带肋方钢管高强混凝土柱轴压性能试验研究

为研究加肋方钢管高强混凝土组合柱的轴压力学性能,以加劲肋刚度为变化参数,进行了7个带肋方钢管高强混凝土短柱试件轴压试验研究,对比分析了试件破坏特征、屈曲模态及应力应变规律。结果表明:设置加劲肋有效延缓了管壁屈曲,改变了管壁屈曲模态以及应力路径,加劲肋刚度对组合柱承载力影响不显著;随着加劲肋刚度增大,钢管环向与纵向应力比增大,钢管对核心混凝土约束作用增大,组合柱纵向刚度增大,钢管纵向屈服应力减小,钢管屈服发生在组合柱达到峰值荷载之后。     

带肋T形钢管混凝土短柱力学性能研究

对5个不同加肋方式和2个无肋的T形钢管混凝土轴压短柱试件进行了试验研究,考察了加肋形式对T形钢管混凝土短柱力学性能的影响。试验结果表明:设置加劲肋提高了T形钢管混凝土轴压刚度和轴压承载力;考虑施工难度、材料成本、承载力提高等因素,试件TR-2的加肋形式最优。采用有限元软件ABAQUS对试件的荷载-变形全过程曲线进行了计算,同时对钢管壁应力、钢管与核心混凝土之间相互作用力进行对比分析。结果表明:总体上计算结果与试验结果吻合较好,T形钢管混凝土设置加劲肋能有效延缓钢管壁向外的局部鼓曲,改善钢管壁的稳定性,所有试件在钢管角部的截面约束效应明显,而全贯通加肋试件在加肋处的截面约束效应也比较明显。     

带肋方钢管混凝土柱偏心受压力学性能研究

在方钢管混凝土管壁内设置纵向加劲肋可提高其管壁的稳定性。采用有限元软件ABAQUS对带肋方钢管混凝土柱偏心受压荷载-变形全过程关系进行计算,计算得到的破坏形态和荷载-变形关系曲线与试验结果符合较好。在此基础上,通过典型算例从变形情况、荷载-变形全过程曲线、核心混凝土的纵向应力分布以及钢管与混凝土相互作用四个方面对带肋方钢管混凝土的工作机理进行分析,并且与相应的无肋方钢管混凝土进行对比。研究结果表明:加劲肋的设置可以增加钢管约束支撑点,减小鼓曲的横向变形值,增强核心混凝土与管壁之间的相互作用,进而有效地延缓构件局部屈曲,改善管壁的稳定性,提高构件的极限荷载;纵向加劲肋宽度越大,构件极限荷载越高,后期延性越好;加劲肋宽度设置应控制在一定范围,能获得较好的综合经济效果。     

带肋薄壁方钢管混凝土轴压短柱受力性能试验研究

为研究带肋薄壁方钢管混凝土轴压短柱的受力性能,以钢管宽厚比、加劲肋宽度和加劲肋个数为参数,对26个薄壁方钢管混凝土短柱进行了试验研究。研究结果表明:对于无肋试件,在达到承载力以前管壁已经发生鼓曲,且试件宽厚比越大,鼓曲越早发生,鼓曲部位的钢管截面越早退出工作,没有发挥出钢管混凝土的优势。设置加劲肋后薄壁方钢管混凝土短柱的受力性能得到明显改善,钢管壁的局部鼓曲得以延缓,材料强度得到了充分利用,试件承载力提高。当试件宽厚比为60、80时,加劲肋宽度对试件承载力影响最明显,加劲肋宽度越大,承载力越高,增加加劲肋个数对试件承载力影响不大;而当试件宽厚比为100时,设置单个加劲肋已不能满足对管壁局部屈曲的抗弯刚度要求,必须增加加劲肋的个数以增加约束钢管变形的支撑点,减小管壁局部屈曲的波长,提高试件局部屈曲的临界荷载。同时利用ABAQUS有限元计算软件对薄壁带肋方钢管混凝土轴压短柱的受力全过程进行了模拟,并将试验结果与有限元模拟结果进行了对比,两者吻合良好,为下一步分析奠定基础。     

Experimental research on mechanical behavior of concrete-filled thin-walled stiffened square steel tubular short column under axial load

为研究带肋薄壁方钢管混凝土轴压短柱的受力性能,以钢管宽厚比、加劲肋宽度和加劲肋个数为参数,对26个薄壁方钢管混凝土短柱进行了试验研究。研究结果表明：对于无肋试件,在达到承载力以前管壁已经发生鼓曲,且试件宽厚比越大,鼓曲越早发生,鼓曲部位的钢管截面越早退出工作,没有发挥出钢管混凝土的优势。设置加劲肋后薄壁方钢管混凝土短柱的受力性能得到明显改善,钢管壁的局部鼓曲得以延缓,材料强度得到了充分利用,试件承载力提高。当试件宽厚比为60、80时,加劲肋宽度对试件承载力影响最明显,加劲肋宽度越大,承载力越高,增加加劲肋个数对试件承载力影响不大;而当试件宽厚比为100时,设置单个加劲肋已不能满足对管壁局部屈曲的抗弯刚度要求,必须增加加劲肋的个数以增加约束钢管变形的支撑点,减小管壁局部屈曲的波长,提高试件局部屈曲的临界荷载。同时利用ABAQUS有限元计算软件对薄壁带肋方钢管混凝土轴压短柱的受力全过程进行了模拟,并将试验结果与有限元模拟结果进行了对比,两者吻合良好,为下一步分析奠定基础。     

穿孔肋拉杆约束方钢管混凝土短柱轴压试验研究

为研究穿孔肋拉杆约束方钢管混凝土短柱的轴压性能,完成了穿孔肋拉杆约束方钢管混凝土短柱与仅设约束拉杆、仅设加劲肋、普通方钢管混凝土短柱对比试件的轴心受压试验;观察了试件的受力全过程和破环特征,分析了试件的荷载-位移曲线、荷载-应变曲线、轴压承载力、延性、含钢率等性能指标.结果 表明:穿孔肋拉杆的设置使钢管壁对核心混凝土的约束作用更趋均匀,改变了钢管的局部屈曲变形状态,显著提高了方钢管混凝土柱的轴压承载力和延性;当柱截面含钢率相同时,与仅设加劲肋的钢管混凝土柱相比,穿孔肋拉杆约束方钢管混凝土短柱的轴压承载力提高了7％,延性提高了30％;与仅设约束拉杆的方钢管混凝土柱相比,穿孔肋拉杆约束方钢管混凝土柱的轴压极限承载力提高了10％,延性提高了19％.     

带肋方钢管混凝土短柱性能研究

文章进行了1根无肋和5根带肋方钢管混凝土柱的轴压试验,通过改变试件的截面形式对试件的荷载-位移曲线、极限承载力等方面进行研究。结果表明,在含钢率不变的前提下,设置加劲肋的方钢管混凝土的极限承载力低于无肋方钢管混凝土,该试验设置的纵向加劲肋在一定范围内能够改善方钢管混凝土短柱的延性性能。     

带肋冷弯薄壁方钢管混凝土柱滞回性能研究

对3根带肋冷弯薄壁方钢管混凝土柱进行滞回试验,主要参数为轴压比。试验结果表明：纵向加劲肋有效延缓了钢管壁局部屈曲的发生;其滞回曲线饱满,具有良好的耗能能力;随着轴压比的增大,柱承载力略有增大,而延性、耗能能力则明显减小;当横向位移大于6倍的屈服位移时,大轴压比的刚度退化速度最快。建立了该类试件的有限元模型,对比可得有限元模拟结果与试验结果吻合较好。基于有限元模型对该类构件开展机理分析和参数分析。结果表明：在带肋冷弯薄壁方钢管的约束下,核心混凝土的强度得到了较大提高;钢管局部屈曲发生在峰值荷载后,局部屈曲只发生在纵向加劲肋和钢管角部间;材料强度、轴压比、钢管宽厚比和长细比等参数对该类构件的承载力有较大影响;混凝土强度、轴压比和长细比对荷载-位移骨架曲线形状有较大影响。基于参数分析建议了该类构件的简化滞回模型,简化计算结果和有限元计算结果吻合较好。     

薄壁方钢管混凝土短柱承载性能非线性有限元分析

采用ANSYS软件,对薄壁方钢管混凝土短柱的承栽性能进行非线性有限元分析.考虑轴压作用下带肋与不带肋两种截面形式的薄壁方钢管混凝土短柱力学性能,并得出其破坏模态,计算结果与试验结果吻合较好.针对该类构件,探讨加劲肋和钢管强度对其承载力的影响.结果表明,设置加劲肋能有效提高薄壁方钢管混凝土短柱的轴压承载力,与不带肋短拄相...     

开孔钢板加劲型方钢管混凝土轴压短柱试验研究

为研究开孔钢板加劲型方钢管混凝土短柱的破坏模式和承载力计算方法,以钢管宽厚比、加劲肋类型、开孔孔径、开孔孔距等为变化参数,设计了23个方钢管混凝土短柱试件,并对其进行轴压试验。对比分析各试件的破坏模式、承载力、加劲刚度及套箍效应等。结果表明:开孔钢板加劲型方钢管混凝土轴压短柱破坏模式取决于加劲刚度,完全加劲时,壁板横向鼓曲波长变短甚至出现"双波",纵向波长变短,波形增多;不完全加劲时,壁板横向呈"单波"鼓曲,与无肋钢管混凝土破坏模式相近。根据研究结果,提出了开孔钢板加劲型方钢管混凝土轴压承载力计算方法和完全加劲的最小加劲刚度计算式,计算结果与试验结果吻合较好。     

Experimental investigation on concrete-filled stainless steel stiffened tubular stub columns

This paper presents an experimental investigation on concrete-filled normal-strength stainless steel stiffened tubular stub columns using the austenitic stainless steel grade EN 1.4301 (304). The stiffened stainless steel tubes were fabricated by welding four lipped angles or two lipped channels at the lips. Therefore, the stiffeners were formed at the mid-depth of the sections. In total, five hollow columns and ten concrete-filled columns were tested. The longitudinal stiffener of the column plate was formed to avoid shrinkage of the concrete and to behave as a continuous connector between the concrete core and the stainless steel tube. The behavior of the columns was investigated using two different nominal concrete cubic strengths of 30 and 60 MPa. A series of tests was performed to investigate the effects of cross-section shape and concrete strength on the behavior and strength of concrete-filled stainless steel stiffened tubular stub columns. The measured average overall depth-to-width ratios (aspect ratio) varied from 1.0 to 1.8. The depth-to-plate thickness ratio of the tube sections varied from 60 to 90. Different lengths of columns were selected to fix the length-to-depth ratio to a constant value of 3. The concrete-filled stiffened stainless steel tubular columns were subjected to uniform axial compression over the concrete core and the stainless steel tube to force the entire section to undergo the same deformations by blocking action. The column strengths, load–axial strain relationships and failure modes of the columns are presented. Several comparisons were made to evaluate the test results. The results of the experimental study showed that the design rules, as specified in the European specifications and the ASCE, are highly conservative for square and rectangular cold-formed concrete-filled normal-strength stainless steel stiffened stub columns.     

Effect of reinforcement stiffeners on square concrete-filled steel tubular columns subjected to axial compressive load

Eight stiffened square concrete-filled steel tubular (CFST) stub columns with slender sections of encasing steel and two non-stiffened counterparts were tested subjected to axial compressive load. Four types of reinforcement stiffeners and steel tensile strips were introduced to postpone local buckling of steel tubes, in which the tensile strip was first used as stiffener in CFSTs. The stiffening mechanism, failure modes of concrete and steel tubes, strength and ductility of stiffened square CFSTs were also studied during the experimental research. A numerical modeling program was developed and verified against the experimental data. The program incorporates the effect of the stiffeners on postponing local buckling of the tube and the tube confinement on concrete core. Extensive parametric analysis was also conducted to examine the influencing parameters on mechanical properties of stiffened square CFSTs.     

Confinement effect of stiffened and unstiffened concrete-filled stainless steel tubular stub columns

This paper presents a comparative study between stiffened and unstiffened concrete-filled stainless steel hollow tubular stub columns using the austenitic stainless steel grade EN 1.4301 (304). Finite element analysis of concrete-filled stainless steel unstiffened tubular stub columns is constructed herein based on the confined concrete model recently available in the literature. It is then compared with the experimental results of concrete-filled stainless steel stiffened tubular stub columns. The stiffened stainless steel tubular sections were fabricated by welding four lipped angles or two lipped channels at the lips. The longitudinal stiffener of the column plate was formed to avoid shrinkage of the concrete and to act as a continuous connector between the concrete core and the stainless steel tube. The behavior of the columns was investigated using two different nominal concrete cubic strengths of 30 and 60 MPa. The overall depth-to-width ratios (aspect ratio) varied from 1.0 to 1.8. The depth-to-plate thickness ratio of the tube sections varied from 60 to 90. The stiffened and unstiffened concrete-filled stainless steel tube specimens were subjected to uniform axial compression over the concrete and stainless steel tube to force the entire section to undergo the same deformations by blocking action. The ABAQUS 6.6 program, as a finite element package, is used in the current work. The results of the comparative study showed that the stainless steel tubes in stiffened concrete-filled columns offered a high average of increase in the confinement of the concrete core than that of the unstiffened concrete-filled columns.     

Experimental behaviour of stiffened concrete-filled thin-walled hollow steel structural (HSS) stub columns

Test results on concrete-filled steel tubular stub columns with inner or outer welded longitudinal stiffeners under axial compression are presented in this paper. The research was mainly focused on square hollow section (SHS) columns; two rectangular hollow section (RHS) columns were also tested. A longitudinal stiffener was provided on each side of the stiffened SHS column, while only two stiffeners were welded to the longer sides of the stiffened RHS column. The main experimental parameters considered were the height-to-thickness ratio and stiffener rigidity. In addition, empty tubes with or without stiffeners, as well as unstiffened concrete-filled steel tubes were also tested for comparison. Requirements for stiffener rigidity are developed by modifying a formula presented in the literature. Existing theoretical model and design codes were used to predict the load versus axial strain relationships and load-carrying capacities of the adequately stiffened composite sections respectively; reasonable results were achieved.     

Finite element analysis on axial loading behavior of stub columns of square concrete-filled steel tube with diagonal ribs

为改善方钢管对核心混凝土的约束效应和薄壁钢管混凝土柱的受力性能,提出了带斜拉肋方钢管混凝土柱,其中斜拉肋通长并焊接于钢管两邻边的三分点处。基于有限元软件ABAQUS,对带斜拉肋的方钢管混凝土短柱的轴压受力性能进行了精细化模拟,分析了斜拉肋的设置与否、钢管宽厚比、混凝土强度、斜拉肋厚度、钢材强度、斜拉肋与钢管之间焊缝间隔长度及斜拉肋孔径、间距对轴压力学性能的影响。结果表明：设置斜拉肋可使方钢管混凝土短柱的轴压承载力平均提高14.9%左右,并使方钢管对核心混凝土的约束效果增加,即组合作用系数从1.031平均增加到1.103,尤其可以明显改善大宽厚比方钢管混凝土柱的轴压承载力及组合作用;采用较薄厚度的斜拉肋,可使短柱的组合作用更好,并能充分发挥材料的性能。     

加劲薄壁钢管混凝土柱的试验性能

对加劲薄壁钢管混凝土柱的结构性能进行试验研究。通过在钢管内表面焊接纵向加劲肋实现加强的作用。同时对12个不带加劲肋的钢管混凝土柱进行试验,部分柱的填充混凝土中加有钢纤维。试验结果表明,加劲肋可以有效延迟钢管局部屈曲现象的出现。当加劲构件达到最大承载量时钢板才出现屈曲,所以相比普通钢管混凝土,加劲钢管混凝土具有更高的适用性。     

带肋薄壁方钢管混凝土轴压短柱设计探讨

薄壁方钢管混凝土能取得较好的经济效果,适宜在结构中用作柱构件。但薄壁钢管在荷载较大时易发生局部屈曲,且降低对混凝土的约束。研究表明,在钢管纵向设置加劲肋可有效延缓管壁局部屈曲,改善构件工作性能。针对该新型方钢管混凝土轴压短柱,探讨子板件最大宽厚比及加劲肋的最小刚度确定方法。最后利用国内外常用的钢管混凝土设计规范对已有充分加劲的试验构件进行承载力计算,通过分析比较确定这些规范计算公式的适用性,供工程实践参考。     

Experiment study of stirrup-confined concrete-filled square double-skin steel tubular stub columns under axial loading

通过带拉筋方中空夹层钢管混凝土轴压短柱受力性能试验,研究了拉筋配箍率对试件承载力、刚度、延性及横向变形系数的影响。采用混凝土三轴受力状态本构模型和钢材本构模型,应用ABAQUS有限元分析软件建立并验证了带拉筋方中空夹层钢管混凝土轴压短柱三维实体有限元模型,有限元计算结果与试验结果吻合良好;在此基础上,分析了拉筋对内外方钢管和混凝土约束作用机理。研究结果表明:拉筋能有效缓解了方钢管的局部屈曲,对短柱承载力、刚度、延性的提高效果明显;拉筋加强了内钢管对混凝土的约束作用,使得内钢管受力更加合理,并且拉筋配箍率越大,约束作用越明显。     

Experimental behaviour of concrete-filled stiffened thin-walled steel tubular columns

An experimental study on the structural behaviour of concrete-filled stiffened thin-walled steel tubular columns is presented in this paper. The stiffening was achieved by welding longitudinal stiffeners on the inner surfaces of the steel tubes. Companion tests were also undertaken on 12 unstiffened concrete-filled steel tubular (CFST) columns, with or without steel fibres in the infill concrete. The test results showed that the local buckling of the tubes was effectively delayed by the stiffeners. The plate buckling initially occurred when the maximum load had almost reached for stiffened specimens, thus they had higher serviceability benefits compared to those of unstiffened ones. Some of the existing design codes were used to predict the load-carrying capacities of the tested composite columns.     

Seismic behavior of L-shaped concrete-filled steel tubular columns with reinforcement stiffeners

制作了1根对拉钢筋加劲L形截面钢管混凝土柱试件和2根非加劲L形截面钢管混凝土柱试件,对其进行低周往复水平荷载作用下的滞回性能试验,考察对拉钢筋和轴压比对其抗震性能的影响规律。结合OpenSees有限元分析,研究其破坏模式和滞回性能,分析对拉钢筋的作用以及钢管对混凝土的约束作用。结果表明：对拉钢筋能有效限制钢板的局部屈曲以及阴角处钢管和混凝土的脱离,保证钢管和混凝土共同工作;轴压比从0.3增加到0.6时,非加劲L形截面钢管混凝土柱的耗能能力及延性均降低;相同轴压比下,相比非加劲L形截面钢管混凝土柱,对拉钢筋加劲L形截面钢管混凝土柱的破坏程度明显减轻,耗能能力及延性明显提高;有限元分析结果基本能反映试件在低周往复水平荷载作用下的抗震性能。