手风琴效应对预应力波纹腹板钢-混凝土组合梁抗火性能影响研究

Influence of accordion effect on fire resistance of prestressed steel-concrete composite beams with corrugated webs

由于预应力波纹腹板组合梁的腹板存在显著的手风琴效应,使其受力性能不同于普通平腹板组合梁。为了研究手风琴效应对预应力波纹腹板组合梁抗火性能的影响,采用ABAQUS有限元软件建立了考虑端部约束的预应力波纹腹板组合梁在火灾下的数值模型,分析了预应力波纹腹板组合梁在高温下的破坏形式、跨中挠度、拉索张力及组合梁轴力等随温度变化的特点。结果表明:高温下波角30°腹板的局部失稳区域大于波角45°和60°组合梁的失稳区域;波高50 mm的组合梁跨中挠度值最小;波高越大,临界状态时腹板局部失稳区域越大;平直段长度50 mm组合梁跨中挠度最小,轴向刚度更大;腹板厚度对波纹腹板组合梁跨中挠度的影响最为显著;轴向约束作用下的组合梁典型破坏形态是梁端负弯矩区腹板和下翼缘发生局部屈曲;不同轴向约束比下,梁的轴向力从压力转变为拉力时温度为691℃;转角约束比对组合梁的影响主要集中在473℃至临界温度阶段;不同转角约束比下,组合梁轴向压力转变为轴向拉力的温度为677℃。

Due to the obvious accordion effect of corrugated webs, the mechanical properties of prestressed composite beams with corrugated webs are different from those of conventional composite beams with flat webs. In order to explore the influence of accordion effect on the fire resistance of prestressed composite beams with corrugated webs, numerical models of these beams considering end constraints under fire were established by using ABAQUS software. The variation laws of failure modes, mid-span deflection, tension of cable strands, and axial force of composite beams with prestressed corrugated webs with temperature were analyzed. The results show that the local buckling area of the beam with wave angle of 30° is larger than those of 45° and 60°. The deflection of the composite beam with wave height of 50 mm is the smallest. In the critical state, the larger the wave height is, the larger the local buckling area of the web is. In the composite beams with different lengths of flat section, the deflection of the beam with 50 mm flat section is the smallest and the axial stiffness is greater in the axial pressure stage. The thickness of the web has the most significant influence on the deflection of the composite beams with corrugated webs. The typical failure modes of the composite beams under axial constraints are the local buckling of the webs and lower flanges in the area of negative moment at the beam ends. Under different axial constraint ratios, the critical temperature from compression to tension in the beams is around 691 ℃. The rotational constraint ratio has a significant influence on the composite beams at 473 ℃ to critical temperature. Under different rotational constraint ratios, the turning temperature from compression to tension is around 677 ℃.