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

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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.