A model is presented for pushover analysis of reinforced concrete soft-rst-story frames with columns extended toward inside of frames. The model includes a rotational spring of rst-story column and that of beam. The beam spring represents the exural resistance of the section which includes the beam and the second-story column. The yield deformation of each spring is determined based on the observed strain distribution of the longitudinal bars. The proposed model agreed with the test results much better than the conventional model, which provided up to twice of the observed strength and a half of the observed yield deformation.

<p>There are many differences of bond regulations between the AIJ code and the ACI code. In the AIJ code, bond stresses within a distance <i>d </i>from the end of a beam are assumed to be zero because of tension shift, where <i>d </i>is effective depth. By contrast, the ACI code does not. Another difference is checking for continuous bars. The AIJ code considers bond failure of continuous bars although the ACI code does not. The objective of this study is to verify these bond regulations.</p><p>Four RC beam specimens with single layered bars were tested. Test variables were length and the number of cut-off bars. Bond failure was observed before flexural yielding in all the specimens, and tension shift was not observed. The postulate in the ACI code is appropriate in such cases. Bond failure occurred along not only cut-off bars but continuous bars. The observed bond strengths of the continuous bars almost agreed with those calculated from the AIJ code.</p>

A previous paper by our group has presented a model for RC soft-rst-story frames with columns extended toward inside and subjected to opening load. In this paper, a model for closing load is developed with a similar method of the previous paper. The model includes a rotational spring of column and that of beam. The beam spring represents the exural resistance of the beam, the second-story column, the wall panel and the beam stirrups. The yield deformation of each spring is determined based on the observed strain distribution. The proposed model agreed with the test results much better than the conventional model.

Previous papers by our group have presented a model for RC soft-rst-story frames with columns extended toward inside. In this paper, a model for frames with columns extended toward outside is developed with a similar method of the previous papers. The model includes a rotational spring of rst-story column and that of beam. The beam spring represents the exural resistance of the beam and the second-story column. The proposed model agreed with the test results much better than the conventional model, which provided the higher strengths than the observed values and a half of the observed yield deformations.

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