抄録
Twelve reinforced concrete T-beams subjected to positive (slab compression) and negative (slab tension) repeated loads up to failure, were tested. In this report, the stiffness, the cracking and ultimate strength, the stiffness reduction, and the hysteretic characteristics were analized, and were discussed as follow. 1) The calculated stiffness of T-beams with the effective overhanging width of slab required by Eq. (1), proposed by Dr. Y. Higashi, argeed well with the test results. 2) The cracking moment could be approximately predicted by Eq. (3) for both T-beams with compression slabs and tension slabs. Where, the effective overhanging slab widths required by Eq. (2) were used for the calculation of modulus of section. 3) The reinforcement in the slabs act as tension reinforcement in cooperation with beam reinforcement in the negative loading. Yield moment of such T-beams could be assumed by Eq. (4), in which the sum of beam and slab reinforcement was less than balanced steel ratio for the cross-section of beam. 4) Restoring force characteristics of T-beams changed to slip type from bi-linear by many alternately repeated loads, and the relations between equivalent stiffness and repeat numbers were almost same as those of rectangular beams.
