| Title: | THREE-DIMENSIONAL ANALYSIS OF TORSIONALLY LOADED LARGE-DIAMETER BORED PILE GROUPS
This work is supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region (Project No. HKUST6037/01E). |
| DOI No: | 10.1142/9789812701480_0048 |
| Source: | TALL BUILDINGS (pp 311-317)
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| Author(s): | LIMIN ZHANG
Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
CARMEN Y. M. TSANG
Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
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| Abstract: | Large-diameter bored piles are commonly used in groups to support high-rise buildings or bridges. In addition to vertical, lateral, and moment loads, these piles have to resist torsional loadings from the superstructure by eccentricity of lateral loads. Compared with studies on responses of pile groups subjected to vertical, lateral and moment loadings, only limited study on response of torsionally loaded pile groups has been reported. In this paper, three-dimensional analyses are conducted to investigate the torsional response of a single pile and a 2×2 large-diameter bored pile group. The piles are 2 m in diameter, 13.2 m in length, and 6 m in spacing. For the relatively rigid piles studied, the relative twisting angle between the pile head and the pile toe is small for the torsionally loaded single pile and the individual piles in the pile group. However, the movements of the single pile and the pile group under torsion are quite different. The single pile only shows a pure torsional response while the group piles not only twist but also deflect in the direction of torsional movements. The applied torque is resisted by the torsional resistance and the lateral resistance of the group piles. The torsional resistance provided by the individual piles is mobilized at relatively small movements but the lateral resistance is mobilized continuously with the pile group rotation. At large deformations, the applied torque increment is mostly taken by the lateral resistance. The torsional resistance of individual piles is approximately 30% of the total resistance at a twist angle of 1.0 degree. |
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