Experimental Study on Deformability of Steel Column Base Connections

本研究可分为两组。一种是检查框架的力学行为，每个框架连接到不同类型的柱基础，另一种是锚栓暴露部分受到联合张力和剪切的影响。从这项研究中，澄清了以下几点。在连接所有类型柱基的框架中，随着轴向压缩的增加，框架的强度和刚度变大，滞回环的面积也变大。具有外露式或封闭式柱基座的框架的拐点随着作用于其上的侧向力的增加而降低；然而，这种降低不会发生在柱基充分嵌入基础梁的框架中。围封式柱基础和预埋式柱基础的端部固定视点分别位于围封的中间高度和基础梁顶部下方筒形尺寸的1.3倍处。*受拉剪联合作用下锚杆裸露部分力学特性受剪作用时，穿过灌浆层的锚杆与普通结构锚杆相比，极限承载力略有下降，且由于砂浆分离产生较大变形。当剪切面位于反复荷载作用下的锚杆螺纹内时，其承载力下降，而其位移增加的幅度大于单调荷载作用下的锚杆。由《钢管结构设计与制造建议》中公式给出的拉剪联合作用下的极限承载力，一般在荷载作用下较为安全

This study could be divided into two main groups. One was undertaken to examine the mechanical behavior of the frames each connected to different types of column bases, and the other was those of the exposed portions of anchor bolts subjected to combined tension and shear. From this study, the followings were clarified.*Mechanical behavior of frames each connected to different types of column bases In the frames connected to all types of column bases, the strength and rigidity of the frames became large and the area of the hysteresis loops becomes large, as the axial compression increases.The inflection points of the frames having exposed type or encased type column bases lower as the lateral force acting on them increases ; however, such lowering does not occur in the frames whose column bases are sufficiently embedded in foundation beams.The apparent points of end fixation of the encased type column bases and the embedded type column bases are located at the mid-height of the encasement and at a point 1.3 times the tube dimension below the top of the foundation beams respectively.*Mechanical characteristics of exposed portion of anchor bolts under combined tension and shear When subjected to shear, the ultimate capacity of anchor bolts placed through a grout layer shows slight decrease and such bolts show great deformation because of mortar separation compared with normal structural bolts.Where shear plane is located within the threads of the anchor bolts subjected to repeated loading, their capacities decrease and their displacements increase more substantially than in the case where they are subjected to monotonic loadings.The ultimate capacity under combined tesion and shear given by Equation shown in Recommendations for the Design and Fabrication of Tubular Structures in Steel is generally rather on the safe side under