超长混凝土结构后浇带有效作用的关键性影响因素分析

Research on Post-casting Band's Actual Effect in Super Long Reinforced Concrete Structures

超长混凝土结构常常采用后浇带技术减少混凝土收缩的影响,进而控制不出现有害收缩裂缝。后浇带的配筋和宽度是影响后浇带有效作用的两个重要因素。现行《高层建筑混凝土结构技术规程》规定每隔30～40m留设后浇带,带宽800～1000mm,楼板钢筋断开,梁筋通长。工程上,由于后浇带做法不正确导致的工程有害裂缝屡见不鲜。本文利用有限元程序,针对算例分析了后浇带钢筋连接状况和后浇带宽度对后浇带有效作用的影响。结果表明,钢筋连接状况对后浇带的作用有显著影响,在常用的后浇带宽度和间距范围内,后浇带宽度对后浇带作用的影响很小,可优先根据施工要求进行确定。

There are often some later-poured belts in the super long reinforced concrete structure to reduce the influence of concrete shrinkage and to prevent the unacceptable crack.The distributing status of bars in the belts and the width of belts have great effect on the action of the post-casting band.The Technical Specification for Concrete Structures of Tall Building suggests to set a laterpoured belt every 30～40 meters,800～1000mm width,cut the bars in the floor slab and lay continuous bars in the beam.In the construction some unacceptable cracks often occur due to the incorrect setting of the later-poured belts.By the finite element analysis,it discusses the influence of the distributing status of bars in the belts and the width of belts on the effective action.As a result,the distributing status of bars in the belts has great effect on the action of the post-casting band,and the width of belts has little effect on the action.So its width can be decided according to priority of construction requirement.