北京工人体育场超长混凝土结构温度效应和S形弯折钢筋诱导缝研究

Study on temperature effect and a new S-type bending steel induced joint of super-long concrete structure in Beijing Workers’Stadium

北京工人体育场室外看台和檐口环梁周长约800 m,复建时取消了温度伸缩缝设计,属于超长混凝土结构。考虑了不同后浇带封闭时间的影响,对体育场看台温度作用进行了分析。采用温度诱导缝措施,引导结构在诱导缝处开裂,进一步释放温度应力。针对常规诱导缝构造钢筋不连续、施工复杂的问题,提出了一种配置S形弯折钢筋的混凝土诱导缝构造,确定了诱导缝布置最大间距计算方法,并对诱导缝位置的S形弯折钢筋进行实地测量研究。结果表明:诱导缝处混凝土在温度应力作用下首先开裂,能起到进一步释放温度应力的作用;诱导缝处钢筋有更大的变形需求,配置S形弯折钢筋能充分利用其变形能力,且该诱导缝施工方便。

The perimeter of the outdoor grandstand and the cornice ring beam of Beijing Workers’Stadium is about 800 meters,which is a super-long concrete structure,and the temperature expansion joint was cancelled during the reconstruction.In this paper,the temperature effect of the grandstand plate was analyzed by consider the influence of different closure time of the post-pouring belt.The induced joint was adopted to guide the structure to crack at the joint and further release the thermal stress.Aiming at the problems of discontinuous reinforcement and complex construction of conventional induced joints,a novel type of concrete induced joint structure with S-shaped bending steel bar was proposed,the calculation method of the maximum spacing of induced joint was determined,and the bending steel bar was measured in the field.The results show that the concrete at the induced joint first cracks,which can further release the thermal stress.The steel bar at the induced joint has a greater demand for deformation,and the configuration of bending steel bar can make full use of its deformation capacity.