Undertaken with industry, this paper analyses concrete-filled steel tube (CFTs) pile members in deep foundation systems under cyclic and seismic loads considering inelasticity for both pile and soil. Real seismic events have pointed out that piles may fail by forming multiple plastic hinges at various location or global buckling instability. This study confirms that CFT piles efficiently reduce damage in pile-heads and over the pile length, in depths that is difficult to access and repair the damage. The paper performs a set of analyses that enables understanding of the nonlinear mechanical behaviour of CFT piles and soil-structure interaction effects. The capacity margins of the novel foundation system are firstly assessed through controlled loading analyses (i.e., monotonic and cyclic loading histories), and then investigated further by a two-level seismic-intensity analysis. CFT pile damage patterns, displacement profiles and residual displacement are discussed and compared with those of corresponding concrete piles. Moreover, comparisons with four test campaigns taken from the literature confirm the correctness of the adopted nonlinear models for soil-pile interaction and soil inelasticity. Although its simplicity, the developed p-y modeling can successfully account for soil degradation effects making possible the simulation of the rather demanding, but advanced “s” shape of soil's cyclic behaviour, allowing for a reasonable comparison between composite and concrete piles. While the damage areas of both CFT and RC piles are mainly developed in pile heads and stiffness-discontinuous soil layers, CFT piles exhibit a lower damage than that of the RC piles nearly by 40% on average.

随着工业的发展，本文在考虑循环荷载和地震荷载的情况下，分析了深层地基系统中的钢管混凝土桩构件，同时考虑了桩和土的非弹性。真实的地震事件指出，桩可能会因在不同位置形成多个塑料铰链或整体屈曲不稳而失效。这项研究证实，CFT桩可有效减少桩头和整个桩长（在难以接近和修复损伤的深度）中的损伤。本文进行了一系列分析，使您能够了解CFT桩的非线性力学性能以及土-结构相互作用的影响。首先通过受控载荷分析（即单调和周期性载荷历史）评估新型基础系统的能力裕度，然后通过两级地震烈度分析进行进一步研究。讨论了CFT桩的损伤模式，位移曲线和残余位移，并与相应的混凝土桩进行了比较。此外，与文献中的四个测试活动进行比较，证实了采用的非线性模型对桩-土相互作用和土壤非弹性的正确性。尽管简单，但开发的py模型可以成功解决土壤退化的影响，从而可以模拟相当苛刻但先进的“ s”形土壤循环特性，从而可以对复合桩和混凝土桩进行合理的比较。虽然CFT和RC桩的破坏区域主要发生在桩头和刚度不连续的土层中，