摘要
针对分丝管索塔锚固区受力状态问题,以南盘江特大桥(108m+180m+108m三跨矮塔斜拉桥)为背景,进行锚固区混凝土劈裂行为与受力机理研究。首先,综合考虑拉索对索鞍的压力和摩擦力作用,推导拉索沿纵桥向的压力分布公式;然后,建立ABAQUS实体模型并按压力分布公式加载,分析其空间应力分布规律。最后,开展锚固区节段足尺模型试验,采用自平衡反力梁法,分四级张拉斜拉索,最大张拉力为1.09倍设计张拉力,观测并验证锚下混凝土的受力特征。研究结果表明:作用在鞍下混凝土上的压力受摩擦力影响较小,沿纵桥向基本服从均匀分布;锚固区混凝土压应力及拉应力均低于规范限值要求,处于安全工作状态;设计荷载作用下,最大劈裂应力出现在两分丝管索鞍之间的混凝土部分,但应力水平较小,此外两索鞍两侧及与索鞍接触的混凝土区域亦出现较小劈裂应力;索鞍底缘附近的混凝土劈裂应力沿竖向衰减迅速,劈裂应力沿竖向的叠加效应不明显。有限元模型显示,当拉索索力达到25 100kN时,锚固区混凝土达到劈裂极限应力而开裂;在横桥向,竖向压应力由核心区域向两侧逐渐减小,近似成二次抛物线分布;有限元模型应力分布计算结果与模型试验实测结果基本一致,具有可靠性。
Amid at the stress analysis problem in the anchorage zone of an extradosed cable-stayed bridge with saddle anchorage.The sub-tube saddle type cable-to-pylon anchorage zone in the Nanpanjiang Bridge(108 m+180 m+108 mthree-span extradosed cable-stayed bridge)was chosen to study the stress distribution and mechanism under the saddle.Firstly,the pressure distribution and friction of cable applied on the saddlewas comprehensive considered,to deduce the formula of cable pressure along longitudinal direction.Then,the ABAQUS solid element model with formula press distribution was developed to analyze the spatial stress distribution.At the end,the full-scale model test was conducted using self-balanced reaction beam loading method,and the cable force was applied through four level steps,the maximum tension was 1.09 times the design value,and the stress characteristics of concrete under anchorage were observed and verified.The results show that the variation of concrete pressure under the saddle had little effect with the friction and kept uniform distribution along longitudinal direction,and the concrete compression and tension stress in the saddle anchorage zone are less than the specification limit and in the safe working state.Under design loading,the largest splitting stress located at the middle part concrete of two sub-tube anchorage,but the stress level is relatively small,and outer side of two anchorage and the concrete connected to the anchorage also appeared small splitting stress.The concrete splitting stress under the anchorage bottom decreased rapidly along vertical direction,and the superimposed effect of splitting stress along vertical direction is indistinctive;the finite element model show when cable force reached 25 100 kN,the anchorage concrete reach splitting limit stress and begin to crack.On transversal direction,vertical compression stress decrease from core zone to two outer side,approximately showing parabolic distribution.The finite element model stress distribution results is consistent with mod
作者
汤颖颖
李英帅
牛艳伟
黄平明
TANG Ying-ying;LI Ying-shuai;NIU Yan-wei;HUANG Ping-ming(School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China;School of Science, Chang'an University, Xi'an 710064, Shaanxi, China)
出处
《长安大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2018年第6期127-134,145,共9页
Journal of Chang’an University(Natural Science Edition)
基金
国家自然科学基金项目(51208056)
中央高校基本科研业务费专项资金项目(310821161013
300102218213)
