抄録
This paper describes an evaluation method for the residual deformation of high-rise reinforced concrete structures by considering the P-δ effect. The method is based on the hysteretic characteristics of reinforced concrete structures, and its effectiveness is assessed using single degree-of-freedom (SDOF) systems.
Chapter 2 shows that the evaluation method of residual deformation in consideration about the P-δ effect. Reinforced concrete structures have distinctive hysteretic characteristics that depend on the maximum deformation, and therefore, the cumulative plastic deformation is equal to the maximum plastic deformation. As the above result, the residual deformation, which does not include the P-δ effect, can be deal with the average of the maximum positive and negative deformations, according to Eq. (1-b). When the P-δ effect is considered, the residual deformation becomes large to the maximum deformation side, because the central axis of vibration tends to deviate in one direction under the influence of the P-δ effect. This feature suggests that the residual deformation including the P-δ effect can be evaluated by multiplying a ratio of the maximum deformation of the positive and the negative side, according to Eq. (4). As described above, the maximum residual deformation can be evaluated using the maximum plastic deformation, as shown by Eq. (5-b).
Chapters 3 and 4 describe the seismic response analyses conducted using six SDOF models; in these analyses, the stability coefficient θ was varied. The influence of the P-δ effect is assessed by the stability coefficient θ, and viewing the results by the value of the stability coefficients. These analyses yielded two findings. One was the accuracy of the above mentioned equations, and the other, interesting seismic behaviors.
With regard to the first finding, owing to the hysteretic characteristics of reinforced concrete structures, the relationship between the analysis results and the results estimated by Eq. (4) showed dispersion. However the values estimated using Eq. (4), were in good agreement with the analysis results compared to those obtained using Eq. (2-b). With regard to the second finding, it was observed that the residual deformation increased by the response in small amplitude after the maximum deformation. These behaviors do not depend on the variation in the stability coefficient θ. Based on the interpretation of the hysteretic characteristics of reinforced concrete structures, the maximum residual deformation can be approximated as the deformation at the maximum plastic deformation. Thus, we proposed that the residual deformation of high-rise reinforced concrete structures, including the P-δ effect, could be evaluated by considering the unloaded deformation of the maximum response values.
