Stress Transfer between Steel Tubular Column and Infill Concrete at A Connection of H-Beams to Concrete Filled Tubular Columns with Diagonal Braces

2003年，我们对钢管混凝土短柱进行了推挤试验，以研究钢管柱与填充混凝土之间的粘结强度，以及由于梁柱连接的贯通隔膜而产生的机械剪切连接效应。2004年，对由管状混凝土柱、h形梁和斜撑组成的框架模型进行了试验，以保证建筑框架的实际粘结强度和机械剪切连接件的效果。从试验中得出以下结论：(1)通过刺柱试验追溯了钢管混凝土粘结强度的传统认识。即粘结强度受管状截面形状（圆形或矩形空心截面）的影响较大，但受混凝土强度的影响不大。(2)贯通式隔膜对机械剪切接头的影响，可以用较低的强度来预测，或者用较低的强度来预测，或者用较低的强度来预测，或者用较低的强度来预测，即使在较大的安全裕度下，也可以用较低的抗剪屈服强度来预测。事实上，轴承强度在强度预测中占主导地位。在这种情况下，应考虑混凝土围压效应，使围压效应引入较大的安全裕度。(3)框架模型采用外隔膜加筋连接时，应力通过粘结作用从钢管传递到混凝土。在框架模型中观察到的粘结强度与钢管混凝土短柱的推拔试验结果几乎相似，其中顶部只有混凝土部分承受压缩荷载，底部只有钢管支撑。在另一项试验中，混凝土和钢管都在顶部承受压缩荷载，其粘结强度与框架模型得到的强度相比低估太多。(4)当框架模型采用横切式隔膜连接时，应力从钢管传递到混凝土时，可以预期力学剪切连接效应。尽管所有的框架模型都被设计为具有非常大的混凝土浇筑孔的隔膜，但柱基处暴露的混凝土部分被其自身的轴压应力压碎，而轴压应力必须从钢管传递过来。因此，在一般情况下，通过横断膜片连接的机械剪切连接效果可能足够大，以供实际使用。少

In 2003,we performed a push-out test of concrete-filled tubular stub columns to investigate the bond strength between tubular columns and infill concrete and the mechanical shear connector effect due to the cut-through diaphragm for beam-to-column connections. In 2004,frame models composed of a concrete-filled tubular column, H-shape beam and diagonal brace are tested to ensure the realistic bond strength and the effect of mechanical shear connectors in building frames.From the tests, the following conclusive remarks were introduced :(1)The conventional knowledge about the bond strength of concrete-filled tubes were traced by the stab column test. That is the bond strength is affected by tubular section shapes (circular or rectangular hollow section) strongly, but not so much by the concrete strength.(2)The effect of mechanical shear connector caused by the cut-through diaphragm can be predicted by the lower strength either the bearing strength between infill concrete and diaphragm in … More a tube or the shear yield strength of a diaphragm plate even with a large safety margin. In fact, the bearing strength dominated the strength prediction. In such a case, the concrete confining effect should be considered, so that the large safety margin is introduced by the confining effect.(3)In case of frame models with outside diaphragm stiffened connections, the stress transfers from a steel tube to concrete by the bond action. The bond strength observed in the frame models is almost similar to the one obtained from push-out test of concrete-filled tubular stub columns, where only concrete section is subjected to compressive load at the top and only steel tubular potion is supported at the bottom. The bond strength from another test where both of concrete and steel tube are subjected to compressive load at the top will give too much underestimation for the strength obtained from the frame model.(4)In case of frame models with cut-through diaphragm connections, the mechanical shear connector effect can be expected for stress transfer from steel tube to concrete. Even though all of the frame models were designed to have the diaphragm with very large hole for concrete casting, the exposed concrete portion at the column base crushed by the it own axial compressive stress which must be transferred from the steel tube. Therefore, in general, the mechanical shear connecting effect by cut-through diaphragm connections may be large enough for the practical use. Less