利用砂浆填充FRP管对受压钢构件进行加固

介绍提高受压钢构件抗弯性能的加固方法,砂浆填充FRP管套在钢构件外侧,管端采用FRP织物包裹。对18个双向轴对称截面试件进行三轴压缩试验,得到试件的荷载-应变曲线和失效模式,证实其承载能力和延性得到了提高。对试件钢骨截面、长细比及端部包裹FRP织物层的影响进行了研究。结果表明,加固后,失效模式从由于整体屈曲引起的钢构件中部屈服转变为钢构件端部的局部损伤;因此,试件的承载能力提高了44%～215%,延性增加高达877%。细分模型用于加固构件的计算,由此计算出的承载能力与试验结果相符。     

高轴压比下中高剪跨比双钢板-混凝土组合剪力墙抗震性能试验研究

通过对4片高轴压比、中高剪跨比双钢板-混凝土组合剪力墙的拟静力试验,研究该类组合剪力墙在低周往复水平荷载作用下的受力性能和破坏模式,分析其延性、刚度、承载力、耗能等性能指标,以及剪跨比、轴压比、距厚比（栓钉间距与钢板厚度之比）等因素对其抗震性能的影响。试验结果表明：中高剪跨比试件的破坏模式为压弯破坏;墙体钢板随距厚比的增加更易发生局部屈曲;试件轴压比越大,压屈越明显、屈曲范围越接近试件底部、屈曲发展越迅速;试件刚度和极限荷载受轴压比、距厚比的影响较小,但变形能力随轴压比的增大而降低;试件剪跨比越大、轴压比越小,滞回性能越稳定;试件耗能随变形增大而迅速增长,抗震性能良好。     

轴压比与剪跨比对带约束拉杆双层钢板-混凝土组合剪力墙抗震性能影响研究

为研究轴压比与剪跨比对带约束拉杆双层钢板-混凝土组合剪力墙抗震性能的影响,完成了5个缩尺模型试件的拟静力试验。研究结果表明：试件破坏时底部墙体钢板均受压屈曲,其中低剪跨比（剪跨比为1.0）试件出现典型的剪压破坏现象,而中高剪跨比（剪跨比为1.5~2.0）试件出现典型的压弯破坏现象;高轴压比、低剪跨比的带约束拉杆双层钢板-混凝土组合剪力墙仍具有良好的承载力、变形及耗能能力;增大轴压比可提高试件的承载力,但其变形和滞回性能有所降低;减小剪跨比,试件的承载力和刚度有较大幅度提高,耗能能力有所下降,而延性和承载力退化变化不明显。     

设分配梁与内环板传力构造的巨型钢管混凝土柱抗震性能试验研究

针对7个按1∶5缩尺的设置分配梁加内环板传力构造的巨型钢管混凝土柱试件进行拟静力试验研究,考察了轴压比、长细比、管壁宽厚比及纵向T形加劲肋等因素对此类构件抗震新能的影响。研究结果表明,管壁宽厚比大于60的试件,在达到极限荷载之前（约为极限荷载的63%）发生管壁局部屈曲,延性较差;设置T形加劲肋可有效减小管壁宽厚比,提高管壁局部屈曲强度,改善试件的延性性能及耗能能力;试件位移延性系数随轴压比和试件长细比的增大而降低,刚度退化越明显;在低周反复荷载作用下,同时设置分配梁与内环板传力构造的钢管混凝土柱试件破坏时的位移角超过了规范规定的弹塑性层间位移角限值,满足抗震设计要求,且钢管与核心混凝土变形协调,相应的截面属性和压弯承载力可按平截面假定计算。     

反复荷载作用下L形钢管混凝土柱滞回性能研究

本文介绍了7根L形钢管混凝土柱试件在承受常轴力和水平荷载作用下的试验研究.试验中考虑了不同的轴压比、内部有无加劲和加载方式对试件抗震性能的影响.试验结果表明.内部加劲能够明显地延缓柱子钢板的屈服,而且柱子的耗能能力和延性也有较好的改善.最后通过编写计算程序,对L形钢管混凝土柱的荷载-变形进行了全过程分析.考察了常用的方钢管混凝土柱的钢材和混凝土的本构关系对L形钢管混凝土柱纤维模型数值分析的适用性,计算得到的弯矩一轴力一曲率关系和荷载一位移关系与试验结果吻合较好.     

带约束拉杆双层钢板内填混凝土组合剪力墙抗震性能试验研究

提出一种带约束拉杆双层钢板内填混凝土组合剪力墙,通过对6个剪跨比为2.0、轴压比为0.6的此类剪力墙试件的低周往复加载试验,研究试件的破坏形态、滞回曲线、骨架曲线、承载力退化、刚度退化、位移延性系数和耗能等抗震性能。结果表明：带约束拉杆双层钢板内填混凝土组合剪力墙抗震性能良好,6个试件的屈服位移角平均值为1/147,极限位移角平均值为1/48,位移延性系数平均值为3.57;减小约束拉杆间距和采用梅花式布置约束拉杆的方式,能更好地对钢板和混凝土提供约束,延缓钢板局部屈曲,增大混凝土的极限变形能力,提高剪力墙承载力、延性和耗能能力,减缓承载力退化和刚度退化,改善剪力墙抗震性能。     

T形、L形钢管混凝土柱抗震性能试验研究

本文对6根T形6、根L形钢管混凝土柱进行低周反复荷载试验研究,对试件破坏过程及结果进行了较为详细的描述,给出了荷载-位移曲线及骨架曲线。在此基础上,考虑了轴压比、钢管壁厚、内填混凝土强度对T形、L形钢管混凝土柱承载力和延性的影响。得出如下结论:随着轴压比增加,极限荷载提高不显著或下降,延性随着轴压比增加而下降;极限荷载和延性随着钢管壁厚加大而提高;混凝土强度提高对极限荷载增加很显著,但对延性影响不显著。     

壁式钢管混凝土柱抗震性能试验研究

通过3个截面高宽比为3.0的壁式钢管混凝土柱足尺试件在高轴压比下的低周反复加载试验和有限元分析,研究壁式钢管混凝土柱的破坏模式、滞回行为、承载能力、变形性能和能量耗散能力。结果表明：试件的破坏模式为压弯破坏,破坏区域钢板受压鼓曲、钢管纵向焊缝涨裂、混凝土压溃;试件滞回曲线稳定饱满,无明显捏拢现象;纵向隔板能够约束钢管壁板平面外变形,提高钢板局部屈曲强度;试件破坏时位移延性系数大于3.0,等效黏滞阻尼系数大于0.4,减小钢管壁板宽厚比可有效增加试件耗能能力。设计轴压比为0.54～0.69时,壁式钢管混凝土柱屈服位移角大于0.005rad,极限位移角大于0.02rad,具有良好的变形性能和耗能能力。建立的精细有限元模型可准确预测壁式钢管混凝土柱在恒定轴力和反复水平力下的滞回行为。有限元分析表明,轴压比对壁式钢管混凝土柱的极限位移影响显著,提高含钢率可有效增加其承载力和变形性能。     

带方钢管混凝土端柱隔板连接双钢板-混凝土组合剪力墙抗震性能试验研究

对5个带CFST端柱的隔板连接的双钢板-混凝土组合剪力墙进行了恒定轴压条件下的侧向循环加载试验,考虑了截面高厚比(6.0和8.0)、端柱形式、设计轴压比(0.45和0.60)、剪跨比(1.5和2.0)等参数,研究了该类组合剪力墙延性、承载力、刚度和承载力退化、耗能能力、截面弯矩-曲率关系、剪力-剪切角关系以及腹侧腔室钢板等效应变的变化规律等。研究结果表明：组合剪力墙发生了典型的压-弯破坏;墙体受力过程中经历了钢板的屈服和屈曲及混凝土的压溃等破坏;墙体的滞回曲线饱满;墙体的极限侧移角介于2.3%~4.5%之间,位移延性系数介于3.05~4.45之间,具有良好的变形能力;增加截面高厚比,加强端柱构造,减小剪跨比,墙体的承载力和延性均得到提高;轴压比增大对墙体的承载力和延性有不利影响;组合剪力墙受力过程中的剪切变形呈非线性变化的特点,不应忽略;组合剪力墙的变形未局限于墙体固定端以上的有限范围内,而是在墙体高度方向有较为充分的发展,这是墙体变形能力较好的原因之一。     

轴向循环荷载作用下有矩形缺陷钢管的应变棘轮:数值模型

轴向循环荷载作用下,钢管易产生局部屈曲、起皱及塑性应变。由于反复的开启/关闭和温度变化,海底管道处于加载和卸载循环中。在工作中,由于受腐蚀,壁厚变薄,钢管通常发生材料损伤。建立数值模型,模拟循环荷载作用下有矩形缺陷钢管的棘轮性能。钢管首先受单轴轴向压缩,小幅起皱,随后施加持续轴向循环荷载。采用非线性各向同性/随动(混合)硬化模型,模型各参数通过小型试件的滞回试验获得。钢管棘轮性能的数值结果与试验数据基本吻合。相比于动力性能,表面缺陷对有缺陷钢管的棘轮性能影响更大。基于本模型,还可研究初始应变、应力振幅、加载制度、壁厚和材料硬化属性等因素对有矩形缺陷钢管的棘轮性能和连续塑性屈曲性能的影响。     

Strain ratcheting of steel tubulars with a rectangular defect under axial cycling: A numerical modeling

Cyclic axial loads in tubular steel sections might lead to local buckling, wrinkling and accumulation of plastic strains in the tube. For example, this can be caused by repetitive start-up/shutdown and temperature changes in an offshore pipeline which generates cycles of axial compression/relaxing in the line. During their life time steel tubes may also experience material loss due to corrosion or wall thinning.The current paper reports the result of a numerical modeling of ratcheting behavior of steel tubes with a rectangular defect under cyclic axial loadings. The tubes have been initially subjected to monotonic axial compression beyond initiation of small amplitude wrinkles and subsequently to persistent axial cyclic loads. A nonlinear isotropic/kinematic (combined) hardening model has been adopted for the material, which its parameters have been obtained from cyclic tests conducted on small coupon specimens. The results of the numerical simulation have been compared with experimental data. In general, a reasonable agreement has been noticed between the experimental and the numerical results for the ratcheting behavior of the tubes. It is shown that surface imperfections have a very pronounced effect on the ratcheting response of the defected tubes, as compared to the monotonic responses. The model has also been used to study effects of some key factors such as the initial strain level, the stress amplitude, the mean stress, the loading regime, wall thinning and the material hardening properties on the ratcheting response and on the progressive plastic buckling of steel tubes with a rectangular defect.     

Experimental study on seismic performance of steel‐reinforced recycled concrete frame with infill wall

In order to investigate the seismic performance of steel‐reinforced recycled concrete (SRRC) frame with infill wall, low cyclic loading tests on four frames with infill wall and one frame without infill wall were conducted. The failure modes, hysteresis loops, skeleton curves, bearing capacity, ductility, stiffness degradation, and energy dissipation capacity of specimens were analyzed. The seismic performance of SRRC frames with and without infill wall was compared. The influence of the aspect ratio of infill wall, the axial compression ratio of column, and the distance of horizontal reinforcements of infill wall were investigated. Test results show that compared to the SRRC frame without infill wall, the SRRC frame with infill wall had higher bearing capacity and initial stiffness, but faster stiffness degradation and worse energy dissipation capacity. With the increase of aspect ratio of infill wall and axial compression ratio of column, the bearing capacity and initial stiffness of SRRC frame with infill wall increased, whereas the ductility decreased. With the decrease of distance of horizontal reinforcements of infill wall, the initial stiffness and energy dissipation capacity of SRRC frame with infill wall increased. After the infill wall fails under earthquake, the remaining SRRC frame has good seismic performance.     

Experimental evaluation of cyclic behavior of batten columns

An experimental study was performed for batten columns subjected to combination of constant axial compression and reversed cyclic lateral loads to evaluate their cyclic response, available ductility and post failure behavior under seismic conditions. To determine and evaluate the available ductility of batten columns, the backbone curves have been developed using experimental hysteresis curves of columns. The effect of different parameters such as axial compression, distance between battens and distance between chords on the available ductility of batten columns have further been studied. The results reveal that the available ductility of batten columns is considerably low compared with solid web columns. The failure mode of batten columns is the combination of local and overall buckling of their bottom chords. The geometrical specifications of batten columns have no considerable and uniform effect on their available ductility. Moreover, it is shown that the backbone curves of batten columns are basically different from solid web columns.     

四肢拼合冷弯薄壁型钢截面立柱轴压性能试验研究及数值分析

对不同长细比的8根四肢拼合冷弯薄壁型钢截面立柱的轴压性能进行试验研究,在试验研究的基础上建立考虑材料、几何和接触非线性的有限元模型,并通过对试验试件的数值模拟,验证有限元方法的正确性。采用数值方法分析长细比、连接螺钉间距、截面翼缘宽厚比对四肢拼合冷弯薄壁型钢截面立柱轴压性能的影响。结果表明:试件最终破坏均呈现局部屈曲和畸变屈曲的破坏模式;四肢拼合冷弯薄壁型钢截面立柱的轴压性能具有"1×4≥4"的拼合效应;随着长细比的增大,四肢拼合立柱的最大承载力和刚度逐渐降低;当螺钉间距在150～450mm之间变化时,四肢拼合立柱的最大承载力和刚度变化不大;减小四肢拼合立柱截面的翼缘宽厚比,可以显著提高其最大承载力。     

双锥型压弯(扭)圆钢管的试验研究

双锥型变截面类构件在压弯(扭)复合荷载作用下,受力情况复杂,目前规范尚未给出一套完整的强度、稳定计算公式。本文通过双锥型圆钢管的压弯(扭)载荷试验,对该类型构件在复合荷载作用下的承载能力、破坏模态、位移-荷载曲线及应变-荷载曲线进行了分析比较。试验分析表明:试件的破坏模态表现为结构的局部屈曲,提供一个较小的坡度,便能使塑性区发生内移,以获得更大的延性;双锥型构件比等截面构件具备更好的受力性能,其承载能力的提高与锥体坡度直接相关,对于塑性铰位于交界面处的构件,其承载能力的提高可达40%左右。     

高强冷弯型钢骨架墙体抗剪性能试验研究

对550MPaC型冷弯型钢立柱、550MPa带肋钢板和石膏板组成的高强冷弯型钢骨架墙体进行了16块足尺试件(宽2.4m,高3m)的抗剪试验研究。对带肋钢板+石膏板双面板、单面带肋钢板、单面石膏板和双面无板带交叉扁钢拉条支撑4类墙体试件进行了无竖向力水平单调加载、无竖向力水平低周反复加载和有竖向力水平低周反复加载的试验,得到了各类墙体试件的受剪承载力指标和位移延性系数μ等性能指标。试验结果表明:各类墙体单调加载试件抗剪强度均比反复加载试件高;单面石膏板墙体试件与0.8倍的单面带肋钢板墙体试件的承载力指标之和与双面板墙体试件承载力指标接近;双面无板带交叉扁钢拉条支撑墙体试件抗剪强度是双面板墙体试件的60%~67%;双面板墙体试件延性系数在1.731~2.384之间。     

Cyclic axial response and energy dissipation of cold-formed steel framing members

This paper summarizes results from an experimental program that investigated the cyclic axial behavior and energy dissipation of cold-formed steel C—sections structural framing members. Fully characterized cyclic axial load–deformation response of individual members is necessary to facilitate performance-based design of cold-formed steel building systems. Specimen cross-section dimensions and lengths were selected to isolate specific buckling modes (i.e., local, distortional or global buckling). The cyclic loading protocol was adapted from FEMA 461 with target displacements based on elastic buckling properties. Cyclic response showed large post-buckling deformations, pinching, strength and stiffness degradation. Damage accumulated within one half-wave after buckling. The total hysteretic energy dissipated within the damaged half-wave decreased with increasing cross-section slenderness. More energy dissipation comes at the cost of less cumulative axial deformation before tensile rupture.     

箱板式钢结构住宅底部加强区组合加劲钢板墙抗震性能分析

箱板式钢结构是一种直接采用加肋钢板作为承重墙和楼板的箱式结构.为提高加劲钢板墙(SSPW)的抗震性能,在墙体外侧设置网格加劲板构成组合加劲钢板墙(CSPWs).进行了3个1/3缩尺比例的加劲钢板墙试件的拟静力试验,研究参数包括是否设置网格加劲板、网格加劲板与墙体钢板之间能否相对滑动.分析了加劲钢板墙试件的破坏过程、破坏...     

开孔钢板加劲的矩形钢管钢纤维高强混凝土柱轴压试验研究

为探明加劲肋类型、开孔钢板（PBL）开孔间距、钢纤维体积掺量、混凝土强度等级等对矩形钢管钢纤维高强混凝土（SFRHC）柱轴压破坏模式的影响规律,对10根柱进行了轴压性能试验,得到了其荷载-压缩变形曲线、位移延性系数、耗能指标和破坏模式。研究结果表明：与PBL加劲试件相比,钢板加劲试件和未加劲试件的位移延性系数分别降低11.9%和10.4%,耗能指标分别降低8.3%和5.6%, PBL加劲肋能有效加强钢管与核心混凝土的组合作用。掺入体积率为0.8%钢纤维的PBL加劲试件,其位移延性系数和耗能指标分别提高12.5%和42.3%,钢纤维体积率为0.8%~1.2%时,试件位移延性系数和耗能指标明显提高。加劲SFRHC柱为肋间管壁局部外鼓破坏,PBL加劲柱的破坏位置均位于PBL开孔处,未加劲SFRHC柱为管壁外鼓破坏,对应钢板屈曲处核心混凝土表现为压碎破坏,钢纤维被整体拔出;加劲SFRHC柱沿高度方向破坏位置明显下移,钢板加劲肋和PBL加劲肋均能有效分担轴向荷载。     

HRB600级钢筋高强混凝土柱抗震性能试验研究

为研究HRB600级钢筋高强混凝土柱的抗震性能,进行9根截面尺寸为600mm×600mm的高强混凝土柱在工程实际轴压比条件下的低周反复荷载试验,主要设计变化参数为钢筋等级、箍筋间距、混凝土强度和轴压比。对比分析各试件的破坏形态、滞回性能、承载力、延性、刚度退化和耗能能力,基于试验建立HRB600级钢筋高强混凝土柱的恢复力模型。结果表明：各试件的破坏形态相似,均为延性弯曲破坏,柱底出现塑性铰,纵筋屈曲,混凝土保护层脱落;HRB600级钢筋高强混凝土柱不仅具有较好的滞回性能以及变形与耗能能力,且震后可恢复性能相对较好;高强混凝土柱设计中,HRB600级钢筋与C80混凝土匹配应用效果较优;合理配置箍筋,可使HRB600级钢筋高强混凝土柱在高轴压比条件下的延性系数大于4.0;文章基于足尺构件试验建立的恢复力模型,以期可为相关工程结构抗震弹塑性分析提供参考。