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1.
The rigid body motions of the bridge deck, along with the impact between the bridge deck and the abutments, were the source of extensive damage on skew highway bridges during the 1971 San Fernando earthquake. In this paper, a model for the rigid body motions of skew bridges is presented and analysed. The focus of the model is the appropriate representation of the impact between the bridge deck and the abutments and the explanation of the inducement of in-plane rotational vibrations of the bridge deck as the result of this impact. A simplified model is briefly described first, and the kinematic mechanism of the problem is explained. Then, the analysis of a more detailed and realistic model follows. This model is applied on a short skew bridge located in Riverside, California. The response of this bridge to several earthquake shakings revealed that the planar rigid body rotations of the deck are induced primarily as a result of the skewness of the deck and the impact between the deck and the abutments. 相似文献
2.
为充分了解板式橡胶支座对斜交连续梁桥地震反应的影响,利用OpenSees软件建立简化的斜交桥计算模型进行时程分析,研究板式橡胶支座摩擦滑移效应,以及支座动摩擦系数、剪切刚度、局部脱空等参数对斜交桥地震反应的影响。结果表明:板式橡胶支座考虑摩擦滑移后,不仅桥面位移和转角显著增大,而且出现残余位移和残余转角;随着支座剪切刚度的增大,桥面位移和转角均明显减小;随着桥墩处支座动摩擦系数的增大,桥面位移、转角均呈增长趋势,然而桥台处支座动摩擦系数的影响与之相反;桥墩处局部支座脱空对斜交桥的影响明显大于桥台支座。 相似文献
3.
Abdoul R. Ghotbi 《地震工程与工程振动(英文版)》2014,13(3):357-373
The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and columnbent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction(SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center(PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge confi gurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly. Furthermore, abutment unseating showed an increasing trend due to an increase in skew angle for both fixed-base and SSI models. 相似文献
4.
This paper discusses the dynamic response of a curved bridge deck to a moving vehicle. The bridge deck is idealized as a set of annular sector plates and circular rings rigidly jointed together. On the basis of classical plate and ring theories a method has been developed to obtain the response to a moving vehicle idealized as a spring mass system. After obtaining the normal modes and frequencies and establishing the orthogonality conditions, the problem of the forced motion of the deck is solved by the method of spectral representation. Numerical results have been presented to illustrate the effect of several vehicle and bridge parameters on the response. 相似文献
5.
本文以一座三跨总长60 m的整体桥为案例桥,分别试设计了同跨径的半整体桥、延伸桥面板桥和常规连续梁桥。通过Midas/Civil软件建立四种桥型的有限元模型,并对其进行了E1和E2反应谱分析和时程分析,对比了四种桥型的结构反应峰值（墩顶位移、桥墩及桩基剪力与弯矩、台底位移、桥台桩基剪力与弯矩）。计算结果表明:当桥梁存在15°的斜交角,整体桥、半整体桥在地震动沿平行于桥台长边方向及其垂直方向输入时更不利,而延伸桥面板桥和常规连续梁桥在地震动沿顺桥向和横桥向输入时更不利。四种桥型在地震作用下:整体桥抗震性能最优异,但其台底位移、桥台桩基的剪力和弯矩最大;半整体桥台底位移、桥台桩基的剪力和弯矩最小,其墩顶位移、桥墩及桩基的剪力和弯矩仅比整体桥大;延伸桥面板桥和常规连续梁桥的墩-梁相对位移远大于整体桥和半整体桥,不适用于地震基本烈度高的区域。 相似文献
6.
A method has been developed for the study of the dynamic response of curved bridge decks on the basis of plate equations in polar co-ordinates. A general solution for the forced motion of annular sector plates has been obtained by the method of spectral representation. The specific problem of a moving force on the bridge deck is discussed in detail. A method for obtaining the static response from dynamic analysis is suggested. Numerical results are presented to illustrate the influence of the speed of travel of the force and of the physical parameters of the bridge decks on the deformation. A detailed discussion on the numerical results is also included. 相似文献
7.
Nefize Shaban Alp Caner Ahmet Yakut Aysegul Askan Ali Karimzadeh Naghshineh Arman Domanic Gizem Can 《地震工程与结构动力学》2015,44(6):889-905
Presence of vehicles on a bridge has been observed many times during past earthquakes. Although in practice, the engineers may or may not include the live load contribution to seismic weight in design, current bridge design codes do not specify a certain guideline. A very limited research has been conducted to address this issue from design point of view. The focus of this research is to experimentally assess the effect of a vehicle on the seismic response of a bridge through a large‐scale model. In this scope, a 12‐meter long bridge, having a one lane deck with concrete slab on steel girders, has been shaken under five different ground motions obtained from recent earthquakes that occurred in Turkey, in its transverse direction, both with and without a vehicle on top of the deck. The measured results have indicated that top slab transverse acceleration and bearing displacements can reduce up to 18.7% in presence of a vehicle during seismic tests, which is an indication of reduction in substructure forces. The main reason for the reduction in seismic response of the bridge in the presence of live load can be ascribed to the increase in damping of the system due to mass damper‐like action induced by the vehicle. This beneficial effect cannot be observed in vertical seismic response. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
R.A.Khan T.K.Datta S.Ahmad 《地震工程与工程振动(英文版)》2005,4(1):83-94
A simplified fragility analysis of fan type cable stayed bridges using Probabilistic Risk Analysis (PRA) procedure is presented for determining their failure probability under random ground motion. Seismic input to the bridge support is considered to be a risk consistent response spectrum which is obtained from a separate analysis. For the response analysis, the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses of the springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysis provides a coupled stiffness matrix for the spring system. A continuum method of analysis using dynamic stiffness is used to determine the dynamic properties of the bridges .The response of the bridge deck is obtained by the response spectrum method of analysis as applied to multidegree of freedom system which duly takes into account the quasi - static component of bridge deck vibration. The fragility analysis includes uncertainties arising due to the variation in ground motion, material property, modeling, method of analysis, ductility factor and damage concentration effect. Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM) method of reliability. A three span double plane symmetrical fan type cable stayed bridge of total span 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure are obtained under a number of parametric variations. Some of the important conclusions of the study indicate that (i) not only vertical component but also the horizontal component of ground motion has considerable effect on the probability of failure; (ii) ground motion with no time lag between support excitations provides a smaller probability of failure as compared to ground motion with very large time lag between support excitation; and (iii) probability of failure may considerably increase for soft soil condition. 相似文献
9.
为了揭示近断层地震作用下上承式钢筋混凝土拱桥的动力响应特点,以西南山区某上承式拱桥为背景,用OpenSEES平台建立了全桥非线性动力分析模型,探讨了近断层地震动的输入方式、脉冲效应和竖向地震动等三个关键因素对桥梁动力响应的影响规律。研究结果表明:地震输入方式对拱圈地震响应的影响较小,但对拱上立柱地震响应的影响很大,尤其是拱顶附近的短立柱,在抗震分析中,建议偏安全地采用三向地震输入方式;脉冲效应对拱桥地震响应的影响非常大,会导致拱圈、拱上立柱和桥面板地震响应大幅增加,桥面板残余平面转角甚至增大6倍以上;竖向地震动对拱圈轴力和面内弯矩、拱上立柱纵向弯矩和剪力的影响很大,拱顶处的面内弯矩放大倍数最大可达2.95,总体来说,采用规范所建议的方法考虑竖向地震是偏保守的。 相似文献
10.
Stochastic energy analysis of seismic isolated bridges 总被引：1，自引：0，他引：1
In this paper, a parametric stochastic analysis of isolated bridge is proposed with the aim to assess isolation performance and to investigate effects of energetic influence on protection efficiency. The analysis has been carried out in terms of two stochastic parameters of pear-deck maximum displacement and hysteretic energy response, of which a qualitative trend has been observed.Isolated bridge is described by a simple two degree of freedom (TDoF) Bouc–Wen hysteretic model, which has been introduced for its intrinsic ability in reproducing a wide range of real devices behavior. With the aim of taking into consideration intrinsic stochastic nature of seismic events, the ground motion and the structural response have been described by random vibration approach. Results obtained show that protection achieved by shifting structural natural period and reducing input energy by devices dissipation have counteracting effects if related to deck lateral displacement. 相似文献
11.
Direct displacement-based design of seismically isolated bridges 总被引：1，自引：1，他引：0
A Displacement-Based Design (DBD) procedure for bridges equipped with different seismic Isolation Systems (IS’s) is proposed.
It has been derived from the Direct DBD method recently developed by Priestley and co-workers. The key aspect of the proposed
procedure is the definition of a uniform target displacement of the deck, which is assigned by the designer to accomplish
a given performance level, expressed through limit values of the maximum IS displacement and of the pier drift, respectively.
The proposed design procedure has been developed for four different idealized force-displacement cyclic behaviours of IS’s,
which can be used to describe the response of a wide variety of IS’s, including: (i) Lead-Rubber Bearings (LRB), (ii) High-Damping
Rubber Bearings (HDRB), (iii) Friction Pendulum Bearings (FPB), (iv) Combinations of either Low-Damping Rubber Bearings (LDRB)
or FPB and Viscous Dampers (VD), (v) Combinations of lubricated Flat Sliding Bearings (FSB) and LDRB, (vi) Combinations of
FSB and Steel Yielding Devices (SYD), (vii) Combinations of FSB, Shape Memory Alloy (SMA)-based Re-centring Devices and VD.
In the paper, the background and implementation of the design procedure is presented first, then some validation studies through
nonlinear time-history analyses on different configurations of continuous deck and multi-span simply supported deck bridges
are illustrated. 相似文献
12.
Nonlinear static methods are reliable in the evaluation of the seismic response of planar structural schemes, but they are not very effective in the assessment of three-dimensional building structures. The authors of this paper have recently proposed a nonlinear static approach for asymmetric structures, which is an improvement on that stipulated by seismic codes. This method is based on the observation that the distribution of the maximum dynamic displacements of the deck can be enveloped by two pushover analyses performed by applying the lateral force with two eccentricities with respect to the center of mass of the deck. These eccentricities, named “corrective eccentricities”, are defined so that the two corresponding pushover analyses provide displacements that are equal to those evaluated by nonlinear dynamic analysis at the two sides of the deck. In this paper, the corrective eccentricities are determined for a wide set of single-story systems. The equations for their analytical evaluation are determined and their reliability is demonstrated. Finally, the analysis of a multi-story structure is conducted to show how the method can be applied to real buildings. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
Design of hysteretic dampers with optimal ductility for the transverse seismic control of cable‐stayed bridges 
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下载免费PDF全文 Alfredo Camara Roberto Cristantielli Miguel A. Astiz Christian Málaga‐Chuquitaype 《地震工程与结构动力学》2017,46(11):1811-1833
Cable‐stayed bridges require a careful consideration of the lateral force exerted by the deck on the towers under strong earthquakes. This work explores the seismic response of cable‐stayed bridges with yielding metallic dampers composed of triangular plates that connect the deck with the supports in the transverse direction. A design method based on an equivalent single‐degree of freedom approximation is proposed. This is proved valid for conventional cable‐stayed bridges with 200‐ and 400‐m main spans, but not 600 m. The height of the plates is chosen to (1) achieve a yielding capacity that limits the maximum force transmitted from the deck to the towers, and to (2) control the hysteretic energy that the dampers dissipate by defining their design ductility. In order to select the optimal ductility and the damper configuration, a multi‐objective response factor that accounts for the energy dissipation, peak damper displacement and low‐cycle fatigue is introduced. The design method is applied to cable‐stayed bridges with different spans and deck–support connections. The results show that the dissipation by plastic deformation in the dampers prevents significant damage in the towers of the short‐to‐medium‐span bridges under the extreme seismic actions. However, the transverse response of the towers in the bridge with a 600‐m main span is less sensitive to the dampers. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
14.
为研究强地震作用下,桥台及台后土体对斜交连续梁桥抗震作用的影响。以一座三跨连续斜交箱梁桥为依托,应用sap2000建立不同斜度的模型,针对有、无桥台两种工况,采用非线性时程分析方法,研究了纵向不同地震动强度输入下,桥台及台后土体作用对不同斜度的连续梁桥主梁和桥墩位移的影响规律,并对桥墩的延性性能进行分析。研究结果表明:桥台及台后土体的存在会抑制主梁的纵向位移,大大增加主梁梁端的横向位移,地震动幅值越大,这种作用越明显;桥台及台后土体作用会减小墩顶纵向位移和墩底纵向弯矩,降低桥墩纵向位移延性需求,提高桥墩纵向安全性,斜交角越大,该影响效果越小;桥台作用对桥墩的横向反应几乎无影响。建议在桥梁抗震设计时应考虑桥台以及台后土体的作用,并针对不同斜度的连续梁桥采取相应的抗震措施,以提高其抗震性能。 相似文献
15.
It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities. Since the 1971 San Fernando earthquake, there has been a better understanding of the seismic performance of bridges. Nonetheless, there are no detailed guidelines addressing the performance of skewed highway bridges. Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex. Therefore, there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges. This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees, analytically. Finite element （FE） and simplified beam-stick （BS） models of the bridge were developed using SAP2000. Different types of analysis were considered on both models such as： nonlinear static pushover, and linear and nonlinear time history analyses. A comparison was conducted between FE and BS, different skew angles, abutment support conditions, and time history and pushover analysis. It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles. Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis. Pushover analysis may be used to predict the maximum deformation and hinge formation adequately. 相似文献
16.
Mathematical models and three-dimensional non-linear dynamic analysis procedures are described for determining the seismic response of long, curved (or straight), multiple-span, reinforced concrete highway bridges. Under the action of strong earthquakes, the columns (or piers) of such structures may experience large cyclic inelastic deformations of a coupled form. Also, cyclic slippage of the Coulomb type can take place in the expansion joints of the deck causing multiple impacts and separations to occur. These separations may be sufficiently large to cause tensile yielding of the longitudinal expansion joint restrainer bars (or cables) and, if not controlled, can permit deck spans to fall off their supports resulting in partial or total collapse of the structure. In this paper, a three-dimensional elasto-plastic mathematical model suitable for representing the coupled inelastic flexural behaviour of reinforced concrete columns under cyclic deformations is presented along with a non-linear mathematical model for simulating the non-linear discontinuous behaviour of expansion joints. The procedures used for non-linear seismic response analysis are described and a numerical example is given to illustrate the method. 相似文献
17.
18.
This paper investigates the behavior and the failure mechanism of a double deck bridge constructed in China through nonlinear time history analysis.A parametric study was conducted to evaluate the influence of different structural characteristics on the behavior of the double deck bridge under transverse seismic motions,and to detect the effect of bidirectional loading on the seismic response of this type of bridge.The results showed that some characteristics,such as the variable lateral stiffness,the foundation modelling,and the longitudinal reinforcement ratio of the upper and lower columns of the bridge pier bents have a major impact on the double deck bridge response and its failure mechanism under transverse seismic motions.It was found that the soft story failure mechanism is not unique to the double deck bridge and its occurrence is related to some conditions and structural characteristics of the bridge structure.The analysis also showed that the seismic vulnerability of the double deck bridge under bi-directional loading was severely increased compared to the bridge response under unidirectional transverse loading,and out-of-phase movements were triggered between adjacent girders. 相似文献
19.
Effect of torsional stiffness of prestressed concrete box girders and uplift of abutment bearings on seismic performance of bridges 总被引：1，自引：1，他引：0
Christos P. Katsaras Telemachos B. Panagiotakos Basil Kolias 《Bulletin of Earthquake Engineering》2009,7(2):363-375
Uplift of certain abutment bearings during earthquake may be utilized as a safety mechanism for the protection of the bridge
against excessive stress. For this reason design codes such as Eurocode 8 permit the uplift of such bearings under certain
conditions. Uplift of an abutment bearing occurs when the torque at the deck end exceeds a critical value. Therefore the torsional
stiffness of the deck, before or after concrete cracking, is an important factor. In this work realistic values for the cracked
torsional stiffness of the bridge deck are estimated from a parametric study of typical thin-walled prestressed box girders,
based on non-linear analysis of softened space truss models proposed in the literature. Moreover the interaction between bearing
uplift and pier flexural response is investigated and recommendations for the seismic design of bridges are proposed, taking
into account the possibility of uplift of abutment bearings before or after yielding of the piers. 相似文献
20.
During the 1979 Imperial Valley earthquake, an array of 26 strong-motion accelerometers produced records for the Meloland Road Overpass, a two-span reinforced concrete bridge structure located only 0.5 km away from the causative fault for this earthquake event. This paper describes the application of a new system identification methodology to the array of strong-motion measurements, in order to assess seismic response characteristics of this bridge. Results of this application show that (1) linear models provide an excellent fit to the measured motions of the bridge, despite the fact that it was subjected to very strong shaking; (2) the transverse response of the structure is controlled by its abutment motions, with no significant dynamic amplification in the deck; and (3) the vertical response of the bridge deck at the midlength of its spans is dominated by a single vertical translational mode whereas, above the central pier, the deck's vertical response is most affected by the vertical motions of the pier base and by torsion of the deck. Also, systematic estimates of modal damping ratios and qualitative assessments of states of stress developed in the bridge during the earthquake are provided. 相似文献