预应力混合配筋混凝土构件抗弯性能研究

Research on Flexural Behavior of Prestressed Composite Reinforced Concrete Members

为了研究有粘结预应力AFRP-钢混合配筋混凝土构件的抗弯性能,基于平截面假定和截面内力平衡条件,推导了预应力AFRP-钢混合配筋混凝土构件适筋破坏情形下正截面受弯承载力以及截面开裂弯矩的计算公式,利用推导的计算公式对五组具有相同整体配筋率、不同初始张拉控制应力的预应力混合配筋构件抗弯性能进行了研究,对预应力AFRP-钢混合配筋构件与普通混合配筋构件的极限抗弯承载力与抗裂承载力进行了对比.研究表明:按照给出的预应力AFRP-钢混合配筋混凝土构件抗弯承载力及开裂弯矩计算公式可较好地反映结构的受力特征;在预应力AFRP筋与普通AFRP筋极限抗拉强度相同的情形下,将预应力AFRP筋代替普通AFRP筋材,对AFRP-钢混合配筋混凝土构件极限抗弯承载力提升的效果并不明显;预应力AFRP-钢混合配筋混凝土构件可以有效地提升结构的抗裂承载能力.在算例中,当张拉控制应力σcon接近于预应力AFRP筋极限抗拉强度的25%时,构件抗裂承载力提升78.7%,从而有效延迟了截面裂缝开裂的时间,增大了结构的抗弯刚度.

In order to study the flexural behavior of reinforced concrete components with bonded prestressed AFRP bars and steel bars,based on the assumption of the plane section and the inter-nal force equilibrium of the section, the formula is presented for calculating the flexural capacity and the crack bearing capacity of the cross section of the prestressed AFRP bars and steel bars concrete members. The flexural behavior of five kinds of prestressed concrete members with the same overall reinforcement ratio and different initial tension control stresses is studied by using the derived formulas, and the ultimate flexural capacity and the crack bearing capacity are com-pared between AFRP-steel composite reinforcement members and common mixed reinforcement members. The researches show that the above formula can well reflect the stress characteristics of the structure. In the case of the ultimate tensile strength of prestressed AFRP tendons and ordina-ry AFRP bars,and the prestressed AFRP bars instead of ordinary AFRP bars,the effect on ulti-mate flexural capacity of reinforced concrete members of AFRP-steel bars is not obvious. The pre-stressed concrete AFRP-steel reinforced concrete members can effectively improve the crack re-sistance capacity of the structure. In the example, when the tension control stress is close to 25% of the ultimate tensile strength of prestressed AFRP tendons,the component crack resistance ca-pacity can be increased by 78. 7%. Therefore,the crack time of cross section is effectively delayed and the bending rigidity of the structure is increased.