新型微弯过宽槽钢筋及其性能研究

Study on performance of new-type slightly bended rebar crossing structure wide joint

水工大体积混凝土结构施工中常设宽缝以缓解温度应力,宽缝中常有钢筋通过,若不截断过宽槽钢筋,钢筋内将产生较大应力;若截断过宽槽钢筋,施工非常困难。针对上述难点,提出了新型的微弯过宽槽钢筋,并设计了4种不同尺寸和具体形状。通过数值分析和试验研究,得到了微弯钢筋的受力与变形关系。考虑温度和徐变作用,按施工过程对某上闸首结构进行了施工仿真分析,研究微弯过缝钢筋施工期的应力状态,并和直过缝钢筋进行了对比。对配置有微弯钢筋和直钢筋的轴拉构件进行对比分析,研究微弯钢筋对正常使用阶段混凝土最大裂缝宽度的影响。在以上工作的基础上,以施工期钢筋应力和正常使用阶段混凝土最大裂缝宽度为依据,建议了合适的新型过宽槽钢筋形状与尺寸。

Wide joint is usually set during the construction of hydraulic massive concrete structure to release the temperature stress where the rebar often crosses. The rebar stress would be considerable if the rebar is not cut off,or if the rebar is cut off,it would cause difficulty in construction. Aiming at this difficulty,a new slightly bended rebar crossing structure wide joint are presented and 4 kinds of slightly bended rebar of different size and shape are designed,the relationship between stress and deformation of the rebar is studied by numerical analysis and tests. The stress state of the slightly bended rebar is studied and compared with that of straight rebar via the construction process simulation of an upper lock head structure with the consideration of temperature and creep effects. A comparative analysis of the axial tensile member with slightly bended rebar and straight rebar is performed and the influence of the slightly bended rebar on the maximum crack width of the structures in service is studied. On the basis of the above results,appropriate shape and size of the new-type slightly bended rebar crossing structure wide joints are suggested according to the rebar stress in construction as well as the maximum concrete crack width in service.