预应力损失对连续刚构桥刚度和应力状态的影响分析

Analysis of Impact of Prestress Loss on Stiffness and Stress Condition of Continuous Rigid-Frame Bridge

为研究预应力损失对连续刚构桥刚度和应力状态的影响,以(75+3×130+75)m连续刚构桥为背景,采用有限元法分别计算分析纵向、竖向预应力在不同损失值的情况下,对大跨径连续刚构桥箱梁腹板应力和主梁刚度的影响规律,并与实桥受力状态及腹板开裂情况进行对比分析。结果表明:纵向预应力钢束中的顶板束预应力损失对主梁刚度的降低影响较为显著,竖向预应力损失对其影响不明显;与纵向预应力损失相比,竖向预应力损失对腹板主拉应力的增加影响更为突显,从而加速其开裂;理论计算与实桥对比论证了主梁L/4处是开裂危险截面。

To Study the impact of prestress loss on the stiffness and stress condition of the continuous rigid-frame bridge, a continuous rigid-frame bridge with span arrangement of （75 ＋3× 130＋75） was taken as the study background. The finite element method was used to calculate the influence law of the longitudinal and vertical prestress in different context of loss values on the web stress of the box girder and the main girder stiffness of long-span continuous rigid-frame bridge. The calculated results were compared with the load bearing condition of the real bridge on the con- dition of web cracking. The results indicated that among the longitudinal prestress tendons, the prestress loss of the tendons in the top plates exerted significant influence on the reduction of the main girder stiffness, while the vertical prestress loss had no distinctive influence on the reduction of the main girder stiffness~ compared with the longitudinal prestress loss, the vertical prestress loss had more distinctive influence on the main tensile stress of the webs, which might exacerbate the cracking. It is proved from the comparison of the theoretical calculation and the data measured on the real bridge that the location of L/4 of the main girder is the cracking sensitive section.