Experimental study on seismic performance of mega steel‐reinforced concrete columns subjected to cyclic loads

In recent years, mega steel‐reinforced concrete (SRC) columns have been applied in super tall buildings. The previous research on SRC columns mainly focuses on the components with simple arrangement of shaped steel, such as H‐shaped steel and cross‐shaped steel, with little attention paid to mega SRC columns, which always have complicated encased steel and large steel ratio. The cyclic loading tests were carried out on scaled mega SRC column models with different cross‐section type of encased steel and steel ratio. The principal damage states were investigated throughout the entire testing process. Based on the test results, the effects of steel ratio and the cross‐section type of encased steel on the damage characteristics, hysteretic behavior, ductility, secant stiffness degradation, energy dissipation capacity and maximum crack width were analyzed. The test results indicate that the steel ratio has significant effect on the seismic performance of mega SRC columns while the effect of cross‐section type of encased steel is not significant. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental study on the static performance of steel reinforced concrete columns with high encased steel ratios

The static performances of 12 steel reinforced concrete (SRC) columns with high encased steel ratios subjected to biaxial bending and axial loadings are studied experimentally. The main design parameters of the specimens in this experiment are the encased steel ratio, axial compression ratio, and shape distribution of the encased steel section. The crack formation, failure processes, bearing capacity, and ductility of the specimens are investigated in detail. The experimental results show that the increased encased steel ratio results in the increased bearing capacity and ductility of the specimens. Furthermore, the stiffness of the specimen degenerates gradually beyond the peak point with an increase in the axial compression ratio. In addition, a more extensive shape distribution of an encased steel section has a positive influence on the ductility of the specimen. A comparison of the yield and peak bearing capacities between the experimental results of this study and the predictions according to Eurocode 4 also highlights that Eurocode 4 would underestimate the bearing capacity of SRC columns with high encased steel ratios because it ignores the confinement of concrete provided from the steel section and hoops and it employs a conservative prediction approach for the simplified axial load‐bending moment curve.     

十字形截面钢-混凝土组合异形柱的抗震性能

为研究十字形截面钢-混凝土组合异形柱的抗震性能,对5个不同轴压比、配钢形式的试件进行低周反复加载试验。研究了滞回曲线、骨架曲线、延性性能、刚度退化、耗能性能等抗震性能,对比分析了轴压比和配钢形式对抗震性能的影响。结果表明,轴压比较大的试件具有更高的承载能力,但延性降低、刚度退化速率加快;与普通钢筋混凝土异形柱相比,在异形柱内配置型钢可改善滞回性能、增强刚度、延性性能、承载能力和耗能性能,减轻破坏程度,从而提高抗震性能。配钢形式为T形钢加方钢管的试件除刚度退化外,其他性能均优于实腹型配钢试件。     

型钢混凝土柱粘结滑移的数值模拟

运用ANSYS程序对型钢混凝土构件的非线性有限元分析方法进行了研究,介绍了数值计算中所涉及到的材料模型定义、几何模型建立、单元划分、约束条件处理等问题,并得出了计算结果与试验结果吻合较好的结论。     

钢骨截面延展性对高含钢率SRC柱静力性能的影响研究

钢骨混凝土柱的受力性能受诸多因素影响,钢骨截面延展性是其中的一个重要影响参数。本文首先定义了钢骨截面延展性系数D,以及截面模量影响因子α和约束混凝土影响因子β,用于定量描述钢骨截面延展程度;通过一组含钢率为15%的SRC柱单调压弯试验和有限元数值分析,考察了钢骨截面延展性对构件承载能力和延性性能的影响。研究表明：①高含钢率SRC柱的荷载-位移曲线变化稳定,试验现象发展平缓,承载力高,延性好;②SRC柱的承载力随截面模量因子和约束混凝土因子的增大而线性增加,承载力与截面延展性系数D有良好的线性变化关系;③试件加载后期的剩余承载力随钢骨截面延展性的提高而提高;④结合试验和数值分析结果,推导了高含钢率SRC柱的钢骨翼缘与腹板厚度比限值,并提出了若干设计建议。     

预压型钢混凝土柱滞回特性有限元分析

在型钢混凝土柱基础上提出预压型钢混凝土柱,并对预压型钢混凝土柱研究意义进行了概要分析。采用ANSYS有限元分析软件,通过对9个不同混凝土强度等级、不同型钢预压比、不同轴压比的预压型钢混凝土柱的低周反复荷载试验,得到预压型钢混凝土柱在不同轴压比、型钢预压比下的破坏形态和滞回曲线。研究结果表明:预压型钢混凝土柱有良好的抗震性能,但是其随着轴压比增大和混凝土强度的提高而降低。     

预应力型钢混凝土柱框架结构数值模拟

利用ANSYS有限元分析程序,对一型钢混凝土柱的预应力混凝土框架结构受力性能进行了非线性全过程数值模拟,介绍了ANSYS有限元分析的建模方法及计算中的技术问题,并得出了相关结论。     

钢骨截面延展性对高含钢率SRC柱滞回性能的影响研究

在“钢骨截面延展性对高含钢率SRC柱静力性能的影响研究”的基础之上,该文通过一组含钢率为15%的SRC压弯构件反复加载试验,结合理论分析和有限元数值计算,研究了钢骨截面延展性对高含钢率SRC柱骨架曲线、滞回曲线、耗能能力和延性等抗震性能指标的影响,并分析了钢骨、钢筋和混凝土相互作用的机理。研究表明：①构件承载能力和耗能能力随钢骨截面延展性系数D提高而线性增加;②承载能力、耗能能力、延性和卸载刚度均随钢骨截面模量因子α的增大而显著增大;承载能力随约束混凝土因子β线性增加,但β对滞回曲线和变形能力的影响很小;③在加载后期,钢骨翼缘的局部屈曲和混凝土压溃退出工作是导致承载力下降的主要原因;构件的后期承载力、延性和耗能主要依赖于钢骨的贡献。 关键词：     

型钢混凝土异形柱轴压力系数限值的试验与理论分析

根据17个型钢混凝土(SRC)异形柱试件在低周反复水平力作用下的试验结果,采用大小偏压界限破坏理论和叠加法理论计算了SRC异形柱的轴压力系数限值,并与试验结果进行比较,结果表明:采用大小偏压界限破坏理论的计算结果与实际不符,计算SRC异形柱的轴压力系数限值存在缺陷;而采用叠加法理论的计算结果与试验结果吻合较好,并给出了SRC异形柱的轴压力系数限值。通过对比SRC异形柱的轴压力系数限值和RC异形柱的轴压比限值表明:与RC异形柱相比,SRC异形柱所能承受的轴压力限值明显提高,可有效改善普通RC异形柱因轴压比限值过低而影响其适用范围。     

一种新型混凝土异形柱--型钢混凝土异形柱的概念体系初探

针对型钢混凝土异形柱体系特点,对相关问题进行了评述,分析其特点及具有的优越性和应用前景,并提出了若干需要研究解决的问题.     

钢骨混凝土柱基于ABAQUS的力学性能分析

有限元分析可以作为试验的补充手段,模拟型钢混凝土构件的整个受力和变形过程。为了探讨轴压比和钢骨率的变化对SRC柱的延性和承载力的影响,利用有限元分析软件ABAQUS对型钢混凝土(SRC)柱的受力性能进行了非线性数值分析。为验证分析模型的合理性,首先利用已有的试验数据,建立试件的有限元模型,对试验全过程进行非线性数值模拟,通过对比荷载-位移曲线,验证有限元分析的有效性和准确性。通过建立具有不同轴压比和钢骨率的两组模型,分析了轴压比和钢骨率对构件力学性能的影响,为工程应用提供参考依据。     

型钢混凝土异形柱受剪机理及承载力计算

为研究型钢混凝土(SRC)异形柱的抗震性能,对17个型钢混凝土异形柱试件采用"建研式"加载装置进行低周反复荷载试验,观察了不同配钢形式的SRC异形柱的受力过程和破坏形态。试验表明SRC异形柱的破坏形态有剪切斜压破坏、剪切粘结破坏、剪弯破坏和弯曲破坏;分析了SRC异形柱的破坏机理和特点,给出了荷载-位移滞回曲线和荷载-应变滞回曲线;分别推导了各种配钢形式的SRC异形柱在正向荷载(沿工程轴)以及斜向荷载作用下发生剪切斜压破坏和剪切粘结破坏时的受剪承载力计算公式,计算结果与试验实测值吻合较好。理论分析和试验结果表明:异形柱中的翼缘对构件的抗剪强度有提高作用,提高的程度与荷载作用方向和柱的肢长肢厚比有关,但在肢长肢厚比一定的前提下与肢厚的改变无关。T、L形截面柱的斜向抗剪强度大于正向加载抗剪强度,而十字形截面柱的斜向抗剪强度小于正向加载抗剪强度。     

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.     

Numerical simulation of concrete filled steel tube columns against BLAST loads

Concrete filled steel tubes (CFST) have been widely used in constructing high-rise buildings, arch bridges and factories for the past few decades. In this research, numerical studies were carried out to investigate the flexural behaviour of CFST columns under both static and dynamic loads. The numerical models were calibrated and validated against a number of experimental data where the proposed models showed very good agreement with the test results. The results indicated that CFST columns showed good resistance against flexural loads under both static and dynamic loading conditions and therefore it has the potential to be widely used in these areas where potential blast attacks or frequent earthquakes are expected. The verified numerical model can also be extended to predict performances of concrete-infilled steel tubes under different loading conditions.     

双向偏压钢骨混凝土T形柱的试验研究

为了了解钢骨混凝土T形柱的双向偏心受压下的力学性能,制作了6根含钢骨率不同的钢骨混凝土T形柱的双向大偏心及双向小偏心受压的试件。在试验过程中,观察了试验现象,分析了试验数据,得出了相应关系的曲线,并对各种曲线进行了详细的分析,从而了解异形柱的受力性能及破坏机理。通过试验,明确了钢骨混凝土异形柱承载力的破坏特征、影响因素,含钢率越大,构件的承载能力提高越明显、延性越好。钢骨与混凝土之间可以很好地共同工作,直至破坏。     

新型截面型钢混凝土柱抗震性能试验研究

提出配置扩大十字型钢和45°布置十字型钢两种截面形式的新型型钢混凝土柱,通过4个新型与1个普通型钢混凝土柱的低周反复荷载试验,研究新型截面型钢混凝土柱在较高轴压比下的破坏特征、滞回和骨架特性,并分析配钢形式和轴压比对柱抗震性能的影响。试验结果表明：新型截面型钢混凝土柱在压、弯、剪共同作用下均发生了弯曲破坏,在加载后期,即使纵筋外鼓屈服以及型钢翼缘局部屈曲,柱的竖向承载力仍较为稳定;新型截面型钢混凝土柱试件滞回曲线饱满,无捏缩现象,等效黏滞阻尼系数均达到0.45以上,并且截面配钢率相差不大的情况下,其变形和耗能能力明显大于普通型钢混凝土柱;新型截面型钢混凝土柱在高轴力下的承载能力和变形性能良好,其轴压比限值可比规范规定有所提高。     

翼缘削弱的型钢混凝土框架抗震性能研究

为了研究翼缘削弱的型钢混凝土框架的抗震性能,对一榀两跨三层型钢混凝土框架模型进行了低周反复荷载试验。框架模型按"强柱弱梁"原则设计,且对节点核心区附近梁端工字形型钢的上、下翼缘采取狗骨式削弱,并适当增加最大削弱部位纵向钢筋的配筋率。通过对框架模型顶层施加低周反复水平荷载,观察了框架模型的破坏过程,测得框架模型的荷载-位移滞回曲线和骨架曲线以及各阶段的荷载和位移值,并分析了框架模型的延性、耗能、强度降低、刚度退化以及破坏机制。试验结果表明:框架模型的承载能力、变形能力和耗能能力高,延性大(延性系数大于7),满足延性框架的抗震要求。进一步分析了翼缘削弱在型钢混凝土框架中的具体作用。分析结果表明:翼缘削弱不仅能将塑性铰从梁端根部转移到翼缘削弱部位,从而降低节点核心区所受的剪力以及梁柱连接焊缝的应力,而且有利于框架形成梁铰耗能机构,从而提高框架的整体耗能能力。翼缘削弱能有效提高型钢混凝土框架的抗震性能,可在型钢混凝土     

低周反复荷载作用下型钢混凝土异形柱的抗剪承载力分析

从剪应力分布入手,分析型钢混凝土(SRC)异形柱中翼缘对抗剪承载力的影响,得出翼缘对抗剪强度的提高系数。根据试验得到的各构件的破坏形态和破坏机理,分别推导各种配钢形式的SRC异形柱在正向荷载(沿工程轴)以及斜向荷载作用下剪切斜压和剪切黏结破坏的抗剪承载力计算公式,计算结果与试验实测值均吻合较好。理论分析和试验结果表明:T、L形柱的斜向抗剪强度大于正向,而十形柱的斜向抗剪强度小于正向。研究结果可供工程设计参考。     

型钢混凝土异形柱空间框架地震响应试验研究

为研究型钢混凝土异形柱空间框架的地震响应,首次对缩尺比为1/4的三榀两跨五层框架模型进行地震模拟振动台试验,输入El Centro波、Taft波和兰州波,分析模型的动力特性、应变响应、加速度响应、位移响应、基底剪力和滞回性能。结果表明：强震作用下,型钢混凝土异形柱框架形成典型的梁铰破坏机制,满足“强柱弱梁”的抗震设计要求|随着输入地震波加速度峰值的增大,结构累积损伤逐渐增加,自振频率逐渐降低,阻尼比增大,加速度和位移响应峰值出现时刻向后推迟;结构在进入塑性阶段的过程中发生扭转变形|基底剪力呈现出先快后慢的增长趋势|滞回曲线饱满,表现出良好的耗能能力。型钢混凝土异形柱框架能够满足强柱弱梁和大震不倒的抗震设防要求。     

钢骨高强混凝土框架柱开裂荷载的试验研究

在11根钢骨高强混凝土框架柱的单调，低周反复加载试验基础上，通过理论分析和相关试验数据的回归，考虑了钢骨高强混凝土框架柱与钢骨混凝土框架柱开裂荷载计算的区别，并给出了计算公式。