Experimental Study on Deformability of Steel Column Base Connections

这项研究可以分为两大类。一个是检查每个连接到不同类型柱脚的框架的力学性能，另一个是检查地脚螺栓在拉剪联合作用下裸露部分的力学性能。通过本研究，明确了以下几点：*在与各种柱脚连接的框架中，与不同类型柱脚连接的框架的受力性能，随着轴压的增加，框架的强度和刚度变大，滞回环面积变大，外露式和外包式柱脚的转折点随着侧向力的增加而降低；然而，柱基充分嵌入基础梁的框架则不会发生这种下降。外包式柱基和嵌入式柱基的表观端部固定点分别位于围护结构的中间高度和基础梁顶部以下管尺寸的1.3倍处。*地脚螺栓外露部分在受拉和受剪联合作用下的力学特性，与普通结构螺栓相比，穿过灌浆层的锚杆的极限承载力略有下降，但由于砂浆的分离，这种螺栓产生了较大的变形。在反复荷载作用下，当剪切面位于锚杆的螺纹内时，其能力下降，而位移增加得更多。按《钢管结构设计与制造建议》中的公式给出的拉剪联合极限承载力一般是偏于安全的。

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