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1.
常规装配式混凝土柱脚连接常采用灌浆套筒作为连接方式,为克服地震作用损伤集中于连接区而不利于抗震和修复的问题,提出了一种基于小型超高性能混凝土(UHPC)壳的装配式柱脚连接。采用UHPC预制成环形壳状,设置于预制混凝土柱脚区域,控制该柱脚连接在地震作用下损伤出现的部位。进行了3个足尺试件的试验,对比分析了滞回和骨架曲线、强度和刚度退化以及耗能能力,研究了预制UHPC壳尺寸对抗震性能的影响,提出了骨架曲线简化计算模型。结果表明：该连接形式在地震作用下的混凝土破坏区域转移至UHPC壳上边缘;抗震性能总体良好;较厚较短的UHPC壳更加有利于提高基于小型UHPC壳的装配式混凝土柱脚连接的抗震性能;提出的简化计算模型在一定程度上反映了该连接的内在机理,可用于该连接形式的分析和设计。 相似文献
2.
从板式橡胶支座及混凝土挡块抗震设计角度,以一座典型的3跨预应力混凝土连续梁桥为例,结合概率地震需求分析及桥墩、支座等抗震关键构件极限破坏状态,建立不同支座及挡块分析模型的中小跨径梁桥地震易损性曲线,研究考虑支座滑移效应及挡块破坏的中小跨径梁桥的易损性特征。研究结果表明:不考虑橡胶支座的滑移效应及混凝土挡块破坏,桥墩地震破坏概率明显增大,且会低估支座破坏概率;桥梁系统易损性受支座破坏状态的影响显著,需设置合理的限位装置;在中小跨径梁桥地震易损性分析中,考虑支座的滑移效应及混凝土挡块的破坏十分必要。 相似文献
3.
全装配式预制混凝土结构梁柱组合件抗震性能试验研究 总被引：15，自引：1，他引：15
采用足尺模型对比试验方法对现浇高强混凝土梁柱组合件、预制混凝土结构高强混凝土后浇整体式梁柱组合件和高强预制混凝土结构全装配式梁柱组合件在低周反复荷载作用下的开裂破坏形态、滞回特性、骨架曲线、强度与刚度退化特性、耗能能力、节点核心区域的剪切变形、梁端与柱端的转动变形等抗震性能指标进行了系统研究。结果表明：高强预制混凝土结构后浇整体式梁柱组合件与现浇高强混凝土结构梁柱组合件具有相同的抗震能力，全装配式预制混凝土梁柱组合件的抗震性能和主要抗震性能指标与现浇高强混凝土梁柱组合件和预制混凝土结构后浇整体式梁柱组合件存在明显的差异。对于实际工程应用，应采取必要措施增加全装配式节点的耗能能力。 相似文献
4.
《地震工程与工程振动》2015,(3)
为研究横桥向地震作用下板式橡胶支座对桥梁抗震性能的影响,比较了传统延性抗震设计方法与考虑支座摩擦滑移抗震设计方法的差异,采用Open Sees软件建立桥梁有限元模型,对一简支变连续梁桥进行了非线性增量时程分析,对比研究桥梁支座、挡块和桥墩的受力性能,并根据延性系数对桥梁各构件的损伤顺序进行了分析。研究结果表明:按传统延性体系设计时,桥梁破坏首先从墩底开始,在大震作用下会造成墩底发生严重损伤;考虑支座摩擦滑移时,桥梁损伤首先是支座和挡块的破坏,然后是墩柱发生损伤,支座摩擦滑移后可大大减小传递到下部结构的地震力,大震下桥墩保持弹性或只发生轻微损伤,建议桥梁抗震设计时采用考虑支座摩擦滑移的抗震设计方法。 相似文献
5.
为研究预制超高性能混凝土(UHPC)模板钢筋混凝土(RC)柱的抗震性能,并验证预制UHPC模板在往复荷载作用下是否发生剥离,考虑轴压比、剪跨比、箍筋间距和保护层厚度,设计制作6根免拆模板柱(PTC)和1根RC对比柱试件,对其进行拟静力试验,研究其破坏形态、滞回性能、变形和耗能能力以及强度和刚度退化规律等。结果表明,与加载方向垂直的预制UHPC模板大约在PTC试件峰值荷载的70%时发生剥离,与加载方向平行的预制UHPC模板在试件最终破坏时剥离;在剪跨比、轴压比和箍筋数量均分别相同的条件下,由UHPC模板加10 mm混凝土作为保护层的试件,其抗震性能相对较好,但其承载力和前期刚度略有减小。 相似文献
6.
为了提高采用板式橡胶支座的斜梁桥横向抗震能力,揭示其在不同设计参数下的横向抗震行为,考虑板式橡胶支座的滑移、钢筋混凝土挡块的滞回力学性能、桥台-背土效应等非线性因素,采用OpenSEES建立某连续斜梁桥的三维分析模型,提出支座位移评价指标、主梁平面转角指标、墩柱曲率延性指标和抗剪指标,研究不同挡块强度和间隙组合下桥梁的横向抗震性能。研究表明:同时增大挡块强度和间隙,总体上会降低支座的横向变形,但会增加其纵向变形;挡块强度越高,主梁的横向位移有所下降,但平面转角越大,对两侧桥台处的支座抗剪越不利;挡块强度越高,间隙越小,墩柱越有可能进入弹塑性状态。在本文桥例中,当挡块强度取40%支反力,间隙取0.08m时,所有抗震指标都可满足规范要求。 相似文献
7.
装配式预应力混凝土双柱桥墩抗震性能研究进展 总被引：4，自引：0，他引：4
装配式预应力混凝土双柱桥墩是一种在上世纪铁路桥梁中广泛应用的一种桥墩形式.随着城市高架、跨海大桥、高速铁路等工程的不断新建,需要继续采用这种具有突出优点的桥墩方案.但是对于装配式双柱墩的设计及其抗震性能,目前仍然缺乏系统的研究.这已成为困扰桥梁设计工程师和业主的技术难题,从而限制了装配式双柱墩在我国桥梁建设中的应用.为了解决此技术难题,本文对目前的研究现状进行了剖析,并对进一步的研究思路和研究内容进行了详细分析.在此基础上进行的研究将为装配式双柱墩在我国的推广应用提供可靠的基础研究资料. 相似文献
8.
为改善预制装配式桥墩的抗震性能和施工容错能力,提出一种装配式桥墩新型连接方式:超高性能混凝土(Ultra-High-Performance Concrete,UHPC)墩周连接。设计并制作1个现浇桥墩试件和1个UHPC墩周连接装配式桥墩试件,对两个试件进行拟静力试验;建立UHPC墩周连接装配式桥墩试件的三维实体非线性有限元模型,对比研究新型装配式桥墩的抗震性能及其影响因素。结果表明:UHPC墩周连接装配式桥墩与整体现浇桥墩表现出相似的抗侧力性能和自复位能力,二者的抗震性能基本等同。对比分析非线性有限元模型与实际桥墩试件的滞回曲线,二者拟合程度较高,验证了建模方法的可靠性和模拟结果的准确性。UHPC连接段高度对该装配式桥墩抗震性能的影响不大,保证钢筋搭接长度即可。轴压比、立柱高度和搭接钢筋配筋率对该装配式桥墩抗震性能的影响较为明显:在轴压比为0.1~0.3时,试件刚度和水平承载力随轴压比的增大而增大,残余位移随轴压比的增大而减小;立柱高度由2.0 m提高至2.5 m时,高度越大该装配式桥墩的水平承载能力和累积滞回耗能越小;湿接缝处搭接钢筋配筋率由1.01%增至1.57%时,该装配式桥墩的水平承载能力和残余位移相比原配筋试件性能有较明显的提升。 相似文献
9.
《地震工程与工程振动》2016,(4)
针对汶川地震中板式橡胶支座梁桥梁体横向移位严重的震害现象,提出了在原约束体系基础上增设X形板弹塑性挡块的抗震加固设计方法。以一座典型板式橡胶支座简支梁桥为研究对象,建立了可合理模拟支座滑动效应、挡块力学性能和墩柱滞回性能的全桥精细化有限元数值模型。选择国内外实际地震动进行横桥向非线性地震反应分析,研究了梁体与钢筋混凝土挡块横向间隙、X形板弹塑性挡块力学性能等两大参数对抗震加固效果的影响。研究表明:钢筋混凝土挡块与梁体间可预留一定横向间隙,X形板弹塑性挡块屈服强度可控制为上部结构恒载反力的5%;与抗震加固前相比,抗震加固设计能有效控制墩梁相对位移,同时减小桥墩结构地震反应,显著提高桥梁结构抗震性能。 相似文献
10.
为深入了解整体式桥梁的动力特性和抗震性能,建立台-土有限元模型,并提出合理的台-土相互作用数学模型,然后利用Midas Civil整体模型研究台-土相互作用、桩-土相互作用、桥墩构造等因素对整体式桥梁抗震性能的影响。结果表明：与简支梁相比,同等跨度下整体式桥梁的纵向刚度明显提高,但横向刚度差距不大;台后土的约束刚度大小对桥梁的静动力特性不产生明显影响,整体式桥梁根据我国现有规范计算台后地震力相对保守;改变桩-土约束刚度对整体式桥梁的抗震性能影响不大;提高桥墩的横向刚度,将独柱墩改为双柱墩能大幅提高结构抗震性能。研究结论及台后土压力系数的计算方式,可供整体式桥梁抗震计算提供参考。 相似文献
11.
12.
After the occurrence of various destructive earthquakes in Japan, extensive efforts have been made to improve the seismic performance of bridges. Although improvements to the ductile capacities of reinforced concrete (RC) bridge piers have been developed over the past few decades, seismic resilience has not been adequately ensured. Simple ductile structures are not robust and exhibit a certain level of damage under extremely strong earthquakes, leading to large residual displacements and higher repair costs, which incur in societies with less-effective disaster response and recovery measures. To ensure the seismic resilience of bridges, it is necessary to continue developing the seismic design methodology of RC bridges by exploring new concepts while avoiding the use of expensive materials. Therefore, to maximize the postevent operability, a novel RC bridge pier with a low-cost sliding pendulum system is proposed. The seismic force is reduced as the upper component moves along a concave sliding surface atop the lower component of the RC bridge pier. No replaceable seismic devices are included to lengthen the natural period; only conventional concrete and steel are used to achieve low-cost design solutions. The seismic performance was evaluated through unidirectional shaking table tests. The experimental results demonstrated a reduction in the shear force transmitted to the substructure, and the residual displacement decreased by establishing an adequate radius of the sliding surface. Finally, a nonlinear dynamic analysis was performed to estimate the seismic response of the proposed RC bridge pier. 相似文献
13.
汶川大地震简支梁桥落梁震害与设计对策 总被引：2，自引：0，他引：2
总结了5.12汶川大地震中简支梁桥落梁震害及主要影响因素,发现除地震山体滑坡等地质灾害外,断层地表破裂、近断层地震动效应、桥台胸墙冲切破坏、防落梁构造措施单一及桥梁体型复杂等因素都是引起简支梁桥落梁震害的重要原因。提出了简支梁桥防落梁设计的基本理念及相关技术方案要点为允许墩梁间发生滑移,以降低桥墩承受的地震惯性力,以及盖梁提供允许的最大滑移长度及支座支承宽度,再辅助挡块或拉索限位器等共同防止落梁发生。最后结合现行规范,以拉索限位器为例给出了简支梁桥防落梁设计方法。 相似文献
14.
Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seismic responses more accurately, proper analytical models of bearings and shear keys should be developed. Based on a series of cyclic loading experiments and analyses, rational analytical models of laminated elastomeric bearings and shear keys, which can consider mechanical degradation, were developed. The effect of the mechanical degradation was investigated by examining the seismic response of a small-to-medium-span bridge in the transverse direction under a wide range of peak ground accelerations (PGA). The damage mechanism for small-to-medium-span highway bridges was determined, which can explain the seismic damage investigation during earthquakes in recent years. The experimental results show that the mechanical properties of laminated elastomeric bearings will degrade due to friction sliding, but the degree of decrease is dependent upon the influencing parameters. It can be concluded that the mechanical degradation of laminated elastomeric bearings and shear keys play an important role in the seismic response of bridges. The degradation of mechanical properties of laminated elastomeric bearings and shear keys should be included to evaluate more precise bridge seismic performance. 相似文献
15.
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
16.
Many highway bridges were severely damaged or completely collapsed during the 2008 Wenchuan earthquake.A field investigation was carried out in the strongly affected areas and over 320 bridges were examined. Damage to some representative highway bridges is briefly described and a preliminary analysis of the probable causes of the damage is presented in this paper. The most common damage included shear-flexural failure of the pier columns, expansion joint failure, shear key failure, and girder sliding in the transversal or longitudinal directions due to weak connections between girder and bearings. Lessons learned from this earthquake are described and recommendations related to the design of curved and skewed bridges, design of bearings and devices to prevent girder collapse, and ductility of bridge piers are presented.Suggestions for future seismic design and retrofitting techniques for bridges in moderate to severe earthquake areas are also proposed. 相似文献
17.
Experimental research and finite element analysis of bridge piers failed in flexure-shear modes 总被引：2，自引：1，他引：1
In recent earthquakes, a large number of reinforced concrete （RC） bridges were severely damaged due to mixed flexure-shear failure modes of the bridge piers. An integrated experimental and finite element （FE） analysis study is described in this paper to study the seismic performance of the bridge piers that failed in flexure-shear modes. In the first part, a nonlinear cyclic loading test on six RC bridge piers with circular cross sections is carried out experimentally. The damage states, ductility and energy dissipation parameters, stiffness degradation and shear strength of the piers are studied and compared with each other. The experimental results suggest that all the piers exhibit stable flexural response at displacement ductilities up to four before exhibiting brittle shear failure. The ultimate performance of the piers is dominated by shear capacity due to significant shear cracking, and in some cases, rupturing of spiral bars. In the second part, modeling approaches describing the hysteretic behavior of the piers are investigated by using ANSYS software. A set of models with different parameters is selected and evaluated through comparison with experimental results. The influences of the shear retention coefficients between concrete cracks, the Bauschinger effect in longitudinal reinforcement, the bond-slip relationship between the longitudinal reinforcement and the concrete and the concrete failure surface on the simulated hysteretic curves are discussed. Then, a modified analysis model is presented and its accuracy is verified by comparing the simulated results with experimental ones. This research uses models available in commercial FE codes and is intended for researchers and engineers interested in using ANSYS software to predict the hysteretic behavior of reinforced concrete structures. 相似文献
18.
In lack of seismic provisions in the pre-Eurocode ages, most of the existing Hungarian bridges were not designed for seismic actions, therefore their seismic performance is questionable. The most commonly used structural type in highway construction is the integral precast multi-girder bridge. These bridges are typically constructed as continuous multi-support systems with monolithic joints at each support, thus their behavior may be significantly different from those applying simply supported beams and conventional bearings. A parametric fragility analysis of a wide range of different layouts is carried out using detailed and advanced non-linear numerical models. The results indicate that the abutment joints are highly vulnerable and piers are also critical for longer bridges. The study implies that without seismic design, integral precast multi-girder bridges are highly susceptible to pier shear failure, the probability of collapse is relatively high. The results also provide a solid basis for retrofit planning as well as for development of design concepts of newly built structures in moderate seismic zones. 相似文献
19.
The paper presents a numerical investigation on the behaviour of reinforced concrete bridge piers subjected to horizontal seismic input. The scope of the investigation is to quantify the phenomenon of bending-induced axial vibrations. The results of a set of analyses conducted on single-column bent systems indicate that flexural cracking produces, in fact, significant axial vibrations. This effect is particularly relevant in squat elements with low axial force where the sway of the cross-sectional neutral axis under alternate bending causes strong hammering impulses at crack closure. Quantification of the effects related to this phenomenon can be determinant for the seismic assessment of existing bridges as well as for the design of new bridges. Likewise, performance and design forces of bearings and other anti-seismic devices can be estimated with more accuracy, based on the expected level of combined vertical and horizontal acceleration response on decks. The pier overall flexural response is not significantly altered by the fluctuation in axial force associated to these impulses, although local moment–curvature behaviour is, due to axial–bending interaction. Shear resisting mechanisms should be more sensitive to these vibrations and shear failure anticipated when a reduction in the axial contribution to the section shear capacity occurs. A tentative equation for the prediction of this flexural-induced vertical acceleration component is proposed based on simplified section kinematics and elastic impact analysis. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献