再生混凝土梁与普通混凝土梁的受力性能等效方法研究

为实现再生混凝土梁与普通混凝土梁的受力性能等效，以普通混凝土梁在整个服役期间的受力性能作为等效转换目标，建立了一种适用于公路桥梁规范的受力性能等效方法。针对以弯曲破坏为主的钢筋混凝土梁，从承载能力极限状态的弯矩、正常使用极限状态的挠度和最大裂缝宽度以及耐久性四个方面建立受力性能等效方程，将再生混凝土梁等效转换为具有相同受力性能的普通混凝土梁，并结合试验梁进行了实例等效说明。研究表明：正常使用极限状态中的最大裂缝宽度条件能够自动满足等效要求；当普通混凝土梁横截面高度和环境条件保持不变时，再生混凝土梁的横截面高度随着再生混凝土与普通混凝土氯离子扩散系数之比的增大而增大；相同氯离子扩散系数之比下，再生混凝土梁与普通混凝土梁的横截面高度之比随着普通混凝土梁横截面高度的增大而减小，随着环境条件的逐渐恶化而增大；对于再生粗骨料取代率分别为50%、100%的再生混凝土梁，等效后其横截面高度仅比对应普通混凝土梁增加了约10%；建立的等效后再生混凝土梁的横截面高度和再生混凝土与普通混凝土的平均抗压强度之比的关系式，可以简化等效计算过程。建立的受力性能等效方法可为再生混凝土梁的工程应用提供一定参考。

Research on equivalent method of mechanical performance of recycled concrete beams and ordinary concrete beams

To achieve the mechanical performance performance of recycled concrete beams to ordinary concrete beams, the mechanical performance of ordinary concrete beams during the entire service period was taken as the target of equivalent conversion. A mechanical performance equivalent method which is suitable for the China Highway Bridge Code was proposed. In this paper, for the reinforced concrete beams with bending failure, the recycled concrete beam was equivalently converted to the ordinary concrete beam based on the mechanical performance equivalent equations which were established from four aspects, including bending moment of ultimate state bearing capacity, deflection and maximum crack width of serviceability limit state, and durability. To explain the equivalent process, examples were given by using the tested beams. The results show that the maximum crack width of serviceability limit state automatically meets the equivalent requirements. When the cross-sectional height of the ordinary concrete beam and the environmental condition remain unchanged, the cross-sectional height of the recycled concrete beam increases with the ratio of the chloride diffusion coefficient of recycled concrete to that of the ordinary concrete. Under the same chloride diffusion coefficient ratio, the ratio of cross-sectional height of the recycled concrete beam to that of the ordinary concrete beam decreases with the increase of the cross-sectional height of ordinary concrete beam, and increases with the gradual deterioration of environmental condition. For recycled concrete beams with recycled coarse aggregate replacement proportion of 50% and 100% respectively, the equivalent cross-sectional height of the recycled concrete beam is only about 10% higher than that of the corresponding ordinary concrete beam. The established relationship between the equivalent cross-sectional height of the recycled concrete beam and the ratio of the average compressive strength of recycled concrete to that of ordinary concrete can simplify the equivalent calculation process. The structural performance equivalent method established in this paper can provide guidance for practical applications of recycled concrete beams.