关于两桩承台配筋形式的探讨

Discussion on the form of reinforcement for two pile caps

承台是保证上部结构沿传力路径有效传递的重要构件,起着承上启下的作用。因此,对桩基承台的受力分析、承载力问题及承台配筋形式的研究具有十分重要的理论意义和工程意义。《建筑桩基技术规范》(JGJ94-2008)对于三桩及多桩承台的设计给出了明确的计算方法,设计的可操作性比较好,但是对于工程中常用的两桩承台没有提供相应的设计方法及依据。目前,关于两桩承台的设计以及配筋形式,设计人员尚未达成共识。介绍了盈建科结构计算软件(YJK)给出的两桩承台3种不同的配筋形式:纵筋+分布筋、纵筋+箍筋、双层双向。前两种配筋形式将承台视为“梁”,采用的是梁式配筋形式,第三种将承台视为“板”,按照板元双层双向配筋。同时以广州南沙某住宅楼为例,介绍了不同设计院给出两桩承台的配筋形式:一种是按照纵筋+箍筋的形式计算和配筋;一种是按照板元计算,采用双层双向的形式配筋,还有一种做法是采用板元计算结果,但是按照纵筋+箍筋的形式配筋,即采用梁式配筋。结合不同形式的配筋分析了各自存在的问题,给出了两桩承台配筋形式的建议,为设计及施工人员掌握两桩承台的设计和计算提供参考,使两桩承台的配筋形式更加经济合理,符合工程实际。

Piles cap is an important component to ensure the effective transmission of the superstructure along the force transmission path and plays the role of connecting the preceding and the following.Therefore,it is of great theoretical and engineering significance to study the stress analysis,bearing capacity and reinforcement form of pile cap.Technical Code for Building Pile Foundation(JGJ94-2008)provides a clear calculation method for the design of three-pile and multi-pile caps,and the design has good operability.However,there is no corresponding design method and basis for two-pile caps commonly used in engineering.At present,designers have not reached a consensus on the design and reinforcement form of the two pile caps.This paper introduces three different reinforcement types of two pile caps given by YJK software:longitudinal reinforcement+distributed reinforcement,longitudinal reinforcement+stirrup reinforcement and double-layer bidirectional reinforcement.The first two forms of reinforcement will be regarded as the“beam”,the beam type reinforcement form,the third will be regarded as the“plate”,according to the plate element double directional reinforcement.At the same time,taking a residential building in Nansha,Guangzhou as an example,the reinforcement forms of two pile caps given by different design institutes are introduced:one is calculated and reinforced according to the form of longitudinal reinforcement+stirrup reinforcement;One is to calculate according to the plate element,using double two-way form reinforcement,there is a method is to use the plate element calculation results,but in accordance with the longitudinal reinforcement+stirrup form reinforcement,namely the use of beam type reinforcement.Combined with different forms of reinforcement,the existing problems are analyzed,and the suggestions of reinforcement form of two pile caps are given,which can provide reference for designers and constructors to master the design and calculation of two pile caps,so that the reinforcement form of two pile caps is more economical and reasonable,and in line with the engineering practice.