杭配置に偏心を有する杭支持構造物の地震時ねじれ挙動に関する研究

摘要

In this study, centrifuge model tests have been carried out to evaluate the torsional behavior of pile-supported buildings with the eccentric distance between the center of gravity of the superstructure and the center of rigidity of the piles. Three models were considered; a 9-pile model without eccentricity, an 8-pile model which lacks a corner pile, and a 7-pile model which lacks two corner piles. It was found from the test that the maximum response of the torsional angle of a foundation increases in accordance with the eccentricity which is defined as the same method as the superstructure. The analysis was then carried out to simulate the result of the 7-pile model. In the analysis, a three-dimensional frame model was used, and soil around the piles was modeled as two directional horizontal axial elements and shear springs. A comparison between experimental and analytical results shows a possibility that this numerical model is capable of considering the dynamic torsional behavior of buildings supported by unsymmetrically arrayed piles.%場所打ちRC杭の設計においては、杭先端を拡底させて支持力を 確保することが多いため、杭の軸断面は必ずしも負担軸力に応じて 設定されているとは限らない。そのため、高層棟と低層棟の基礎を 一体として設計する場合や、コアの偏在などの要因で上部建物の重 量分布に偏りがある建物では、重量分布と杭頭付近の軸径より定ま る杭基礎の水平剛性分布た大きな偏心が生じる可能性がある。