基于体外预应力加固的简支梁束界

Cable Zone for Simply Supported Beams Strengthened by External Prestress

体外预应力加固技术作为一种主动加固方法,现已广泛应用于桥梁加固中。对于预应力混凝土构件,合理的预应力钢束线形有利于保证结构承载力及使用性能。针对体外预应力加固简支梁的束界进行研究,提出体外预应力法加固简支梁的束界概念,依据我国现行规范,对各类预应力构件提出束界控制条件并分别推导出束界理论解。此外,提出了预应力钢束使用效率的概念,通过约定使用效率对前述束界进一步界定。应用有限元建模对基于理论束界的不同体外预应力布束方案的钢束使用效率和应力进行分析,结果表明,所述束界是安全有效的,可以满足使用阶段抗裂性要求和施工阶段应力要求;体内预应力钢束使用效率随束距增大而减小,体外预应力钢束使用效率随束距增大而增大。

As an active strengthening method, the external prestressing technique has been widely used in bridges strengthening. For prestressed concrete member, with a rational shape of prestressed strands, bearing capacity and the performance of structures can be ensured. Aimed at research in ca- ble zone of simply-supported beam strengthened with external prestressed strands, the concept of ca- ble zone of simply-supported beam strengthened with external prestressed strands has been put for- ward. Based on current specification, controlling condition of cable zone to all kinds of prestressed concrete member was presented and the analytical solutions to external cable zone are acquired. More- over, the concept of prestressed strands service efficiency was put out, by what further demarcation to external cable zone can be conducted. Finite element modeling was employed to analyze the strands service efficiency and stress of various external strands layouts that based on analytical cable zone, the results showed that the cable zone is safe and effective that both crack resistance requirements in serv- ice stage and stress requirements in external prestressing tensioning stage can be satisfied; the service efficiency of internal prestressed strands decreased while which of external prestressed strands in- creased with the increase of external strands eccentricity.