Study on Elucidation of Anchorage Mechanism in Composite Structural Members Using Concrete

本项目的第一阶段是在试验的基础上明确钢筋混凝土结构中90度钩形梁杆的锚固性能。我们提供了12个墙梁节点试件，这些试件对墙筋布置、l型梁杆锚固和特殊筋的存在有一定的影响。得到以下结果：(1)尾杆方向向上或侧向布置而非向下布置时，锚固强度均有所提高；(2)提供多根剪力杆，使传递应力区变宽，锚固强度增大；(3)在钩杆内侧水平布置一根粗钢筋，由于粗钢筋具有抗剪键作用，锚固强度提高；(4)考虑墙杆的销钉作用，可以提出较好的锚固强度估算方程。该项目的第二阶段是明确型钢在钢筋混凝土结构中的锚固性能。采用t形锚钢对钢筋混凝土基础梁与钢柱基础连接进行加载试验，得到如下结果：锚固件试验结果表明：(1)锚固钢的抗拔力与锚固钢的展开长度成正比；(2)锚固钢的横截面几何第二弯矩和锚固钢的长度对剪切荷载-位移关系的初始刚度没有影响，但横截面几何第二弯矩的增大使最大抗剪力增大；(3)在剪切和拉拔共同作用下，锚固钢的最大抗剪能力降低了10 ~ 20%；(4)在梁柱节点试验中，锚固钢在受拉锚固达到屈服后，在横向梁上设置锚固钢，其锚固强度保持不变。

The first stage of this project was to clarify anchorage performances of 90-degree hooked beam bars in reinforced concrete structures on the basis of experimetns. We provided twelve wall-beam joint specimens that had some variables on arrangements of wall reinforcement and L-shaped beam bar anchorage and on existence of special bars. The following results were obtained : (1) anchorage strength increased when the direction of tail bars was arranged upward or lateral, not downward, (2) providing many wall-tie bars made transmit stress zone become wider and anchorage strength increase, (3) anchorage strength of hooked bars increased when an additional fat steel bar was arranged horizontally at inside of the hooks because the bar resisted as a shear key, and (4) the good equation estimating anchorage strength could be proposed by considering the dowel action of wall bars.The second stage of this project was to clarify anchorage performance of shape-steels in steel & reinforced concrete structures. The following results were obtained from loading tests of connections between RC foundation beams and a steel column base using T-shaped anchor steels : from the anchorage element tests, (1) pullout resistance of anchor steels was proportional to development length of the anchor steels, (2) geometrical second moment of cross area and length of anchor steels did not affect on initial stiffness of shear load vs. displacement relationship but increase of geometrical second moment of cross area enlarged maximum shear resistance, (3) maximum shear resistance decreased by 10 to 20% when anchor steels were subjected to combination of shear and pullout forces, and (4) from the beam-column joint tests, anchorage strength was kept without deterioration by anchor steels set in transverse beams after the tensile anchor steel reached to yielding.