T形多腔钢-混凝土组合构件压弯性能研究

Mechanical behavior of T-shaped multi-partition steel-concrete composite member under eccentric compression

多腔钢-混凝土组合构件通过变化截面高厚比可作为组合柱、组合短肢剪力墙和组合剪力墙,灵活地应用在具体结构中,在结构外缘采用T形多腔钢-混凝土组合构件可减少室内结构柱外露。为此,针对截面高厚比为3~8的T形多腔钢-混凝土组合构件开展压弯性能研究。以截面高厚比和试件高宽比为变化参数,对4个T形多腔钢-混凝土组合构件在偏压荷载作用下的压弯力学性能进行了试验研究,并对试件的变形发展过程、破坏模式和承载力进行了分析。在试验研究的基础上,运用有限元模型分析了偏压荷载作用下T形多腔钢-混凝土组合构件的受力全过程和多腔钢管与混凝土的相互作用,并分析了截面高厚比、混凝土强度、钢材强度和钢板厚度等参数对构件压弯力学性能的影响。研究结果表明:构件在偏压荷载作用下发生整体弯曲破坏模式;多腔钢管对核心混凝土的不均匀约束作用表现为腔体角部大于内隔板对混凝土的约束,内隔板中部大于自由边钢板中部对混凝土的约束;截面高厚比是影响构件截面压弯承载力相关曲线的关键参数。在此基础上提出了适用于不同截面高厚比的T形多腔钢-混凝土组合构件的压弯承载力计算公式。

The multi-partition steel-concrete composite members(MSCM) can be flexibly used as composite columns, composite shear walls with restricted width and normal composite shear walls by altering the sectional height to thickness ratio. In particular, T-shaped MSCM is usually used on the outer edge of the structure to reduce the exposure of the indoor structural column. To investigate the mechanical behavior of T-shaped MSCMs with the sectional height to thickness ratios varied from 3 to 8 under eccentric compressive load, four T-shaped MSCM specimens were designed and constructed to test and observe their respective behavior and failure modes. The deformation behavior, failure modes and bearing capacity of all specimens were obtained. Then the finite element(FE) software ABAQUS was employed to investigate the mechanical behavior of T-shaped MSCMs under eccentric compression. Comparison between the predicted and test results indicates that the developed FE model could adequately simulate the mechanical behavior of T-shaped MSCMs. Thereafter, parametric analyses were performed to study the influences of the sectional height to thickness ratio, concrete strength, steel strength and thickness of steel plate on the mechanical behavior of MSCMs under eccentric compression. The results indicate that all specimens fail due to global bending. The sectional height to thickness ratio has the most significant effect on MSCMs’ axial load and bending moment interaction diagram. In addition, the confinement of the multi-partition steel tubes on inner concrete is non-uniform in each partition, in which the confinement is larger at the corner while smaller around the inner diaphragm. The minimum confinement exists at the middle of the free steel plate in each partition. Based on the analysis above, a simplified formula was suggested to predict the load capacity of T-shaped MSCMs under both compression and bending.