BFRP筋无粘结预应力混凝土梁受弯性能理论分析

Theoretical Analysis of the Flexural Behavior of BFRP Bar Unbonded Prestressed Concrete Girder

在试验研究的基础上进行了理论分析。详细分析了BFRP筋无粘结预应力梁张拉、加载过程中应力变化；分析了BFRP筋无粘结预应力混凝土梁破坏模式及极限承载力计算方法；提出计算BFRP筋无粘结部分预应力梁开裂后短期刚度的“等受拉刚度代换法”，及计算平均裂缝宽度的“两步等效法”，计算值与试验值符合较好；BFRP筋无粘结预应力梁耗能能力随预应力度的提高而降低，根据试验结果提出耗能比例系数计算公式。

Through the experiment research, the theoretical analysis of the unbonded prestressed concrete beams is carried out as follows： The stress development of concrete beams reinforced with unbonded prestressed BFRP bars during the pull and load process is theoretically analyzed. Through the comparative analysis of several possible failure modes, the ductility design proposals of the beams reinforced with unbonded prestressed BFRP bars are put forward. On the condition that the beam cracks, the method of ＂replacement as the same tensile stiffness＂ which calculates short-term stiffness, and the method of ＂two-step replacement＂ which calculates average crack width are suggested. The calculation result is in accord with the experimental results. The energy consuming capacity of the concrete beams reinforced with unbonded prestressed BFRP bars will be weakened as the prestressing degree increases when it is limited to a certain range. The calculation forinula of energy consuming ratio is suggested.