中性盐雾环境锈蚀H型钢柱抗震性能试验研究

通过7根锈蚀H型钢柱的低周往复荷载试验,研究锈蚀对H型钢柱破坏形态、承载力、变形、延性、耗能等方面的影响。结果表明: 锈蚀钢柱的翼缘和腹板变形范围及屈曲中心高度呈减小趋势,部分钢柱屈曲中心高度降低了约30%;随着质量损失率增加,滞回环梭型饱满程度越低,所包围的面积越来越小;钢柱的承载力下降明显;钢柱位移延性系数及累积滞回耗能不断减小,并基于试验数据建立了锈蚀H型钢柱位移延性系数的退化模型及累积滞回耗能与循环次数的关系。锈蚀导致钢柱截面面积减小,同时点蚀的存在引起应力集中,减弱了其塑性变形能力。反复荷载作用下,钢柱塑性变形累积,局部屈曲导致承载力下降,抗震性能降低。     

中性盐雾环境锈蚀H型钢柱抗震性能试验研究

通过7根锈蚀H型钢柱的低周往复荷载试验,研究锈蚀对H型钢柱破坏形态、承载力、变形、延性、耗能等方面的影响。结果表明:锈蚀钢柱的翼缘和腹板变形范围及屈曲中心高度呈减小趋势,部分钢柱屈曲中心高度降低了约30%;随着质量损失率增加,滞回环梭型饱满程度越低,所包围的面积越来越小;钢柱的承载力下降明显;钢柱位移延性系数及累积滞回耗能不断减小,并基于试验数据建立了锈蚀H型钢柱位移延性系数的退化模型及累积滞回耗能与循环次数的关系。锈蚀导致钢柱截面面积减小,同时点蚀的存在引起应力集中,减弱了其塑性变形能力。反复荷载作用下,钢柱塑性变形累积,局部屈曲导致承载力下降,抗震性能降低。     

中性盐雾环境锈蚀H型钢柱抗震性能试验研究

通过7根锈蚀H型钢柱的低周往复荷载试验,研究锈蚀对H型钢柱破坏形态、承载力、变形、延性、耗能等方面的影响。结果表明:锈蚀钢柱的翼缘和腹板变形范围及屈曲中心高度呈减小趋势,部分钢柱屈曲中心高度降低了约30%;随着质量损失率增加,滞回环梭型饱满程度越低,所包围的面积越来越小;钢柱的承载力下降明显;钢柱位移延性系数及累积滞回耗能不断减小,并基于试验数据建立了锈蚀H型钢柱位移延性系数的退化模型及累积滞回耗能与循环次数的关系。锈蚀导致钢柱截面面积减小,同时点蚀的存在引起应力集中,减弱了其塑性变形能力。反复荷载作用下,钢柱塑性变形累积,局部屈曲导致承载力下降,抗震性能降低。     

用可靠度理论确定屈曲约束支撑钢框架的设计原则

根据同济大学采用国产低碳钢Q195、Q235与宝钢新开发的低屈服点钢BLY160、BLY225研制的两种型号屈曲约束支撑(TJ-I型与TJ-II型)的大量试验结果,应用统计分析与可靠度理论,确定了屈曲约束支撑钢框架的设计原则。给出了具有明确概率意义的,在使屈曲约束支撑达到其极限承载力的外荷载下,框架柱、梁的内力与其设计承载力的比例极限。可保证在罕遇地震作用下,屈曲约束支撑能充分发挥其抗震耗能作用,同时框架柱、梁的可靠度指标β分别不低于3.2与2.7,为国产屈曲约束支撑在抗震工程中的应用提供参考。     

H型钢防屈曲支撑抗震性能试验研究

提出一种H型钢防屈曲支撑（HBRB）以便于对结构中既有H型钢构件进行抗震加固,同时可避免传统H型钢防屈曲支撑中过早发生内芯局部屈曲破坏的现象发生。该支撑的耗能内芯采用H型钢,约束构件由2个U形钢和2块钢板通过高强螺栓拼接而成。为了研究HBRB的抗震性能,对3个试件进行拟静力试验,结果表明,构造合理的HBRB具有稳定的滞回耗能能力。通过分析试件破坏模式发现：将端部加劲肋布置在翼缘两侧有利于避免H型钢防屈曲支撑内芯应变集中及约束构件局部鼓曲破坏的发生;端部加劲肋和外部约束构件之间的间隙过大会导致加劲肋和H型钢内芯焊缝撕裂;采用低电流、多道焊缝施焊有利于提高防屈曲支撑的疲劳性能。在轴向荷载作用下,H型钢内芯除了发生整体弯曲变形外,腹板和翼缘作为板件还会分别发生自身的高阶屈曲;翼缘和腹板在屈曲后与约束构件接触,相当于对H型钢增加额外的侧向约束,使其整体稳定承载力明显提升。     

不同约束H型钢柱火灾后力学性能试验研究

通过对3根柱顶受不同约束的H型钢柱的火灾后力学性能的对比试验研究,讨论不同约束对H型钢柱火灾后力学性能的影响。3种约束条件分别为:柱顶对称约束、柱顶非对称约束和自由膨胀。火灾中及火灾后的试验结果显示,H型钢柱的升温和降温过程存在一定的滞后性,受火后的H型钢柱仍有较高的轴压承载力,最终破坏时伴随着翼缘和腹板的局部屈曲,约束性质对H型钢柱火灾后的力学性能有明显的影响,也即受对称约束的H型钢柱在火灾后轴压作用下的纵向应变明显不同于非对称约束的情况,而且非对称约束钢柱压曲破坏前的整体刚度明显高于对称约束。火灾后H型钢柱沿强轴方向的侧向弯曲形状呈S形变化,这一特征对于受对称约束和自由膨胀的钢柱更为明显。     

H型钢连接L形方钢管混凝土组合异形柱偏压性能研究

为提升方钢管混凝土组合异形柱加工制作的便捷性与精度、减小焊接对板件变形的影响，提出了新型H型钢连接L形方钢管混凝土组合异形柱(LCFST-H),并研究其偏压荷载下的力学性能。设计了两个试件进行偏压加载试验，建立计算模型开展有限元分析。在验证有限元模型准确性的基础上，分析了H型钢连接板尺寸、方钢管截面尺寸、柱高度等参数对组合异形柱偏压受力性能的影响。结果表明：构件破坏形式为整体弯曲失稳与局部屈曲破坏，达到极限承载力后，单肢柱之间仍能通过H型钢连接板很好地协同工作，具备一定承载能力，体现出较高的延性性能。方钢管截面尺寸和柱高度对其偏压性能影响较大。结合相关规范，给出了H型钢连接L形方钢管混凝土组合异形柱单向偏压承载力计算公式，公式计算结果与有限元结果吻合较好。     

局部约束方钢管混凝土柱约束件设计方法

提出了一种新型方钢管混凝土柱结构形式 :局部约束方钢管混凝土柱。它通过在方钢管混凝土柱的塑性铰区域设置局部约束以有效提高柱在往复荷载作用下的延性 ,克服传统方钢管混凝土柱由于局部屈曲而导致的延性不足的抗震缺陷。建立了约束件设计的塑性铰模型 ,应用该模型设计了 4个分别采用钢板、钢带和角钢约束件的约束钢管混凝土试件 ,并进行了往复荷载试验。试验结果表明 :局部约束可有效提高柱的延性 ,增加柱的耗能能力 ;同时说明了该设计方法的有效性。     

钢框架刚性节点力学性能分析

为了研究钢框架刚性连接节点的力学性能,文中以H型钢柱腹板厚度、梁截面形式及加劲肋为参数,设计六组T形刚性节点,利用ABAQUS有限元软件建立刚性节点模型,分析钢框架刚性节点在低周反复循环荷载下的滞回性能;对刚性节点数值分析得到节点的滞回曲线、骨架曲线。结果表明,增大柱的腹板厚度能一定程度提高节点承载力及初始刚度;梁截面为H型钢的抗震性能优于梁截面形式为钢管型的;梁柱节点连接处设置加劲肋能有效提高节点的力学抗震性能。     

一般大气环境锈蚀钢柱抗震性能试验与数值分析

为研究锈蚀对钢柱抗震性能的影响,对20个钢板试件和7个H型钢柱试件进行一般大气环境加速腐蚀试验。通过锈蚀钢板单调拉伸与低周往复加载试验研究锈蚀钢板单调与循环加载性能的差异性,揭示锈蚀钢材强度、延性退化规律,建立锈蚀钢材循环本构模型;通过锈蚀H型钢柱拟静力试验,研究锈蚀钢柱在地震作用下的损伤过程、破坏形态及性能退化规律,结果表明:锈蚀导致柱脚塑性范围更加集中,并加快屈曲发展,从而引起承载力、刚度、延性和耗能能力显著退化,且较大的轴压比将进一步加快钢柱破坏过程。最后,提出考虑锈蚀程度的损伤钢柱抗震性能数值模拟方法,并进行参数化扩展分析,研究均匀/非均匀锈蚀程度、锈蚀分布范围等影响因素对H型钢柱抗震性能的影响规律,结果表明:非均匀锈蚀导致钢柱抗震性能退化更加严重,且当钢柱翼缘或柱脚发生锈蚀时,抗震性能退化更为显著。     

Seismic behavior of wide-flange steel column with confined potential plastic hinge

This experimental project investigates and validates an innovative method to confine the potential plastic hinge zone of hot-rolled H-shape (or wide-flange) steel column for improved seismic behavior. Based on fundamental mechanics, the concept aims at controlling the local buckling of the flange and web elements of the H-shape steel in the potential plastic hinge region of a column. In the experimental program, six model columns were tested under constant axial load and cyclic lateral forces acting in either the weak or the strong axes. Compared with the conventional H-shape steel model columns, the model columns with their potential plastic hinge zone confined by either steel strips or reinforced concrete cover, exhibited excellent seismic performance with large ductility. Analytical efforts to compare with the test results were also made using simple moment-curvature analysis.     

Monotonic and cyclic behavior of concrete-filled steel-tube beam-columns considering local buckling effect

A mathematical model is developed to evaluate the monotonic and cyclic behavior of concrete-filled steel tube (CFST) beam-columns with rectangular cross section. The model includes the reduction in the steel compressive strength due the local buckling effect. The degradations in unloading and reloading stiffness of steel tube due to local buckling are also included. The model is based on fiber element method in which uniaxial stress–strain material laws are used for cross section components. The results obtained from the mathematical model were compared with experimental results for columns under monotonic as well as cyclic loads. It is observed that the proposed model predicts well the columns and beams nonlinear behavior compared with the experimental results.     

H形钢构件双轴压弯滞回试验的设计和实现

设计了一套H形钢构件双向压弯滞回加载测量试验系统,用以实现H形钢构件在三轴受力时的加载和试件响应的精确测量。试验系统具有如下特点:加载系统采用万向铰-跟动装置系统,能够精确实施既定的加载方案,避免加载时产生附加弯矩和扭矩,有效消除摩擦力的影响;试验位移测量系统能够精确测量得到试件加载时的三维空间响应;试验应变测量布置可考察柱底部翼缘和腹板屈服及屈曲的发生,并可利用加载时弹性段的应力反算水平反力,进而计算其摩擦力;试验结果显示试验加载和测量系统相对都比较稳定,所得到的试验结果可靠,可以进行H形钢构件双轴压弯滞回性能的研究。     

残余应力和应变率对地震作用下钢柱的循环屈曲影响

对4个足尺W型柱试件进行受压屈曲试验,研究强震下多层支撑钢框架中柱的屈曲性能。工况包括单调、循环的轴心和偏心加载。在其中一个试验中施加动力循环荷载,在另一个循环试验中施加端弯矩。柱截面尺寸为W310×129(类型1),材质为ASTMA992钢。研究柱的长细比为48时绕弱轴屈曲的性能。基于杆件横截面的纤维离散化,采用数值方法模拟试件的响应。在数值模型中,描述并考虑了柱残余应力和应变率对材料属性的影响。研究表明:在地震作用下,钢柱能持续几个非线性屈曲循环,并承受重力荷载。仅在首次屈曲时,残余应力对柱的性能有影响,并在屈曲和降低受压承载力之前逐渐降低柱的切向刚度。强震下的高应变率提高了柱的屈曲强度和后屈曲强度。当采用非线性梁柱单元时,能充分预测钢柱的循环屈曲性能。在本模型中,通过横截面纤维离散化考虑了残余应力和应变率的影响。     

Seismically induced cyclic buckling of steel columns including residual-stress and strain-rate effects

Compression buckling tests were performed on four full-scale W-shaped column specimens to investigate the buckling response of columns in multi-storey braced steel frame structures subjected to seismic strong ground motions. The test protocols included monotonically and cyclically applied concentric and eccentric axial loading. One test was conducted under dynamic cyclic loading. End moments were applied on one cyclic test. The columns were W310×129 compact (class 1) sections made with ASTM A992 steel. Weak axis buckling was studied and the column had an effective slenderness ratio of 48. The response of the test columns was also examined using numerical simulations based on fibre discretization of the member cross-section. Column residual stresses and strain rate effects on the material properties were both characterized and accounted for in the numerical models. The study showed that steel columns can sustain several cycles of inelastic buckling under seismic induced loading while maintaining sufficient compressive resistance to support the applied gravity loads. Residual stresses affected the column response only at the first buckling occurrence with a gradual reduction of the columns’ tangent stiffness prior to buckling as well as a reduction of the column’s compressive resistance. High strain rates anticipated during strong earthquakes increased the column buckling and post-buckling strengths. The cyclic buckling response of steel columns can be predicted adequately when using nonlinear beam-column elements and cross-section fibre discretization provided that residual stresses and strain rate effects are included in the modelling.     

Nonlinear finite element analysis of behaviors of steel beam–continuous compound spiral stirrups reinforced concrete column frame structures

Many tests and numerical research for RCS frame consisted of reinforced concrete (RC) column and steel (S) beam have been conducted in the USA and Japan over the past decades; they showed that the performance of the RCS system is superior to traditional concrete frame and steel frame. Up to the present, no research reports on composite CCSHRCS frame structure consisted of high‐strength concrete columns confined with continuous compound spiral stirrups (CCSHRC) and steel (S) beam. Herein, an accurate finite element model of composite CCSHRCS frame is developed; the finite element model is investigated in order to fully include important factors such as local buckling of steel beam and nonlinear behavior of confined concrete; the validity of the proposed models is examined by comparing with the results of cyclic loading experiments on the RCS frame in reference. With the proposed model, the effect of composite CCSHRCS frame is discussed in detail. Copyright © 2012 John Wiley & Sons, Ltd.     

莱钢产轧制H型钢构件受力性能的理论与试验研究(Ⅳ)H型钢构件轴心受力性能的理论分析

对国产轧制H型钢截面构件进行了轴心受压承载力的理论研究。通过有限元方法 ,对国产轧制H型钢轴心受压构件的极限承载力进行了弹塑性和几何非线性的有限单元法理论分析 ,同时考虑了热轧型钢的残余应力和构件的初始缺陷。计算了 114根国产轧制H型钢轴心受压构件的极限承载力 ,得出国产轧制H型钢轴心受压构件极限承载力的主要公式。提出了便于设计人员应用的轴心受压修正公式。     

Nonlinear analysis of concrete-filled thin-walled steel box columns with local buckling effects

Local buckling of steel plates reduces the ultimate loads of concrete-filled thin-walled steel box columns under axial compression. The effects of local buckling have not been considered in advanced analysis methods that lead to the overestimates of the ultimate loads of composite columns and frames. This paper presents a nonlinear fiber element analysis method for predicting the ultimate strengths and behavior of short concrete-filled thin-walled steel box columns with local buckling effects. The fiber element method considers nonlinear constitutive models for confined concrete and structural steel. Effective width formulas for steel plates with geometric imperfections and residual stresses are incorporated in the fiber element analysis program to account for local buckling effects. The progressive local and post-local buckling is simulated by gradually redistributing the normal stresses within the steel plates. Two performance indices are proposed for evaluating the section and ductility performance of concrete-filled steel box columns. The computational technique developed is used to investigate the effects of the width-to-thickness ratios and concrete compressive strengths on the ultimate strength and ductility of concrete-filled steel box columns. It is demonstrated that the nonlinear fiber element method developed predicts well the ultimate loads and behavior of concrete-filled thin-walled steel box columns and can be implemented in advanced analysis programs for the nonlinear analysis of composite frames.     

Strength of slender concrete filled high strength steel box columns

The use of thin walled steel sections coupled with concrete infill has been used on various building projects with great advantage. The currently available international standards for composite structures are limited to the design of concrete filled steel columns with compact sections. However, there is limited research work in the literature available which is concerned with slender concrete filled thin-walled steel columns. This paper presents a comprehensive experimental study of thin walled steel sections utilising high strength steel of a thin walled nature and filled with normal strength concrete. A numerical model is developed herein in order to study the behaviour of slender concrete filled high strength steel columns incorporating material and geometric non-linearities. For this analysis, the equilibrium of the member is investigated in the deformed state, using the idealised stress–strain relationships for both the steel and concrete materials, considering the elastic and plastic ranges. This paper presents both an experimental and theoretical treatment of coupled local and global buckling of concrete filled high strength steel columns sometimes termed interaction buckling. The experimental results of columns with high strength steel casings conducted herein by the authors are used for comparison. The effect of the confined concrete core is also addressed and the method shows good agreement with the experimental results of concrete filled steel columns with compact sections. The behaviour of concrete filled steel slender columns affected by elastic or inelastic local buckling is also investigated and compared with relevant experimental results. The paper then concludes with a design recommendation for the strength evaluation of slender composite columns using high strength steel plates with thin-walled steel sections, paying particular attention to existing codes of practice so as not to deviate from current design methodologies.     

Seismic behavior and strength of square tube confined reinforced-concrete (STRC) columns

A steel tube confined reinforced-concrete (STRC) column is an ordinary RC column where most of the lateral ties are in the form of a thin steel tube. Twenty-three square tube confined concrete stub columns were tested in this paper under cyclic or monotonic axial compression. A design equation to calculate the axial load strength of square tube confined concrete stub columns is proposed in this paper. A total of five beam-columns have been studied under combined axial compression and lateral cyclic loads. The test results indicate that the columns confined with square steel tubes exhibit much higher flexural strength, displacement ductility, and energy dissipation ability than common RC columns confined with lateral ties. Fiber models were also developed for STRC beam-columns in this paper.