预应力连续组合梁负弯矩区抗弯承载力分析

ANALYSIS ON THE BENDING CAPACITY OF THE NEGATIVE-MOMENT REGION IN PRESTRESSED CONTINUOUS COMPOSITE BEAMS

预应力钢-混凝土连续组合梁具有承载力高、变形小等诸多优点,作为一种新型的横向承重构件,在工程中得到了广泛的使用。其负弯矩区承载能力计算与变形分析是其设计的关键,目前规范还是空白。因此,有必要对其刚度、变形及抗弯承载力进行研究。该文基于换算截面法,引入混凝土参与受拉工作的程度系数,确定了组合梁截面抗弯刚度,进而推出了预应力钢-混凝土连续组合梁负弯矩区的弹性抗弯承载力计算公式;基于简化塑性理论,得到了负弯矩区的极限抗弯承载力计算方法;研究表明连续组合梁能够显著提高截面刚度与减少开裂。该文公式计算结果与实测值均吻合较好,满足工程精度要求。

The prestressed continuous steel-concrete bearing capacity, small deformation and so on, and composite beams have lots of advantages, such as high have been widely used in engineering as a new transverse bearing component. The calculation of capacity and the deformation analysis on a negative-moment region is the key to the design of the prestressed continuous steel-concrete composite beams, and current corresponding specification is still blank. Thusly, it is necessary to research the stiffness, the deformation and a bending capacity formulation. The bending stiffness of the cross-section of the composite beams was determined, and the bending capacity in the state of an elastic limit was calculated with the method of a conversion section principle by the introduction of the degree coefficient of concrete participation in tension. Besides, the bending capacity of composite beams bearing a negative bending moment in the ultimate limit state was deduced by using simplified plasticity theory. The research shows that it is very useful to improve the rigidity of the cross section and slow cracking of continuous composite beams. It turns out that the calculation values are in a good agreement with the experimental results, which meet the engineering accuracy.