In this study, we conducted the experiments of the restoring force characteristics of column rocking found in the temple buildings using large-diameter columns on the basis of the Japanese traditional construction methods, and especially experimental verification was conducted on the effects of varying axial force and the horizontal cross members, because experiments with these parameters had not been examined so far. The configuration of the specimens is shown in Fig. 1, and the parameter of specimens is given in Table1. There were two types of test specimens: a test specimen with only a column and one with horizontal cross members at the top and bottom of the column. The obtained results are summarized below.
In the case of the specimens with horizontal cross members, the hysteresis loop at the initial deformation due to the nonlinearity was expanded (Fig. 5), and the embedment of wood by transverse compression was observed in the horizontal members (Photo1). Especially when the axial force was changed, the horizontal members are remarkably damaged.
The theory-based formula is valid for the specimens with only a column in comparison with the test results (Fig. 8), but the determination method of bearing stiffness which is an important constant is a future issue. On the other hand, in the case of the specimens with horizontal cross members, the restoring force calculated by the theory-based formula is much lower than the experimental results because the assumed failure mode is different between the theory and experimental result.
Comparing the relationship between bending moment and rotational angle of the end of the column where the P-Δ effect has been removed (Fig. 9), in the case of the specimens with only a column, the bending moment remains constant after yielding near 1/100 radian. However, in the case of the specimens with varying axial force, the rigidity increased after yielding in response to the increased axial force. Also, in the case of the specimens with horizontal cross members, the rigidity gradually increased after yielding because the embedment of wood by transverse compression of the horizontal cross members is a dominant failure mode. As a result of the comparison of non-dimensional data (Fig. 10), there is a significant difference in the specimens with horizontal cross members in comparison with other test conditions, and the maximum yield strength is about 50% in comparison with the specimens with only a column.
Based on the conclusions in this paper, we will establish an evaluation formula for the case with horizontal cross members and useful application methods for actual design and analysis in the future.
