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Free vibration analysis of piled raft foundation by FE-BE coupling method
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
Jagat Jyoti Mandal, Sayandip Ganguly
Strong superstructure built on a weak sub structure is similar to human with weak legs. Hence proper choice and accurate analysis of sub structure is very important which mainly depends on the nature of supporting soil. Pile foundation is considered as good solution where bearing capacity of soil is low and significant settlement is to be resisted. Generally in case of pile foundation a group of pile is constructed and tied together using a pile cap, The main purpose of the pile cap is to distribute the load from structure to piles under the cap. This pile cap is designed for structural capacity only. But the contribution of pile cap is significant when it is in direct contact with soil. Pile raft foundation is the one in which pile as well as pile cap takes part in the load distribution mechanism. The piled-raft foundation needs evaluation of number of factors to come up with proper analysis or design models that simulate actual site condition. In many cases raft foundation induces excessive settlement which is not acceptable due to serviceability requirements. Placing a number of piles in suitable manner under the raft reduces such settlement and restricts settlement to an acceptable range. In addition to settlement control, the bearing capacity of the whole system also improves. The conventional design methods used for pile groups may lead to a higher number of piles under the pile cap in some critical cases. Using piled raft, this number can be reduced where pile is mainly used as settlement reducer.
behavior and seismic design of steel piles
Published in Federico M. Mazzolani, Stessa 2003, 2018
Close inspection of the piles under this bridge indicated that almost all piles showed signs of yielding and separation of mill-scale and rust cover over a length of about one meter just below the pile cap. It could be observed that a partial plastic hinge has formed just under the pile cap with a length of about 30 to 50cm as shown in Figure 1. None of the piles showed any sign of local or overall buckling. A visual inspection of the area around the pile cap was conducted and measurements of the opening of the joints between the pile cap and soil or the pile cap and the undamaged riprap adjacent to the pile cap were taken. These investigations indicated that the pile cap might have moved horizontally at least about 10 to 12 cm in both directions relative to its surrounding soil and riprap.
Free vibration analysis of piled raft foundation by FE-BE coupling method
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
Jagat Jyoti Mandal, Sayandip Ganguly
Strong superstructure built on a weak sub structure is similar to human with weak legs. Hence proper choice and accurate analysis of sub structure is very important which mainly depends on the nature of supporting soil. Pile foundation is considered as good solution where bearing capacity of soil is low and significant settlement is to be resisted. Generally in case of pile foundation a group of pile is constructed and tied together using a pile cap, The main purpose of the pile cap is to distribute the load from structure to piles under the cap. This pile cap is designed for structural capacity only. But the contribution of pile cap is significant when it is in direct contact with soil. Pile raft foundation is the one in which pile as well as pile cap takes part in the load distribution mechanism. The piled-raft foundation needs evaluation of number of factors to come up with proper analysis or design models that simulate actual site condition. In many cases raft foundation induces excessive settlement which is not acceptable due to serviceability requirements. Placing a number of piles in suitable manner under the raft reduces such settlement and restricts settlement to an acceptable range. In addition to settlement control, the bearing capacity of the whole system also improves. The conventional design methods used for pile groups may lead to a higher number of piles under the pile cap in some critical cases. Using piled raft, this number can be reduced where pile is mainly used as settlement reducer.
Theoretical studies on dynamic impedances of symmetrically–distributed inclined piles with an elevated pile cap
Published in Marine Georesources & Geotechnology, 2023
Weida Ni, Zhigang Shan, Liuyuan Zhao, Wen Liu, Li Shi
An elevated pile–cap foundation was utilized to support the wind turbine. The foundation consists of six inclined piles (6), evenly distributed around a circle with a diameter () of 11 meters at the elevation of pile head. The pile is composed of a steel pipe () with a diameter of 2.5 meters and a wall thickness () of 33 millimeters. The embedded () and total lengths () of the pile are 80 meters and 130 meters, respectively, resulting in an elevated length () of 50 meters (). The pile is inclined at a 1:5 ratio corresponding to a rake angle () of arctan(0.2), as illustrated in Figure 2. The heads of the inclined piles are embedded in to a circular concrete cap with a diameter of 16 meters and a height of 4.5 meters, as depicted in Figure 2.
Micropiles below groundwater at the south auditorium block site, Buffalo, New York
Published in DFI Journal - The Journal of the Deep Foundations Institute, 2018
Mary C. Nodine, Paul Eggers, Michael P. Walker, Donald E. Aubrecht
Pile caps were designed for the maximum micropile load based on an eccentricity analysis after ACI load factors for dead, live, wind, and seismic loads were applied. Through an iterative process of revising the pile cap thickness and determining the governing design criteria (shear or flexure), pile cap reinforcement requirements were selected. A majority of the pile caps were governed by shear limit states given the high column and pile loads, so thicknesses up to 82 inches were required for some pile caps (Pile Cap D2 was thicker due to subbasement geometry). Considerations for reinforcement requirements included the ability to fully develop tension in the reinforcement given the pile cap geometric constraints (i.e. maximum bar size of #8 was required due to side clearances), spacing requirements for constructability, and providing sufficient confinement to prevent concrete breakout due to high micropile loads. A completed subbasement pile cap is shown in Fig. 8.
Effect of saturation on response of a single pile embedded in saturated sandy soil to vertical vibration
Published in European Journal of Environmental and Civil Engineering, 2020
Mohammed Y. Fattah, Bushra S. Zabar, Faris S. Mustafa
A case study using finite-element software for the dynamic analysis and structural design of a machine foundation on piles in homogeneous sandy soil was reported by Fattah et al. (2015). A parametric study was carried out to investigate the effect of the foundation geometry, the amplitude and frequency of the dynamic load, and the damping ratio. It was concluded that as the pile cap thickness increases the oscillation of displacement decreases due to material damping inherent in the concrete of the pile cap. There is a limit of the pile cap size at which its stiffness governs its dynamic response. Above this size the weight of the pile cap overrides its stiffness effect, and the additional weight leads to an increase in pile displacement.