Seismic Behavior of Diaphragm-Through Connections of Concrete-Filled Square Steel Tubular Columns and H-Shaped Steel Beams

Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.

Influence of Axial Load Ratio on Shear Behavior of Through-Diaphragm Connections of Concrete-Filled Square Steel Tubular Columns

Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular columns. The analysis reveals that smaller axial load ratio can improve the shear bearing capacity and ductility while larger axial load ratio will decrease the shear behavior of the through-diaphragm connections. The parametric studies indicate that the axial load ratio should be limited to less than 0.4 and its influence should be considered in the analysis and design of such connections.

Low cyclic fatigue performance of concrete-filled steel tube columns

Eight concrete-filled steel tubular(CFT) columns were tested subjected to cyclic loading under constant axial load. Experimental parameters included axial compression ratio, loading sequences, and strength of concrete and steel. The seismic performance of CFT columns and failure modes were analyzed. The test results show that different axial load ratios and loading sequences have effects on the load carrying capacity, ductility and energy dissipation capacity of CFT columns, as well as the failure modes of the CFT columns. The failure pattern can be categorized into two types: local buckling failure of steel tube in compression zone, and low cycle fatigue tearing rupture failure of steel tube. The seismic behavior was evaluated through the energy index obtained from each cycle.

An Experimental Study of Composite Columns Filled with Eucalyptus nitens Timber under Axial Compression

Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an innovative composite column.The composite column was comprised of a rectangular steel tube with E.nitens timber infill.The nonlinear compressive behaviour of the composite column filled with E.nitens wood for both dry and wet conditions was examined.The same tests on rectangular steel tubes and bare dry and wet E.nitens samples were also undertaken as a comparison.For samples with different conditions,the ultimate capacity was evaluated and the effect of each condition on the compressive behaviour of the composite column was clarified.The steel tubes showed greater ductile behaviour,and more ductility was found in the wet samples.The steel tubes with E.nitens timber infill samples exhibited a greater linear elastic range connected with higher maximum loads,while the bare timber samples could support only lower maximum loads.The results from this research were promising for the use of rectangular steel tubes with E.nitens timber infill in structural applications.

波纹钢板组合框架节点抗震性能试验研究

基于波纹钢-钢管混凝土组合柱与U形外包波纹钢-混凝土组合梁,以“强节点弱构件”的设计原则提出了一种施工便捷、传力明确的节点连接方式。对中节点试件进行了低周往复加载下的拟静力试验,分析了节点的破坏形态、滞回曲线、耗能能力、延性、梁端塑性铰区以及节点核心区关键部位钢材的应变变化,通过有限元软件对节点进行模拟,并与试验进行对比发现二者吻合较好。研究表明:试件最终破坏的位置为梁端理想塑性铰区,节点核心区域未发生明显破坏,实现了塑性铰的外移;试件滞回曲线饱满,等效黏滞阻尼系数为0.206,延性系数为3.67,说明试件具有较好的耗能能力以及延性。节点域钢材各位置应变分布均匀,传力效果良好,节点核心区未屈服,梁下翼缘塑性铰区应变达到屈服应变,节点工作性能良好,能有效传递弯矩以及剪力。

钢管混凝土框架-整体装配式填充墙抗震性能

为消除填充墙对框架的不利影响,充分发挥钢管混凝土框架变形能力强、延性好的优势,采用在钢管混凝土框架柱与填充墙间预留缝隙,填充墙与型钢梁间柔性连接的构造措施。为验证该种连接的可靠性,研究钢管混凝土柱框架-整体装配式填充墙的抗震性能及相互作用机理,进行了1个足尺单榀两跨两层框架填充墙模型的低周反复荷载试验。基于试验,分析了填充墙的损伤演化过程、钢管混凝土柱框架和连接件的变形及结构整体的抗震性能。研究表明:钢管混凝土柱框架-整体装配式填充墙滞回曲线饱满,耗能能力强;加载点极限移位角达1/41时,整体结构仍具有稳定的承载力,延性较好;装配式填充墙板-框架间的柔性连接,削弱了框架传递给填充墙板的荷载,延缓和减轻了整体装配式填充墙板损伤;填充墙板与装配式钢框架整体连接可靠,发挥了框架变形能力强、延性好的优势;整体结构后期承载能力稳定,具有良好的抗震性能和安全储备。

内填木芯钢管混凝土短柱轴压性能有限元分析

在钢管混凝土内部填充部分木芯能够在不大幅降低钢管混凝土柱承载力的情况下,有效减轻钢管混凝土柱的自重。采用ABAQUS有限元软件建立内填木芯钢管混凝土短柱实体模型,研究了不同含木率、木芯截面形状、钢管截面形式和钢管壁厚等参数对内填木芯钢管混凝土短柱轴压性能的影响。结果表明:一定范围内,内填木芯使得钢管混凝土短柱的承载力有所下降,但是柱的强重比却逐渐增大;木芯的截面形式对柱的承载力总体上影响较小。同时借鉴约束钢管的本构关系,提出内填木芯钢管混凝土轴压短柱承载力的简化计算式。采用建议计算式对内填木芯钢管混凝土轴压短柱进行承载力计算,计算结果与有限元模拟值、试验值吻合良好。

基于ABAQUS的木材填充钢管混凝土组合短柱轴压性能分析

为了研究钢管壁厚、木材尺寸、混凝土强度和钢材强度对木材填充钢管混凝土组合短柱轴压性能的影响,本文采用ABAQUS有限元软件,对木材填充钢管混凝土组合短柱进行了非线性有限元分析,计算和分析了木材填充钢管混凝土组合短柱轴压时的破坏形态和荷载-位移曲线,经过与试验数据对比,两者吻合较好。研究表明:提高材料强度、钢管壁厚和减小木材尺寸可以提高木材填充钢管混凝土组合短柱的峰值荷载;钢材对剩余承载力的影响较大;提高钢材强度、木材尺寸和钢管壁厚可以显著提高木材填充钢管混凝土组合短柱的结构效率,低强度混凝土试件结构效率最低。