L形截面钢纤维高强钢筋混凝土柱及复合柱偏心加载试验

研究钢纤维对L形截面高强钢筋混凝土柱和混凝土复合柱的性能的影响。对16根L形截面钢纤维柱进行试验研究。主要参数为混凝土抗压强度、荷载偏心率、长细比影响以及钢纤维含量。对L形截面钢筋混凝土柱的试验结果进行了讨论。此外,基于材料的非线性特性对试样进行了分析。采用ACI318规范中的弯矩放大法对长细比影响加以考虑。结果表明:高强混凝土中加入钢纤维能够增强L形截面钢筋混凝土柱和复合柱的结构特性,有利于抵抗双向弯曲和轴向加载。     

钢管混凝土边框钢纤维混凝土中高剪力墙受弯承载力计算方法

为改善中高剪力墙的抗震性能,提出钢管混凝土边框钢纤维混凝土剪力墙.通过8个剪跨比为1.5的钢管混凝土边框钢纤维混凝土中高剪力墙和1个剪跨比为1.5的钢管混凝土边框混凝土中高剪力墙的低周反复加载试验,研究钢管混凝土边框钢纤维混凝土中高剪力墙的受力机理及破坏模式,分析钢纤维体积率、钢纤维掺加高度、混凝土强度和轴压比对其抗震...     

钢筋活性粉末混凝土柱高温全过程受力性能试验研究

在高温试验炉中对大尺寸钢筋活性粉末混凝土（RPC）柱和普通混凝土柱开展了高温试验,以及高温后的抗压试验,获取了柱高温下的截面温度场与轴向变形发展,分析了控制温度与轴压荷载对高温后钢筋RPC柱受压性能的影响。结果表明：掺入体积分数为2%的钢纤维和0.3%的PP纤维,避免了RPC高温爆裂的发生,且有利于提高钢筋RPC柱的高温抗裂能力;轴压荷载有效抑制了钢筋RPC柱高温下的膨胀与高温后收缩裂缝的产生,但高温与荷载的耦合作用降低了钢筋RPC柱高温后的剩余承载力与变形能力;钢筋RPC柱在经历600 ℃和800 ℃高温作用后,其承载力分别下降了39%和68%,轴向刚度分别下降了68%和83%;相比于普通钢筋混凝土柱,钢筋RPC柱高温后的承载力降低幅度更大,但其剩余截面强度相对更高;基于材料试验获得的温度-强度相关关系,提出了钢筋RPC柱高温后的剩余承载力计算式,预测值与试验值较为接近。     

Experimental research on mechanical behavior of reinforced reactive powder concrete columns at whole process of high temperature

在高温试验炉中对大尺寸钢筋活性粉末混凝土（RPC）柱和普通混凝土柱开展了高温试验，以及高温后的抗压试验，获取了柱高温下的截面温度场与轴向变形发展，分析了控制温度与轴压荷载对高温后钢筋RPC柱受压性能的影响。结果表明：掺入体积分数为2%的钢纤维和0.3%的PP纤维，避免了RPC高温爆裂的发生，且有利于提高钢筋RPC柱的高温抗裂能力；轴压荷载有效抑制了钢筋RPC柱高温下的膨胀与高温后收缩裂缝的产生，但高温与荷载的耦合作用降低了钢筋RPC柱高温后的剩余承载力与变形能力；钢筋RPC柱在经历600 ℃和800 ℃高温作用后，其承载力分别下降了39%和68%，轴向刚度分别下降了68%和83%；相比于普通钢筋混凝土柱，钢筋RPC柱高温后的承载力降低幅度更大，但其剩余截面强度相对更高；基于材料试验获得的温度-强度相关关系，提出了钢筋RPC柱高温后的剩余承载力计算式，预测值与试验值较为接近。     

钢管混凝土边框钢纤维混凝土剪力墙受剪承载力计算

通过5个钢管混凝土边框钢纤维混凝土剪力墙和1个钢管混凝土边框混凝土剪力墙的低周反复加载试验,研究钢管混凝土边框钢纤维混凝土剪力墙的受力机理及破坏模式,分析钢纤维体积率和混凝土强度对其抗震性能的影响。结果表明：钢管混凝土边框钢纤维混凝土剪力墙的破坏模式为剪切破坏;墙体裂缝主要为典型的斜裂缝,钢纤维可有效限制剪力墙裂缝宽度,改善裂缝形态;随着钢纤维体积率的增大,剪力墙受剪承载力、延性和耗能能力明显提高;其他影响因素相同的条件下,钢纤维体积率为0.5%、1.0%和1.5%的剪力墙受剪承载力较未掺钢纤维剪力墙的分别提高了4.4%、12.7%和18.6%;随着混凝土强度的提高,剪力墙受剪承载力和耗能能力明显提高,但延性降低;其他影响因素相同的条件下,钢纤维混凝土强度等级为CF60、CF80剪力墙的受剪承载力较CF40剪力墙的分别提高了24%和37%。结合对文中及国内外相关文献试验数据的综合分析,提出了考虑钢纤维体积率和混凝土强度等影响的钢管混凝土边框钢纤维混凝土剪力墙受剪承载力计算方法,与试验结果吻合较好。     

高轴压比钢纤维超高强混凝土短柱延性的试验研究

试验旨在研究在较高轴压比条件下,钢纤维对超高强混凝土短柱抗震延性的改善作用。短柱试件的剪跨比均为2.0,强度为103.6~114.8MPa,钢纤维的体积含纤率分别为0.5%、1.0%、1.5%。采用简支梁加载图式进行了低周反复荷载试验。观测了试件在荷载作用下的开裂和破坏的发展过程,分析了不同钢纤维含量对短柱的破坏形态、滞回特性的影响。试验结果表明:未掺钢纤维的试件,在高轴压作用下,发生了脆性特征明显的剪切破坏,延性很差;随着钢纤维含量的增加,试件的破坏形态向具有一定延性特征的弯剪破坏转变;同时延性得到大大改善,位移延性和极限弹塑性位移角分别可最大增加50.2%、96.1%,最后给出了抗震设计条件下的最小钢纤维体积含纤率的建议值。     

Experimental behaviour of eccentrically loaded slender circular hollow steel columns in-filled with fibre reinforced concrete

This paper is based on the experimental study of twelve slender steel tubular columns of circular sections filled with both plain and fibre reinforced concrete. The specimens were tested under eccentric compression to investigate the effects of fibre reinforced concrete on the strength and behaviour of slender composite columns. The slenderness ratio was considered to be the main test parameter. Hollow steel sections of similar specimens were also tested as reference columns. The test results were illustrated by load-deflection and load-strain curves. Various characteristics such as strength, stiffness, ductility, energy absorption capacity and failure mode are discussed. Interpretation of the experimental results indicates that the use of fibre reinforced concrete as infill material has a considerable effect on the strength and behaviour of slender composite columns.     

钢纤维钢筋高强混凝土柱延性的试验研究

做了九根钢纤维高强混凝土柱在单调荷载下的变形试验,其立方体抗压强度为５１．６～７０．８ＭＰａ,试验轴压比为０．３０１～０．５４６,钢纤维体积率为１．０％～２．０％。将试验结果与普通高强混凝土柱试验结果对比,表明在高强混凝土柱中掺入钢纤维是解决高强混凝土柱脆性大、延性差的一个有效途径。在各项条件基本相同的情况下,由于钢纤维的作用对延性系数的提高幅度达４１．３％,对极限压应变的提高幅度达３０．６％。     

CFRP-钢复合管约束型钢高强混凝土短柱的轴压力学性能

对8根碳纤维增强复合材料(CFRP)-圆/方钢复合管约束型钢高强混凝土（C-C/STCSRC）短柱和4根CFRP约束圆钢管型钢高强混凝土（C-CTSRC）短柱进行了轴压试验,分析了CFRP约束效应系数、钢管截面形式以及钢管受力性能对CFRP-圆/方钢复合管约束型钢高强混凝土（C-C/STCSRC）轴压短柱力学性能的影响。结果表明:CFRP-圆钢复合管约束型钢高强混凝土（C-CTCSRC）轴压短柱的极限承载力提高率随着约束效应系数的增加呈指数形式增长;在柱核心混凝土截面面积相同时,CFRP-圆钢复合管约束型钢高强混凝土（C-CTCSRC）轴压短柱的极限承载力比CFRP-方钢复合管约束型钢高强混凝土（C-STCSRC）轴压短柱的极限承载力高50%以上;在弹性工作阶段,CFRP约束圆钢管型钢高强混凝土（C-CTSRC）柱的弹性模量高于CFRP-圆钢复合管约束型钢高强混凝土（C-CTCSRC）柱的弹性模量;CFRP-圆钢复合管约束型钢高强混凝土（C-CTCSRC）柱的极限承载力高于CFRP约束圆钢管型钢高强混凝土柱的极限承载力;CFRP与钢管黏结良好时,CFRP与钢管能够协同工作。     

钢管钢纤维高强混凝土短柱轴心受压试验研究

对7根圆钢管钢纤维高强混凝土短柱和3根圆钢管高强混凝土短柱进行了轴心受压试验,研究钢纤维掺量、含钢率和混凝土强度等级对钢管钢纤维高强混凝土短柱受力性能的影响。研究结果表明：随着钢纤维体积掺量的增加,钢管钢纤维高强混凝土短柱的延性逐渐增大,承载力略有提高;随着含钢率的增加,钢管钢纤维高强混凝土短柱的承载力和延性均增大;随着混凝土强度等级的增加,钢管钢纤维高强混凝土短柱的承载力增大,延性逐渐降低;掺入钢纤维对钢管高强混凝土短柱的破坏模式几乎没有影响。最后给出了钢管钢纤维高强混凝土短柱承载力计算式。     

Experimental study on steel tubular columns in-filled with plain and steel fiber reinforced concrete

An experimental investigation on the structural behaviour of steel tubular columns in-filled with plain and steel fiber reinforced concrete is presented in this study. A total of 16 concrete-filled steel tubular columns were constructed and tested subjected to biaxial bending and short-term axial load. The main variables considered in the test study were the cross section, slenderness, concrete compressive strength and the load eccentricity. In the presented study, a theoretical method for the prediction of ultimate strength capacity and load-deflection curves of concrete filled steel tube columns is proposed. In the analysis procedure, the nonlinear behaviour of the materials is considered and the slenderness effect has been taken into account. The experimental ultimate strength capacities and load-deflection curves of both plain and steel fiber concrete-filled tube columns have been compared with the analysis results and discussed in the paper. The results indicate that the addition of steel fibers in core concrete has considerable effect on the behaviour of concrete-filled steel tube columns.     

Numerical simulation of concrete encased steel composite columns

This paper investigates the behaviour of pin-ended axially loaded concrete encased steel composite columns. A nonlinear 3-D finite element model was developed to analyse the inelastic behaviour of steel, concrete, longitudinal and transverse reinforcement bars as well as the effect of concrete confinement of the concrete encased steel composite columns. The interface between the steel section and concrete, the longitudinal and transverse reinforcement bars, and the reinforcement bars and concrete were also considered that allowed the bond behaviour to be modeled and the different components to retain their profile during the deformation of the column. Furthermore, the initial overall (out-of-straightness) geometric imperfection was carefully incorporated in the model. The finite element model has been validated against published experimental results. The main objective of the study was to understand the structural response and modes of failure of the columns and to assess the composite column strengths against current design codes. The study covered slender, non-slender, stub and long concrete encased steel composite columns. The concrete strengths varied from normal to high strength (20-110 MPa). The steel section yield stresses also varied from normal to high strength (275-690 MPa). Furthermore, the variables that influence the composite column behaviour and strength comprising different slenderness ratios, concrete strength and steel yield stress were investigated in a parametric study. It is shown that the increase in structural steel strength has a small effect on the composite column strength for the columns having higher relative slenderness ratios due to the flexural buckling failure mode. The composite column strengths obtained from the finite element analysis were compared with the design strengths calculated using the American Institute for Steel Construction AISC and Eurocode 4 for composite columns. Generally, it is shown that the EC 4 accurately predicted the design strength for the concrete encased steel composite columns having a concrete cylinder strength of 30 MPa and structural steel yield stresses of 275 and 460 MPa, which are in the limits of the code, which otherwise, was generally conservative. The AISC predictions were quite conservative for all the concrete encased steel composite columns.     

纤维网增强混凝土复合材料约束混凝土应力-应变关系研究

为研究纤维网增强混凝土(TRC)加固层对混凝土柱的约束性能,对13根混凝土柱试件(包括10根TRC加固柱和3根对比柱)进行了轴心受压试验,分析了纤维网层数、短切纤维及混凝土强度对TRC加固效果的影响,基于试验结果提出了TRC约束混凝土应力-应变关系简化计算模型.研究结果表明:TRC加固可改善混凝土柱的轴压破坏形态;与未...     

HRB600级钢筋钢纤维高强混凝土柱抗震性能研究

为研究HRB600级钢筋高强高性能混凝土柱的抗震性能，进行了6根大尺寸方形截面(600mm×600mm)混凝土柱在高轴压比条件下的低周反复荷载试验，包括2根HRB600级钢筋普通高强混凝土柱和4根HRB600级钢筋钢纤维高强混凝土柱，对比分析了各试件的破坏形态、滞回性能、承载力、刚度退化规律、延性和耗能能力。在试验基础上建立了HRB600级钢筋钢纤维高强混凝土柱的恢复力模型。研究结果表明：钢纤维可以减小高强混凝土柱的裂缝宽度，有效防止混凝土保护层脱落，减小柱的残余变形，提高柱的震后恢复性能；HRB600级钢筋钢纤维高强混凝土柱的变形能力良好，随着钢纤维掺量的增加，高强混凝土柱的位移延性系数逐渐增大；基于试验数据建立的HRB600级钢筋钢纤维高强混凝土柱恢复力模型计算精度良好；该类型柱可较好地满足现行抗震设计规范要求，宜于推广应用。     

纤维高强混凝土抗剪性能的试验研究

通过84根尺寸为100mm×100mm×400mm的高强混凝土、钢纤维高强混凝土、聚丙烯纤维高强混凝土试件在剪切荷载作用下的抗剪试验,研究了纤维类型和纤维体积率(掺量)对高强混凝土抗剪强度及在剪切荷载作用下变形性能的影响。结果表明,纤维的加入有效地改善了高强混凝土的抗剪强度及变形性能。初裂抗剪强度和变形、极限抗剪强度和变形以及抗剪韧性均随纤维体积率(掺量)的增加而增大,试件破坏时能保持完整性。根据试验结果,建立了钢纤维高强混凝土及聚丙烯纤维高强混凝土抗剪性能的剪力传递模型和数学表达式。     

钢纤维增强混凝土动态力学性能及HJC本构模型参数标定

探讨了不同体积掺量钢纤维和镀铜钢纤维对混凝土动态力学性能的影响,以及标定本构模型参数对钢纤维混凝土和镀铜钢纤维混凝土的适用性。在高强混凝土中掺加0.5%、1%、1.5%体积掺量的钢纤维制备7组试件,分别进行静态力学性能试验和分离式霍普金森压杆试验（SHPB）,基于静态、动态力学结果修正Holmquist-Johnson-Cook（HJC）本构模型参数,并利用有限元分析软件验证HJC模型参数的有效性。结果表明,在0.5%、1%、1.5%体积掺量下,混凝土动态峰值抗压强度随纤维掺量的增加而提高。标定的HJC模型对钢纤维混凝土的动态峰值抗压强度预测效果良好,模拟得到的应力-应变曲线与SHPB试验结果大致吻合。以侵蚀准则模拟得到动态冲击试验试件破坏过程,为钢纤维混凝土的抗冲击设计提供参考。     

Seismic performance of CFST column to steel beam joint with RC slab: Experiments

The objective of this research is to investigate the seismic behaviour of the composite joint consisting of circular concrete filled steel tubular (CFST) column and steel beam with reinforced concrete (RC) slab. Six specimens, including four interior and two exterior joints, were tested under constant axially compressive load on the top of the columns and cyclic loads at the ends of the beams. The main experimental parameters were the type of the joint, the axial load level on the CFST column and the section configuration of the beam. Several indexes that could reflect the seismic behaviour of the composite joint, such as the ductility, the strength degradation, and the energy dissipation capacity were analyzed. It was found that the composite joints exhibited favorable seismic performance.     

钢纤维钢筋混凝土柱延性系数的研究

编制了电算程序对钢纤维钢筋混凝土柱的延性系数进行计算 ,通过比较本文程序和文献 [3 ]提出的延性系数简化计算方法的计算结果 ,纠正了存在于文献 [3 ]的计算方法的几个错误之处 ,验证了本文电算程序的正确性。利用这个电算程序 ,通过例子 ,研究了钢纤维钢筋混凝土柱中 ,钢纤维体积含量、轴压比、纵向钢筋配筋率、柱截面宽度、柱截面高度和混凝土强度对延性系数的影响     

传统风格建筑方形SRC-圆形RC变截面组合柱抗震性能试验研究

为研究传统风格建筑方形型钢混凝土(SRC)-圆形钢筋混凝土(RC)变截面组合柱的抗震性能,对2个足 尺传统风格建筑变截面组合柱进行了低周反复加载试验,得到了试件的破坏形态、滞回特性、刚度和强度退 化、延性及耗能性能。研究表明：传统风格建筑方形SRC-圆形RC变截面组合柱的破坏主要是由变截面处上柱 型钢和钢筋屈服及混凝土压碎剥落造成的;试件滞回曲线饱满,刚度和强度退化小;破坏时,试件的位移延 性系数介于3.18～3.76之间,等效黏滞阻尼系数介于0.289～0.338之间,具有良好的变形和耗能性能。在试 验基础上,利用ABAQUS建立试件三维模型,进行了混凝土强度、轴压比、型钢屈服强度、上下柱线刚度等参 数对其抗震性能影响的参数分析。试验及分析结果表明：随混凝土强度、型钢屈服强度增大,试件的水平承 载力增大,但其延性降低;增大轴压比,试件的水平承载力降低,延性系数减小;而随上、下柱线刚度比增 大,试件的水平承载力和延性增大。     

生态钢纤维混凝土弯曲韧性和断裂性能

为掌握生态钢纤维混凝土的弯曲韧性和断裂性能,分别对掺率(体积分数)为1.0%,1.7%,2.4%的2种异形生态钢纤维混凝土和掺率为0.7%,1.3%的原生高强钢纤维增强混凝土进行了无切口梁四点弯曲韧性试验和切口梁三点弯曲断裂试验。研究结果表明:生态钢纤维掺率为1.0%时,无切口梁四点弯曲荷载 挠度曲线和切口梁三点弯曲荷载 挠度及荷载 切口张开位移曲线在达到峰值后都出现局部陡降,试件残余强度较小,断裂韧度值较低,纤维对改善混凝土弯曲韧性和断裂性能的作用较小;当生态钢纤维掺率为1.7%时,混凝土弯曲韧性和断裂性能均得到显著提高,混凝土在变形达到15δ_ult,p（δ_ult,p为素混凝土峰值荷载对应的挠度）或70D_ult,p（D_ult,p为素混凝土峰值荷载对应的切口张开位移）水平时,依然具有较高的持荷能力和较好的韧性,波浪型生态钢纤维混凝土断裂能和断裂韧度是素混凝土的27.59倍和8.35倍;生态钢纤维掺率为2.4%时,混凝土弯曲韧性指标、断裂能和断裂韧度进一步增加;掺率为1.7%的生态钢纤维混凝土增韧和抗断裂效果与掺率为0.7%的原生高强钢纤维混凝土相当。