先张空心板支座附近底板开裂原因及防治措施

Causes and Prevention Measures of the Bottom Plate Cracking Near the Support of Pretensioned Hollow Slab

为探讨先张空心板支座附近底板常出现横向开裂原因及其控制措施,根据实际先张空心板支座底板裂缝特点,基于精细化的空间实体模型,分析了荷载作用下先张空心板预应力筋失效孔的存在、数目及布置方式对其底板的影响,明晰了该类空心板底部裂缝的主要原因,并针对性地提出了防治措施。研究表明:预应力筋失效孔引起的底板应力过大是先张空心板支座附近底板开裂的主要原因,建议在进行先张法空心板设计时应计入预应力筋失效孔的影响,同时对钢束端部失效段的孔洞应采取填充等必要措施。

To investigate the cause for the frequent occurrence of transverse cracks near the support of pretensioned hollow slabs and their control measures,based on the characteristics of the cracks in the bottom plate of the pretensioned hollow slab support and a refined spatial entity model,this study analyzes the impact of the existence,number and arrangement of prestressed tendons failure holes in pretensioned hollow slabs on their bottom plates under load.The main causes of cracks at the bottom of this type of hollow slab are identified,and targeted prevention and control measures are proposed.The research indicate that the excessive stress caused by prestressed tendon failure holes is the primary reason for the cracking of the bottom plate near the support of pretensioned hollow slabs.It is recommended that the impact of prestressed tendon failure holes should be considered during the design of pretensioned hollow slabs,and necessary measures such as filling should be taken for the holes in the failed sections at the ends of the steel tendons.