一种基于改进超弹性Zener模型的高阻尼橡胶隔震支座速度相关性本构模型

目前高阻尼橡胶隔震支座已在土木工程中得到广泛应用,但由于高阻尼橡胶隔震支座的材料组成成分比较复杂,特别是大量阻尼材料的采用导致支座的应力应变关系与其加载速度相关,而目前的支座本构模型很难精确地模拟这种力学特性。因此该文从高阻尼支座的橡胶材料特性出发,提出了一个基于改进超弹性Zener模型的高阻尼支座本构模型,该模型由两个超弹性弹簧和一个非线性阻尼器单元组成,能够精确表达高阻尼支座的速度相关性。在模型中,对超弹性弹簧建立新的应变能函数,并通过附加刚度系数α来模拟高阻尼橡胶材料的初始刚度。通过高阻尼橡胶材料的多步松弛试验和在不同速度下的循环剪切试验来识别模型中的参数。通过支座试验验证了提出的模型,运用基于速度控制的实时子结构试验系统分析了某隔震桥梁在地震作用下的动力反应,并基于试验结果对该文提出的本构模型在隔震结构非线性分析中的准确性进行了验证。     

大跨度悬索桥地震反应分析及其抗震性能评价

对一座大跨度悬索桥进行了地震反应谱分析和线性、非线性的地震时程分析,并在此基础上对该桥进行了抗震性能验算.反应谱分析考虑了周期和阻尼比调整,时程分析时考虑了地震动空间变异性的影响,非线性分析考虑几何刚度变化、大位移以及梁柱效应的影响.抗震性能验算分为强度验算和位移验算.     

滑动摩擦支座隔震桥梁地震反应分析

多滑面摩擦隔震支座具有刚度和阻尼的自适应性,在基于性能的桥梁抗震设计中有广泛的应用前景。本文以某近海连续梁桥为工程背景,考虑海洋软土条件,应用p-y法模拟桩-土相互作用,通过单摩擦摆（FPS）串联组成多滑动面摩擦摆支座（MFPS）模型,并建立全桥有限元模型。采用反应谱法和快速非线性分析（FNA）两种方法,对设置单滑面摩擦摆支座和多滑面摩擦摆支座的两种不同支座的隔震桥梁体系进行地震响应分析。对比分析两种方法得到的两种隔震桥梁结构的支座滞回性能和墩底剪力等的地震响应规律。研究结果表明,两种支座均具有较好的隔震效果,采用MFPS支座的桥墩的地震响应比FPS支座有所减小,且具有较大位移能力。     

预应力混凝土扁梁框架地震响应试验与理论分析对比

为了研究预应力混凝土扁梁框架的动力特性和地震响应,本文在一榀无粘结和一榀有粘结预应力混凝土扁梁框架拟动力试验数据的基础上,运用有限元软件进行非线性时程分析,在一定程度上对比试验数据。分析结果表明:框架结构由于损伤累积引起结构整体刚度和阻尼比的变化,导致结构自振周期发生变化,进而影响结构在地震中的各种响应。利用有限元软件进行结构地震作用下各种响应的分析,是可行有效的。     

Dynamic analysis of non-planar coupled shear walls with stiffening beams using Continuous Connection Method

In this paper, the dynamic analysis of non-planar non-symmetrical coupled shear walls on a rigid foundation has been considered. The analysis deals with coupled shear walls having a finite number of stiffening beams, whose properties vary from region to region along the height. In the analysis, Continuous Connection Method (CCM) and Vlasov׳s theory of thin-walled beams are employed to find the stiffness matrix of the structure. The system mass matrix has been found in the form of lumped masses at the heights where the unit forces have been applied. Following the free vibration analysis, uncoupled stiffness, damping and mass matrices have been found employing the mode superposition method. A time-history analysis has been carried out using Newmark numerical integration method to find the system displacement vector for every time step. Finally, a computer program has been prepared in Fortran language and an asymmetrical example has been solved. The results have been verified via comparisons with those of the SAP2000 structural analysis program using frame method and a perfect match has been observed.     

半漂浮式主梁钢管混凝土拱桥黏滞阻尼器减震设计

为研究大跨半漂浮体系中承式钢管混凝土拱桥黏滞阻尼器参数选取与减震效果,以某计算跨径320 m中承式钢管混凝土拱桥为工程背景,采用MIDAS/Civil软件建立有限元模型,在动力特性分析的基础上提出黏滞阻尼器减震方案,并基于非线性动力时程分析方法研究了黏滞阻尼器的参数选取与减震效果。结果表明:半漂浮体系中承式钢管混凝土拱桥的纵飘振型出现较早,振型参与质量所占比重大,黏滞阻尼器参数选取主要应考虑梁端纵桥向容许位移和阻尼器连接构件所能承受的阻尼力; 对相同的阻尼指数,主梁梁端最大纵桥向位移响应随着阻尼系数的增大呈非线性减小,阻尼器轴力随着阻尼系数的增大几乎呈线性增大; 阻尼指数在0.2～0.4之间变化时,阻尼指数越大,同时满足梁端位移与阻尼力要求的阻尼系数可选范围越大; 设置黏滞阻尼器后,梁端纵桥向位移响应显著减小,拱顶纵桥向位移有所增加,除拱顶处拱肋轴力略有减小外,其余各处轴力、剪力与弯矩均有所增加,但内力响应绝对值不大; 研究成果可为同类桥梁减震设计提供参考。     

半漂浮体系斜拉桥抗震性能及其减震措施研究

本文以某主跨为340m的半漂浮体系双塔斜拉桥为工程背景,基于实测动力特性修正后的斜拉桥非线性有限元模型,分析了工程背景斜拉桥的抗震性能及其减震措施。研究表明:修正后的半漂浮体系双塔斜拉桥有限元模型可以较为准确的模拟工程背景桥的实际状态;在卓越周期较大的Chi-chi地震波作用下,工程背景桥会产生较大的构件内力和梁端纵桥向位移,可能导致桥梁发生损伤。通过粘滞阻尼器参数分析可知,阻尼系数C=20000k N·s/m为该桥的最优阻尼系数,在塔梁连接处安装该纵桥向粘滞阻尼器后,工程背景斜拉桥的构件内力及梁端纵桥向位移明显减小,抗震效果显著。     

钢筋混凝土框架结构防屈曲支撑加固振动台试验研究

为验证某多层钢筋混凝土框架结构采用防屈曲支撑加固后在地震作用下的抗震性能,以实际工程为背景,对未加固结构及采用防屈曲支撑加固结构进行了1/5比例缩尺模型振动台试验,主要研究了模型结构的动力特性、阻尼比、地震反应、防屈曲支撑的耗能能力及震后防屈曲支撑的性能变化。试验结果表明：未加固模型结构在地震输入下未能实现规范的“三水准”抗震目标,采用防屈曲支撑加固后的模型结构改柱铰机制为梁铰机制,地震反应得到有效控制,最大位移降低率达97%;防屈曲支撑在多遇地震作用下仅增加结构抗侧刚度,分担地震剪力约占地震总剪力的34%~49%,设防及罕遇地震作用下防屈曲支撑屈服变形明显,有效提高结构阻尼,耗散的能量占地震输入总能量的25%~51%;不同型号防屈曲支撑震后性能变化有较大差异,防屈曲支撑结构体系的破坏形态为防屈曲支撑首先断裂失效,进而梁柱破坏。     

基于有限位移的中小跨径梁式桥抗震概念设计

以中小跨径梁式桥的抗震设计方法为研究对象,对汶川地区的中小跨径梁式桥进行了系统、全面的震害调查,总结了梁式桥的震害形式,采用统计分析的方法分析了各类构件的损伤情况,探明了汶川地震中梁式桥具有主梁移位多、支座、挡块震害多、桥墩震害少、主梁落梁少的显著特点;通过振动台试验和数值模拟方法,对梁式桥梁震害的机理进行了研究。结果表明,主梁与板式橡胶支座间的相对滑动起到隔震作用,减小了桥墩的地震内力响应,明显减少了桥墩震害,桥面连续协调了主梁位移,桥台约束了主梁的纵向位移是汶川地震中落梁少的主要原因。根据中小跨径梁式桥震害分析和机理研究,提出了利用主梁与支座间产生有限相对滑动、减小上部结构加速度响应,减少桥墩损伤的抗震设计概念。     

铰链式护坡及其地震反应特性分析

考虑土与结构动力相互作用的影响,建立了铰链式护坡的非线性动力相互作用的有限元分析模型,对其进行了地震反应数值模拟,分析了在不同地震动作用下的应力、加速度和相对水平位移反应特性,结果表明：在相同强度和频谱的地震动作用下,护坡中上部和底部的最大动应力幅值较大,护坡顶部和底部的加速度和水平位移较大;在相同强度和不同频谱的地震动作用下,在Loma Prieta波作用下护坡的动力反应比Kobe波作用下护坡的动力反应大。从护坡的地震反应特性考虑,护坡顶部和底部是地震动作用下的薄弱区域,在抗震设计中应引起重视。另外,对于护坡的中上部也应引起相应的重视。     

Shaking table model test and numerical analysis of a long‐span cantilevered structure

This paper presents an earthquake‐resistance study program of a long‐span cantilevered story building. The program consists of a shaking table test study and nonlinear seismic analysis using finite element modeling technique. A 1/30 scale model of the prototype structure was designed and manufactured and then tested via the shaking table facility. Dynamic responses of the prototype structure under different earthquake excitation loadings were simulated. Dynamic properties, acceleration, and deformation responses of the scale down model under different intensity levels of earthquake were studied. The dynamic behavior, cracking pattern, and the likely governing failure mechanism of the structure were analyzed and discussed as well. The seismic responses of the prototype building were deduced and analyzed in terms of the similitude law. Furthermore, elaborate finite element models were established, and nonlinear numerical analysis of the prototype structure was conducted. The errors in the seismic response of the structure caused by structural simplification of scale down modeling are found small, and the dynamic behavior of the structure was not altered in the earthquake excitations. This test study provides a benchmark to calibrate the finite element model and a tentative guide in seismic design of such long‐span cantilevered story buildings.     

基于数值流形法的土质边坡动力稳定性分析

由于对NMM动力作用下边坡的稳定分析研究较少,利用数值流形法（NMM）对这一问题进行了分析研究,引入黏性阻尼来耗散系统的能量,通过算例验证了NMM求解边坡永久位移的有效性;利用地震动力时程分析得到的边坡应力场计算出了边坡的动力安全系数时程曲线,并搜索得到地震时程下最小安全系数及其对应的边坡最危险滑裂面,将该最危险滑裂面模型作为NMM的计算模型进行永久位移的计算且与Newmark法得到的结果进行对比,两者结果相近。结果表明：NMM可有效进行边坡动力稳定分析、模拟计算边坡的永久位移。     

Experimental research on the multilayer compartmental particle damper and its application methods on long-period bridge structures

Particle damping technology has attracted extensive research and engineering application interest in the field of vibration control due to its prominent advantages, including wide working frequency bands, ease of installation, longer durability and insensitivity to extreme temperatures. To introduce particle damping technology to long-period structure seismic control, a novel multilayer compartmental particle damper (MCPD) was proposed, and a 1/20 scale test model of a typical long-period self-anchored suspension bridge with a single tower was designed and fabricated. The model was subjected to a series of shaking table tests with and without the MCPD. The results showed that the seismic responses of the flexible or semi-flexible bridge towers of long-period bridges influence the seismic responses of the main beam. The MCPD can be conveniently installed on the main beam and bridge tower and can effectively reduce the longitudinal peak displacement and the root mean square acceleration of the main beam and tower. In addition, no particle accumulation was observed during the tests. A well-designed MCPD can achieve significant damping for long-period structures under seismic excitations of different intensities. These results indicate that the application of MCPDs for seismic control of single-tower self-anchored suspension bridges and other long-period structures is viable.     

Dynamic response analysis of an offshore platform due to seismic motions

A three-dimensional (3D) numerical model for dynamic response analysis of seismic-induced motions is developed using the modal analysis and substructure methods. The developed model and an impedance function method are applied to an offshore platform with a pile-soil foundation system. The Newmark β method is used as a time integration scheme. The displacement and bending stresses at selective nodal points on the structure are computed for various maximum seismic accelerations and the shear-wave velocities of soil. Using a reliability index obtained by the Monte Carlo Simulation method, we successfully performed a reliability evaluation at the critical points of the structure for various seismic motions and soil conditions.     

不同开启角度双层圆柱拱壳体系抗震性能的数值分析及试验研究

通过薄壁钢管模型对不同开启角度双层圆柱拱壳体系的抗震性能进行数值分析及试验研究。圆柱拱壳分析模型包含了6种开放角度和4种基本频率。利用MIDAS软件建立了24种双层圆柱拱壳结构模型,施加阻尼比为5%的3种不同的地震作用。研究了水平和垂直地震作用下分析模型在X、Y、Z三个方向上的动力响应特性。此外,对缩尺薄壁钢管模型进行了振动台试验。将试验结果和数值分析结果进行对比,二者加速度反应分布情况相似。水平地震作用下,数值分析和试验均在1/4和3/4节点处出现最大值,在中心节点处出现较小值。研究结果显示,圆柱拱壳模型最佳开启角度为90°。     

建筑物三维分析模型及其用于结构地震反应分析的可靠性

日本理化学研究所地震防灾研究中心与加拿大英属哥伦比亚大学的研究人员合作,共同开发和进一步发展了用于研究结构物地震反应的三维分析模型,并采用该模型编制了计算机程序,用于模拟结构物的地震反应,研究地震破坏机理.运用该分析模型的建模方法和对一设有地震仪的钢筋混凝土框架建筑物进行了分析.通过将分析结果与该建筑物在1994年Northridge地震中的记录和损伤情况进行比较,验证了作者所开发的三维分析模型和计算机程序的可靠性.     

One-dimensional wave equation analyses for pile responses subjected to seismic horizontal ground motions

This paper presents a numerical one-dimensional wave equation analysis technique for piles and pile groups subjected to seismic horizontal ground motions in liquefiable zones. The so-called Earthquake Wave Equation Analysis for Piles (EQWEAP) procedure is introduced for piles subjected to horizontal earthquake excitations. Disregarding the effects of kinematic soil–pile interaction, the seismic responses of piles can be obtained by approximating the free-field ground response analysis, the ultimate earth pressure model, and the ground displacement profiles. The nonlinearities of the concrete piles were modeled using the approximate tri-linear moment–curvature relationships. A case study and application concerns were presented. Although the analysis is in one dimension, it is found to be effective and able to provide a rapid estimation in foundation design when seismic pile behaviors are of interest. The advantages of this analysis are the time efficiency of the seismic design of pile foundations and the relative simplicity of the analysis. In addition, it suggests alternative modeling for the dynamic analysis adopting the commonly known static models and/or methods.     

Dynamic characteristics and seismic response of frame–core tube structures,considering soil–structure interactions

In order to study the dynamic characteristics and seismic response of high‐rise buildings with a frame–core tube structure, while considering the effect of soil–structure interactions (SSIs), a series of shaking table tests were conducted on test models with two foundation types: fixed‐base (FB), in which the superstructure was directly affixed to the shaking table, and SSI, consisting of a superstructure, pile foundation, and soil. To increase the applicability of the model to the dynamic characteristics of real‐world tall buildings, the superstructure of test models was built at a scale of 1/50. This simulated a 41‐floor high‐rise building with a frame–core tube structure. The mode shape, natural frequency, damping ratio, acceleration and displacement response, story shear, and dynamic strain were determined in each of the test models under the excitation of simulated minor, moderate, and large earthquakes. The SSI effect on frame–core tubes was analyzed by comparing the results of the two test models. The results show that the dynamic characteristics and seismic response of the two systems were significantly different. Finally, these results were verified by performing a numerical analysis on the differences in the seismic responses of the FB and SSI numerical models under various simulated seismic conditions.     

Influence of geotextile arrangement on seismic performance of mid-rise buildings subjected to MCE shaking

Geotextile layers make it possible to construct mid-rise buildings sitting on shallow foundations in unfavourable soil conditions; this study investigates how the arrangement of geotextiles affects the seismic performance of mid-rise buildings under Maximum Considered Earthquake (MCE) shaking. The geotextile arrangement considered here includes the stiffness (5000?kN/m – 12000?kN/m), the length with respect to width of the foundation (B) (1B – 4B), the number of geotextile layers (1 – 7 layers), and their spacing (250?mm – 1000?mm). FLAC3D is used for the numerical simulation and to carry out nonlinear dynamic analysis in the time domain, and an inelastic constitutive model is used to simulate the behaviour of the structure and the geotextile layers under seismic loads. Variations in the shear modulus of soil and the corresponding damping ratio with cyclic shear strain are considered using a hysteretic damping algorithm to model the reasonable dissipation of energy in the soil. The interface between the foundation and ground surface, including the material and geometrical nonlinearities, are used to capture any possible slide and uplift in the foundations. The results are presented with regard to the geotextile arrangement considered, and include the tensile force mobilised in the geotextile layers, the response spectra at the bedrock and ground surface, the shear force developed in the structure, the maximum rocking angle of the foundation, permanent foundation settlement, maximum lateral displacement and the maximum and residual inter-storey drifts. The results show that the geotextile layers close to the edges of the foundation sustained most of the stress induced by foundation rocking, and the geotextile arrangement has a significant influence on the seismic response of mid-rise buildings. Thus, to satisfy the seismic performance of buildings and to optimise the design of foundations reinforced with geotextiles, the stiffness, length, number and spacing of the geotextile layers should be designed with great care.     

荆岳长江大桥结构体系减震效能分析

荆岳长江大桥主桥为主跨816m双塔不对称混合梁斜拉桥,滩桥为主跨154m的七跨连续预应力混凝土梁桥;大桥抗震设防标准为8级;主要对抗震设防标准、性能目标和输入地震动参数、减震耗能装置进行研究;建立动力分析模型,采用反应谱和线性和非线性时程分析方法分析了主桥不同约束状态下的地震响应,以及大桥结构体系的减震效能,验证减震结构体系的合理性。