大偏心体外预应力节段梁的非线性分析

Nonlinear Analysis of the Externally Prestressed Segmental Beams with Large Eccentricity

预应力梁的体外筋等效为其作用在梁上的等效荷载,并由荷载作用前后锚具和转向座的不同位移计算出体外筋的变形和力,进而对体外预应力梁进行非线性分析.基于此通用方法,文中用3种方法分析大偏心体外预应力节段梁.(1)假设节段梁为通长的现浇梁,忽略节段单元内的普通钢筋,只考虑通长的预应力筋.(2)假设节段梁为通长的现浇梁,同时假设普通钢筋也是通长的.(3)在节缝处加设一个节缝单元,其长度与钢筋的最小锚固长度有关.在节缝单元中,只考虑穿过其中的预应力筋;而对于节段单元,还考虑其中的普通配筋.试验和理论计算表明,大偏心体外预应力现浇梁和节段梁的受力性能相近,且主要取决于体外筋.可用方法(1)分析大偏心体外预应力节段梁.

The external tendon of prestressed beam is equivalent to the equivalent load exerting on this beam; deformation and force of external tendon are calculated from different displacements of anchorages and deviators before and after the loading; and then, nonlinear analysis of externally prestressed beam is carried out. Based on this method in common use, three kinds of analyses are presented here to analyse externally prestressed segmental beams with large eccentricity. Firstly, assume the segmental beam to be monolithic, consider only the continuous prestressed strand and neglect the action of the reinforcement in the segment Secondly, assume the segmental beam to be monolithic, and the reinforcement in the segments to be continous as well. Thirdly, add the segmental joint a segmental element, of which the length relates to minimum anchorage length of the reinforcenent. In the element of segment joint, only the continuous prestressed strand is considered; while in the element of segment, the common reinforcement is considered as well. As indicated by both testing and theoretical calculation, the flexural performance of the segmental beam with large eccentricity and that of monolithic beam are similar to each other, which depends chiefly on the external tendon; the externally prestressed segmental beams with large eccentricity can be analysed by the first method.