An experimental study on the rocking behavior of circular and square footings under slow-cyclic loading

Khezri, Ali; Hosseini, Seyed Majdeddin Mir Mohammad; Moradi, Mohamadali; Maleki, Mahdi Rasouli; Rahmani, Fereshteh

doi:10.1007/s41062-022-00829-5

Cited by 4 publications

(3 citation statements)

References 32 publications

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“…Furthermore, circular footings showed inferior moment capacity compared with square footings. This may be due to the square footing's greater second moment of area compared with the circular footings [51].…”

Section: Foundation Moment Capacitymentioning

confidence: 99%

Effect of Footing Shape on the Rocking Behavior of Shallow Foundations

Khezri,

Moradi,

Mir Mohammad Hosseini

et al. 2024

Buildings

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Sources such as wind or severe seismic activity often exert extreme lateral loading onto the shallow foundations supporting high-rise structures such as bridge piers, buildings, shear walls, and wind turbine towers. Such loading conditions may cause the foundation to exhibit nonlinear responses such as uplift and bearing capacity mobilization of the supporting soil (i.e., rocking behavior). Previous numerical and experimental studies suggest that while such inelastic behaviors may engender residual deformations in the soil–foundation system, they offer potential benefits to the overall integrity of structures through dissipating energy and reducing inertia forces transmitted to the superstructure, thereby limiting seismic demand on structural elements. This study investigates the effect of footing shape on the rocking performance of shallow foundations in different subgrade densities and initial vertical factor of safety (FSv). To this end, a series of reduced-scale slow cyclic tests under 1 g condition were conducted using a single degree of freedom (SDOF) structure model. The performance of different footing shapes was studied in terms of moment capacity, recentering ratio, rocking stiffness, damping ratio, and settlement. For three foundations with different length-to-width ratios, the results indicate that increasing the safety factor and length-to-width ratio leads to thinner, S-shaped moment–rotation curves, mainly owing to the enhanced recentering capability and the P-δ effect. Moreover, across all foundation types, the repetition of a limited loading cycles with consistent rotation amplitude does not cause stiffness degradation or moment capacity reduction.

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Section: Foundation Moment Capacitymentioning

confidence: 99%

Effect of Footing Shape on the Rocking Behavior of Shallow Foundations

Khezri,

Moradi,

Mir Mohammad Hosseini

et al. 2024

Buildings

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“…Such studies signified that as the foundation F.S.v increases, foundation settlement and energy dissipation decrease, and conversely, its rotational stiffness, moment capacity, and recentering capability increase. [32][33][34] Foundation embedment depth is also an influential parameter in the rocking behavior of foundations. Studies on rocking foundations have often been carried out on surface foundations (without embedment depth), while in practice, foundations are commonly buried in the ground.…”

Section: Introductionmentioning

confidence: 99%

“…A majority of the previous studies have identified the initial vertical factor of safety (F.S.v) as an influential parameter on the rocking behavior of foundations. Such studies signified that as the foundation F.S.v increases, foundation settlement and energy dissipation decrease, and conversely, its rotational stiffness, moment capacity, and recentering capability increase 32–34 …”

Section: Introductionmentioning

confidence: 99%

Investigation of rocking mechanism of shallow foundations on sand via PIV technique

Moradi

Hosseini

Khezri

2023

Earthq Engng Struct Dyn

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Adoption of the rocking isolation concept in foundation design is considered as an effective method in reducing seismic loads of structures. Despite much research conducted on the rocking behavior of foundations, concerns regarding the practical application of the rocking foundation design concept still prevail. The concerns primary stem from the lack of accurate understanding and knowledge associated with the soil‐foundation deformation mechanisms during rocking motions. Determination of deformation mechanisms and soil mass failure modes during foundation rocking helps to gain insight into the rocking behavior, recognize influential factors on foundation settlement or uplift, and propose appropriate improvement strategies to control foundation deformations. The primary objective of this study is to investigate the deformation behavior and failure modes of the soil mass beneath a rocking foundation with various initial static vertical factors of safety (F.S.v) and embedment depths. To this end, a series of reduced‐scale slow‐cyclic tests under 1g condition have been conducted using a single degree of freedom (SDOF) model. To determine soil deformation mechanisms, soil displacement fields have been measured using Particle Image Velocimetry (PIV) technique. Soil deformation mechanisms during loading and unloading paths, as well as causes leading to the foundation settlement or uplift have been evaluated and discussed. Additionally, changes in the effective soil‐foundation contact area in different loading cycles have been examined based on the PIV results. Based on the results, soil deformation mechanisms in the loading portions include soil densification, wedge deformation and scoop deformation. As the footing embedment depth increases, wedge deformation mechanism becomes limited, while scoop deformation mechanism becomes stronger. Additionally, as the foundation F.S.v increases, the depth of influenced zone of the rocking foundation decreases and the soil displacement occurs to a more limited depth.

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