Analytical and Experimental Assessment of Seismic Vulnerability of Beam-Column Joints without Transverse Reinforcement in Concrete Buildings
Analytical and Experimental Assessment of Seismic Vulnerability of Beam-Column Joints without Transverse Reinforcement in Concrete Buildings
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混凝土建筑无横向钢筋梁柱节点地震脆弱性分析与试验评估
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发表时间：
2011
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通讯作者：
Wael M. Hassan
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作者：
Wael M. Hassan
混凝土建筑中无横向钢筋梁柱节点地震易损性的分析与试验评估加州大学伯克利分校土木与环境工程系博士学位论文混凝土建筑中的梁柱节点是保证建筑物在地震荷载作用下结构完整性的关键构件。地震勘测报告说，梁柱连接不充分可能造成重大破坏。在某些情况下，折叠式角节点的破坏可能导致建筑物倒塌。自20世纪60年代以来，人们在提高建筑构件（包括梁柱节点）的抗震性能方面取得了许多进展。新的设计和详细的方法，预计将产生新的建设，将表现令人满意的强烈地震震动。很少有人关注可能在地震中脆弱的老建筑的梁柱节点。在20世纪70年代发展延性细节之前建造的混凝土建筑通常缺乏接缝横向钢筋。现有文献中关于此类节点的性能研究相对较少，但存在着对此类节点性能的担忧，本文旨在提高对既有建筑中无侧限梁柱边节点和角节点抗震性能的认识和评估.进行了广泛的文献调查，建立了一个包含约100个试验的数据库。通过对数据的研究，确定了最重要的参数以及每个参数对抗震性能的影响。调查和评估了用于非约束节点强度和变形评估的可用分析模型和指南。特别是ASCE 41现有建筑文件证明在节点抗剪强度估计方面是相当保守的。在确定这些模型的不足之处，两个新的联合剪切强度模型，债券capacitymodel，和两个轴向capacitymodel设计和定制专门为无侧限梁柱节点开发。在本研究的实验室试验阶段，我们设计、建造了四个足尺角梁-柱节点（包括板），并对其进行了测量、测试和分析。这些试件分别在单向和双向位移控制的准静态加载条件下进行了试验，加载条件包括模拟倾覆地震力矩效应的轴向荷载，轴向荷载在拉伸和高压缩荷载之间变化，达到柱轴向承载力的50%左右。试验参数为轴压水平、加载历史、节点纵横比和梁配筋率。试验结果表明，较高的轴向荷载提高了节点的抗剪强度，降低了节点的变形能力，破坏模式为无梁屈服纯剪破坏。相反，高的轴向载荷并不影响节点在显著梁屈服后的抗剪强度，但是，它大大增加了它们的位移延性。联合纵横比被证明是在决定联合剪切强度的工具，这是越深的联合较低的剪切强度。双向加载降低了单轴主轴上接头的表观强度。然而，圆形剪切强度相互作用是一个合适的近似预测双轴强度。基于文献数据库调查、抗剪承载力模型和轴压承载力模型以及试验结果，本文提出了一种基于节点剪应力-转角骨架本构曲线的有限元构件分析模型，用于混凝土框架结构无侧限梁柱节点的计算机数值模拟。所建立的有限元模型考虑了轴向荷载、节点破坏模式、节点高宽比和节点轴向承载力的影响。所提出的骨架曲线与所建立的节点单元在模拟当前试件和以前的试验节点的试验响应方面表现出很高的精度。最后，基于所建立的剪切和轴向承载力模型，对无约束梁柱节点的轴向破坏易损性进行了参数研究。通过参数研究，比较了无侧限梁柱节点和剪切临界柱的轴向破坏潜力，为研究地震作用下折叠式建筑物的轴向倒塌提供了初步的认识.
ABSTRACT Analytical and Experimental Assessment of Seismic Vulnerability of Beam-Column Joints without Transverse Reinforcement in Concrete BuildingsbyWael Mohamed HassanDoctor of Philosophy in Engineering - Civil and Environmental EngineeringUniversity of California, BerkeleyProfessor Jack P. Moehle, ChairBeam-column joints in concrete buildings are key components to ensure structural integrity ofbuilding performance under seismic loading. Earthquake reconnaissance has reported thesubstantial damage that can result from inadequate beam-column joints. In some cases, failure ofolder-type corner joints appears to have led to building collapse.Since the 1960s, many advances have been made to improve seismic performance ofbuilding components, including beam-column joints. New design and detailing approaches areexpected to produce new construction that will perform satisfactorily during strong earthquakeshaking. Much less attention has been focused on beam-column joints of older construction thatmay be seismically vulnerable. Concrete buildings constructed prior to developing details forductility in the 1970s normally lack joint transverse reinforcement. The available literatureconcerning the performance of such joints is relatively limited, but concerns about performanceexist.The current study aimed to improve understanding and assessment of seismic performanceof unconfined exterior and corner beam-column joints in existing buildings. An extensiveliterature survey was performed, leading to development of a database of about a hundred tests.Study of the data enabled identification of the most important parameters and the effect of eachparameter on the seismic performance.The available analytical models and guidelines for strength and deformability assessment ofunconfined joints were surveyed and evaluated. In particular, The ASCE 41 existing buildingdocument proved to be substantially conservative in joint shear strength estimation. Uponidentifying deficiencies in these models, two new joint shear strength models, a bond capacitymodel, and two axial capacity models designed and tailored specifically for unconfined beamcolumnjoints were developed. The proposed models strongly correlated with previous testresults.In the laboratory testing phase of the current study, four full-scale corner beam-column jointsubassemblies, with slab included, were designed, built, instrumented, tested, and analyzed. Thespecimens were tested under unidirectional and bidirectional displacement-controlled quasi-staticloading that incorporated varying axial loads that simulated overturning seismic moment effects.The axial loads varied between tension and high compression loads reaching about 50% of thecolumn axial capacity. The test parameters were axial load level, loading history, joint aspectratio, and beam reinforcement ratio. The test results proved that high axial load increases jointshear strength and decreases the deformability of joints failing in pure shear failure mode withoutbeam yielding. On the contrary, high axial load did not affect the strength of joints failing inshear after significant beam yielding; however, it substantially increased their displacementductility. Joint aspect ratio proved to be instrumental in deciding joint shear strength; that is thedeeper the joint the lower the shear strength. Bidirectional loading reduced the apparent strengthof the joint in the uniaxial principal axes. However, circular shear strength interaction is anappropriate approximation to predict the biaxial strength. The developed shear strength modelspredicted successfully the strength of test specimens.Based on the literature database investigation, the shear and axial capacity models developedand the test results of the current study, an analytical finite element component model based on aproposed joint shear stress-rotation backbone constitutive curve was developed to represent thebehavior of unconfined beam-column joints in computer numerical simulations of concreteframe buildings. The proposed finite element model included the effect of axial load, mode ofjoint failure, joint aspect ratio and axial capacity of joint. The proposed backbone curve alongwith the developed joint element exhibited high accuracy in simulating the test response of thecurrent test specimens as well as previous test joints.Finally, a parametric study was conducted to assess the axial failure vulnerability ofunconfined beam-column joints based on the developed shear and axial capacity models. Thisparametric study compared the axial failure potential of unconfined beam-column joint with thatof shear critical columns to provide a preliminary insight into the axial collapse vulnerability ofolder-type buildings during intense ground shaking.
DOI：
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发表时间：
2014
期刊：
影响因子：
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作者：
財津周平;Effendi Mahmud Kori;松尾真太朗;河野昭彦;窪寺弘顕;Cheng Hong
通讯作者：
Cheng Hong