Soil-Rounding Effect on Embedded Rocking Foundation via Horizontal Slow Cyclic Tests

Ko, Kil‐Wan; Ha, Jeong‐Gon; Park, Heon-Joon; Kim, Dong-Soo

doi:10.1061/(asce)gt.1943-5606.0001848

Cited by 24 publications

(4 citation statements)

References 23 publications

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“…The outcomes of the bearing capacity tests on square, circular, and rectangular footings placed on loose and dense subgrade conditions are presented in Figure 3. This study defines the ultimate bearing capacity as the load at which the load-settlement curve peaks or, in the absence of a peak, the load at which the vertical stiffness's rate of change becomes constant [2,23,47]. Table 2 includes the corresponding values at these points.…”

Section: Vertical and Horizontal Loading Systemsmentioning

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: Vertical and Horizontal Loading Systemsmentioning

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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“…Kokkali et al 41 measured soil-foundation contact stress distribution at distinct moments during foundation rocking motions using a tactile pressure sensor placed beneath the foundation. Ko et al 42 have also employed three earth pressure transducers attached to the side, edge, and middle of the foundation, to monitor the variations in the earth pressure and examine the soil-rounding phenomena during foundation rocking motions. A more focused study on the foundation deformation mechanisms and development of failure modes within the soil was conducted by Knappet et al 43 using PIV technique combined with high-speed videography and photogrammetry.…”

Section: Introductionmentioning

confidence: 99%

“…measured soil‐foundation contact stress distribution at distinct moments during foundation rocking motions using a tactile pressure sensor placed beneath the foundation. Ko et al 42 . have also employed three earth pressure transducers attached to the side, edge, and middle of the foundation, to monitor the variations in the earth pressure and examine the soil‐rounding phenomena during foundation rocking motions.…”

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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“…Giouvanidis and Dong [8] compared the results of the conventional design approaches of bridge columns with design approaches that consider rocking isolation effects. Different researchers used shaking table tests to investigate the behavior of rocking foundations on sands [9][10][11] while, for better simulation of stress distribution of models, some other researchers employed centrifuge tests to investigate the behavior of rocking foundations [12][13][14][15][16][17]. Kim et al [18] and Liu et al [19] used centrifuge tests to investigate the behavior of low rises buildings with rock foundations.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Behavior of Bridge Piers Considering Rocking Isolation Constructed on Non-plastic Silts and Sands Using 1g Shaking Table Tests

Irani

Hajialilue-Bonab

Sarand

et al. 2023

Period. Polytech. Civil Eng.

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Occurred damages on the bridge piers during earthquakes lead to significant financial losses worldwide every year and can cause social problems by disrupting traffic flow and transportation services. Rocking isolation of foundations is one of the damage reduction approaches to avoid structural damage on piers by transferring plastic hinges from piers to underlying soil media. The behavior of rocking foundations on non-plastic silts has not been investigated well until now in the literature. In this research, the characteristic seismic behavior of a bridge pier considering rocking isolation is evaluated using small-scale physical modeling tests. To this aim, eight shaking table tests (with sinusoidal excitations) are conducted where both sandy and silty materials are employed as the soil media. In addition to the effects of the underlying soil, the effects of the critical contact area ratio of the foundation and frequency of input motions are evaluated. Achieved results indicate that the considered bridge pier shows the same behavior trend for underlying silty soil and sandy one. However, because of the frequency-dependent behavior of non-plastic silty soil, the pier attracts lower accelerations and higher moments. Therefore, the achieved results show that the proposed design approaches of rocking foundations that are mostly extracted based on experimental studies on sands (or rarely on clay) can lead to non-conservative designs in silty soils.

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Soil-Rounding Effect on Embedded Rocking Foundation via Horizontal Slow Cyclic Tests

Cited by 24 publications

References 23 publications

Effect of Footing Shape on the Rocking Behavior of Shallow Foundations

Effect of Footing Shape on the Rocking Behavior of Shallow Foundations

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

Investigation on the Behavior of Bridge Piers Considering Rocking Isolation Constructed on Non-plastic Silts and Sands Using 1g Shaking Table Tests

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