超高强混凝土短柱抗震性能的试验研究

通过对12根剪跨比λ=2．0的超高强混凝土短柱在低周反复荷载下抗震性能的试验研究,分析了其破坏形态,并研究了轴压比和配箍率对试件滞回特性和抗震延性的影响,提出了满足一定延性要求（μ△≥3．0）超高强混凝土短柱的轴压比限值和箍筋加密区的最小配箍特征值的建议值。该值可为现行规范的修订提供参考。     

型钢高强混凝土柱抗震性能的试验研究

通过14根型钢高强混凝土柱的低周反复加载试验，得到了型钢高强混凝土柱在压、弯、剪共同作用下的主要破坏形态，并探讨了剪跨比、配箍率、混凝土强度对型钢高强混凝土柱滞回曲线、耗能能力以及延性的影响。试验结果表明，型钢高强混凝土柱具有抵御二次地震作用的能力，其抗震性能优于钢筋混凝土柱。     

CRB600H级箍筋混凝土短柱抗震性能研究

为研究高强箍筋混凝土柱抗震性能,通过对CRB600H级高强箍筋混凝土短柱低周往复加载试验展开数值模拟研究。利用OpenSEES中的Nonlinear Beam Column单元、零长度截面转动弹簧单元和零长度剪切弹簧单元,建立了考虑弯-剪耦合效应的抗震数值分析模型。分析轴压比、剪跨比对CRB600H级箍筋柱的滞回性能、刚度退化、延性及耗能性能的影响,并以HRB400级箍筋柱进行对比分析,结果表明：轴压比越大的构件水平抗剪承载力,延性和耗能能力越差;剪跨比越大构件的水平抗剪承载力越低,延性和耗能能力越好;CRB600H级和HRB400级箍筋柱,两者承载力接近,CRB600H级箍筋柱延性和抗震性能更好。     

地震作用下高强混凝土柱延性计算方法研究

阐述了延性的定义及其对于结构和构件的重要性与作用,并指出了当前延性计算方法存在的缺陷。收集了国内63个高强混凝土柱的试验数据,逐次分析了轴压比、配箍特征值、纵筋配筋率、保护层厚度、剪跨比与延性指标的关系。研究表明,配箍特征值与延性的关系呈现出线性相关性,并建立了它们之间的关系式。通过10个高强混凝土柱试验数据证明,该表达式计算方便且计算结果比较准确,相对误差在15%之内。     

高强混凝土框架柱的地震损伤模型

本文首先讨论了现有的几种地震损伤模型及其特点,然后计算出试验框架柱累积滞回耗能随加载循环水平的变化,分析和讨论了轴压比、箍筋形式、配箍率、纵向配筋率、混凝土强度等级以及剪跨比对累积滞回耗能的影响。根据现有的损伤模型,对试验框架柱的损伤指数进行了分析比较,给出了符合高强混凝土框架柱和普通混凝土框架柱的地震损伤模型。根据损伤指数随加载循环水平的变化规律,分析和讨论了剪跨比、轴压比以及配箍率对损伤的影响。最后通过对各地震损伤模型的比较分析,提出了高强混凝土框架柱的地震损伤模型。     

型钢混凝土异形柱的轴压比限值研究

利用有限元数值积分法编写了型钢混凝土(SSC)异形柱轴压比限值的计算机程序,利用该程序可以计算任意荷载角、任意配钢形式的SSC异形柱的轴压比限值.对不同配钢形式、不同配钢率、不同截面尺寸、不同混凝土强度等级、不同荷载角作用下的SSC异形柱的轴压比限值进行深入分析.得出了以下主要结论:荷载角、配钢形式、截面尺寸对轴压比限值有明显影响;合理配钢的SSC异形柱的轴压比限值比钢筋混凝土(RC)异形柱有所提高;箍筋约束混凝土作用对轴压比限值有明显提高.     

核心型钢混凝土柱的轴压比限值试验研究

基于界限破坏时的内力平衡条件,推导了核心型钢混凝土柱轴压比限值的理论计算公式,计算分析了配钢率、混凝土强度等级、柱截面尺寸等因素对核心型钢混凝土柱轴压比限值的影响。进行了5个1/2比例模型柱试件的低周反复加载试验,验证了配置核心型钢对提高混凝土柱的抗震性能和轴压比限值的有效性。计算和试验结果表明,在混凝土柱中配置一定数量的核心型钢,可以有效提高轴压比限值。本文建议的方法可以较为合理地确定核心型钢混凝土柱的轴压比限值,供工程实践参考。     

反复荷载下型钢混凝土柱受扭损伤试验研究

为研究型钢混凝土柱在反复荷载下的受扭损伤,完成了11根型钢混凝土柱和1根钢筋混凝土柱复合受扭试验。通过试验观察了构件的受力过程和破坏特征,研究两种不同型钢混凝土柱的裂缝开展与分布规律。基于能量守恒定律,考察了柱截面配钢形式、扭弯比、轴压比、混凝土强度等级、配箍率以及配钢率对累积损伤的影响。研究结果表明:型钢混凝土柱的损伤演变分为3个阶段:弹性阶段、弹塑性阶段和破坏阶段;配钢形式、扭弯比和配箍率是影响型钢混凝土柱损伤程度的重要因素;配型钢,降低扭弯比和提高配箍率对于损伤指标分别最大降低了22.1%、14.3%和14.0%;损伤指标受轴压比、配钢率和混凝土强度等级影响程度较小。     

带暗柱混凝土等肢十字形柱轴压比限值调整系数研究

许多研究已表明异形柱设置暗柱后能有效提高截面延性,但目前为止对带暗柱异形柱轴压比限值的研究尚为空白,从而影响了带暗柱异形柱的工程应用.针对工程中应用十分广泛的十字形异形柱,采用全过程非线性分析方法,在C++平台上编制程序,计算了不同抗震等级、不同肢长下的带暗柱与不带暗柱钢筋混凝土等肢十字形柱,在不同纵向受力钢筋配筋率与体积配箍率下的截面曲率延性比;并根据<混凝土异形柱结构技术规程>JGJ149-2006给出的不同抗震等级下的异形柱截面曲率延性比的要求,确定出带暗柱与不带暗柱的等肢十字形柱的轴压比限值,进而求出同一肢长下的带暗柱与不带暗柱的轴压比限值的比值;最后通过回归分析方法得到带暗柱等肢十字形柱轴压比限值的调整系数的2种确定方法.在实际应用中可根据<混凝土异形柱结构技术规程>中规定的不带暗柱十字形柱的轴压比限值,利用该调整系数求出带暗柱的等肢十字形柱的轴压比限值.     

T形配钢钢骨混凝土柱抗震性能数值分析

为研究非对称配钢钢骨混凝土柱的抗震性能,基于12根T形配钢钢骨混凝土柱的拟静力试验研究进行非线性数值模拟,了解其破坏机制、承载力、延性及耗能能力,探讨轴压比、配钢率、剪跨比对抗震性能的影响。结果表明,低周反复荷载作用下T形配钢钢骨混凝土柱滞回曲线饱满,具有良好的延性和耗能能力。在峰值荷载前,数值模拟结果与试验结果吻合较好。轴压力在一定范围内提高了试件承载力,但降低了延性;增大配钢率能提高试件的承载力、刚度和延性,使得峰值荷载后试件的性能退化趋于平缓;剪跨比对试件破坏形态有显著影响,随剪跨比的增大试件延性性能提高。     

Seismic performance of steel reinforced ultra high-strength concrete composite frame joints

To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirrup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.     

高强钢筋混凝土短肢剪力墙抗震性能试验研究

通过对采用高强钢筋的6片T形混凝土短肢剪力墙和采用高强钢筋高强混凝土的6片L形短肢剪力墙进行低周往复加载试验,研究了T形和L形的破坏形态与性能差异,分析了高厚比、轴压比、配箍间距等参数对构件破坏形态、滞回耗能、骨架曲线、延性及耗能等抗震性能的影响,对比分析了构件与普通短肢剪力墙的抗震性能差异。试验结果表明:采用腹板端部箍筋加密的方式可减轻构件端部的损伤和降低正负向加载时承载力和延性的不对称性;T形构件中高厚比为5的试件表现为弯曲破坏,其他构件表现为弯剪破坏;试验中高厚比小的构件相对于高厚比大的试件延性耗能更好,轴压比增大,构件承载力提高但延性降低;与普通短肢剪力墙相比,T形短肢剪力墙承载力和变形能力提高,耗能增加,L形短肢剪力墙承载力提高较大,极限位移增大,构件后期变形能力略有降低,但可以满足抗震性能要求。     

Hysteretic behavior of special shaped columns composed of steel and reinforced concrete (SRC)

This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped(SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine T-shaped SRC columns, four L-shaped SRC columns and four +-shaped SRC columns were tested to examine the effects of shape steel confi guration, loading angle, axial compressive ratio and shear-span ratio on the behavior(strength, stiffness, energy dissipation, ductility, etc.) of SRCSS column specimens. The failure modes and hysteretic performance of all the specimens were obtained in the tests. Test results demonstrate that the shear-span ratio is the main parameter affecting the failure modes of SRCSS columns. The specimens with small shear-span ratio are prone to shear failure, and the primary failure planes in SRCSS columns are parallel to the loading direction. As a result, there is a symmetry between positive and negative loading directions in the hysteretic curves of the SRCSS columns. The majority of displacement ductility coeffi cients for all the specimens are over 3.0, so that the SRCSS columns demonstrate a better deformation capacity. In addition, the equivalent viscous damping coeffi cients of all the specimens are greater than 0.2, indicating that the seismic behavior of SRCSS columns is adequate. Finally, the superposition theory was used to calculate the limits of axial compressive ratio for the specimens, and it is found that the test axial compressive ratio is close to or smaller than the calculated axial compressive ratio limit.     

Research on seismic behavior and shear strength of SRHC frame columns

The seismic behavior of steel reinforced high strength and high performance concrete(SRHC)frame columns was investigated through pseudo-static experiments of 16 frame columns with various shear span ratios,axial compression ratios,concrete strengths,steel ratios and stirrup ratios.Three kinds of failure mechanisms are presented and the characteristics of experimental hysteretic curves and skeleton curves with different design parameters are discussed.The columns’ductility and energy dissipation were quantitatively evaluated based on seismic resistance.The research results indicate that SRHC frame columns can withstand extreme bearing capacity,but the abilities of ductility and energy dissipation are inferior because of SRHC’s natural brittleness.As a result,the axial load ratio should be restricted and some construction measures adopted,such as increasing the stirrup ratio.This research established effect factors on the bearing capacity of SPHC columns.Finally,an algorithm for obtaining ultimate bearing capacity using the flexural failure mode is established based on a modified planesection assumption.The authors also established equations to determine shearing baroclinic failure and shear bond failure based on the accumulation of the axial load force distribution ratio.The calculated results of shear bearing capacity for different failure modes were in good agreement with the experimental results.     

高强钢筋增强UHPC-NC组合柱抗震性能研究

为探讨高强钢筋增强UHPC-NC组合柱抗震性能,基于大型有限元程序ABAQUS,结合UHPC、NC和高强钢筋材料本构关系,校准损伤塑性模型中相关参数,建立高强钢筋增强UHPC-NC组合柱抗震有限元模型。通过与3个NC柱和3个UHPC柱拟静力试验结果对比,验证分析模型的有效性。在此基础上,进一步探讨轴压比、纵筋直径、纵筋强度、箍筋间距和UHPC高度等敏感参数对高强钢筋增强UHPC-NC组合柱抗震性能的影响。结果表明,高强钢筋增强UHPC-NC组合柱位移延性系数随轴压比、纵筋直径和箍筋间距的增大而降低,随纵筋强度和UHPC高度的增加表现出先增大后逐渐平缓的趋势,合适的UHPC替换高度能充分发挥高强钢筋和UHPC材料特性并取得良好的经济性。     

Experimental investigation of damage behavior of RC frame members including non-seismically designed columns

Reinforced concrete (RC) frame structures are one of the mostly common used structural systems, and their seismic performance is largely determined by the performance of columns and beams. This paper describes horizontal cyclic loading tests often column and three beam specimens, some of which were designed according to the current seismic design code and others were designed according to the early non-seismic Chinese design code, aiming at reporting the behavior of the damaged or collapsed RC frame strctures observed during the Wenchuan earthquake. The effects of axial load ratio,shear span ratio, and transverse and longitudinal reinforcement ratio on hysteresis behavior, ductility and damage progress were incorporated in the experimental study. Test results indicate that the non-seismically designed columns show premature shear failure, and yield larger maximum residual crack widths and more concrete spalling than the seismically designed columns. In addition, longitudinal steel reinforcement rebars were severely buckled. The axial load ratio and shear span ratio proved to be the most important factors affecting the ductility, crack opening width and closing ability, while the longitudinal reinforcement ratio had only a minor effect on column ductility, but exhibited more influence on beam ductility. Finally, the transverse reinforcement ratio did not influence the maximum residual crack width and closing ability of the seismically designed columns.     

反复荷载作用下型钢混凝土L形柱的受力性能

为了揭示型钢混凝土L形柱在地震作用下的受力性能,设计8个试件进行低周反复加载试验.试验分两批,第一批4个试件采用"建研式"加载,另外4个采用"悬臂柱式"加载.试验中考虑截面配钢形式、荷载加载方向、轴压比和剪跨比4个参数的影响.由试验获得了型钢混凝土L形柱的主要破坏形态和滞回曲线,分析了各参数对构件的破坏特点及滞回性能的影响,并对不同加载方式的试验结果进行了理论诠释.结果表明:型钢混凝土L形柱的破坏形态主要为剪切斜压破坏、剪弯破坏和弯曲破坏,破坏形态与剪跨比有关;构件具有良好的延性,极限侧移角大,耗能能力强,抗震性能好;L形柱截面不对称,采用"悬臂柱式"加载时,滞回曲线不对称,而"建研式"加载时,由于受到加载装置上下端头的约束,试件的滞回曲线对称.在框架结构中型钢混凝土L形柱受到刚性楼盖的约束,在水平荷载作用下滞回曲线是对称的.研究结果可供工程设计参考.     

钢桁架(ST)约束混凝土组合柱抗震性能研究

目前,组合柱在建筑结构中进行了广泛应用和研究,研究表明:截面形式对组合柱的抗震性能有很大影响。首先,对钢桁架(ST)约束混凝土组合柱进行了试验研究。并在此基础上,利用有限元软件ABAQUS建立了数值分析模型;其次,基于数值分析模型,分析了组合柱中各部件的应力应变状态,分别考察了轴压比、缀板排列方式、体积配箍率、角钢肢宽与肢厚等因素对柱抗震性能的影响;最后,给出了组合柱在不同抗震等级下轴压比限值的建议值,可为后续组合柱的研究提供参考。研究表明:随着轴压比的增大,组合柱的延性变差,承载力先增大后减小;合理的缀板排列方式可有效抑制角钢的局部屈曲;随着体积配箍率的增大,组合柱的承载力有一定提升,延性提高较为显著;随着角钢肢宽和肢厚的增加,组合柱的承载力和延性均有显著提升。