波纹腹板预应力U型钢-混凝土组合梁高温性能参数研究

Study on High Temperature Performance Parameters of Corrugated Web Prestressed U-beam-concrete Combination Beams

为探索不同参数对波纹腹板预应力U型钢-混凝土组合梁的抗火性能的影响,建立了该类组合梁在高温下的热-力耦合模型,研究了上部混凝土板板宽、板厚及波纹钢腹板波高、波角和平直段长度等几何参数对组合梁抗火性能的影响。结果表明:组合梁高温下的临界状态为形成塑性铰的强度破坏。混凝土板宽度越大,板厚越高,形成的不均匀温度场越明显,削弱了压应力集中现象,提升了组合梁的高温承载力。波纹钢腹板剪弯段承担了主要的剪力,波高越小腹板混凝土的吸热作用越弱,临界状态下钢腹板屈曲变形越明显;波角过大高温下钢腹板抵抗平面外变形能力越强,但会降低下翼缘钢板高温下的利用率;平直段长度对腹板混凝土吸热作用及钢腹板抵抗平面外变形能力影响不明显。高温后预应力拉索发挥主要抗弯作用,预应力比越大,组合梁抗弯刚度越大,高温下组合梁达到的变形限值越小,但对临界温度的影响不明显。

In order to explore the effects of different parameters on the fire resistance of corrugated web prestressed U-type steel-concrete composite beams,a thermal-force coupling model of such composite beams at high temperatures was established,and the effects of geometrical parameters,such as the width and thickness of the upper concrete slab,and the wave height,wave angle,and flat section length of the corrugated steel web,on the fire resistance of composite beams were investigated.The results show that the critical state of the combined beam at high temperature is strength damage with the formation of plastic hinge.The larger the width of the concrete slab and the higher the slab thickness,the more obvious the formation of inhomogeneous temperature field,which weakened the phenomenon of compressive stress concentration and improved the high temperature bearing capacity of the combined beam.The corrugated steel web shear bending section bears the main shear force,the smaller the wave height,the weaker the heat-absorbing effect of the web concrete,the more obvious the buckling deformation of the steel web in the critical state.The wave angle is too large at high temperatures,the stronger the resistance of the steel web to out-of-plane deformation,but it will reduce the utilisation of the lower flange steel plate at high temperatures.The length of the flat section has no obvious influence on the heat-absorbing effect of the web concrete and the resistance of the steel web to out-of-plane deformation.After high temperature,the prestressing cable plays the main role of bending resistance,the larger the prestressing ratio is,the larger the bending stiffness of the combined beam is,and the smaller the deformation limit value of the combined beam is reached at high temperature,but the effect on the critical temperature is not obvious.