（1 大连理工大学建设工程学部， 大连 116024； 2 中核能源科技有限公司，  北京 100193）

［摘要］基于修正压力场理论，对按《压水堆核电厂预应力混凝土安全壳设计规范》(NB/T 20303—2014)配筋设计的钢筋混凝土单元进行受剪承载力计算，以确定混凝土受拉对承载力的贡献。计算表明，由于混凝土的抗拉强度较低、峰值应力和应变较小，主拉应力方向混凝土达到峰值拉应力时钢筋尚未起到明显的抗拉作用，而钢筋受拉达到屈服强度时，混凝土因软化承担的拉应力已经很小，对单元的受剪承载力起不到明显的作用。考虑混凝土的受拉承载作用的单元最大受剪承载力比忽略混凝土的受拉承载作用的提高幅度不大，同时考虑到混凝土属于脆性材料，抗拉强度不易保证，设计中忽略混凝土的受拉承载作用是可行的。虽然《压水堆核电厂预应力混凝土安全壳设计规范》（NB/T 20303—2014）中平面受剪配筋计算公式不反映混凝土的贡献，并不代表混凝土不起作用，混凝土的作用体现在连接墙水平和竖向两个方向的钢筋并承受平行于裂缝的压力，即与水平和竖向两个方向的钢筋形成桁架以压杆的形式承载。

［关键词］核电厂； 钢筋混凝土单元； 平面内剪切； 修正压力场理论

中图分类号：X946文献标识码：A文章编号：1002-848X(2018)16-0051-08

Study on in-plane shear of RC element based on the  modified compressive filed theory

Zhang Nailong1, Sun Yunlun2, Gong Jinxin1

(1 Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China; 2 Chinergy Co.,  Ltd.,  Beijing 100193, China)

Abstract:A study on in-plane shear of RC element  which was designed according to Design requirements for prestressed concrete containments for pressure water reactor nuclear power plants (NB/T 20303—2014) in nuclear power plant based on the modified compressive filed theory (MCFT) was carried out in order to investigating the contribution of the concrete. It is revealed that due to the low tensile stress, low peak stress and strain of concrete, the reinforcements do not have a significant tensile effect when the concrete reaches its peak in principal tensile stress direction. While when the reinforcements reach yielding stress, the principal tensile stress of concrete reduces to a lower value because of post-peak softening, so it has very little influence on the ultimate shear capacity of reinforced concrete element.Considering the minor contribution of concrete in tension at the ultimate state of the RC element and brittle property of the concrete material, as well as its tensile strength being no easily guaranteed, it is reasonable to do the design regardless of the contribution of concrete in tension. Although the calculation formula of planar shear reinforcement in Design requirements for prestressed concrete containments for pressure water reactor nuclear power plants (NB/T 20303—2014) does not reflect the contribution of concrete, it should be noted that it does not mean that the concrete has made no contribution. The contribution of concrete reflects in connecting reinforcements in horizontal and vertical directions and resisting the compression paralleled to the cracks. The concrete works as a compressive stud in the truss model in which the reinforcements work as ties.

Keywords:nuclear power plant; reinforced concrete element; in-plane shear; modified compressive filed theory

*国家科技重大专项（2014ZX06902011）。

作者简介：张乃龙，硕士研究生，Email: profznl@163.com。