后张法无粘结预应力梁开裂前挠度试验

Deflection Test of Non-Crack Post-tensioned Unbonded Prestressed Beam

为研究全预应力梁和部分预应力梁中预应力度与梁短期刚度的相关关系,制作了一根预应力混凝土梁,对梁施加不同的预应力。在各级预应力下,在三分点施加集中力,采集未开裂预应力梁在不同集中荷载作用下的挠度值。通过对采集到的挠度值计算分析发现,梁的短期刚度随着预应力的增加而不断增加,这与目前中国现行的《规范》中不出现裂缝的预应力梁的短期刚度与预应力无关的规定相矛盾。为了更精确地计算预应力混凝土梁的变形性能,文章建议在其短期刚度的计算需要考虑预应力的影响。

In order to research the relationship between the prestressing force and the short-term stiffness of the full-prestressed concrete beam and the partial-prestressed concrete beam, a prestressed concrete beam was made and different prestressing force was inflicted to the beam. Under all levels of prestressing force, we exert a concentrated force at the third point. At the same time, the deflection of this beam was collected under different kinds of concentrated load value. Through the calculation and analysis of the calculated deflection value, it is found that the short-term stiffness of the beam increases with the increasing of the prestress, which leads to a certain deviation in the calculation formula of the short-term stiffness of prestressed beams without cracks, that are stipulated in Code for design of concrete structures and specification for Design of highway reinforced concrete and prestressed concrete. In order to accurately calculate the deformation performance of the prestressed concrete beams, the paper suggests that it needs to take the influence of prestressing force into account in the calculation of short-term stiffness.