摘要
超长混凝土地下结构普遍不设结构缝,通常采用下列抗裂措施:验算控制截面最大裂缝宽度(仅考虑重力荷载效应),预留温度后浇带降低成型收缩拉应力,用构造配筋与加强混凝土养护控制温度裂缝。研究表明,这些常规抗裂措施的综合效果难以定量判断,存在较大不确定性,不能保证此类结构的抗裂性能可满足抗渗漏、耐久性与正常使用要求。针对此问题,结合某新建工程,模拟其超长混凝土地下结构浇筑成型步骤、先后浇筑混凝土之间变形差约束作用、各部位构件实际内力增加过程,考虑混凝土弹性模量与收缩变形规律、环境最大可能降温、后浇带构造的影响,不考虑混凝土初始缺陷与后期裂缝的影响,用MIDAS软件进行了组合应力弹塑性时程分析,以预测结构实际抗裂性能,所述计算方法与结果可供同类结构设计与施工参考。
Generally structural gap is not set in super-long concrete underground structures. Common anti-crack measures include using temperature post-casting hand to control concrete tension stress in shrinkage, setting detail rebar with careful concrete curing to control temperature cracks and considering only gravity load when checking maximum crack width on control sections. Researches show that comprehensive effects of the common measures are difficult to quantitatively be estimated and lack of validity, and this kind of structure is not ensured to fulfill requirements of anti-leakage, durability and serviceability. In view of the situation, combined with a newly-buih project, simulations were made on super-long concrete underground structure casting process, deformation difference constraints effects of successively casted concrete and actual stress increase process of each component. The influence of concrete elasticity modulus, the shrinkage and deformation law, the maximum drop in environment temperature and the post-casting hand construction was considered, and the influence of initial defects and later cracks was not considered. The elastic-plastic time-history analysis on the combined stress in concrete was processed by MIDAS calculation program to predict actual antl-crack performance. The calculation method and the results can be referenced by design and construction of similar structures.
出处
《建筑结构》
CSCD
北大核心
2014年第16期21-25,共5页
Building Structure
关键词
超长混凝土地下结构
后浇带
温度裂缝
抗裂设计
控制部位
组合应力
弹塑性时程分析
super-long concrete underground structure
post-casting band
temperature crack
anti-crack design
controlregion
combined stress
elastic-plastic time-history analysis
