国产热轧普通工字钢轴心受压杆件承载能力的研究

本文对以18号热轧工字钢为轴心受压杆件的承载能力进行了试验和理论研究。测定了截面的残余应力,进行了拉伸试件试验、短柱试件试验以及中、长柱试件试验。用切线模量理论对轴心受压柱曲线进行了分析,并同中、长柱试验结果做了比较。用极限强度理论对柱的极限承载能力进行了计算,由于全部冀缘存在着受拉残余应力,按极限强度理论所得柱曲线具有较高的屈曲强度。     

T形方钢管混凝土组合异形柱偏压性能试验研究

T形方钢管混凝土组合异形柱具有良好的力学性能,以试件长度、偏心距、偏心方向为试验参数,设计9个不同长细比的试件进行偏心受压试验,观察试件的破坏形态,得到荷载-应变曲线和荷载-挠度曲线,并分析各参数对试件偏心受压性能的影响。试验结果表明:长度为600mm的试件发生了强度破坏,长度为1 500、1 800mm的试件发生了弯曲失稳破坏;试件长度越长,弯曲破坏特征越明显;偏心距越大,偏压承载力越低;偏心方向对偏心受压性能的影响相对较小。与相关规范计算结果对比发现,按DBJ/T 13-51—2010计算的结果与试验结果吻合最好。研究结果表明,T形方钢管混凝土组合异形柱延性较好,方钢管之间可以协同工作,偏心受压力学性能良好。     

碳纤维增强复合材料筋活性粉末混凝土中长柱小偏心受压受力性能试验研究

为探究碳纤维增强复材(CFRP)配筋活性粉末混凝土(RPC)中长柱的偏心受压受力性能,对其进行了偏心受压静载试验,得到了CFRP配筋RPC柱的破坏形态、极限承载力、荷载-变形关系曲线以及CFRP筋与混凝土的荷载-应变分布曲线。试验结果表明:CFRP配筋RPC柱有较高的承载能力;试件因混凝土压碎而破坏;试件的侧向挠度沿柱高的分布接近正弦分布。     

细晶粒钢筋混凝土柱偏心受压性能试验研究

对9根400 MPa级细晶粒钢筋混凝土柱开展偏心受压性能试验,研究轴向力偏心距、纵向受压钢筋配筋率、混凝土强度和长细比对柱偏心受压性能的影响,描述各试件的破坏过程,分析了其荷载-钢筋/混凝土应变曲线、荷载-挠度曲线以及破坏形态的特点。研究表明,现行混凝土结构设计规范关于钢筋混凝土偏心受压柱极限承载力、平均裂缝间距和最大裂缝宽度的计算理论与试验吻合较好。400 MPa级细晶粒钢筋屈服强度设计值取为360 MPa时,细晶粒钢筋混凝土偏压柱承载力具有足够的安全系数并偏向于保守。正常使用极限状态下,400 MPa级细晶粒钢筋混凝土大偏心受压柱在短期荷载作用下的最大裂缝宽度满足要求。     

型钢部分包裹再生混凝土偏心受压短柱(强轴)受力性能试验研究

为了研究型钢部分包裹再生混凝土短柱(强轴)的偏心受压性能,设计了6个试件并进行静力加载试验,不同试件的主要变化参数为再生粗骨料取代率、偏心率。通过试验获得了试件的破坏形态、承载力、荷载-挠度曲线、荷载-应变曲线,采用国外相关规范的计算方法对型钢部分包裹再生混凝土短柱(强轴)的偏心受压承载力进行计算,并与试验结果进行了对比分析。研究结果表明:试件的极限承载能力随着再生粗骨料取代率和偏心距的增大而减小;根据规范ANSI/AISC 360-10计算的型钢部分包裹再生混凝土短柱(强轴)的偏心受压承载力与试验结果较为吻合。     

胶合竹柱偏心受压试验研究

作为一种天然纤维增强复合材料,胶合竹材料的应用有利于推动建筑行业可持续发展。实际建筑中柱子大多处于偏心受压状态,为了研究胶合竹柱偏心受压下的力学性能,对具有不同偏心距的胶合竹柱开展了偏心受压试验研究。研究结果表明,对于不同的偏心受压柱试件,最终均因跨中附近受拉侧纤维首先断裂而破坏;随着初始偏心距的增大,试件的极限荷载降低,相同荷载作用下试件的侧向变形增大;弯曲变形过程中,试件侧向挠度曲线基本符合正弦半波曲线,柱跨中截面平均应变基本呈线性分布,符合平截面假定;同时,给出了胶合竹柱偏心受压极限承载力的建议计算公式,计算结果与试验结果吻合良好。     

碳纤维布(CFRP)加固钢筋混凝土偏心受压柱的试验研究

对碳纤维布(CFRP)横向约束的混凝土矩形偏心受压柱进行了静载性能的试验研究,测得了小偏心受压柱加固后的极限承载力及其箍筋和CFRP的荷载-应变曲线,并在小偏心范围内,对不同偏心率下的CFRP加固混凝土柱受压的特点作了分析。试验结果表明:外贴CFRP能有效地提高小偏心受压混凝土柱的抗压极限承载力,且其极限承载力的提高幅度随偏心距减小而增大。最后参考《混凝土结构设计规范》对外贴CFRP的小偏心受压柱的抗压极限承载力提出了实用的计算公式,计算值与试验结果基本吻合。     

钢管再生混凝土柱轴压及其核心混凝土多轴力学性能研究

将钢管再生混凝土结构用于实际工程中,长细比是对其力学性能影响的重要因素之一。首先对核心再生混凝土进行了多轴拉压试验,给出了其本构关系;对4种不同长细比的12根钢管再生混凝土柱进行了轴心受压试验,分析了长细比对其极限承载力、荷载-位移曲线、荷载-应变曲线、荷载比-横向变形系数曲线的影响。结果表明:随着试件长细比的增大,钢管再生混凝土柱的极限承载力显著下降,长细比增加50%,其承载力下降3. 3%左右;纵向应变减小,环向应变增加;钢管对核心再生混凝土的套箍约束作用开始增强的时间越早。基于试验研究和理论分析,给出了考虑长细比的钢管再生混凝土柱承载力计算公式。在上述基础上,对其进行了ABAQUS有限元模拟研究,模拟结果与试验结果吻合较好。     

配筋钢管混凝土柱抗压性能

对配筋钢管混凝土柱的轴心受压性能进行了试验研究和理论分析;研究了配筋钢管混凝土短柱的受力性能、变形能力和破坏形态,给出了变形和极限承载能力的试验结果;分析了加配钢筋的作用及其对钢管混凝土柱变形和极限承载力的影响。最后探讨了配筋钢管混凝土短柱轴心受压承载力的计算方法,给出了简化计算公式。结果表明,钢管混凝土短柱加配钢筋以后,改变了其破坏形态,提高了其极限承载能力和变形性能。     

预应力钢带加固钢筋混凝土柱试验研究

通过对2根预应力钢带加固钢筋混凝土柱与2根未加固钢筋混凝土柱的力学性能进行对比试验,研究预应力钢带加固对钢筋混凝土轴心受压柱、偏心受压柱的破坏形态、承载力、刚度、变形能力的影响。试验结果表明:预应力钢带加固钢筋混凝土柱的破坏形态与未加固试件基本相同,但加固试件初裂荷载更大;加固后钢筋混凝土轴心受压试件、偏心受压试件承载力分别提高24%、20%,承载力提升效果显著;预应力钢带加固对轴心受压试件轴向刚度明显提高,从初始加载到荷载达到80%极限荷载的不同加载水平下,加固后轴压试件的轴向刚度与未加固试件轴向刚度的比值在1.12~1.18;经预应力钢带加固后,偏心受压试件极限荷载对应的侧向挠度增大了37%,偏压试件变形能力明显增强。     

Experimental study on bearing capacity of stainless steel lipped C section stub columns

This paper studies the failure mechanism and the bearing capacity of stainless steel lipped C section stub columns under axial and eccentric compression. A series of tests were performed on S30408 stainless steel, including 16 mechanical property tests, 10 axially loaded and 28 eccentrically loaded stub column tests. Flat and corner coupon tests were conducted to investigate the anisotropy, the hardening index and the stress–strain behavior of stainless steel. Stub column tests were carried out to obtain the load–displacement curves, the bearing carrying capacity and the section strain variation. Comparison of test results with code predictions indicates that the design strengths are lower than the experimental strengths, and that the deviation between test and predicted results reduces as the section plate slenderness coefficient increases.     

An experimental behaviour of concrete-filled steel tubular columns

In this paper results of tests conducted on 27 concrete-filled steel tubular columns are reported. The test parameters were the column slenderness, the load eccentricity covering axially and eccentrically loaded columns with single or double curvature bending and the compressive strength of the concrete core. The test results demonstrate the influence of these parameters on the strength and behaviour of concrete-filled steel tubular columns. A comparison of experimental failure loads with the predicted failure loads in accordance with the method described in Eurocode 4 Part 1.1 showed good agreement for axially and eccentrically loaded columns with single curvature bending whereas for columns with double curvature bending the Eurocode loads were higher and on the unsafe side. More tests are needed for the case of double curvature bending.     

Nonlinear behaviour of eccentrically loaded FR concrete-filled stainless steel tubular columns

This paper investigates the nonlinear behaviour of eccentrically loaded fibre reinforced (FR) concrete-filled stainless steel tubular composite columns. A nonlinear 3-D finite element model for the axially loaded composite columns, recently reported by the author, was extended to study the structural performance of the eccentrically loaded composite columns. The columns were pin-ended subjected to an eccentric load acting along one axis. The model accounted for the inelastic behaviour of the composite column components, effect of FR concrete confinement and interface between the stainless steel section and concrete. The measured initial local and overall geometric imperfections were carefully incorporated in the model. The finite element model has been validated against tests previously reported by the author. Furthermore, the variables that influence the eccentrically loaded composite column behaviour and strength comprising different eccentricities, different column slenderness and different concrete strengths were investigated in an extensive parametric study comprising 72 columns. The composite column strengths and moment resistances predicted from the finite element analysis were compared with the design composite column strengths and moment resistances calculated using the Eurocode 4. The study has shown that finite element modelling could effectively assess the accuracy of the design rules in current codes of practice.     

Experimental investigation of eccentrically loaded fibre reinforced concrete-filled stainless steel tubular columns

This paper presents an experimental investigation of axially and eccentrically loaded plain and fibre reinforced (FR) concrete-filled stainless steel circular tubular columns. The composite columns were pin-ended subjected to axial and eccentric loads. The stainless steel tubes were relatively slender having a diameter-to-plate thickness ratio of 50. The composite columns had different lengths varied from 3D to 12D. The column ultimate loads, load–axial shortening relationships, load–strain relationships, load–mid-height lateral deflection relationships and failure modes of the concrete-filled stainless steel circular tubular columns were measured from the tests. The study has shown that FR concrete-filled stainless steel tubular columns offer a considerable increase in column ductility compared with plain concrete-filled tubular columns. The test ultimate loads were compared with the design ultimate loads calculated using the Eurocode 4 for composite columns. Generally, it has been shown that the EC4 accurately predicted the ultimate loads of axially loaded concrete-filled stainless steel circular tubular columns, but were quite conservative for predicting the ultimate loads of the eccentrically loaded columns. It has also been shown that the conservatism of the EC4 predictions is increased as the eccentricity is increased. The test results provide useful information regarding the behaviour of FR concrete-filled stainless steel columns.     

卷焊圆管、方管轴压杆的脆性屈曲

钢管截面构件受压时为脆性屈曲,可靠指标β与普通压杆理应有所不同,但目前国内有关设计规范(程)对此都没有反映。本文采用弹塑性梁柱理论、数值积分法计算了卷焊圆管、方管截面轴压杆完整的荷载-位移曲线,分析了纵向焊接残余应力、初弯曲、板件宽厚比(径厚比)对钢管压杆屈曲及屈曲后性能的影响,提出了圆管、方管截面轴压杆稳定承载力计算方法。     

楔形压杆的非弹性稳定研究

在已有的楔形单元弹性刚度方程的基础上,推导了它的弹塑性增量刚度方程,并利用所得到的结果研究了轴心和偏心楔形压杆在强轴平面内的非弹性稳定,得到了各种楔率下楔形压杆的柱子曲线和轴力-弯矩相关曲线.     

HRBF500钢筋混凝土偏心受压柱承载力的试验研究

通过对9根HRBF500钢筋混凝土偏心受压柱和1根HRB400钢筋混凝土偏心受压柱的试验,分析了荷载-钢筋应变、混凝土应变曲线以及破坏形态的特点。在试验和理论分析的基础上,提出HRBF500钢筋在混凝土柱中的强度设计取值为450 MPa和受压承载力计算公式的建议。     

Eccentrically loaded concrete encased steel composite columns

This paper presents a nonlinear 3-D finite element model for eccentrically loaded concrete encased steel composite columns. The columns were pin-ended subjected to an eccentric load acting along the major axis, with eccentricity varied from 0.125 to 0.375 of the overall depth (D) of the column sections. The model accounted for 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 allowing the bond behaviour to be modelled and the different components to retain its profile during the deformation of the column. The initial overall geometric imperfection was carefully incorporated in the model. The finite element model has been validated against existing test results. The concrete strengths varied from normal to high strength (30–110 MPa). The steel section yield stresses also varied from normal to high strength (275–690 MPa). Furthermore, the variables that influence the eccentrically loaded composite column behaviour and strength comprising different eccentricities, different column dimensions, different structural steel sizes, different concrete strengths, and different structural steel yield stresses were investigated in a parametric study. Generally, it is shown that the effect on the composite column strength owing to the increase in structural steel yield stress is significant for eccentrically loaded columns with small eccentricity of 0.125D. On the other hand, for columns with higher eccentricity 0.375D, the effect on the composite column strength due to the increase in structural steel yield stress is significant for columns with concrete strengths lower than 70 MPa. The strength of composite columns obtained from the finite element analysis were compared with the design strengths calculated using the Eurocode 4 for composite columns. Generally, it is shown that the EC4 accurately predicted the eccentrically loaded composite columns, while overestimated the moment.     

薄壁轴压焊接方管柱整体稳定-局部稳定相互作用问题的研究

本文采用曲壳有限单元法计算了具有各种宽厚比的薄壁轴压焊接方管截面的极限承载力,以及相应的长柱构件的柱子曲线。计算时计入了各种初始缺陷。通过将本文计算结果与各规范设计方法计算结果的比较,分析了规范方法的误差原因,提出了改进的薄壁方管截画有效面积的计算公式和轴压焊接薄壁方管柱的设计方法。经与本文理论计算结果相比,证明本文建议的设计方法精度较好。