钢管混凝土短柱的抗震性能和抗剪强度分析

钢管混凝土短柱在地震中易遭受脆性剪切破坏。为评估圆形或方形钢管短柱的性能,对轴向恒载和侧向往复荷载组合作用下的8个短柱构件进行了测试。测试的构件包括3个圆形钢管柱和3个方形钢管柱,另外2个为普通钢筋混凝土短柱(其中一个为圆形柱,另一个为方柱)。试验结果表明:普通钢筋混凝土短柱在遭受脆性剪切破坏时延性很差,但由于外层薄钢管对核心混凝土的包裹作用,使得钢管混凝土短柱的延性明显增强。圆形钢管混凝土短柱的侧向承载强度随着轴向加载率的增大而增大,但轴向加载率对其塑性变形能力的作用不大。对于方形钢管混凝土短柱,抗剪强度会随着轴向加载率的增大而增大,但塑性变形能力会随着轴向加载率的增加而减小。钢管混凝土短柱中,圆形钢管比方形钢管能更有效地防止核心混凝土发生剪切破坏。基于试验和分析结果,采用了改进的ACI设计方法来计算方形和圆形钢管柱的名义抗剪强度。     

Seismic behavior and strength of tubed steel reinforced concrete (SRC) short columns

The seismic behavior of tubed SRC short columns has been investigated by testing eight specimens subjected to combined constant axial compression and lateral cyclic load. Three circular tubed SRC columns (CTSRC) and three square tubed SRC (STSRC) columns were tested in this research with two common SRC columns for comparison. Different axial load ratios (n₀=0.3, 0.4 and 0.5) have been adopted for the constant axial load. The test results indicate that the shear strength, plastic deformation capacity, ductility index, and energy dissipating capacity of the tubed SRC short columns were much higher than those of the SRC columns with the same steel ratio and axial compressive load. The lateral load strength of CTSRC and STSRC short columns increased with an increment in axial load level, while the axial load ratio has no obvious effect on the plastic deformation capacity of CTSRC and STSRC short columns. The steel tubes prevented the shear failure of the concrete more effectively in the circular columns than in the square ones. Shear connector studs should be used in CTSRC and STSRC short columns to prevent bond failure between concrete and flanges of the steel section. A modified ACI design method was adopted to calculate the nominal shear strength of STSRC columns as well as CTSRC columns.     

Shear strength and behavior of tubed reinforced and steel reinforced concrete (TRC and TSRC) short columns

Tubed RC and SRC short columns are special kinds of concrete filled tubular columns but the steel tube does not pass through the beam–column connection and is shorter than concrete core. In areas that suffered earthquakes, the short columns are vulnerable to brittle shear failure. TRC and TSRC short columns are widely used in bridges, high-rise buildings and large factories. So it is important to investigate the behaviors and approaches to improve the ductility of these kind of columns. The aim of this study is to develop a nonlinear finite element model (FEM) for TRC and TSRC short columns and to compare the results with those experimentally captured. Depending on the FEM results, the elastic–plastic method was used to analyze the stress status of the steel tube. A modified ACI design method is adopted to calculate the nominal shear strength of TRC and TSRC short columns based on the FEM and analysis results.     

方钢管约束钢筋高强混凝土超短柱抗震性能试验研究

本文进行3个剪跨比为1.5的方钢管约束钢筋高强混凝土超短柱和1个钢筋混凝土对比试件的试验研究,试验中的主要参数为轴压比(0.35,0.45和0.55)。试验结果表明,由于钢管对核心高强混凝土的约束作用和钢管的抗剪作用,方钢管约束钢筋混凝土超短柱的抗剪承载力、延性、变形能力和耗能性能明显高于钢筋混凝土超短柱。轴压为0.35的方钢管约束钢筋混凝土超短柱的破坏模式为弯曲破坏,而轴压比为0.45和0.55的方钢管约束钢筋混凝土超短柱的破坏模式为剪切破坏。随轴压比的提高,方钢管约束钢筋混凝土超短柱的抗剪承载力提高,但延性系数和极限变形能力降低。对钢管的弹塑性应力分析结果表明,水平荷载施加过程中,发生弯曲破坏试件的钢管不屈服,而发生剪切破坏试件的钢管可能在下降段屈服。根据试验结果和钢管应力分析结果建立方钢管约束钢筋混凝土柱的抗剪承载力公式,提出设计建议,可为工程实践提供参考。     

钢管约束钢筋混凝土转换短柱抗震性能试验研究

钢管约束钢筋混凝土短柱具有优越的延性和弹塑性层间变形能力,因此在转换柱中应用时可显著提高转换结构的整体抗震性能。对大连中国石油大厦外筒的钢管约束钢筋混凝土转换短柱进行了抗震性能模型试验,模型比例为1∶6。试验中的主要参数为轴压比、剪跨比和对拉钢筋设置。试验结果表明,钢管约束混凝土短柱中,钢管对核心混凝土的有效约束限制了核心混凝土剪切破坏的产生,改变了钢筋混凝土短柱在水平地震作用下的剪切脆性破坏模式。在抗震工程中采用钢管约束钢筋混凝土柱可有效提高钢筋混凝土框架短柱的延性、弹塑性层间变形能力和耗能性能,从而显著提高结构的整体抗震性能。     

Behavior and strength of tubed RC stub columns under axial compression

This paper presents an experimental and analytical study on the behavior of axially compressed tubed RC stub columns. Forty specimens including twenty circular tubed RC (STRC) and twenty square tubed RC (STRC) stub columns were tested to investigate the failure mode and axial load strength of tubed RC columns subjected to axial compression. The effect of diameter/width to thickness ratio of the tubes and compressive strength of concrete were also studied. The effect of height to diameter/width ratio of the separated tube in tubed RC columns was studied to investigate the effect of bond and friction between tube and concrete on the behavior of tubed RC columns. Elastic–plastic analysis on the steel tube was employed to study the mechanism of tubed RC stub columns subjected to axial compression. Equations for the prediction of the ultimate axial load strength of tubed RC stub columns were proposed and the results from prediction were compared with the test results.     

钢筋混凝土框架短柱抗剪承载力分析

总结了国内外几个主要的钢筋混凝土框架短柱抗剪承载力计算公式,结合太平洋地震研究中心(PEER)的短柱抗剪拟静力试验数据库,对各公式进行了对比分析,得出各公式计算的短柱抗剪承载力与试验结果基本成线性关系的结论.     

Seismic behavior and moment strength of tubed steel reinforced-concrete (SRC) beam-columns

The seismic behavior of tubed SRC beam-columns has been investigated by testing six specimens subjected to combined constant axial compression and lateral cyclic load. Two circular tubed SRC columns (CTSRC) and two square tubed SRC (STSRC) columns as well as two common SRC columns as comparison were tested in this paper. Different axial load ratio (n₀ = 0.3 and 0.5) have been adopted for the constant axial load. The test results indicated that the flexural strength of a CTSRC column was much higher than that of a common SRC column with the same steel ratio and axial compressive load, whereas there was little difference on the flexural strength of a STSRC columns and a common SRC column. The ductility, plastic deformation capacity and energy dissipation capacity of CTSRC and STSRC columns were much higher than those of common SRC columns with the same steel ratio and axial compressive load. The flexural strength increased as the axial load ratio increased for CTSRC and STSRC columns, while an opposite trend was observed for the plastic deformation capacity. The flexural strength and plastic deformation capacity of CTSRC columns were clearly higher than that of the STSRC beam-columns with the same steel ratio and axial load ratio. A modified EC4 code method has been proposed for the calculation of the moment strength for tubed SRC columns.     

圆钢管约束钢筋混凝土短柱抗震性能试验研究

进行了3个剪跨比为1.5的圆钢管约束钢筋混凝土短柱和1个钢筋混凝土对比试件的拟静力试验研究,试验中的主要参数为轴压比(0.35,0.45和0.55)。试验结果表明：钢筋混凝土短柱的破坏模式为剪切破坏,延性和变形能力很差;圆钢管约束钢筋混凝土短柱的破坏模式为弯曲破坏,延性和变形能力优越。外包钢管对核心混凝土的约束作用限制了核心混凝土的受剪开裂,改变了钢筋混凝土短柱的破坏模式,显著提高了钢筋混凝土短柱的受剪承载力、延性、变形能力和耗能性能。随轴压比的提高,圆钢管约束钢筋混凝土短柱的水平承载力提高,延性系数降低,但轴压比对圆钢管约束钢筋混凝土短柱的极限变形能力无明显影响。对钢管的弹塑性应力分析结果表明：水平荷载施加过程中,钢管并未受剪屈服。根据试验结果建立了圆钢管约束钢筋混凝土短柱的荷载-位移恢复力模型,提出了设计建议,可为工程实践提供参考。图10表2参12     

Axial load behavior and strength of tubed steel reinforced-concrete (SRC) stub columns

This paper presents experimental and analytical studies on the behavior of tubed SRC stub columns subjected to axial compressive load. Fourteen circular tubed SRC (CTSRC) and fifteen square tubed SRC (STSRC) stub columns were tested to investigate the failure mode and axial loaded behavior of tubed SRC columns. The effect of diameter/width to thickness ratio of the tubes was studied. The effect of height to diameter/width ratio of the separated tubes in tubed SRC columns was studied to investigate the effect of bond and friction between tube and concrete on the behavior of tubed SRC columns. The test results indicated that tubed SRC stub columns exhibited higher axial load capacity than common SRC columns with the same volumetric steel ratio. Elastic–plastic analysis on the steel tube was employed to study the mechanism of tubed SRC stub columns subjected to axial compression. Equations for the prediction of the axial load strength of tubed SRC stub columns were also proposed based on the proposed experimental results.     

方钢管约束型钢混凝土短柱抗震性能试验研究

进行了3个剪跨比为1.5的方钢管约束型钢混凝土短柱和1个相同用钢量的型钢混凝土对比试件的拟静力试验研究,试件的主要变化参数为轴压比(0.3,0.4和0.5)。试验结果表明：轴压比为0.3的方钢管约束型钢混凝土柱的破坏模式为弯曲破坏,而轴压比为0.4和0.5的方钢管约束型钢混凝土柱的破坏模式为剪切破坏和粘结破坏相结合。相同用钢量条件下,方钢管约束型钢混凝土短柱的受剪承载力、延性、层间变形能力和耗能性能明显优于型钢混凝土柱。随轴压比的增加,方钢管约束型钢混凝土短柱的受剪承载力提高,但延性和极限变形能力降低。对钢管的弹塑性应力分析结果表明：水平荷载施加过程中,发生弯曲破坏试件的钢管不屈服,而发生剪切破坏试件的钢管在下降段屈服。图8表2参13     

Hysteretic behavior and design of square tubed reinforced and steel reinforced concrete (STRC and/or STSRC) short columns

The square tubed reinforced and steel reinforced concrete (STRC and STSRC) short columns are ordinary RC and/or SRC short columns where most of the lateral reinforcement is in the form of thin-walled steel tubes. In this study, six specimens of STRC and STSRC short columns were experimentally tested under constant axial compression and cyclic lateral load to investigate the seismic performance of both kinds of structure. The main parameters were the axial load ratio and status of longitudinal reinforcement. Nonlinear 3D finite element model was developed to simulate the monotonic behavior and strength of tested specimens. The behavior and strength of extra assumed specimens were predicted using the developed FEM model. Depending on the test and analysis results, a design formula was proposed to predict the shear strength of STRC and/or STSRC short columns.     

大连市体育馆钢管约束钢筋混凝土短柱设计

钢管约束钢筋混凝土柱就是在普通钢筋混凝土柱外设置薄壁钢管,钢管在梁柱节点区断开,不直接承担纵向荷载,只对核心混凝土起约束作用。由于钢管不通过梁柱节点区,因此钢管约束钢筋混凝土柱与钢筋混凝土梁连接方便;且钢管约束钢筋混凝土柱承载力高,抗震性能优越,是一种具有广泛应用前途的新型组合结构形式。钢管约束钢筋混凝土柱在大连市体育馆工程中的应用,解决了钢筋混凝土超短柱抗震性能差的问题;且钢管约束钢筋混凝土柱的用钢量低,施工方便,经济效益和综合效益显著。     

型钢混凝土短柱受剪承载力计算模型研究

型钢混凝土（steel reinforced concrete,SRC）结构因承载力高、刚度大、耐火及耐久性能好等优点在高层及超高层建筑中被广泛使用,其中SRC柱作为主要竖向承重及抗侧力构件,其在地震作用下承载能力直接影响整体结构在地震作用下的响应。目前,对于SRC短柱受剪承载力计算方法有待深入研究,而各国规范或规程中使用的基于强度叠加法的半经验-半理论计算公式缺乏明确的力学模型作为支撑。为此,利用SRC短柱中钢筋混凝土（reinforced concrete,RC）部分与型钢及其内部混凝土部分的剪切变形相互关系,确定了RC部分与型钢及内部混凝土组合体到达其受剪承载力的先后顺序,并以此提出了基于强度叠加法的SRC短柱受剪承载力计算模型,并将该模型及现行规范的计算结果与文献记载的66个发生剪切破坏的SRC短柱的试验结果进行了对比。结果表明：模型可准确预测文献记载的66个发生剪切破坏的SRC短柱的受剪承载力;模型中对RC部分与型钢及其内部混凝土部分剪切变形的考量可准确定义SRC短柱在峰值荷载时的剪力分配机制,在实际工程设计时可依此判断SRC短柱中RC部分与型钢及其内部混凝土部分的承载力利用率,使SRC短柱的受剪承载力最大化。     

超高强混凝土短柱受剪强度的试验研究

近年来,随着现代建筑向大跨、高层方向发展,超高强混凝土(高于C100)正得到日益广泛的应用。超高强混凝土的优异性能是具有更高的强度和更好的耐久性,但随着混凝土强度等级的提高,呈现出愈来愈显著的脆性。建筑物承重柱的设计是关系到建筑物在大震下能否倒塌的关键。现行《混凝土结构设计规范》(GB50010-2002)中规定混凝土强度等级的适用范围为C15~C80,目前对超高强混凝土框架柱受剪强度的研究并不多见。实际工程的需要和现行规范、规程指导的脱节形成的矛盾变得日益尖锐。针对上述现状,本文开展了在低周反复荷载作用下,14根超高强混凝土框架短柱受剪强度的试验研究,其混凝土的强度变化范围为95.6MPa~118.6MPa。通过试验,研究了短柱的破坏形态。根据试验结果,框架短柱受剪强度偏下限,提出了可供实际工程设计参考的超高强混凝土框架短柱的受剪承载力计算公式,计算结果与试验值较为吻合。     

钢管混凝土和套管混凝土短柱的抗剪强度和性能分析

TRC和TSRC短柱都是钢管混凝土柱的特殊形式。在这两种短柱中,钢管并不会跨越梁柱连接,并且长度也短于混凝土核心筒。在地震区,短柱容易产生脆性剪切破坏。TRC和TSRC短柱广泛应用于桥梁、高层建筑和大型厂房,所以对短柱的剪切破坏及如何提高此类柱的延性便显得非常重要。研究目的是为TRC和TSRC短柱的计算开发一个非线性有限元模型,并将计算结果与试验结果进行对比。基于有限元计算结果,采用弹塑性方法来分析钢管的应力状态,并利用一个改进的ACI设计方法去计算TRC和TSRC短柱的名义抗剪强度。     

轴力作用下钢管短柱的性能和强度分析

对轴力作用下钢管短柱的性能和强度进行了试验和数值分析。对包括20个圆形和方形钢管混凝土短柱在内的40个构件进行了试验,以分析其在轴压作用下的破坏模式和轴向承载强度。同时也对管的径(宽)厚比和混凝土的抗压强度的影响进行了分析。对钢管混凝土柱中管的高径(宽)比的影响进行分析,以探究钢管和混凝土之间的粘结和摩擦对钢管混凝土柱性能的影响。利用钢管的弹塑性分析研究轴压下短柱的受力机制。提出了公式用以预测钢管混凝土短柱的极限轴向承载强度,并将预测结果与试验结果进行了对比。     

玄武岩纤维布约束钢筋砼柱的轴心受压试验研究

玄武岩纤维由于其良好的力学性能、较好的稳定性和较低的价格使其在土木工程中的应用前景广阔,但目前玄武岩纤维在土木工程中应用的相关研究还极少。通过15根外包玄武岩纤维布（BFRP）约束钢筋混凝土圆柱轴心受压试验,对其进行分析,并考虑箍筋对约束柱极限强度的影响,提出FRP承载力计算公式,计算结果和大量试验结果吻合良好,可供工程设计和进一步研究。     

梁高对钢筋混凝土梁抗剪强度的影响

根据钢筋混凝土梁的抗剪强度随梁高的增加而降低的观点，分析了现行规范GBJ10-89中(4．2．3-2)和(4．2．3-4)公式中存在的不足，并对此提出修正，以供参考。     

中等剪跨比RC剪力墙拉-弯-剪受力性能试验研究

为研究中等剪跨比钢筋混凝土(RC)剪力墙的拉-弯-剪受力性能，对4个RC剪力墙开展了在恒定轴拉力和往复水平力作用下的拟静力试验。RC墙剪跨比为1.5，尺寸和配筋均相同，仅轴拉力变化。结果表明：RC墙分别发生了剪切破坏、弯曲-剪切破坏和弯曲破坏；轴拉力致使RC墙的水平承载力降低，竖向钢筋平均拉应力比ns从0.20增大到0.80时，RC墙峰值荷载降低了约55%；中等剪跨比RC墙弯曲-剪切耦合效应明显，墙底部截面弯曲屈服后，塑性铰区的剪切变形也表现出显著的非线性；轴拉力和往复水平力作用下墙体发生显著的轴向伸长，引起墙体受剪承载力退化，竖向钢筋平均拉应力比ns=0.40的RC墙，其受力由弯曲机制向剪切机制转变，出现了弯曲-剪切破坏，基于转动角软化桁架模型和轴向伸长的实测数据，定量计算了该类墙体的受剪承载力退化，揭示了弯曲-剪切破坏机理。最后，验证了美国ACI 318—14和中国JGJ 3—2010中RC墙正截面拉弯承载力计算方法和公式的适用性。