Study on the Improvement in Bearing Capacity and Deformability of Prestressed High Strength Concrete Pile

提高预应力高强混凝土桩承载力及变形能力的研究

• 批准号: 59460150
• 负责人: KOKUSHO Seiji
• 金额: $ 4.67万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1984
• 资助国家: 日本
• 起止时间: 1984 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-59460150/
• 关键词: PHC pile; Deformability; Brittle failure; Filled concrete; High tension spiral hoop; Pile - footing connection; 耐震設計

This report is the summary of the experimental study about the Prestressed High Strength Concrete Pile (PHC Pile) subjected to lateral load. The objective of this study was to investigate the reinforcing method by which the brittle failure could be prevented and the deformability of the pile could be improved.The B-type PHC piles of the Japanese Industrial Standard were mainly tested. The outer diameter of the pile was 30 cm. The magnitude of axial load was determined assuming that the pile was supported on firm stratum where the Standard Penetration Test Number was about 50. That is, 35 tf was for sustained loading. 0 tf and 70 tf were for temporary loading. 105 tf corresponded to the limit bearing load of the pile. The shear span to outer diameter ratio of pile was 3.0 assuming that pile head was fixed in the footing and the surrounding soil was fairly soft.As for the B-type PHC pile generally used in site, the amount of spiral hoop should be increased in order to prevent the brittle … More failure. It could not be prevented, however, under 105 tf of axial force, even if the pile was laterally reinforced by seven times amount of spiral hoop as much as that of generally used pile. So the specimens were reinforced as follows: the hollow part was filled with concrete and they were reinforced by high tension spiral hoop. The amount of spiral hoop was about 25 times as much as that of generally used pile. As the results, it was confirmed that the axial force of 105 tf could be kept until the displacement reached above 1/20 rad. in rotation angle of member.Furthermore, the experiment was carried out concerning the connection between the pile head and footing, in order to solve the problems generated by the rupture of longitudinal reinforcement and the cut-off of the pile head and to improve the deformability. As the results, the following method was proved to be effective for improving the axial load carrying ability and deformability: the amount of spiral hoop was increased, the pile head was cut off including longitudinal reinforcement of pile, the hollow part of the pile was filled with concrete, the deformed bars were longitudinally arranged in the filled concrete and they were bonded in the footing.The stress transfer mechanism in the pile-footing connection was analyzed. As a result, the fundamental data concerning the aseismic design of pile foundation subjected to lateral load. Less

本文是对预应力高强混凝土桩(PHC桩)在水平荷载作用下的试验研究总结。本研究主要对日本工业标准中的B型PHC桩进行了试验研究，探讨了防止脆性破坏、改善桩的变形能力的加固方法。桩的外径为30厘米。轴向荷载的大小是假定桩支撑在坚硬的地层上的，标准贯入试验次数约为50。也就是说，35Tf用于持续负荷。0Tf和70Tf用于临时加载。105Tf对应于桩的极限承载荷载。假定桩头固定在桩基内，桩周土质较软，桩的剪跨外径比为3.0.对于现场常用的B型PHC桩，应增加螺旋箍的数量，以防止…的脆性更多的失败。然而，在105Tf的轴力作用下，即使采用7倍于一般桩的螺旋箍进行横向加固，也不能防止这种情况的发生。因此，对试件进行了如下加固：空心部填充混凝土，并采用高张力螺旋箍进行加固。螺旋箍的数量是常用桩的25倍左右。结果表明，在位移达到1/20rad以上时，可以保持105Tf的轴向力。此外，还对桩头与桩基的连接进行了试验，以解决纵向钢筋断裂和桩头截断带来的问题，提高桩身的变形能力。结果表明，增加螺旋箍的数量，截断桩头包括桩的纵向配筋，在桩的空心处填充混凝土，将变形钢筋纵向布置在填充混凝土中，并将其粘结在基础中，可以有效地提高桩身的轴向承载能力和变形能力。从而为水平荷载作用下的桩基抗震设计提供了基础数据。较少

项目成果

黒正清治: 日本建築学会大会学術講演梗概集. B. 1241-1242 (1986)

Seiji Kuromasa：日本建筑学会会议学术讲座摘要 B. 1241-1242 (1986)。

黒正清治: 日本建築学会大会学術講演梗概集. B. 977-980 (1985)

Seiji Kuromasa：日本建筑学会会议学术讲座摘要 B. 977-980 (1985)。

和田章: 日本建築学会構造系論文報告集. 364. 111-120 (1986)

Wada, Akira：日本建筑学会结构系统学报。364. 111-120 (1986)

黒正清治: 日本建築学会大会学術講演梗概集. B. 1255-1256 (1986)

Seiji Kuromasa：日本建筑学会会议学术讲座摘要 B. 1255-1256 (1986)

Seiji KOKUSHO: "Bearing Capacity and Deformability of High Strength Prestressed Concrete Piles under Axial and Lateral Forces (Part 6)" Report of the Annual Meeting, Architectual Institute of Japan. B. 1241-1242 (1986)

Seiji KOKUSHO：《轴向力和横向力作用下高强度预应力混凝土桩的承载能力和变形能力（第6部分）》年会报告，日本建筑学会。