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

本工程的第一阶段是在试验的基础上，对钢筋混凝土结构中90度弯曲梁的锚固性能进行了研究。提供了12个墙梁节点试件，这些试件在墙体配筋、L梁筋锚固方式以及特殊筋的存在等方面存在一定的变异性。结果表明：(1)当尾筋方向向上或横向布置而不是向下布置时，锚固强度增加；(2)设置较多的墙体拉筋使传递应力区变宽，锚固强度增加；(3)钩杆内侧水平布置一根粗钢筋作为剪力键，提高了钩筋的锚固强度；(4)考虑墙筋的粘结作用，提出了估算锚固强度的良好公式。通过对钢筋混凝土地基梁与钢柱底部T形锚杆节点的加载试验，得出以下结论：(1)锚杆抗拔力与锚杆的发展长度成正比；(2)截面几何二阶弯矩和锚筋长度对初始剪切荷载-位移关系没有影响，但截面几何二阶弯矩的增大增大了最大剪力；(3)锚杆在剪力和拔出共同作用下，最大抗剪强度降低了10~20%；(4)梁柱节点试验表明，在抗拉锚筋达到屈服后，设置在横梁中的锚筋保持了锚固强度不变。

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.