摘要
预应力混凝土连续(刚构)箱梁桥设置竖向预应力筋是为了减少和控制腹板主拉应力、防止开裂,然而在设置了竖向预应力后.箱梁腹板开裂现象仍然普遍存在。竖向预应力难以达到设计要求是导致腹板开裂主要原因之一,该文主要在不考虑应力集中的前提下,研究竖向预应力孔道灌浆问题对竖向预应力效果的影响。对常张高速沅水大桥进行变截面箱梁腹板应力分析,得到竖向预应力孔道削弱对腹板应力水平的影响,并采用等效主拉应力增量法对腹板竖向预应力进行折减分析。该文研究表明:箱梁腹板竖向预应力孔道灌浆不理想,将会引起截面抗剪刚度、抗弯刚度及抗压刚度的削弱,从而导致主拉应力σ_(?)增大及竖向预应力作用的折减,势必将对结构安全造成不利影响。
The vertical pre-stressed reinforcement installed in the pre-stressed concrete continuous (rigid frame) box beam bridge is to decrease and control the main tension stress of the web and to prevent the creaking.But after setting up the vertical pre-stress,the creaking appearance of box beam web still commonly exists.The vertical pre-stress hard to reach the design requirement is one of the main reasons leading the wed creaking.The article studies the influence of the vertical pre-stressed hole pouring on the vertical pre-stress effect under the premise mainly not considering the stress centralization.The article carries out the non-uniform box beam web stress analysis for Changzhang Expressway Yuanshui Bridge,gets the influence of vertical pre-stressed hole weakening on the web stress level,and uses the equivalent main tension stress incremental process to carry out the reduction analysis of the web vertical pre-stress.The study in the article makes clearly that the poor ideal of web vertical pre-stressed hole pouring will cause the weakening of the sectional shear stiffness,bonding stiffness and compressive stiffness so as to lead the increment of the main tension stress and the reduction of the vertical pre-stress action.It certainly will cause the unfavorable in- fluence on the structure safety.
出处
《城市道桥与防洪》
2008年第10期117-122,共6页
Urban Roads Bridges & Flood Control
关键词
预应力混凝土箱梁
竖向预应力
孔道灌浆
主拉应力
折减系数
pre-stressed concrete box beam
vertical pre-stress
hole pouring
main tension stress
reduetion coefficient
