改善钢筋混凝土低矮剪力墙抗震性能的研究

普通钢筋混凝土低矮剪力墙抗震性能较差，其抗震性能的改善一直受到工程界的关注。总结了一些改善低矮剪力墙抗震性能的国内外研究成果，包括：开缝低矮剪力墙、带暗支撑低矮剪力墙、设耗能装置的低矮剪力墙和低矮组合剪力墙等。在此基础上，提出了一种新型耗能剪力墙，并进行了初步的试验研究。     

双向单排配筋混凝土低矮剪力墙抗震性能试验研究

双向单排配筋混凝土低矮剪力墙适用于多层住宅结构。对4个原型的剪跨比为1.0配筋混凝土低矮剪力墙进行了低周反复荷载试验研究,包括1个双向双排配筋混凝土低矮剪力墙和3个双向单排配筋混凝土低矮剪力墙。其中1个双向单排配筋混凝土低矮剪力墙加设暗支撑,用以研究暗支撑对这种新型墙体的作用。在试验研究的基础上,对比分析了各剪力墙的刚度及其衰减过程、承载力、延性、滞回特征、耗能能力及破坏特征。试验表明,经过合理设计,这种双向单排配筋混凝土低矮剪力墙可以满足多层住宅结构抗震要求。     

Global damage indexes for the seismic performance assessement of RC structures

When performing the seismic risk assessment of new or existing buildings, the definition of compact indexes able to measure the damaging and safety level of structures is essential, also in view of the economic considerations on buildings rehabilitation. This paper proposes two series of indexes, named, respectively, Global Damage Indexes (GDIs), which are representative of the overall structure performance, and Section Damage Indexes (SDIs), which assess the conditions of reinforced concrete (RC) beam‐column sections. Such indexes are evaluated by means of an efficient numerical model able to perform nonlinear analyses of the RC frame, based on the continuum damage mechanics theory and fiber approach. An improvement of a two‐parameter damage model for concrete, developed by some of the authors, which guarantees a better correlation between the Local Damage Indexes (LDIs) and the material's mechanical characteristics, is also presented. For the reinforcement, a specific LDI, named ‘steel damage index’, which takes into account the plastic strain development and the bar buckling effect, is proposed. The numerical model has been employed to simulate several experimental tests, in order to verify the accuracy of the proposed approach in predicting the RC member's behavior. Nonlinear static and dynamic analyses of two RC frames are carried out. The robustness of the method, as well as the effectiveness of the GDIs in assessing the structural conditions, are demonstrated here. Finally, comparisons between the evolution of GDIs and the achievement of the performance levels as proposed in FEMA 356 are reported. Copyright © 2009 John Wiley & Sons, Ltd.     

Assessment of European seismic design procedures for steel framed structures

This paper assesses the fundamental approaches and main procedures adopted in the seismic design of steel frames, with emphasis on the provisions of Eurocode 8. The study covers moment-resisting as well as concentrically-braced frame configurations. Code requirements in terms of design concepts, behaviour factors, ductility considerations and capacity design verifications, are examined. The rationality and clarity of the design principles employed in Eurocode 8, especially those related to the explicit definitions of dissipative and non dissipative zones and associated capacity design criteria, are highlighted. Various requirements that differ notably from the provisions of other seismic codes are also pointed out. More importantly, several issues that can lead to unintentional departure from performance objectives or to impractical solutions, as a consequence of inherent assumptions or possible misinterpretations, are identified and a number of clarifications and modifications suggested. In particular, it is shown that the implications of stability and drift requirements as well as some capacity design checks in moment frames, together with the treatment of post-buckling response and the distribution of inelastic demand in braced frames, are areas that merit careful consideration within the design process.     

填充墙对框架结构抗震性能的影响

框架填充墙结构在汶川地震中产生了严重的震害,我国现行抗震设计对填充墙的考虑难以保证结构在地震下的抗震性能,研究一套简单有效考虑填充墙在地震中不利影响的设计方法是亟需解决的问题。本文按规范设计框架结构算例分别进行弹性、静力弹塑性和非线性动力分析,考察填充墙在弹性和非线性阶段对框架结构的刚度、内力和变形的影响,特别是在强震中的不利影响;从中寻找弹性设计与非线性反应之间的关系而提出弹性设计中考虑填充墙不利影响的方法。结果表明,均匀满布填充墙对框架结构抗震总体上是有利的;填充墙平、立面不均匀布置对框架结构抗震不利;填充墙约束效应易产生附加剪力和短柱破坏。最后根据分析结果提出设计、管理中考虑填充墙影响的方法和措施。     

Non-linear seismic analysis of base-isolated RC frame structures

In this paper, seismic analysis of plane RC frame structures with High Damping Rubber Bearings (HDRBs) base-isolation systems is performed in the non linear range. For RC members, a modified version of hysteretic Park model is used. For HDRB isolators, a new hysteretic model is presented, which is able to accurately predict the mechanical response in the large strain range. The dynamic equilibrium equations are solved making use, at each time step, of a block iterative Newton–Raphson scheme: the frame is divided into superelements (beams and columns) with master nodes at the extremities and internal local nodes for the computation of relations between end moments and relative rotations at superelement extremities. The effectiveness of HDRB base-isolation systems to reduce inelastic deformations in the RC superstructures is investigated through some numerical examples. Copyright © 1999 John Wiley & Sons, Ltd.     

再生混凝土低矮剪力墙抗震性能试验研究

为了研究不同再生骨料取代率对剪力墙性能的影响,进行了4个剪跨比为1.0的低矮剪力墙的低周反复荷载试验研究,包括1个普通混凝土剪力墙和3个再生混凝土剪力墙.在试验的基础上,分析了各剪力墙的承载力、延性、刚度、滞回特征、耗能及破坏特征.研究表明:与普通混凝土剪力墙相比,再生混凝土低矮剪力墙的抗震性能略差,且随着再生骨料掺量的增加,再生混凝土剪力墙的性能呈下降趋势;暗支撑的设置能够明显改善再生混凝土低矮剪力墙的抗震性能;在一定的条件下,再生混凝土可用于一些剪力墙结构的抗震设计.     

RC剪力墙结构小震与中震设计对比及其抗震性能研究

近年来,国内学者强调对于复杂和超限结构需进行中震性能设计,即在小震弹性设计后进行中震下的承载力复核及调整,然而中震设计能否提高结构整体抗震性能仍存在争议.为探究中震设计与小震设计方法的差异,本文依据现行规范,以设防烈度、结构高度和场地类别为变化参数,建立了48个典型RC剪力墙模型,并分别以"小震"、"高规中震"、"广东...     

低层装配式钢筋混凝土水平坐浆墙体抗震性能试验研究

为了研究低层装配式钢筋混凝土水平坐浆墙体的抗震性能,对3个不同剪跨比的低层装配式钢筋混凝土水平坐浆墙体进行了低周反复荷载试验。根据试验结果,分析了剪跨比对墙体的破坏形态、承载力、变形能力、刚度退化和耗能能力的影响。结果表明:随着剪跨比的减小,墙体的破坏形态由弯曲破坏转为剪切破坏;试件SW2和试件SW3的承载力相对于试件SW1分别提高68%和110%,延性分别降低21.8%和37.5%;试件SW1的耗能能力最好,刚度退化速度最缓慢;预制钢筋混凝土墙板与现浇边缘构件协同合作,连接处无竖向裂缝,墙体整体性较好,具有良好的抗震性能,可用于我国城镇建设中的低层住宅结构。     

规则钢筋混凝土异形柱框架结构的抗震性能研究

本文按现行规范及技术规程设计了设防烈度为8度的一个规则的钢筋混凝土异形柱框架,并进行了单向水平地震作用下的空间三维非线性地震反应分析,考查了异形柱框架结构在设防和罕遇地震水准下的整体抗震性能,对结构能否达到抗震设防目标进行了初步评价。结果表明,8度区按规范设计的结构在设防烈度及罕遇烈度地震作用下基本能够达到预期的抗震设防目标。     

型钢连接装配式低矮剪力墙抗震性能试验研究

采用带锚筋的锚板、腹板、端板以及加劲板作为连接件,能够通过干式连接方法将上下预制剪力墙构件连为整体。为研究该新型全装配式剪力墙的受力性能和抗震性能,设计了2个剪跨比为0.783的试件和1个相同剪跨比及配筋率的现浇整体墙体,并进行了低周往复拟静力试验,分析了该全装配式剪力墙的承载能力、刚度、延性性能和耗能能力等。研究结果表明:现浇整体墙体和全装配式剪力墙的破坏形式均为受剪破坏,全装配式剪力墙的极限位移角大于现浇整体墙体极限位移角,分别为1/77和1/133,轴压比为0.3时平均延性系数3.47,低于现浇整体墙体平均延性系数4.62;但该全装配式剪力墙具有较高的承载能力和耗能能力。型钢与剪力墙的锚筋需采用穿孔塞焊的形式连接,避免锚筋与锚板焊接的位置发生剪断的现象。     

Assessment of a capacity spectrum seismic design approach against cyclic and seismic experiments on full‐scale precast RC structures

Within the last decades, simplified methods alternative to dynamic nonlinear analysis have been developed to estimate the seismic performance of structures toward a performance‐oriented design. Considering drift as the main parameter correlated with structural damage, its estimation is of main importance to assess the structural performance. While traditional force‐based design deals with calibrated force reduction factors based on the expected structural ductility, other methods are based on the definition of a viscous damping factor defined as a function of the expected energy dissipated by the structure. An example is the capacity spectrum method. This method can be applied even without any a priori calibration or designer arbitrariness. This allows considering several peculiarities of the seismic behavior of precast structures, which may be influenced by nontraditional hysteresis of connections and members, interaction with the cladding panels, P‐δ effects, etc. The paper aims at verifying the soundness and accuracy of this method through the comparison of its predictions against the results of cyclic and pseudodynamic tests on precast structures, including single‐ and multistory buildings either stiff or flexible, obtained on full‐scale building prototypes tested within the framework of recent research projects (namely, “Precast Structures EC8,” “Safecast,” and “Safecladding”). Two simple methodologies of determination of the equivalent viscous damping from a force‐displacement cycle, based on the dissipated energy in relation to 2 different estimates of the elastic strain energy, are addressed and compared. Comments on the possible use of this procedure for the estimation of the seismic performance of precast structures are provided.     

中高层钢筋混凝土异形柱框架-抗震墙结构的抗震性能研究

本文通过对一幢中高层住宅在不同水准地震作用下进行的弹性计算和弹塑性动力时程分析,研究了钢筋混凝土异形柱框架-剪力墙结构的动力特性和抗震能力。结果显示该结构整体抗侧刚度大,抗震性能较好。进入塑性阶段后,塑性铰分布合理,满足了结构延性设计的要求。     

不同连梁跨高比带暗支撑双肢剪力墙抗震性能试验研究

为探讨不同连梁跨高比带暗支撑双肢剪力墙的抗震性能,进行了2组连梁跨高比分别为1．0和1．5的4个4层双肢剪力墙1／4缩尺模型的抗震性能试验研究。较系统地分析了结构的刚度及其退化过程以及承载力、延性、耗能、破坏机制和破坏特征等。结果表明,连梁跨高比相对小的带暗支撑双肢剪力墙抗震性能较好。承载力计算结果与实测值符合较好。     

Probabilistic seismic performance assessment of lap-spliced RC columns retrofitted by steel wrapping jackets

In this study, the seismic fragility curves of two reinforced concrete (RC) columns that were lap-spliced at the bottom and retrofitted with steel wrapping jackets were generated. Their seismic performance was probabilistically assessed in comparison to that of lap-spliced or continuous reinforcement RC columns. This study used two types of steel wrapping jackets, a full jacket and a split jacket. Analytical models of the four types of columns were developed based on the experimental results of the columns using OpenSEES, which is effective in conducting nonlinear time history analyses. A suite of ten artificial ground motions, modified from recorded ground motions, was used to perform nonlinear time history analyses of the analytical models with scaling of the peak ground acceleration from 0.1 g to 1.0 g in increments of 0.1 g. The steel wrapping jackets did not increase the medians for yield (slight damage state) of the lap-spiced column and did not exceed the corresponding median of the continuous reinforcement column. However, the two steel jackets increased the medians for failure by 1.872 and 2.017 times, respectively, and exceeded the corresponding median of the continuous reinforcement column by 11.8% and 20.5%, respectively.     

施工缝对框架结构抗震性能影响的数值分析

为研究施工缝对框架结构抗震性能的影响,利用提出的施工缝模型,基于OPENSEES平台建模进行静力非线性分析和非线性动力时程分析。通过对比整浇框架与带缝框架的顶点最大位移、层间位移角、塑性铰出现和分布规律等明确施工缝对框架结构的抗震性能的影响程度。结果表明,施工缝使框架结构的变形和层间位移角显著增大,并且使8、9度区框架结构的层间位移角分布发生改变;施工缝使柱端更易出现塑性铰,更易发生"强梁弱柱"的破坏模式;在高烈度区,施工缝的影响比较显著,如果忽略其影响,将会高估框架结构的抗震性能。     

A comparative application of different EC8-3 procedures for the seismic safety assessment of existing structures

An application of the EC8-3 procedure for safety assessment is presented herein. Besides testing the applicability of the code procedure, this application aims to assess the consistency of the safety assessment results that are obtained. Based on the application of the EC8-3 procedure, the study assesses if the different methods of analysis that are permitted lead to similar safety results and identifies the factors that may affect these results. Furthermore, the results obtained by the EC8-3 procedure are complemented by a probabilistic approach yielding their corresponding fragility values. By comparing the D/C ratios and the probabilistic results, the application aims to determine if similar D/C ratios lead to similar probabilistic results. Furthermore, the application tries to determine if a correlation can be established between the D/C ratios and the expected fragility values.     

改善钢筋混凝土短柱抗震性能的研究

简要介绍了改善钢筋混凝土短柱抗震性能的若干措施。为进一步提高短柱的抗震性能，本文提出了内藏“斜向劲性核心束”矩形截面混凝土短柱，并进行了7根短柱的抗震性能试验研究，试验表明，内藏“斜向劲性核心束”矩形截面混凝土短柱比普通矩形截面短柱的抗震性能显著提高。     

RC框架结构地震易损性分析方法研究进展

21世纪我国经济急速发展,人口也急剧增长,这也使得地震对人类生命和财产安全造成的威胁更大,结构抗震研究需求日益增加。地震易损性分析技术对于结构破坏和损失预测都有着非同一般的应用价值,因此受到了国内外土木工程抗震界的广泛关注和研究。首先介绍了地震易损性分析的基本概念,具体地论述了用于地震易损性分析的三种方法,同时总结出此三种方法各自的优缺点;其次以RC框架结构为例论述了国内外地震易损性分析领域的研究发展,从上个世纪90年代开始进行了系统的梳理和分析。说明了地震易损性分析在研究过程中由于不确定性的存在而导致对分析结果准确度的影响;最后指出要想得到更接近于真实的易损性分析结果,还需考量易损性分析中的不确定参数,揭示了地震易损性分析研究领域所面临的挑战。