权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

A Study on Seismic Load Distribution Applied to Pile Foundation

桩基地震荷载分布研究

基本信息

批准号：
02805068
负责人：
SUGIMURA Yoshihiro
金额：
$ 1.15万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02805068/
关键词：
lateral resistance of pile infinite pile finite pile stress of pile inertia force dynamic analysis response displacement method load distribution method 杭杭基礎地震荷重分布曲げモ-メント

项目摘要

In earthquake resistant design of buildings supported by pile foundation, horizontal resistance of pile has been analyzed under the condition that a concentrated horizontal load is subjected to pile head as a seismic inertia force of superstructure. Because computed stresses of pile are decreasing rapidly with depth, section of lower part of piles is apt to be designed to have a corresponding lower capacity. But according to the results of recent research works such as sesmic response analysis or earthquake observation of pile-supported buildings, it has been clarified that comparatively large stresses are also produced in lower part of piles as well as pile head, i.e., response of soil deposits controls mainly behavior of piles. A new analytical method, therefore, is proposed in this study to get horizontal resistance of piles to static load distribution by introducing effects of seismic response of soil deposits.Firstly, general solutions for deflection curve of infinite piles subjec … More ted to three types of loading, such as a single concentrated load, uniformly distributed load and triangularly distributed load were derived from bending theory of beams on elastic medium by the same procedure as M. Hetenyi's solutions. Secondly, solutions for actual finite piles were getting by numerical analysis introducing the boundary conditions at pile head and pile tip, and the continuity conditions at the boundaries of each layer of infinite piles. In other words, correcting solutions were computed by numerical analysis, the summation of which and solutions of infinite piles satisfies the boundary conditions and continuity conditions of each layer.Seismic response analysis was carried out for combination of 4 models of soil deposits and 3 models of buildings, i.e., 5 storied, 10 storied and 15 storied buildings. From the results on stresses of piles, it is seen that effects of inertia force of superstructure are distinctive at pile head but response of soil deposits is dominant at lower part of piles. Next, time histories of bending moment of pile at each depth were separated into the components of response of soil deposits and of inertia force of superstructure. As for the latter, distribution of bending moment of pile is very similar to the one by the existing design method, while the other, it is necessary to evaluate up to second natural mode at least to simulate distribution of bending moment of pile, if exists an intermediate soil layer which has extremely different rigidity to other layers. Lastly, composition method for components of response of soil deposits and inertia force of superstructure was investigated to get the design bending moment of piles. And then, following results were obtained. 1) Summation of absolute values explains well bending moment distribution of piles for the case of Ts>Tb (Ts:the first natural period of soil deposits, Tb:the first natural period of buildings). 2) On the other hand, root of summation of square is better for the both cases of Ts=Tb and Ts<Tb. Less

在桩基结构的抗震设计中，桩的水平抗力是在桩顶承受集中水平荷载作为上部结构的地震惯性力的情况下进行分析的。由于桩身计算应力随深度的增加而迅速减小，桩身下部截面的承载力容易相应降低。但根据近年来的研究工作，如桩基建筑物的地震反应分析或地震观测结果，已经阐明，在桩的下部和桩头也产生了较大的应力，即，土层的响应主要控制桩的性状。本文提出了一种新的考虑土层地震反应影响的桩水平抗力分布解析方法，首先给出了考虑土层地震反应影响的无限长桩的挠度曲线的一般解，然后给出了考虑土层地震反应影响的桩水平抗力分布解析解，最后给出了考虑土层地震反应影响的桩水平抗力分布解析解。 ...更多信息本文从弹性介质梁的弯曲理论出发，按M. Hetenyi的解决方案。其次，通过引入桩顶和桩端边界条件，以及无限长桩各层边界的连续性条件，对实际有限长桩进行数值分析，得到其解。即通过数值分析计算修正解，修正解的总和与无限长桩的解满足各层边界条件和连续性条件。5层，10层和15层的建筑。桩身应力分析结果表明，上部结构的惯性力在桩头处的影响比较明显，而桩下部的土层反应则占主导地位。其次，将桩身各深度处的弯矩时程分解为土层响应分量和上部结构惯性力分量。对于后者，桩身弯矩分布与现有设计方法的桩身弯矩分布非常相似;而对于另一种情况，如果存在刚度与其它土层相差很大的中间土层，则至少需要计算第二阶固有振型才能模拟桩身弯矩分布。最后，研究了桩身沉降响应分量与上部结构惯性力分量的合成方法，得到桩身设计弯矩。然后，得到以下结果。1)当Ts>Tb（Ts为土的第一固有周期，Tb为建筑物的第一固有周期）时，绝对值之和能很好地解释桩身弯矩的分布。2)另一方面，对于Ts=Tb和Ts<Tb的两种情况，平方和的根更好。少