应用OpenSees计算双钢管高强砼柱的水平力—位移滞回曲线

应用OpenSees计算外方内圆复合钢管高强混凝土柱（简称双钢管高强混凝土柱）的水平力—位移滞回曲线。分析了双钢管高强混凝土柱的单元和截面纤维划分。钢管材料采用双线性模型Steel02,混凝土模型采用Concrete02,圆钢管内和钢管之间的混凝土采用Susantha模型,考虑钢管对混凝土的约束作用,计算得到的水平力—位移滞回曲线与试验结果符合较好。在此基础上,应用OpenSees对双钢管高强混凝土柱进行参数影响分析,讨论了轴压比、方钢管壁厚（宽厚比）、径宽比、径厚比对双钢管高强混凝土柱抗震性能的影响。结果表明：增大轴压比,延性降低;增大方钢管壁厚（减小宽厚比）,水平承载力增大;增大圆钢管直径和壁厚,有助于提高双钢管高强混凝土柱的竖向和水平承载力能力,增大耗能能力。     

高强钢筋高强混凝土短肢剪力墙抗震性能试验研究与数值模拟分析

通过对6个L形和6个一字形高强钢筋高强混凝土短肢剪力墙进行拟静力试验和OpenSees有限元模拟相结合的方法,研究构件的抗震性能,得到试件的破坏形态及滞回曲线,骨架曲线,承载力等性能指标,并模拟分析了同高厚比下试件的轴压比依次从0.1增加到0.6,的抗震性能。结果表明:在低周往复荷载作用下试件主要为弯剪破坏;OpenSees能较好的模拟高强钢筋高强混凝土短肢剪力墙的弹塑性行为,试验结果与数值模拟结果吻合较好;采用高强钢筋高强混凝土使试件承载力显著提高,极限位移增大;承载力随轴压比提高,但高轴压比下腹板受压时易造成试件的迅速破坏,承载力迅速降低,提高配箍率使试件承载力提高,且能延缓试件端部损伤,提高试件后期的塑形变形能力。     

PVA-ECC加固桥墩抗震性能试验与数值研究

为了全面研究工程水泥基复合材料（ECC）加固桥墩的抗震性能,对采用聚乙烯醇纤维增强水泥基复合材料（PVA-ECC）加固的桥墩进行了拟静力试验。并基于有限元分析软件OpenSees建立了数值模型,通过对比数值模拟结果与试验结果,验证有限元分析的有效性,在此基础上对PVA-ECC加固桥墩进行数值参数分析,探讨轴压比、新旧材料厚径比及体积配箍率变化对桥墩抗震性能的影响规律。结果表明:数值模拟的滞回曲线与骨架曲线和试验基本吻合;与普通混凝土桥墩相比,新旧材料厚径比为0.10时,即可获得优异的延性性能,ECC加固的桥墩变形性能显著提升,极限位移提高,滞回曲线更加饱满,抗震性能更加优异。对于高轴压比情况,为了确保ECC加固桥墩的延性性能,应根据实际情况增加新旧材料厚径比;ECC材料可部分替代箍筋作用,适用于箍筋配置不足的桥墩加固,PVA-ECC具有较好的工程抗震加固的作用。     

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。     

应用OpenSees模拟钢管混凝土不等跨框架抗震性能

基于一榀方钢管混凝土柱-H型钢梁不等跨平面框架的抗震性能试验,应用OpenSees有限元软件,模拟了低周反复荷载作用下框架的荷载-位移曲线,并对其抗震性能影响参数进行分析。研究结果表明:OpenSees中塑性铰纤维单元模拟栓焊连接的H型钢梁具有合理性。混凝土强度对框架的抗震性能影响较小,提高钢材强度可以有效提升框架结构的承载力和延性,其中Q345具有较高的性价比。柱截面宽厚比越小,框架承载力越高。轴压比增大会对框架抗震性能产生不利影响,工程中应避免出现高轴压比。在钢管混凝土不等跨框架结构设计中,钢梁跨度要综合考虑梁截面抗弯能力和梁柱线刚度比,其变梁异型中节点宜选择合适的梁高比。     

型钢高强混凝土柱轴压比限值的试验研究

通过20个型钢高强混凝土柱的低周反复加载试验对其受力性能进行了研究，分析了剪跨比、轴压比、配箍率以及混凝土强度对型钢高强混凝土柱延性的影响，提出了不同剪跨比、不同配箍率的型钢高强混凝土柱的轴压比限值。其中，剪跨比大于2．0的型钢高强混凝土柱的轴压比限值由大、小偏心界限破坏时力的平衡条件并结合试验结果确定，而剪跨比小于2．0的型钢高强混凝土柱的轴压比限值则通过与剪跨比大于2．0的型钢高强混凝土柱的延性对比加以确定。     

FRP管约束活性粉末混凝土方柱抗震性能研究

为了探究纤维增强聚合物（fiber reinforced polymers,FRP）管约束活性粉末混凝土（reactive powder concrete,RPC）方柱在低周反复荷载作用下的抗震性能,利用有限元软件ABAQUS对FRP管约束RPC方柱进行了数值模拟,并对不同轴压比、配箍率和FRP管厚度条件下约束柱的抗震性能进行了分析。结果表明:采用有限元模型对FRP管约束RPC方柱进行模拟是可靠的,有限元模拟结果和试验结果吻合较好;轴压比为0.2~0.6时,峰值荷载随轴压比的增大而增大,轴压比为0.7时的峰值荷载较0.6时反而下降;配箍率、FRP管厚度的增加可以改善约束柱的抗震性能,延缓强度和刚度的退化;FRP管厚度为0.501mm时的约束效果最好。     

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。     

CFRP约束预压混凝土棱柱的轴压试验研究

通过42个混凝土棱柱体的轴压试验,研究了混凝土、CFRP约束混凝土和CFRP约束预压混凝土3种情况的棱柱体试件在轴压力作用下的应力-应变关系,与此同时还得出了混凝土方柱在预压后用CFRP加固再受荷时,试件的峰值应力随预加轴压比的增加的变化规律,并给出了考虑预加轴压比影响的峰值应力的计算公式,为在役混凝土结构构件的加固设计提供试验依据.     

高强高性能混凝土剪力墙的研究现状及展望

对国内外高强高性能混凝土剪力墙的研究现状进行了综述与分析,内容涉及高强高性能混凝土剪力墙的抗震性能试验、有限元分析理论、抗震设计方法和抗火研究等方面.重点阐述了轴压比、剪跨比、配筋率、混凝土强度等级等因素对高强高性能混凝土剪力墙力学性能的影响;同时,结合高强高性能混凝土剪力墙在实际工程中的应用情况,提出了一些亟待解决的问题.     

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.     

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.     

免拆超高性能混凝土模板钢筋混凝土柱抗震性能研究

为研究预制超高性能混凝土(UHPC)模板钢筋混凝土(RC)柱的抗震性能,并验证预制UHPC模板在往复荷载作用下是否发生剥离,考虑轴压比、剪跨比、箍筋间距和保护层厚度,设计制作6根免拆模板柱(PTC)和1根RC对比柱试件,对其进行拟静力试验,研究其破坏形态、滞回性能、变形和耗能能力以及强度和刚度退化规律等。结果表明,与加载方向垂直的预制UHPC模板大约在PTC试件峰值荷载的70%时发生剥离,与加载方向平行的预制UHPC模板在试件最终破坏时剥离;在剪跨比、轴压比和箍筋数量均分别相同的条件下,由UHPC模板加10 mm混凝土作为保护层的试件,其抗震性能相对较好,但其承载力和前期刚度略有减小。     

钢管高强混凝土叠合柱抗震性能与受力机理的试验研究

本文通过四个钢管高强混凝土又叠合柱与一个普通高强混凝土柱在周期往复荷载作用下抗震性能的试验研究。     

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。     

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.     

Prediction of the force–drift envelope for RC columns in flexure by the CAE method

A non‐parametric empirical approach, called the conditional average estimator (CAE) method, has been applied for the prediction of the normalized lateral force–drift envelope of reinforced concrete (RC) rectangular columns, as well as their characteristic drifts (effective yield drift, capping drift and ultimate drift), and drift‐related parameters (the ratio between the effective yield drift and elastic drift, and two ductility measures). A subset of the PEER RC column database was used. Five input parameters were employed: axial load index, index related to confinement, shear span index, concrete compressive strength, and longitudinal reinforcement index. The results suggest that the relations between the input and output parameters are complex, and that it is difficult to isolate the influence of a single parameter. Nevertheless, some trends were observed. The axial load index is the most influential input parameter. All the results decrease with an increasing axial load index, whereas they increase with an increasing longitudinal reinforcement index. An increase in the index related to confinement results in increases in the ultimate drift and in ductility. The influence of the shear span index is the most complex. The influence of the concrete strength is small with the exception of two output parameters related to elastic drift, which substantially decrease with increasing strength. The dispersion of the results is relatively large. The results of the predictions can be used for mathematical modelling of moment–rotation backbone curves for plastic hinges, and for the estimation of the deformation capacity of columns in seismic performance assessments. Copyright © 2007 John Wiley & Sons, Ltd.