• Coupled systems mechanics
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• v.5 no.4
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• pp.285-304
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• 2016

The effects of large rotations and p-delta on the dynamic response of a structure subjected to seismic loading and local uplift of its foundation were analyzed in this work. The structure was modeled by an equivalent flexible mat mounted on a rigid foundation that is supported either by a Winkler soil type or a rigid soil. The equations of motion of the system were derived by taking into account the equilibrium of the coupled foundation-mat system where the structure was idealized as a single-degree-of-freedom. The obtained nonlinear coupled system of ordinary differential equations was integrated by using an adequate numerical scheme. A parametric study was performed then in order to evaluate the maximum response of the system as function of the intensity of the earthquake, the slenderness of the structure, the ratio of the mass of the foundation to the mass of the structure. Three cases were considered: (i) local uplift of foundation under large rotation with the p-delta effect, (ii) local uplift of foundation under large rotation without including the p-delta effect, (iii) local uplift of foundation under small rotation. It was found that, in the considered ranges of parameters and for moderate earthquakes, assuming small rotation of foundation under seismic loading can yield more adverse structural response, while the p-delta effect has almost no effect.

• Journal of Environmental Science International
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• v.27 no.8
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• pp.641-650
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• 2018

Paddy-upland rotation system is one of the important cropping system for improving soil quality and crop productivity. we conducted to investigate the effect of paddy-upland rotation system on soil properties and crop productivity in reclaimed tidal land. The paddy-upland rotation could be effective to conserve soil water contents and prevent from salt damage when cultivating upland crops. The first two years of maize cultivation after rice cultivation could be effective to secure stable production. However, in case of soybean crop, the rotation effect might be lower than that of maize. In the first year, the yield of soybean was 214 kg/10a. In the second and third year, the yields of soybean decreased consecutively to 152, 123 kg/10a respectively. In this paper, it would be suggested that maize be cultivated for up to two years and soybean be cultivated for one year after rice crop grown in reclaimed tidal land. This study could be provide basic data of the physico-chemical properties applicable to paddy-upland rotation system at reclaimed tidal lands.

• Earthquakes and Structures
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• v.25 no.2
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• pp.135-148
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• 2023

The structure-soil-structure interaction (SSSI) effect in adjacent structures may affect the liquefaction-induced damage of shallow foundation structures. The existing studies only analysed the independent effects on the structural dynamic response but ignored the coupling effect of height difference and distance of adjacent structures (F) on liquefied foundations on the dynamic response. Therefore, this paper adopts finite element and finite difference coupled dynamic analysis method to discuss the effect of the F on the seismic response of shallow foundation structures. The results show that the effect of the short structure on the acceleration response of the tall structure can be neglected as F increases when the height difference reaches 2 times the height of the short structure. The beneficial effect of SSSI on short structures is weakened under strong seismic excitations, and the effect of the increase of F on the settlement ratio gradually decreases, which causes a larger rotation hazard. When the distance is smaller than the foundation width, the short structure will exceed the rotation critical value and cause structural damage. When the distance is larger than the foundation width, the rotation angle is within the safe range (0.02 rad).

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.69-78
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• 2016

A suction bucket foundation has been considered to be a potential foundation type for offshore wind turbines. A suction bucket foundation is usually installed in soft soil, so the accumulated displacement of the foundation may occur under long-term cyclic loads. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The dry model ground was prepared to have two different soil densities by air-pluviation method. The model tests were performed varying the embedment depth of the suction bucket, the soil density, and the amplitude of cyclic load. A one-way horizontal cyclic load was applied over $10^4$ cycles. Test results showed that the accumulated rotation of the suction bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the suction bucket foundations in dry sandy ground under long-term cyclic horizontal loads.

• Steel and Composite Structures
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• v.35 no.2
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• pp.279-294
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• 2020

Foundation of a building is damaged under service loads during construction. First visit shows that the foundation has been punched at the 6 column's foot region led to building rotation. Foundation shear punching occurring has made some stresses and deflections in construction. In this study, progressing of damage caused by foundation shear punching and inverse loading in order to resolve the building rotation has been evaluated in the foundation and frame of building by finite element modeling in ABAQUS software. The stress values of bars in punched regions of foundation has been deeply exceeded from steel yielding strength and experienced large displacement based on software's results. On the other hand, the values of created stresses in the frame are not too big to make serious damage. In the beams and columns of ground floor, some partial cracks has been occurred and in other floors, the values of stresses are in the elastic zone of materials. Finally, by inverse loading to the frame, the horizontal displacement of floors has been resolved and the values of stresses in frame has been significantly reduced.

• Geomechanics and Engineering
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• v.4 no.3
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• pp.173-190
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• 2012

With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.157-171
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• 2009

A 151 storey super high-rise building located in an area of reclaimed land constructed over soft marine clay in Songdo, Korea is currently under design. This paper describes the design process of the foundation system of the supertall tower, which is required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behaviour of the foundation system due to these loads and foundation stiffness influence the design of the building super structure, displacement of the tower, as well as the raft foundation design. Therefore, the design takes in account the interactions between soil, foundation and super structure, so as to achieve a safe and efficient building performance. The site lies entirely within an area of reclamation underlain by up to 20m of soft to firm marine silty clay, which overlies residual soil and a profile of weathered rock. The nature of the foundation rock materials are highly complex and are interpreted as possible roof pendant metamorphic rocks, which within about 50m from the surface have been affected by weathering which has reduced their strength. The presence of closely spaced joints, sheared and crushed zones within the rock has resulted in deeper areas of weathering of over 80m present within the building footprint. The foundation design process described includes the initial stages of geotechnical site characterization using the results of investigation boreholes and geotechnical parameter selection, and a series of detailed two- and three-dimensional numerical analysis for the Tower foundation comprising over 172 bored piles of varying length. The effect of the overall foundation stiffness and rotation under wind and seismic load is also discussed since the foundation rotation has a direct impact on the overall displacement of the tower.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2002.03a
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• pp.123-123
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• 2002

• Earthquakes and Structures
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• v.16 no.6
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• pp.691-704
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• 2019

This study simulates the responses of large-scale bridge piers under pseudo-dynamic tests to investigate the performance of four types of numerical models that consider the nonlinear behavior of the pier and the rocking behavior of the footing. In the models, beam-column elements with plastic hinges are used for the pier, two types of foundation models (rotational spring and distributed spring models) are adopted for the footing behavior, and two types of viscous damping models (Rayleigh and dashpot models) are applied for energy dissipation. Results show that the nonlinear pier model combined with the distributed spring-dashpot foundation model can reasonably capture the behavior of the piers in the tests. Although the commonly used rotational spring foundation model adopts a nonlinear moment-rotation property that reflects the effect of footing uplift, it cannot suitably simulate the hysteretic moment-rotation response of the footing in the dynamic analysis once the footing uplifts. In addition, the piers are susceptible to cracking damage under strong seismic loading and the induced plastic response can provide contribution to earthquake energy dissipation.

• Clinics in Shoulder and Elbow
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• v.25 no.4
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• pp.282-287
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• 2022

Background: Muscular forces drive proximal humeral fracture deformity, yet it is unknown if arm position can help mitigate such forces. Our hypothesis was that glenohumeral abduction and humeral internal rotation decrease the pull of the supraspinatus and subscapularis muscles, minimizing varus fracture deformity. Methods: A medial wedge osteotomy was performed in eight cadaveric shoulders to simulate a two-part fracture. The specimens were tested on a custom shoulder testing system. Humeral head varus was measured following physiologic muscle loading at neutral and 20° humeral internal rotation at both 0° and 20° glenohumeral abduction. Results: There was a significant decrease in varus deformity caused by the subscapularis (p<0.05) at 20° abduction. Significantly increasing humeral internal rotation decreased varus deformity caused by the subscapularis (p<0.05) at both abduction angles and that caused by the supraspinatus (p<0.05) and infraspinatus (p<0.05) at 0° abduction only. Conclusions: Postoperative shoulder abduction and internal rotation can be protective against varus failure following proximal humeral fracture fixation as these positions decrease tension on the supraspinatus and subscapularis muscles. Use of a resting sling that places the shoulder in this position should be considered.