摘要
钢管混凝土拱桥为超静定结构,温度变化、主梁收缩徐变等会使主梁和拱肋中产生次内力。针对某1~80 m钢管混凝土拱桥,开展了整体温度和局部温度变化分析及后浇带影响主梁沉降和收缩徐变的分析。结果表明:整体温度变化所引起的温度及内力效应最小,拱肋温度变化会产生最大的位移效应,而主梁温度变化会引起最大的内力效应;拱肋温度上升及下降时,主梁与拱肋均会产生同步、同方向的位移变化趋势,同时会在全桥范围内尤其是梁体跨中产生更大的内力效应;与升温过程相比,主梁降温会在全桥范围内尤其是梁体跨中及端部产生更大的内力效应,主梁降温15℃时,引起的最大轴力为跨中的-17448 kN,最大弯矩为梁端的5434 kN·m,主梁降温15℃时,在拱脚局部出现了大于2 MPa的拉应力,主梁降温对于拱脚受力更为不利;最后,从混凝土初凝时间和主梁沉降、收缩徐变3个方面论证了设置主梁后浇带的必要性和重要性,表明一次浇筑主梁所产生的收缩变形等同于主梁降温13℃的变形效应,设置后浇带,减少了结构因混凝土收缩产生的裂缝,也可起到补偿结构在施工过程中的几何缺陷、降低结构次内力以及方便施工等作用。
Concrete filled steel tubular arch bridge is a statically indeterminate structure.Temperature change,shrinkage and creep of main beam will produce secondary internal forces in main beam and arch rib.For a 1-80 m concrete-filled steel tubular arch bridge,the overall and local temperature changes and the influence of post cast strip on the settlement,shrinkage and creep of the main beam are analyzed.The results show that the temperature and internal force effects caused by the overall temperature change are the smallest,the arch rib temperature change will produce the maximum displacement effect,and the girder temperature change will cause the maximum internal force effect;when the temperature of the arch rib rises and falls,the displacement of the main beam and the arch rib will change synchronously and in the same direction.At the same time,it will produce greater internal force effect in the whole bridge,especially in the middle of the beam span;compared with the temperature rise,the cooling of the main beam will produce greater internal force effect in the whole bridge,especially in the middle and end of the beam.When the temperature drop of the main beam is 15℃,the maximum axial force is -17448 kN in the middle of the span,and the maximum bending moment is 5434 kN·m at the beam end.When the temperature drop of the main beam is 15℃,there is a tensile stress greater than 2 MPa at the arch foot,and the cooling of the main beam is more unfavorable to the stress of the arch foot.Finally,the necessity and importance of setting the post pouring belt of the main beam are demonstrated from three aspects:the initial setting time of concrete and the settlement,shrinkage and creep of the main beam.It shows that the shrinkage deformation caused by one-time pouring of the main beam is equivalent to the deformation effect of cooling the main beam by 13℃.Setting the post pouring belt can reduce the cracks caused by concrete shrinkage,it can also compensate the geometric defects of the structure in the construction process,reduce the secondary internal force of the structure and facilitate the construction.
出处
《建筑技术开发》
2022年第5期95-100,共6页
Building Technology Development
关键词
钢管混凝土拱桥
超静定结构
温度次内力
后浇带
收缩徐变
concrete filled steel tubular arch bridge
statically indeterminate structure
temperature secondary internal force
post cast strip
shrinkage and creep