnical Journal 26, no 2 (1 mai 1989) : 260–68. http://dx.doi.org/10.1139/t89-035.
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Monitoring the settlement behaviour of full-scale drilled pier foundation that are in service is seldom possible. This report describes the instrumentation and monitoring program for three of the drilled pier foundations socketed into weak shale used for the Hamilton General Hospital addition, and presents and summarizes the data collected over a period of almost 2 years.The three socketed piers were constructed so that each had different load support conditions. Pier P5 was conventional, and supported loads through shaft resistance in the soil and rock and end bearing in the rock. Pier K3 was similar except shaft resistance in the soil was eliminated by installing a sonotube casing in the upper portion of the shaft. Pier P3, which also had a sonotube casing, was constructed with a void apparatus at the base to eliminate end bearing resistance so that support was achieved only through shaft resistance in the rock socket.Instrumentation included multiple-point rod extensometers, with remote readout, to measure vertical displacements at the top of the pier, top of the rock, and bottom of the socket. Load cells, reinforcing bar load cells, and concrete embedment strain gauges were also installed in an attempt to determine load distribution in the pier foundations.Under approximately full dead loading, less than 3 mm (1/8 in.) settlement has been observed. The settlement and bottom load cell data suggest that very little of the applied loading (less than 5%) has been transferred to the base of the socket. Key words: rock-socketed piers, settlement, load transfer, weak shale, instrumentation, monitoring, full-scale foundations.
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Yuan, Wenting, Xiangtong Wu, Yuren Wang, Zhenliang Liu et Peng Zhou. « Time-Dependent Seismic Reliability of Coastal Bridge Piers Subjected to Nonuniform Corrosion ». Materials 16, no 3 (23 janvier 2023) : 1029. http://dx.doi.org/10.3390/ma16031029.
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Coastal bridge piers suffer random performance deterioration owing to the presence of complex nonuniform corrosion characteristics and material uncertainties. Some of these piers will also be threatened by random earthquakes during a long-term service period, and therefore, structural safety needs to be probabilistically assessed by the seismic reliability method. To deal with this problem, we present a method to calculate the time-dependent reliability of the coastal bridge pier, comprehensively considering the randomness of a seismic event, nonuniform corrosion, and material uncertainty. First, the time-dependent M–N interaction diagrams are established by using the Monte Carlo simulation method. On the basis of the interaction diagrams, the moment resistance reduction function and time-dependent moment resistance distribution are determined. Subsequently, the moment demand under the seismic load is determined using the Poisson model and the response acceleration spectrum. Then, the formulas to calculate the time-dependent reliability of a nonuniform corroded pier are derived on the basis of the theorem of total probability. The proposed method is illustrated with a case study of a coastal bridge pier. It was found that the increase in corrosion damage would obviously increase time-dependent reliability. Furthermore, the increase in submerged zone height delayed the year when the failure section shifts from the pier bottom to the bottom of the splash and tidal zone, and it reduces the failure probability of the coastal pier. The research results presented herein show that the nonuniform corrosion manifestations influence the failure mode–related time-dependent seismic reliability of the coastal bridge pier.
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Gong, Pei Song, Bo Chen, Chun Fang Song et Xiu Li Li. « Assessment on the Thermal Stresses of Concrete Bridge Piers under Solar Radiation ». Applied Mechanics and Materials 204-208 (octobre 2012) : 2045–50. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.2045.
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The time-varying thermal stresses of a concrete pier are actively studied in this study with the aiding of the commercial package ANSYS. Thermal boundary conditions are utilized to obtain the temperature distribution of the concrete bridge pier. The surface temperature of the pier is measured by using a thermal infrared imager at different time instants. The different boundary conditions are applied to determine the structural temperature distribution and compute the thermal deformation. The made observations demonstrate that the horizontal deformation is much larger than that in vertical deformation due to the influence of the constraints on the top and bottom sides of the pier. The thermal stresses of the example bridge pier are not very large except for the local areas on top of the piers. It is seen that the numerical models can successfully predict the structural time-varying temperature effects
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Xiao, Yong Gang, et Yu Jun Liu. « Effect of Local Concrete Strength Decline on High Piers' Nonlinear Stability ». Applied Mechanics and Materials 204-208 (octobre 2012) : 3099–103. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3099.
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The nonlinear stability of three main piers of Xiniu bridge was analysed with RM Bridge V8i in this paper. The change of high pier’s nonlinear stability with the strength decline of high pier’s local concrete and variation of high pier’s height were also respectively researched.The results show that nonlinear stability coefficients will be lower if one segment of high pier’s concrete strength declines. It also indicate that the nonlinear stability coefficients drop is related to the decrease of the concrete strength, the distance between the segment at the bottom of pier, and the height of pier.
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Xu, Junming, Yanmin Jia et Dongwei Liang. « Shaking table test on single segment prefabricated concrete bridge pier connected by grouting sleeve ». International Journal of Structural Integrity 13, no 1 (9 novembre 2021) : 164–84. http://dx.doi.org/10.1108/ijsi-07-2021-0079.
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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.
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Zhang, Jia Wen. « The Wind-Induced Response of High-Pier Long-Span Continuous Rigid Frame Bridge ». Advanced Materials Research 639-640 (janvier 2013) : 502–9. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.502.
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The fluctuating wind field is simulated for digital by using the AR method. A three-dimension finite element model of high-pier long-span rigid frame bridge is presented in this paper. Based on this model, the gust-induced static response of the bridge under the longest cantilevered construction stage is computed. By comparing with those of two similar span rigid frame bridges with low piers, the gust-induced response characteristics of the internal force under the bottom of the piers of the high-pier long-span bridges are investigated, which is helpful for the safe design of bridges. The buffeting responses of the bridge under the longest cantilevered construction stage are also calculated in the time domain, taking account of the longitudinal and vertical turbulence action. Through the spectral analysis of the response, the comfort index of Diekemann is obtained. The effects of buffeting response on the workers’ safety under the most unfavorable construction stage are discussed.
23
Wang, Hui, Guo Ding, Huan Tang et Ling Kun Chen. « Numerical Seismic Analysis of Simply-Supported Girder Railway Bridge under High-Speed Train Load ». Applied Mechanics and Materials 80-81 (juillet 2011) : 566–70. http://dx.doi.org/10.4028/www.scientific.net/amm.80-81.566.
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Along with rapid development of high-speed railway in many countries, recently research on seismic response of high-speed railway bridge under train load has raised much concern among researchers. The whole bridge finite element model is establish to analysis the seismic responses of simply-supported girder railway bridge subjected to high-speed train in this paper, ICE series high speed vehicle is employed as train live load, the vehicle is simulated by moving spring-mass system, The track irregularities can be obtained by Simpack software, the birdge incluing superstructure and substructure is three-dimensional space beam element, the bottom of piers is proposed consolidated. elastic seismic responses of bridge system and elastic-plastic deformation of piers considering different train speeds are calculated. The calculation results indicate that, seismic responses of bridge system are increase with the increase of train speed and earthquake intensity, and the bottom of piers will step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred within 1.4 meters of bottom of pier. The numerical results can provide some references for design of high-speed railway bridge.
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Yao, Bo Qiang, Jun Dong et Zhi Gang Qi. « Studies on the Dynamic Performance of the Continuous Rigid Frame Bridge Impacted by the Damage at Some Key Positions of the Side Piers ». Advanced Materials Research 1020 (octobre 2014) : 137–42. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.137.
Texte intégralRésumé :
Continuous rigid frame bridge is widely used in bridge construction because of its superior characteristics, with its piers increasing. Shown in previous studies, the key positions of the side pier or lower pier at the top and the bottom of the pier yield firstly and then get into the plastic stage in the action of earthquake. So in this condition, dynamic analysis of the continuous rigid frame bridge impacted by the consolidation damage that may occur at the pier top and the bottom is studied in the paper. In the process, the consolidation damage degree is introduced in order to characterize the damage qualitatively. And then Midas/Civil 2010 is adopted to analyze the structure by modeling. Finally, some conclusions are obtained, including that the consolidation damage has a significant impact on the dynamic features, effect on the structure when the damage respectively happens at the two key sections is extremely close, and almost all value of the dynamic feature changes is located in the condition when the damage degree is less than 10%. The job above all in this paper may provide a valuable reference for the seismic analysis and the technique of damage identification and location in continuous rigid frame bridge.
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Yan, Lei, Qingning Li, Chun Han et Haotian Jiang. « Shaking Table Tests of Curved Bridge considering Bearing Friction Sliding Isolation ». Shock and Vibration 2016 (2016) : 1–14. http://dx.doi.org/10.1155/2016/6245062.
Texte intégralRésumé :
Specific to severe damage to curved bridges in earthquakes caused by the excessive force of the fixed bearings and piers, a new seismic design method on curved bridges considering bearing friction sliding isolation is proposed in this paper. Seismic model bridge and isolation model bridge with similarity ratio of 1/20 were made and the shaking table comparison test was conducted. The experimental results show that the isolation model curved bridge suffered less seismic damage than the seismic model curved bridge. The fundamental frequencies of the seismic model bridge and isolation model bridge decreased and the damping ratio increased with the increase of seismic intensity. Compared with seismic curved bridge, the maximum reduction rates of peak acceleration along the radial and tangential directions on the top of pier of the isolation model curved bridge were 47.3% and 55.5%, respectively, and the maximum reduction rate of the peak strain on the bottom of pier of the isolation model curved bridge was 43.4%. For the isolation model curved bridge, the maximum reduction rate of peak acceleration on the top of pier was 24.6% compared with that on the bottom of pier. The study results can provide experimental basis for the seismic design of curved bridges.
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Liu, Yanfang, Wenxue Zhang, Xiuli Du et Weigang Bao. « Shaking Table Tests on Wrap Rope Connect Device for Continuous-Beam Bridges with Different Pier Heights ». Advances in Civil Engineering 2022 (25 août 2022) : 1–12. http://dx.doi.org/10.1155/2022/5219261.
Texte intégralRésumé :
To investigate the cooperative and isolation effectiveness of the wrapped rope connect device (WRCD) on continuous-beam bridges with different pier heights, shaking table tests were conducted on a typical three-span continuous-beam bridge model. The model had additional pier stiffness and applied the WRCD. Two actual seismic waves with different spectral characteristics and multiple intensities were used for input ground motion. By examining the performance and measured structural response under various excitations, WRCD could effectively improve the overall cooperative effect of the model structure for a limited increase in the input seismic energy of the system. The acceleration ratio from the fixed pier top to the movable pier top increased from∼17% without the WRCD to∼32% with it. The strain-response ratio of the pier bottom decreased from its maximum of 24.8 times to 3.6 times after the device was applied. There is a specific relationship between the influence and the pier height of the structure, and the rules for high and low piers slightly differ. The movable and fixed ports can be coordinated by setting reasonable design parameters of the WRCD, which can be used for the seismic design of continuous-beam bridges with different pier heights.
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Witzany, Jiri, et Tomas Cejka. « RELIABILITY AND FAILURE RESISTANCE OF THE STONE BRIDGE STRUCTURE OF CHARLES BRIDGE DURING FLOODS ». JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, no 3 (30 septembre 2007) : 227–36. http://dx.doi.org/10.3846/13923730.2007.9636441.
Texte intégralRésumé :
The most frequent damage and collapse of some of the spans of Charles Bridge during floods occurred namely in its central part which was exposed to an intense flow of backwater and erosion of the bridge pier footing bottom, which the originally relatively shallow foundations of the piers on boxes were not able to resist for a longer time (the floods of 1432, 1496, 1784, 1890). The stone vault bridge structure was damaged due to scouring of the bridge piers foundations, their successive tilting and settlement accompanied by degradation, and finally collapse of the adjoining bridge vaults. The foundation of piers on caissons and execution of caisson rings in 1892 and 1902 to 1904 in this part of the bridge, together with measures avoiding the piling up of objects in front of the bridge, enabled the bridge to withstand the impact of more than a hundred‐year flood during the events of August 2002. The numerical analysis proved an extreme sensitivity of the stone vault bridge structure to the effects of changes in the footing bottom shape. Due to the changes in the footing bottom (angular rotation, subsidence, shifting), normal and shear stresses arise in the stone vault bridge structure, and exceed the load‐bearing capacity of the masonry causing its disintegration. The fundamental measure to prevent the bridge vaults from failure due to the changes in the footing bottom shape is to secure reliably the bridge piers foundations. The increased rigidity of the stone bridge structure achieved by the interaction with the additionally inserted reinforcing structure and by bracing the bridge body filler does not ensure the reliability and safety of the bridge structure from flood‐related failures.
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Shi, Jun, Yuang Deng, Yi Zhang, Feiting Shi et Jian Yang. « Experimental Studies on the Seismic Performance of Prefabricated Circular Hollow Bridge Piers Constructed with PVA Fiber Concrete ». Materials 16, no 5 (28 février 2023) : 1981. http://dx.doi.org/10.3390/ma16051981.
Texte intégralRésumé :
To investigate the seismic performance of prefabricated circular hollow piers with socket and slot connection, eight 1/3.5-scale specimens constructed with polyvinyl alcohol (PVA) fiber at the pier body were tested. The main test variables included the axial compression ratio, grade of pier concrete, shear-span ratio, and stirrup ratio. The seismic performance of prefabricated circular hollow piers was studied and analyzed from the aspects of the failure phenomenon, hysteresis curve, bearing capacity, ductility index, and energy dissipation capacity. The test and analysis results showed that all specimens suffered from flexural shear failure, and the increase in axial compression ratio and stirrup ratio would lead to more significant spalling of the concrete at the bottom of the specimen, but the existence of PVA fiber would improve this phenomenon. In a certain range, the increase in axial compression ratio, stirrup ratio, and the decrease in shear span ratio can improve the bearing capacity of the specimens. However, an excessive axial compression ratio would easily lead to a decrease in the ductility of the specimens. The increase in the stirrup ratio and shear-span ratio caused by the change in height can improve the energy dissipation characteristics of the specimen. On this basis, an effective shear-bearing capacity model of the plastic hinge area of prefabricated circular hollow piers was proposed, and the prediction effects of specific shear capacity models on test specimens were compared.
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Kong, Ling Jun, Yan Bei Chen, Peng Li et Qi Bin Jiang. « The Anti-Seismic Analysis of the Lock-up Device on the Arch Bridge ». Advanced Materials Research 368-373 (octobre 2011) : 1047–50. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.1047.
Texte intégralRésumé :
To study the anti-seismic performance of Lock-up device, the two computational models which are respectively uninstalled Lock-up device and installed Lock-up device on the arch bridge are established. Nonlinear time-history analyses are carried out by the Midas/Civil software in this paper. The interaction between pile and soil is considered in the analyses. The results show that the maximum shear forces of the tops and the maximum bending moments of the bottoms of all piers are quite uniform after the LUD are installed and that the displacements of the top of the fixed pier has been decreased.
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Hou, Zhixing, Jun Wang, Jueyi Sui, Feihu Song et Zhicong Li. « Impact of Local Scour around a Bridge Pier on Migration of Waved-Shape Accumulation of Ice Particles under an Ice Cover ». Water 14, no 14 (11 juillet 2022) : 2193. http://dx.doi.org/10.3390/w14142193.
Texte intégralRésumé :
The migration of a waved-shape accumulation of ice particles under an ice cover (referred to as “ice wave” in this study) is a phenomenon of transport of ice particles during an ice accumulation process in rivers. The migration of an ice wave will affect the pier scour. On the other hand, the local scour at the pier will affect the migration of ice waves. The interaction between the migration of ice waves and local scour around a pier is a very complicated process since not only the channel bed deforms, but also the ice jam develops simultaneously. By conducting a series of flume experiments, the interaction between the local scour around bridge piers and the migration of ice waves was studied. By applying both continuity and momentum equations, an empirical equation has been derived for predicting the thickness of ice waves around the pier. The impacts of the scour hole on the thickness of ice waves around the pier have been studied. The thickness of the wave crest and the migration speed of ice waves have been investigated. Similar to a scour hole in a sand bed, an “ice scour hole” appeared at the bottom of the ice jam around the pier. The existence of the “ice scour hole” affects the development of ice waves. A formula for calculating ice transport capacity has been obtained. Results calculated using the derived formula are in good agreement with those of laboratory experiments.
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Pournazeri, S., S. S. Li et F. Haghighat. « Efficient non-hydrostatic modelling of flow and bed shear stress in a pier scour hole ». Canadian Journal of Civil Engineering 41, no 5 (mai 2014) : 450–60. http://dx.doi.org/10.1139/cjce-2013-0160.
Texte intégralRésumé :
Predicting 3-D flow in a pier scour hole and the associated bed shear stress τb is important for the safe and economical design of bridge piers. This paper combines layered, hydrostatic hydrodynamic computations with non-hydrostatic pressure corrections, exploring a new modelling approach for efficient and reliable predictions of 3-D flow velocity. The law of the wall method is used for estimating τb. Its suitability for incorporation into layered models for bedload transport and pier scour simulations is also discussed. The predicted flow shows realistic features: strong downward flow adjacent to the upstream nose of a circular pier, vortex motions in the vertical and horizontal direction, and meandering flow wakes. The velocity results compare well with available experimental data. In the approach region, τb is uniform. It attains a local maximum immediately before flow enters the scour hole and then drops non-linearly in the scour-hole region toward the pier. In the wake region, τb has very low values. The τb predictions are consistent with the experimental data. In multi-layer models, when applying the law of wall method, one should use near-bed velocities as opposed to bottom-layer velocities to obtain more reliable τb estimates and avoid noisy results, which can cause a numerical instability problem in bedload transport simulations.
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Chen, Ling Kun, Li Zhong Jiang, Zhi Ping Zeng et Bo Fu Luo. « Seismic Response Analysis of High-Speed Railway Bridge Fabricated Round-Ended Piers ». Advanced Materials Research 243-249 (mai 2011) : 3844–47. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3844.
Texte intégralRésumé :
The responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation, the whole finite element model of the multi-span bridge simply supported bridge was set up, and natural vibration properties of structure were analyzed. According to theory of elasticity and elastic-plasticity, parametric study was conducted to assess the influences of different speeds, strong motion record, pier height and earthquake acceleration on the seismic capability of high-speed bridge subjected to different strength of the earthquake, the finite element soft ware and moment-curvature program were employed to calculate the earthquake responses of bridge. The calculation results show that, with the increase of train speed, pier height and earthquake intensity, the earthquake responses of bridge are increase in general, and the bottom of piers step into states of elastic-plasticity under high-level earthquake, elastic-plastic deformation is larger, the stirrup encryption measures should be carried out.
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Wei, Biao, et Shan Shan Li. « Study on a Roller-Footing Isolated Single-Pier System ». Applied Mechanics and Materials 204-208 (octobre 2012) : 2658–61. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.2658.
Texte intégralRésumé :
As to improve bridges’ seismic performance, horizontal earthquake was isolated at the bottom of piers. With one pier system as the object of study, adopting nonlinear time history analysis analyzed the un-isolation system, the traditional isolation system and the new isolation system’s seismic performance especially when the actual earthquake was different from the design earthquake, in which the new isolation system was based on rolling balls. Results shows, as for the new isolation system, the internal force is independent of earthquake accelerations and earthquake periods, therefore, sympathetic vibration will not exist, and the internal force is always too small to destroy the system.
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Suo, Wen Jia, Bing Zhu, Ning Zhao, Fan Wang et Sheng Tan Dou. « Seismic Response Analysis of Railway Continuous Curved Rigid Frame Bridges ». Applied Mechanics and Materials 353-356 (août 2013) : 1846–49. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1846.
Texte intégralRésumé :
To study the effects of seismic waves directions on bridges, the time history analytic method was used. Two bridge types, the railway continuous curved rigid frame bridge and the railway continuous straight rigid frame bridge, have been taken into account. Both the two same span bridges were used for comparative analysis about free vibration and seismic response feature, then some practical application conclusions were obtained. The longitudinal and transversal seismic waves produce the maximum reaction values. Besides, the pier bottom sections and the beam sections at the piers top are the critical sections in the bridges. In addition, this small radius curved bridge can be designed as the straight bridge in seismic design.
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Xu, Qiang, et Xing Jun Qi. « Analysis on Seismic Pounding of Curved Bridge ». Applied Mechanics and Materials 90-93 (septembre 2011) : 800–804. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.800.
Texte intégralRésumé :
Based on the impact phenomenon between the end of the beam and the bridge abutment of the curved continuous bridge during earthquakes, a spatial finite element calculating model with collision element is presented. The law of collision is studied by the nonlinear contact time history analysis method under two three-dimensional ground motions. The variation laws of relative displacement and the internal force at the bottoms of piers are researched. In addition the changing of displacement and internal force at the end diaphragm are studied. The results show that the pounding action can easily lead to significant collision forces between the end beam and the abutment of the curved bridge which increases the axial force of girder evidently. The collision forces and longitudinal displacements from the inner to outer of the diaphragm generally are showed by an increasing trend, and the pounding action is more fierce under Elcentro ground motion than that under Tianjin ground motion.There is no relative displacement of consolided pier, bending moment and shear force of the consolided pier are greater than that of the mobile pier.The conclusions from the present study may serve as a reference base for seismic design of continuous curved bridges.
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Xu, Jian, Jianwei Ren, Songhe Wang, Long Jin et Jun Yuan. « Axial Uplift Behaviour of Belled Piers in Coarse-Grained Saline Soils ». Advances in Civil Engineering 2018 (4 novembre 2018) : 1–16. http://dx.doi.org/10.1155/2018/4735423.
Texte intégralRésumé :
Bearing capacity of belled pier foundation is critical in designing transmission lines in coarse saline soil region. This paper describes model test results on belled pier foundations. Axial uplift behaviours including failure modes, load-displacement curves, and ultimate uplift bearing capacity were discussed. The failure planes in four cases were obtained from pulled out cone-shaped bodies. An empirical equation was developed with a critical parameter of an uplift angle in design. Results indicate the range where the ground uplift shows circular extension at higher loads and the overall shear failure finally occurred. The load-displacement curves are primarily softening, and the uplift bearing capacity for coarse-grained saline soils (CSS) in the crystalline state increases at larger thickness, higher than that in dissolved state. Failure planes all exhibit approximately linear change from bottom to up. The angles of uplift for soils in crystalline and dissolved states can be taken as 34° and 18°, while 32° for the conventional for the sake of safety. Uplift behaviour of belled piers in CSS was modelled incorporating a practical interface model, with both failure planes and plastic range.
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Chen, Ling Kun, Li Zhong Jiang et Peng Liu. « Elasto-Plastic Earthquake Response Analysis of High-Speed Railway Bridge Fabricated Isolation Bearings ». Materials Science Forum 675-677 (février 2011) : 1175–78. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.1175.
Texte intégralRésumé :
Basin rubber bearings are frequently used in high-speed railway bridge or passenger special line railway bridge, lead rubber bearings (LRB) are infrequently used in those railway bridges nowdays, the study on earthquake-resistant capability of railway bridge fabricated isolation bearing - the intelligent and functional structure - would be beneficial in engineering practices. Elasto-plastic earthquake responses of high-speed railway bridges fabricated LRB are studied by means of the finite element program, earthquake responses of railway bridges under high-speed vehicles and different earthquake action fabricated and unfabricated isolation bearing are calculated respectively. The results show that: plastic hinge will develop at the bottom of piers in regard to railway bridges with mid-high and low pier; LRB can reduce displacement and inner forces of structures and improve earthquake-resistant capability of structures effectively.
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Tong, Wu, et Sun Quansheng. « Seismic Damage Study of Asymmetric Continuous Rigid Frame Bridge Based on Nonlinear Time History Analysis ». Open Civil Engineering Journal 9, no 1 (31 juillet 2015) : 489–94. http://dx.doi.org/10.2174/1874149501509010489.
Texte intégralRésumé :
Continuous rigid frame bridge is a common type of bridge in California, where is a seismically active areas. Main structural features of the bridge, including asymmetry, hinge structure, concretion of girder and piers affect the seismic response of the bridge significantly. In order to evaluate the safety of the bridge under earthquake, the nonlinear models of girder, limiting steels in hinge, abutment backfill, abutment bearing, pier are simulated in great detail, and a numerical dynamic overall model, composed of the above components, is made through OpenSees program. On the basis of nonlinear time history analysis with Northridge earthquake load, seismic damage of this kind of bridge is monitored. The research results acquire the accurate damage area of the bridge. Under earthquake, asymmetric continuous rigid frame bridge with curved girder tends to move to the external rim of curve. Asymmetry is detrimental to coinstantaneous vibration of frames, which can cause the large nonlinear damage of limiting steels in hinge. Due to large longitudinal relative seismic response between girder and abutment, the damage of abutment bearing and backfill could be severe. The area on the top and bottom of shorter piers in both sides of bridge is vulnerable because longitudinal steel bars in these areas are liable to yield under repeating shaking of earthquake.
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Wang, Shaojian, Weibing Xu, Xiaomin Huang, Xiaoyu Yan, Jun Ma, Hang Sun, Jin Wang et Yanjiang Chen. « Research on the Pounding Response and Pounding Effect of a Continuous Rigid-Frame Bridge with Fabricated Super-High Piers Connected by Grouting Sleeves ». Sustainability 14, no 18 (9 septembre 2022) : 11334. http://dx.doi.org/10.3390/su141811334.
Texte intégralRésumé :
The dynamic characteristics of a continuous rigid-frame bridge with fabricated super-high piers (CRFB-FSP) connected by grouting sleeves and adjacent continuous beam bridges (AB) are significantly different, and they are prone to pounding under earthquake excitation. At present, the pounding response between the CRFB-FSP and AB is still unclear, and the impact of the pounding on the seismic performance of a CRFB-FSP is still in the exploratory stage. In this study, two 1/20 scaled models of a CRFB-FSP (MB) and a cast-in-place AB were designed and manufactured. Then, according to the research purpose and the output performance of the shaking table, three each of non-long-period (NLP) ground motions and near-fault pulse-type (NFPT) ground motions were selected as the inputs of the excitation shaking table test. The peak ground acceleration (PGA) changes from 0.5 g to 1.5 g. According to the similarity ratio (1/20), the initial gap between the MB and AB was taken as 7 mm (prototype design: 140 mm). Furthermore, the longitudinal pounding response between the CFRB-FSP and AB, as well as its influence on the seismic performance of the CFRB-FSP, was systematically investigated through a shaking table test and finite element analysis (FEA). The results showed that the pounding with the CRFB-FSP easily caused a persistent pounding, which may increase the damage risk of the pier. The peak pounding force under the NFPT ground motion was more significant than under the NLP ground motion, whereas the pounding number under the NFPT ground motion was smaller. The peak pounding force increased with the increase in the initial gap, pounding stiffness, span, and pier height. With and without pounding, the CRFB-FSP reflected higher-order mode participation (HMP) characteristics. After pounding, under the NFPT excitation, the HMP contribution increased significantly compared with that of the without pounding condition, while this effect under the NLP excitation was smaller. The peak displacement of the main beam of the CRFB-FSP increased with the increase in the main beam span, pier height and initial gap. The peak bending moment of the pier bottom increased with the increase in the main beam span and initial gap, however, decreased with the increase in the pier height. Moreover, the peak displacement of the main beam and the peak moment of the pier bottom of the CRFB-FSP both reduced. In contrast, the corresponding seismic response of the AB increased under the same conditions.
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Zhou, Zhao, Junxing Wang et David Z. Zhu. « Energy dissipation in a deep tailwater stilling basin with partial flaring gate piers ». Canadian Journal of Civil Engineering 47, no 5 (mai 2020) : 523–33. http://dx.doi.org/10.1139/cjce-2018-0099.
Texte intégralRésumé :
Flaring gate piers (FGPs) have been used to increase energy dissipation in stilling basins downstream of spillways. For projects with a low water head and large unit discharge together with a deep tailwater level, energy dissipation inside a conventional stilling basin is usually insufficient. This paper proposes a new partial flaring gate pier (partial FGP) scheme to intensify the energy dissipation inside the stilling basin. The results for the no FGP scheme, the conventional FGP scheme, and the partial FGP scheme were compared using a physical model study and numerical simulations. It was found that the partial FGP scheme (the alternation of flaring and no flaring gate piers in chambers) can contain the submerged hydraulic jump and high-speed water jet in the upstream region of the stilling basin. Thus, the water jet from the FGP chamber was forced to laterally diffuse, thereby intensifying the shear friction and turbulent kinetic energy and forming a vertical vortex from the bottom to the surface. Compared with the other two schemes, the flow pattern in the partial FGP scheme was improved significantly with much deeper air entrainment depth inside the stilling basin and much lower turbulent kinetic energy in the outgoing flow. The mean velocity of the outgoing flow also decreased by more than 20%. The common problems of secondary hydraulic jump outside the stilling basin were eliminated.
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Zhong, Tie Yi, Chao Yi Xia et Feng Li Yang. « Study of Parameters Optimization on Seismic Isolated Railway Bridges ». Applied Mechanics and Materials 50-51 (février 2011) : 135–39. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.135.
Texte intégralRésumé :
Based on optimization theories, considering soil-structure interaction and running safety, the optimal design model of the seismic isolation system with lead-rubber bearings (LRB) for a simply supported railway beam bridge is established by using the first order optimization method in ANSYS, which the parameters of the isolation bearing are taken as design variables and the maximum moments at the bottom of bridge piers are taken as objective functions. The optimal calculations are carried out under the excitation of three practical earthquake waves respectively. The research results show that the ratio of the stiffness after yielding to the stiffness before yielding has important effect on the structural seismic responses. Through the optimal analysis of isolated bridge system, the optimal design parameters of isolation bearing can be determined properly, and the seismic forces can be reduced maximally as meeting with the limits of relative displacement between pier top and beam, which provides efficient paths and beneficial references for dynamic optimization design of seismic isolated bridges.
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Wang, Jiyang, Yongjun Wang, Chenglin Wan, Rongda Chen, Chengbin Liu et Zhihua Hu. « Seismic Behavior of RC Bridge Piers Locally Replaced with SFRC-FA Subjected to Torsion Combined with Axial Compression ». Advances in Materials Science and Engineering 2021 (31 mai 2021) : 1–17. http://dx.doi.org/10.1155/2021/8882573.
Texte intégralRésumé :
Under complex seismic forces, the failure characteristics of the plastic hinge region at the bottom of the pier column and the methods improving the ductility have attracted extensive attention. In this study, steel fiber-reinforced concrete with fine aggregate (SFRC-FA) was applied to locally replace the conventional concrete in the potential plastic hinge region at the bottom of the pier column. Five SFRC-FA pier column specimens with different stirrup ratios and different replacement lengths and one conventional reinforced concrete pier column specimen were produced. Using the seismic behavior tests under the combined bending-shear-torsion-axial force, the failure mode, torsional bearing capacity, energy dissipation, and the torsional plastic hinges of the pier columns were investigated. In addition, an equation for calculating the torsional bearing capacity of the new composite pier columns was proposed. The results showed that (1) compared with the reinforced concrete pier column, the plastic hinge was shifted from the bottom of the pier column to the middle of the height of the pier column due to the application of SFRC-FA at the bottom of the pier column, which improved the torsional bearing capacity; (2) the effect of reducing the stirrup ratio of the SFRC-FA replacement region on the torsional bearing capacity, cracking mode, energy dissipation, and ductility was not obvious; (3) the accuracy of the new equation based on the space truss model proposed in this article was verified by comparison with the experiments of this study and other researches.
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Zhang, Chen, Haodi Yan, Muhammad Tahir Jamil et Yonghai Yu. « Improvement of the Flow Pattern of a Forebay with a Side-Intake Pumping Station by Diversion Piers Based on Orthogonal Test Method ». Water 14, no 17 (28 août 2022) : 2663. http://dx.doi.org/10.3390/w14172663.
Texte intégralRésumé :
The flow analysis of the forebay of a lateral intake pumping station with asymmetrical operating pumps was carried out with a realizable k-ε turbulent model and SIMPLEC (Semi Implicit Method for Pressure Linked Equations Consistent) algorithm. The Pressure Inlet boundary condition was adopted and the pressure between the top surface and the bottom surface was linear with the height of the inlet section. The Mass Flow Outlet boundary condition was also adopted to ensure the accuracy and precision of the CFD (Computational Fluid Dynamics) simulation. The diversion pier was selected as the optimization strategy based on the flow parameters. The layout of the diversion piers was designed with four parameters which are the relative length, relative height, width, and straight-line distance of the piers’ tail. Each parameter had three values. Based on the orthogonal test, nine groups of the numerical simulation on different layouts of diversion piers were analyzed with the uniformity of axial flow velocity and weighted average angle of the flow velocity of the inlet cross-section of each pump, reducing the number of tests from 64 (43) groups to 9 groups, improving work efficiency. The results show that the diversion piers had a significant adjustment of uniformity of axial flow velocity and weighted average angle of flow velocity. After optimization of the forebay, the uniformity of axial flow velocity of intake of No.1 pump was 80.26% and the weighted average angle of flow velocity was 77.68°. The above values of the No.2 pump were 98.74% and 87.84°, respectively. The values of the No.4 pump were 93.41% and 77.28°. The results of numerical simulation, which was carried out to estimate the rectification effect under the operation combination of the No.1, No.3, and No.4 pumps, showed that the uniformity and the angle of the No.1 pump were 92.65% and 72.66°, respectively, the uniformity and the angle of No.3 pump were 94.54% and 85.14°, and the uniformity and the angle of the No.4 pump were 75.81% and 78.21°. This research proves that the orthogonal test method, in a reasonable and convenient way, can be applied in hydraulic optimization for a lateral intake pumping station.
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Setiati, N. Retno, et Ireng Guntorojati. « Earthquake hazard mitigation analysis of the pier 231 Harbour Road Bridge ». E3S Web of Conferences 156 (2020) : 05001. http://dx.doi.org/10.1051/e3sconf/202015605001.
Texte intégralRésumé :
Earthquake mitigation for infrastructure, especially bridges, needs to be done to avoid collapse of the bridge structure under earthquake load. The investigation and rehabilitation of existing bridges against earthquake hazards needs to be carried out through a screening process based on The Bridge Inspection Guidelines (Pd No.005-01/P/BM/2011). Based on the results of the inspection and the screening process, it can be determined whether the bridge is able to resist earthquake loads during its service lifetime or needs to be strengthened. This study aims to determine the strength capacity of Harbour Road bridges in resisting earthquake loads based on SNI 2833 2016 and Peta Gempa Nasional 2017 during its service lifetime. Analysis of the pushover structure was carried out at Pierhead 231 which is located on the WiyotoWiyono Harbour Road,Jakarta. The modeling of Harbour Road bridge structure in longitudinal direction consists of piers and concrete girder separated by expansion joint and bearing, while in transverse direction is modeled as a single pier system. Structural analysis modeling is assumed to behave as a system with single degree of freedom (SDOF). Based on the results of pushover analysis, it can be seen the location and level of plastic hinge that occur when the performance point is reached. During design earthquake conditions, the performance point is obtained in the Immediate Occupancy condition and the plastic hinge occurs first at the bottom of the Pier. Structural performance at the time of the earthquake design is still under life safety conditions so the Harbour Road bridge still meets the strength requirements.
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Pagliosa, Paulo Roberto, Mauricio Cantor, Fernando Scherner, Mariana Beatriz Paz Otegui, Aurea Luiza Lemes-Silva, Cintia Dalcuche Leal Martins, Giorgia Freitas Alves, Alessandra Fonseca et Paulo Antunes Horta Jr. « Influence of piers on functional groups of benthic primary producers and consumers in the channel of a subtropical coastal lagoon ». Brazilian Journal of Oceanography 60, no 1 (mars 2012) : 65–73. http://dx.doi.org/10.1590/s1679-87592012000100007.
Texte intégralRésumé :
Artificial habitats have become common in coastal areas worldwide and may influence the structure and functioning of benthic ecosystems. We analyze the influence of piers on the benthic morphofunctional groups of rocky seaweeds and of soft bottom macrofauna in the channel of Conceição Lagoon (southern Brazil). The main impact is a reduction in the luminosity available for photosynthetic activity which is directly related to a decrease in the biomasses of sediment microphytobenthos and of more highly structured macroalgae life-forms. Contrary to expectations, the morphotypes of potentially high biomass productivity, such as articulated coralline, corticated and leathery macroalgae, were in general less abundant and the low biomass foliose and filamentous macroalgae occurred in reference areas but not under the piers. The piers' effects on motile epifauna and infauna functional groups were site-specific and probably related to the general reduction in primary producer organisms in the new habitats. The discretely motile infauna was the only functional group able to thrive under the piers due to their reduced motility and fragile morphological structures, being benefited by the shelter provided by the artificial habitats. Our results showed that the piers might have a negative effect on the base-trophic level organisms responsible for bottom-up controls.
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Kulakova, I. I., et L. V. Vorobyova. « ВІЛЬНОЖИВУЧІ МОРСЬКІ НЕМАТОДИ ПРИБЕРЕЖНОЇ ЗОНИ О. ЗМІЇНИЙ УКРАЇНСЬКОГО ШЕЛЬФУ ЧОРНОГО МОРЯ ». Scientific Issue Ternopil Volodymyr Hnatiuk National Pedagogical University. Series : Biology 75, no 1 (23 juin 2019) : 13–20. http://dx.doi.org/10.25128/2078-2357.19.1.2.
Texte intégralRésumé :
The species diversity, quantitative parameters and spatial distribution of the free-living marine nematodes in the meiobenthic community of the coastal zone area near the Snake Island, Black Sea, Ukraine shelf, have been studied for the first time. In total of 47 species from 5 orders, 14 families and 31 genera were registered. The representatives of orders Monhysterida and Enoplida were most abundant. The results of the comparative analysis of nematode assemblage in dependence of the substrate type are described. The percentage of nematodes in total meiobenthos in piers fouling consisted of 16% only, but on silt bottoms it reached 60.8%. The species diversity also increases on silt bottoms. Four nematode species are registered in piers fouling, but 36 on silts. The omnivores-carnivores consisted of 50% of the nematode assemblage in piers fouling. On silts, the percentage of non-selective deposit feeders reached 47%, but epistrate feeders decreased up to 14%.
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Zhao, Yan, Hong Yu Jiang, Jie Gu et Ru Qin Wang. « Seismic Performance of Reinforced Concrete Rectangular Hollow Bridge Piers ». Advanced Materials Research 859 (décembre 2013) : 95–99. http://dx.doi.org/10.4028/www.scientific.net/amr.859.95.
Texte intégralRésumé :
Hollow rectangular reinforced concrete piers have been widely used in tall-column and long-span bridges. Two large-scale experimental models of the hollow reinforced concrete bridge piers were built to study the seismic performance of the piers subjected to biaxial bending under constant axial load. The objective is to evaluate seismic performances of the model piers and the factors affecting the seismic performance of the model piers by comparing their failure mechanism, bearing capacity, ductility, energy dissipation capacity, etc. The results show that the hollow rectangular specimen experienced flexural failure with plastic hinges formed at the bottom of the piers when subjected to combined axial load and biaxial bending. The bearing capacity of the specimen increases greatly and the ductility decrease insignificantly as the axial compression ratio increases from 0.1 to 0.2, while the energy dissipation capacity is increased by 121.8%, however, the absolute value of total cumulative hysteretic energy is not magnificent.
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Zhang, Wenxue, Kun Liang et Ying Chen. « Relationship between the Vibration Acceleration and Stability of a Continuous Girder Bridge during Horizontal Rotation ». Sustainability 14, no 10 (12 mai 2022) : 5853. http://dx.doi.org/10.3390/su14105853.
Texte intégralRésumé :
To ensure the safety of bridges during horizontal rotation, we propose a method through which it is possible to evaluate the stability of structures in real time by measuring the vibration acceleration of the rotating structure. First, the vibration characteristics collected during the horizontal rotation of a typical high-speed railway bridge were compared with the results of a finite element analysis. Second, the analytic formula to calculate the ratio of vibration acceleration and the pier-bottom-section bending moment for the rotating structure was deduced by considering the beam and pier as an infinite-degree-of-freedom rod. Then, the results of the analytical formula were compared with those of the finite element calculation. Overall, the results showed that the bending moment of the pier bottom (which was related to the stability of the rotating bridge) was affected only by the two asymmetrical vibration modes. The analytic formula built by considering the beam and pier as an infinite degree-of-freedom rod with equal cross-section effectively described the relationship between the vibration acceleration and pier-bottom-bending moment. Finally, the vibration of the rotating bridge was simplified to the superposition of the first two asymmetric vibration modes in the facade. Based on our findings, we were able to provide a formula and some check tables to calculate the permissible value of vibration acceleration for typical high-speed railway bridges.
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Wang, Chang Feng, et Chun Lin Zhu. « Seismic Response of Bridge Isolated with Friction Pendulum Systems ». Applied Mechanics and Materials 256-259 (décembre 2012) : 2122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2122.
Texte intégralRésumé :
Friction pendulum systems are sliding bearing that make use of a spherical concave surface to provide a restoring force and friction force to dissipate earthquakes energy. Seismic response reduction effect of some tall pier and long span simply-supported steel truss girders with FPS is researched by using nonlinear time history analysis method. The results show that seismic response reduction effect is evident for the moment at the bottom of pier and displacement at the top of pier for the tall pier and long span simply-supported steel truss girders.
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Jia, Bu Yu, Xiao Lin Yu, Kang Huang et Quan Sheng Yan. « Study on Dynamic Behavior and Seismic Performance of Cable-Stayed Bridge with Different Auxiliary Pier Positions ». Applied Mechanics and Materials 587-589 (juillet 2014) : 1655–58. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1655.
Texte intégralRésumé :
Choosing the Panzhong Bridge of the Guangzhongjiang highway as the research object, the dynamic behavior and seismic performance of cable-stayed bridge with different auxiliary pier positions were studied. The results show that the position of the auxiliary pier has limited influence on dynamic behavior. Under the action of the earthquake, auxiliary pier restricts the deformation of side span effectively and reduces the bending moment at bottom of the pile caps.