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1.
Steel rectangular section columns with stiffened plates are commonly used for elevated highway bridges in the urban areas of Japan. The seismic design of bridge piers is usually performed by dynamic analysis in the horizontal direction using various independent directional seismic acceleration data. However, this simple treatment does not reflect the effect of bilateral loading as a structural response to inelastic interaction. In this study, unidirectional and bidirectional loading hybrid tests were conducted to examine the seismic response and performance of square cross‐sections of steel bridge piers subjected to bidirectional seismic accelerations. Comparison of the results of unidirectional and bidirectional loading tests revealed that the maximum load is the same as the average of unidirectional loading in the NS and EW directions; however, the maximum response displacement and residual displacement increase in proportion with hard to soft ground types. Moreover, a modified seismic design is proposed considering these bidirectional loading effects. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
钢管混凝土桥墩抗震性能试验研究 总被引：1，自引：0，他引：1
为研究钢管混凝土桥墩的抗震性能,对钢管混凝土桥墩和钢筋混凝土桥墩进行了拟静力对比试验研究。根据试件的破坏发展过程以及各试件的滞回曲线和骨架曲线,分析了其滞回性能、耗能能力、延性、强度退化及刚度退化等抗震性能。试验结果表明,钢管混凝土桥墩的抗震性能明显好于钢筋混凝土桥墩。在含钢率和轴力相同的情况下,钢管混凝土桥墩的滞回曲线比钢筋混凝土桥墩丰满得多,前者的耗能能力约为后者的4.46倍,钢管混凝土桥墩的延性大于钢筋混凝土桥墩;随着轴压比的增大,钢管混凝土桥墩延性有所下降,强度退化加快,但对其刚度退化的影响不大。 相似文献
3.
Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings 
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下载免费PDF全文 Diana Ene Shoichi Kishiki Satoshi Yamada Yu Jiao Yoshinao Konishi Masao Terashima Norihisa Kawamura 《地震工程与结构动力学》2016,45(2):173-192
Hysteretic dampers are used to dissipate earthquake‐induced energy in base‐isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U‐shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full‐scale specimens are conducted in this regard: (i) quasi‐static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi‐static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U‐shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
4.
Over the last two decades, the probabilistic assessment of reinforced concrete (RC) structures under seismic hazard has been developed rapidly. However, little attention has been devoted to the assessment of the seismic reliability of corroded structures. For the life‐cycle assessment of RC structures in a marine environment and earthquake‐prone regions, the effect of corrosion due to airborne chlorides on the seismic capacity needs to be taken into consideration. Also, the effect of the type of corrosive environment on the seismic capacity of RC structures has to be quantified. In this paper, the evaluation of the displacement ductility capacity based on the buckling model of longitudinal rebars in corroded RC bridge piers is established, and a novel computational procedure to integrate the probabilistic hazard associated with airborne chlorides into life‐cycle seismic reliability assessment of these piers is proposed. The seismic demand depends on the results of seismic hazard assessment, whereas the deterioration of seismic capacity depends on the hazard associated with airborne chlorides. In an illustrative example, an RC bridge pier was modeled as single degree of freedom (SDOF). The longitudinal rebars buckling of this pier was considered as the sole limit state when estimating its failure probability. The findings show that the life‐cycle reliability of RC bridge piers depends on both the seismic and airborne chloride hazards, and that the cumulative‐time failure probabilities of RC bridge piers located in seismic zones can be dramatically affected by the effect of airborne chlorides. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
基于位移设计的钢筋混凝土桥墩抗震性能试验研究(Ⅱ):振动台试验 总被引：1，自引：1，他引：0
通过模型振动台试验研究了基于位移设计的钢筋混凝土桥墩的抗震性能。以完成的拟静力试验中的桥墩试件为参考原型,利用基于位移抗震设计方法和现行桥梁抗震规范方法设计了4根1:2的钢筋混凝土桥墩试件并进行了模型振动台试验。对小震、中震和大震作用下桥墩试件的破坏形态、加速度和位移反应、位移延性系数和地震总输入能(耗能)等方面进行了比较分析。综合拟静力试验和振动台试验结果,可以认为基于位移设计的钢筋混凝土桥墩能够达到预期的延性抗震要求。 相似文献
6.
沿着摇摆桥墩的概念提出一种限制位移桥墩连续刚构桥体系。该体系通过对连续刚构桥墩底和承台之间采取一定措施,使桥梁在地震发生时能够在限制的位移量内活动,减小输入到桥梁结构中的能量,达到减震的目的。通过对一座铁路连续刚构桥的分析,发现这种限制位移桥墩连续刚构桥体系能大幅减小桥墩的延性和强度地震需求,减震效果明显,在选择合适的限制位移量的情况下,可保证桥墩在高烈度罕遇地震作用下几乎保持弹性工作状态,震后经简单处理即可保证使用功能,为震后救援工作带来极大便利,也大大减少了修复成本。 相似文献
7.
为探究局部锈蚀矩形截面钢筋混凝土（RC）桥墩重度震损加固后的抗震性能,本文对拟静力破坏后的6个矩形截面RC桥墩试件进行扩大截面加固。通过加载试验,对加固桥墩试件从破坏形态、滞回特性、水平承载力、位移延性、侧向刚度以及耗能等方面进行了系统分析。结果表明:相比于普通箍筋,横向施加预应力的改进扩大截面加固方式对破坏后桥墩试件的抗震性能修复成效更佳;在同等位移幅值下,锈蚀率不断增大,桥墩试件抗震性能呈现逐渐降低的趋势;钢筋锈蚀位置上移,加固后桥墩试件的抗震性能提升;轴压比加大,加固后桥墩试件承载力和侧向刚度增大,但延性降低。 相似文献
8.
活动支座摩擦力对简支梁桥地震反应的影响 总被引：3，自引：0，他引：3
本文介绍在地震作用下活动支座摩擦力简支梁桥桥墩内力和活动支座外墩,梁相对位 影响,以及水平地震系数,摩擦系数变化对固定支座水平地震荷载的影响。文中建议了考察活动以座摩擦力的简支梁桥整体分析模型。 相似文献
9.
It has been well documented that following a major earthquake a substantial percentage of economic loss results from downtime of essential lifelines in and out of major urban centres. This has thus led to an improvement of both performance‐based seismic design philosophies and to the development of cost‐effective seismic structural systems capable of guaranteeing a high level of protection, low structural damage and reduced downtime after a design‐level seismic event. An example of such technology is the development of unbonded post‐tensioned techniques in combination with rocking–dissipating connections. In this contribution, further advances in the development of high‐performance seismic‐resistant bridge piers are achieved through the experimental validation of unbonded post‐tensioned bridge piers with external, fully replaceable, mild steel hysteretic dissipaters. The experimental response of three 1 : 3 scale unbonded, post‐tensioned cantilever bridge piers, subjected to quasi‐static and pseudo‐dynamic loading protocols, are presented and compared with an equivalently reinforced monolithic benchmark. Minimal physical damage is observed for the post‐tensioned systems, which exhibit very stable energy dissipation and re‐centring properties. Furthermore, the external dissipaters can be easily replaced if severely damaged under a major (higher than expected) earthquake event. Thus, negligible residual deformations, limited repair costs and downtime can be achieved for critical lifeline components. Satisfactory analytical–experimental comparisons are also presented as a further confirmation of the reliability of the design procedure and of the modelling techniques. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
Damage investigation of small to medium-span highway bridges in Wenchuan earthquake revealed that typical damage of these bridges included: sliding between laminated-rubber bearings and bridge girders, concrete shear keys failure, excessive girder displacements and even span collapse. However, the bearing sliding could actually act as a seismic isolation for piers, and hence, damage to piers for these bridges was minor during the earthquake. Based on this concept, an innovative solation system for highway bridges with laminated-rubber bearings is developed. The system is comprised of typical laminated-rubber bearings and steel dampers. Bearing sliding is allowed during an earthquake to limit the seismic forces transmitting to piers, and steel dampers are applied to restrict the bearing displacements through hysteretic energy dissipation. As a major part of this research, a quarter-scale, two-span bridge model was constructed and tested on the shake tables to evaluate the performance of this isolation system. The bridge model was subjected to a Northridge and an artificial ground motion in transverse direction. Moreover, numerical analyses were conducted to investigate the seismic performance of the bridge model. Besides the test bridge model, a benchmark model with the superstructure fixed to the substructure in transverse direction was also included in the numerical analyses. Both the experimental and the numerical results showed high effectiveness of this proposed isolation system in the bridge model. The system was found to effectively control the pier-girder relative displacements, and simultaneously, protect the piers from severe damage. Numerical analyses also validated that the existing finite element methods are adequate to estimate the seismic response of bridges with this isolation system. 相似文献
11.
Giuseppe Abbiati Oreste S. Bursi Philippe Caperan Luigi Di Sarno Francisco Javier Molina Fabrizio Paolacci Pierre Pegon 《地震工程与结构动力学》2015,44(13):2221-2240
This paper deals with the seismic response assessment of an old reinforced concrete viaduct and the effectiveness of friction‐based retrofitting systems. Emphasis was laid on an old bridge, not properly designed to resist seismic action, consisting of 12 portal piers that support a 13‐span bay deck for each independent roadway. On the basis of an OpenSEES finite element frame pier model, calibrated in a previous experimental campaign with cyclic displacement on three 1:4 scale frame piers, a more complex experimental activity using hybrid simulation has been devised. The aim of the simulation was twofold: (i) to increase knowledge of non‐linear behavior of reinforced concrete frame piers with plain steel rebars and detailing dating from the late 1950s; and (ii) to study the effectiveness of sliding bearings for seismic response mitigation. Hence, to explore the performance of the as built bridge layout and also of the viaduct retrofitted with friction‐based devices, at both serviceability and ultimate limit state conditions, hybrid simulation tests were carried out. In particular, two frame piers were experimentally controlled with eight‐actuator channels in the as built case while two frame piers and eight sliding bearings were controlled with 18‐actuator channels in the isolated case. The remaining frame piers were part of numerical substructures and were updated offline to accurately track damage evolution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
12.
在桥梁的震后抢通工作中,桥梁结构的快速损伤评估是恢复交通的关键环节。以具有代表性的铁路矩形桥墩为研究对象,通过4组拟静力试验验证有限元建模方法的合理性,并对1 000组桥墩有限元模型分别按照纵桥向和横桥向进行耐震时程分析,通过搭建BP神经网络对地震动力响应的需求结果进行拟合,构建铁路矩形桥墩震损快速评估模型,最终通过一座三跨混凝土梁桥验证该模型的适用性。研究结果表明：配筋率、配箍率、剪跨比和轴压比是影响桥墩地震损伤的四种主要因素,长宽比、混凝土和钢筋强度是影响桥墩地震损伤的三项次要因素;当发生PGA为0.32g的设计地震时,通过数值分析和神经网络模型快速评估这两种方法计算所得桥梁四个桥墩轻微损伤概率分别为96.7%、44.6%、49.1%、96.7%和95.6%、40.4%、60.9%、95.8%,中度损伤概率分别为40.1%、1.2%、1.6%、40.1%和37.4%、2.3%、6.0%、37.7%;BP神经网络算法能够有效建立构造参数与地震响应之间的联系,输出误差处于合理范围内,回归程度较好。基于BP神经网络的桥梁地震损伤评估模型具有较好的普适性,能替代部分数值仿真计算工作。 相似文献
13.
考虑高强钢筋、ECC等高性能材料在桥梁工程中的推广应用,针对普通钢筋混凝土桥墩抗震性能相对较差的情况,研究高强钢筋ECC-RC复合桥墩的桥梁抗震性能。通过OpenSees平台建立普通RC桥墩桥梁、ECC-RC复合桥墩桥梁及高强钢筋ECC-RC复合桥墩桥梁非线性有限元模型,采用增量动力法和"能力需求比"分析方法建立桥梁各构件及系统的地震易损性曲线,探讨高强钢筋及ECC对桥梁抗震性能的影响。研究表明:ECC-RC、高强钢筋ECC-RC复合桥墩及其桥梁系统的地震易损性均有改善,且高强钢筋ECC的改善效果更显著,高强钢筋ECC-RC复合桥墩支座的地震易损性有所降低,高强钢筋及ECC的应用有助于提高桥墩和桥梁系统抗震性能和安全性,特别是在中震及大震作用下这一现象更加明显。 相似文献
14.
Miguel B. Brito Mitsuyoshi Akiyama Yoshitaka Ichikawa Hiroki Yamaguchi Riki Honda Naomitsu Ishigaki 《地震工程与结构动力学》2020,49(8):817-837
A novel low-cost friction sliding system for bidirectional excitation is developed to improve the seismic performance of reinforced concrete (RC) bridge piers. The sliding system is a spherical prototype developed by combining a central flat surface with an inclined spherical segment, characterized by stable oscillation and a large reduction in response accelerations on the flat surface. The inclined part provides a restoring force that limits the residual displacements of the system. Conventional steel and concrete are employed to construct a flat-inclined spherical surface atop an RC pier. The seismic forces are dissipated through the frictions generated during the sliding movements; hence, the seismic resilience of bridges can be ensured with a low-cost design solution. The proposed system is fabricated utilizing a mold created by a three-dimensional printer, which facilitates the use of conventional concrete to construct spherical shapes. The concrete surface is lubricated with a resin material to prevent abrasion from multiple input ground motions. To demonstrate the effectiveness of the system, bidirectional shaking table tests are conducted in the longitudinal and transverse directions of a scaled bridge model. The effect of the inclination angle and the flat surface size is investigated. The results demonstrate a large decrease in response acceleration when the system exhibits circular sliding displacement. Furthermore, the inclination angle that generates the smallest residual displacement is identified experimentally. 相似文献
15.
为研究不同加固方式对钢筋混凝土(RC)圆截面桥墩抗震性能的影响,利用OpenSees有限元软件建立了普通RC桥墩以及分别采用钢套管、碳纤维增强聚合物(CFRP)、体外预应力筋进行加固的桥墩数值分析模型,对模型输入远断层地震动,进行增量动力分析。以墩顶峰值位移角与震后残余位移角为指标,对比分析了桥墩加固前后的地震响应。结果表明:采用钢套管、体外预应力筋和CFRP加固后,RC桥墩的峰值位移与震后残余位移均减小,钢套管加固方式对桥墩峰值位移的降低幅度最大,体外预应力筋加固方式对抑制桥墩震后残余位移的效果最好;随着剪跨比的增大,3种加固方式对桥墩在地震动作用下位移响应的抑制作用均逐步减小;随着轴压比的增大,3种加固方式对RC桥墩峰值位移的抑制作用逐步降低。 相似文献
16.
Previous failure analyses of bridges typically focus on substructure failure or superstructure failure separately. However, in an actual bridge, the seismic induced substructure failure and superstructure failure may influence each other. Moreover, previous studies typically use simplified models to analyze the bridge failure; however, there are inherent defects in the calculation accuracy compared with using a detailed three-dimensional (3D) finite element (FE) model. Conversely, a detailed 3D FE model requires more computational costs, and a proper erosion criterion of the 3D elements is necessary. In this paper, a multi-scale FE model, including a corresponding erosion criterion, is proposed and validated that can significantly reduce computational costs with high precision by modelling a pseudo-dynamic test of an reinforced concrete (RC) pier. Numerical simulations of the seismic failures of a continuous RC bridge based on the multi-scale FE modeling method using LS-DYNA are performed. The nonlinear properties of the bridge, various connection strengths and bidirectional excitations are considered. The numerical results demonstrate that the failure of the connections will induce large pounding responses of the girders. The nonlinear deformation of the piers will aggravate the pounding damages. Furthermore, bidirectional earthquakes will induce eccentric poundings to the girders and different failure modes to the adjacent piers. 相似文献
17.
Effects of seismic isolation on the seismic response of a California high‐speed rail prototype bridge with soil‐structure and track‐structure interactions 下载免费PDF全文
下载免费PDF全文 With the launch of the high‐speed train project in California, the seismic risk is a crucial concern to the stakeholders. To investigate the seismic behavior of future California High‐Speed Rail (CHSR) bridge structures, a 3D nonlinear finite‐element model of a CHSR prototype bridge is developed. Soil‐structure and track‐structure interactions are accounted for in this comprehensive numerical model used to simulate the seismic response of the bridge and track system. This paper focuses on examining potential benefits and possible drawbacks of the a priori promising application of seismic isolation in CHSR bridges. Nonlinear time history analyses are performed for this prototype bridge subjected to two bidirectional horizontal historical earthquake ground motions each scaled to two different seismic hazard levels. The effect of seismic isolation on the seismic performance of the bridge is investigated through a detailed comparison of the seismic response of the bridge with and without seismic isolation. It is found that seismic isolation significantly reduces the deck acceleration and the force demand in the bridge substructure (i.e., piers and foundations), especially for high‐intensity earthquakes. However, seismic isolation increases the deck displacement (relative to the pile cap) and the stresses in the rails. These findings imply that seismic isolation can be promisingly applied to CHSR bridges with due consideration of balancing its beneficial and detrimental effects through using appropriate isolators design. The optimum seismic isolator properties can be sought by solving a performance‐based optimum seismic design problem using the nonlinear finite‐element model presented herein. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
18.
An investigation is presented of the collapse of a 630 m segment (Fukae section) of the elevated Hanshin Expressway during the 1995 Kobe earthquake. The earthquake has, from a geotechnical viewpoint, been associated with extensive liquefactions, lateral soil spreading, and damage to waterfront structures. Evidence is presented that soil–structure interaction (SSI) in non‐liquefied ground played a detrimental role in the seismic performance of this major structure. The bridge consisted of single circular concrete piers monolithically connected to a concrete deck, founded on groups of 17 piles in layers of loose to dense sands and moderate to stiff clays. There were 18 spans in total, all of which suffered a spectacular pier failure and transverse overturning. Several factors associated with poor structural design have already been identified. The scope of this work is to extend the previous studies by investigating the role of soil in the collapse. The following issues are examined: (1) seismological and geotechnical information pertaining to the site; (2) free‐field soil response; (3) response of foundation‐superstructure system; (4) evaluation of results against earlier studies that did not consider SSI. Results indicate that the role of soil in the collapse was multiple: First, it modified the bedrock motion so that the frequency content of the resulting surface motion became disadvantageous for the particular structure. Second, the compliance of soil and foundation altered the vibrational characteristics of the bridge and moved it to a region of stronger response. Third, the compliance of the foundation increased the participation of the fundamental mode of the structure, inducing stronger response. It is shown that the increase in inelastic seismic demand in the piers may have exceeded 100% in comparison with piers fixed at the base. These conclusions contradict a widespread view of an always‐beneficial role of seismic SSI. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
19.
混凝土的数值计算模型在滞回性能分析中往往比较难收敛，利用有限元软件ADINA提供Drucker-Prager模型的Cap修正屈服准则确立的非协调参数Drucker-Prager模型对预应力节段拼装混凝土桥墩进行数值分析，对预应力节段拼装桥墩在低周往复荷载作用下的滞回性能进行分析。通过比较采用非协调参数Drucker-Prager模型建立的数值模型计算得到的滞回曲线与试验得到的结果，两者吻合程度较高。基于这一成果可以通过数值模拟的方式获得预应力节段拼装桥墩的滞回曲线与相关数据，可应用于预应力节段拼装桥墩抗震计算和设计。 相似文献
20.
为克服利用OpenSEES进行预制拼装桥墩纤维模型分析时干接缝区域模拟困难的问题,提出一种由刚性单元、非线性梁柱单元、零长度单元配合ENT单压材料组成的干接缝单元。通过基于干接缝单元的纤维模型数值模拟结果与文献中的1:3.5缩尺桥墩拟静力试验结果对比发现:该干接缝单元不仅解决了墩身混凝土压溃带来的模型不收敛问题,而且考虑了墩身节段宽度对干接缝区域的影响,使预制拼装桥墩干接缝处的力学性能更接近实际的力学性能;数值模拟结果与试验结果吻合较好证明了该干接缝单元用于模拟预制拼装桥墩干接缝区域的可行性。在此基础上设置耗能钢筋、外包钢管和墩底橡胶支承垫层作为桥墩附加耗能装置,对预制拼装桥墩进行拟静力循环加载模拟,研究不同耗能装置对预制拼装桥墩的滞回能力、预应力筋内力、累积耗能、残余位移以及等效刚度等性能参数的影响。结果表明:设置耗能钢筋和外包钢管可以显著提高预制拼装桥墩的耗能能力、水平承载力和刚度,降低预应力损失;设置墩底橡胶支承垫层也能提高预制拼装桥墩的耗能能力,但会降低桥墩的水平承载力和刚度,应根据桥墩自身刚度谨慎选择橡胶垫层的刚度。 相似文献