Figure 1-2
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The application results of foundations in a tamped ditch in complex geotechnical conditions are strongly considered. The article informs about the experience of the effective foundation application instead of pile foundations. Also, a special attention is given to stress-strain analysis in the active zone of the soil basement of the foundation in a...
Citations
... relationship between pile diameter and lateral displacement at different lateral loads.Reese et al.[41], O'Neill and Murchison[42] and Basu et al.[43] defined the allowable lateral displacement of 25 mm corresponding to the allowable service pile lateral load capacity. So that the allowable design lateral load should be taken as 60 kN and 90 kN for piles of diameter 0.8 m and 1.2 m, respectively. ...
Coastal soil formation covers many places all over the world in which the upper soil layer is soft to very soft clay extended to great depths followed by a stiff layer such as dense to very dense sand. Due to the low shear strength, the high compressibility of the upper soft clay and the vast advances in construction of tall and heavy buildings, large diameter piles are utilized to safely transfer large vertical and/or lateral loads to the bearing stratum. The main objective of this research is to analysis and design of large diameter piles especially piles with diameters larger than 1.2 m as most of the design criteria are controlled by relatively smaller diameters usually ranging between 0.6 m to 1.2 m. Hence, a parametric study is performed using Finite Element Method to study the behavior of large diameter piles under vertical and lateral loads. This numerical modeling aims to assess the actual lateral load capacities for large diameter pile then recommend guidelines for designing such piles in such weak soil formation. Results show that piles with diameters less than or equal to 1.6 m should safely carry a lateral load less than 100 kN. While piles with diameters larger than 1.6 m can safely carry lateral loads up to 200 kN to satisfy the serviceability conditions. The study also showed that, increasing the pile embedment length in the end bearing layer has no significant effect on the lateral load capacity of large diameter piles.
... For analysing the PSI, the continuum based methods (pioneered by [8]) are the most realistic and conceptually more appealing ones. However, these are less popular, involving either complicated mathematics or not providing simple and practical steps to obtain the pile deflection [9]. Many practicing engineers therefore opted for a simpler beam on Winkler foundation approach which evaluates the E s (modulus of subgrade reaction) values along the pile length by means of the discrete and closely spaced p (soil pressure per unit pile length) − y (pile lateral deflection) curves along the pile length. ...
Lateral responses of a pile are governed by its mutual interaction with the supporting soil, known as the Pile-Soil Interaction (PSI), which in turn influences its structural limit states. The present study evaluates the seismic limit states for bridge pile in sand, while incorporating the parametric influences of pile and soil assessed through PSI. Such influences have not been dealt with in the past, except for the p (soil-pile reaction) – y (pile deflection) responses (though with only few pile parameters). Pile cross sectional size, grades of concrete and reinforcement, longitudinal and transverse reinforcement ratios, axial load ratio and the sand effective friction angle are observed to affect the PSI and consequently the limit states. Thus, limit states are proposed as parameterised expressions, generated through regression on the limit state data obtained by analysing the damage model (developed herein) for the pile-soil system samples generated over wide ranges of the influential parameters. These expressions, validated through the compliance with the expected trends and a fair agreement with a test result, can be readily used to obtain the expected values of the limit states over a broad range of parametric
combinations and without requiring analysis repetition. These, in turn, can contribute to reliable estimation of fragility of a bridge system with the given properties for its pile foundation.
... In general, some methods [20,21] are available for piles in homogeneous soil. Davisson and Gill [22] and Basu et al. [23] studied the behaviour of laterally loaded piles in layered soil. The concept of strain wedge theory was utilized by Ashour et al. [24] and Ashour and Norris [25], to study the characteristics of piles in layered soils under lateral load. ...
In this present study, a Beam on Nonlinear Winkler Foundation approach has been utilized to study the effect of ground improvement on deformation characteristics of laterally loaded pile. Fourth-order governing differential equation of pile deformation has been solved, and a simplified pile–soil stiffness matrix has been developed. The optimum depth (from ground surface) up to which engineering properties of soil require to be improved has been ascertained using a computer code developed in MATLAB utilizing the developed soil–pile stiffness matrix. This optimum depth can be defined as the depth beyond which the improvement in engineering properties of soil (e.g., deformation modulus) has negligible effect on deformation characteristics of laterally loaded pile. Optimum depth has been suggested for different slenderness ratios of piles installed in soft-to-medium-stiff clayey soil deposit, and statistical equations have been developed to find the optimum depth of ground improvement for different pile slenderness ratios (L/D) and relative stiffness (Ep/Es) of pile. The study reveals that the optimum layer improvement ratio (L1/L) reduces with the increased pile slenderness ratio (L/D) and increases with the increased relative stiffness (Ep/Es) of pile. Design charts have been proposed to get a preliminary estimation of lateral pile capacity in virgin clay as well as improved clay for different layer improvement ratios (L1/L).
... Load resistance mechanism of pile foundation (source: Basu et al. 2008) Pile capacity mainly depends on the type of pile and the soil condition in which the piles are embedded. Because of this, the CPT/PCPT based methods based on the direct approach incorporate several different correlation factors, which depend on the type of piles and soils. ...
The geotechnical design of a pile foundation is concerned with the determination of the safe magnitude of an external load that the foundation can carry without jeopardizing the stability of the supported structure. In recent years, in-situ sounding tests are becoming a more attractive method to predict pile capacity due to the rapid development of testing instruments, improved understanding of their mechanics and interpretation, and cost efficiency. The cone penetration test (CPT) and its upgraded version, the piezocone penetration test (PCPT), are the most widely used in situ sounding tests to predict pile capacity. This research report compared eight CPT-based and three PCPT-based methods for potential application of the best performer(s) by the Nebraska Department of Transportation (NDOT) to predict pile capacity. Several statistical as well as non-statistical comparison criteria were adopted. According to the evaluation output, the modified (calibrated) Tumay and Fakhroo (1982) method was found to be the best performer for H-piles, and the modified De Ruiter and Beringen (1979) method was found to be the best performer for pipe and precast prestressed concrete piles. For a complete design of pile foundations, the settlement criterion has to be incorporated. The settlement of pile foundations must not exceed a certain tolerable magnitude of settlement to ensure the safety of the structure supported. In this regard, this research project adopted the t-z curve approach to predict pile settlements. Several existing t-z curve approaches based on analytical and numerical techniques were assessed and their relative accuracy was investigated. An easy to use software for the computation of settlement was also developed.
... Metode Kontinum Elastis Homogen mengasumsikan tanah di sekitar tiang sebagai kontinum tiga-dimensi. Menurut Salgado et al. (2008), pemodelan tanah sebagai Kontinum tiga-dimensi secara konsep merupakan pemodelan yang lebih akurat. lebih akurat. ...
Analisa daya dukung lateral merupakan aspek penting dalam perancangan fondasi untuk mengantisipasi kegagalan fondasi tiang. Salah satu metodenya adalah p-y curve yang merupakan pengembangan dari metode Balok pada Fondasi Winkler. Metode p-y curve memodelkan tanah sebagai pegas non-linier. Metode ini diperkenalkan oleh McClelland dan Focht pada tahun 1956 dalam bentuk kurva hubungan reaksi tanah dengan defleksi akibat beban lateral. Metode p-y curve lebih umum digunakan karena tahap pengerjaannya yang tidak rumit jika dibandingkan dengan metode lainnya dan hasilnya dapat diandalkan. Akan tetapi, metode p-y curve tidak memperhitungkan pengaruh bentuk penampang karena tiang disederhanakan menjadi model tiang satu dimensi dengan pendekatan empiris. Penelitian ini membandingkan pengaruh lubang pada penampang spun pile dan tiang baja tubular terhadap p-y curve menggunakan metode yang diusulkan oleh Georgiadis (2010) dengan p-y curve yang dibentuk dengan program LPILE. Hasil dari penelitian ini menunjukkan bahwa p-y curve untuk tiang dengan penampang solid lebih kaku daripada tiang dengan penampang void.
... Znanym środkiem zaradczym jest zastosowanie modelu dwuparametrowego, np. Pasternaka (Henry, 1986), w którym sąsiadujące ze sobą sprężyny nie są niezależne (Basu, Salgado i Prezzi, 2008). Jakość modelu Winklera czy Pasternaka znacznie poprawia jego delinearyzacja w postaci tzw. ...
... Architectura, 17 (2), 37-51. doi: 10.22630/ASPA.2018.17.2.13 kon strukcji inżynierskich, przykładowo w pracach Basu, Salgado i Prezzi (2008), jak również Versteijlena, Metrikine'a i van Dalena (2016), w których wykazano, że wyniki otrzymywane dla pali-słupów turbin wiatrowych (ang. off-shore monopiles) i grup palowych są porównywalne z przestrzenną ana lizą MES, pod warunkiem zastosowania wyrafinowanej techniki identyfikacji "współczynnika podłoża" C. ...
... Począwszy od prac Bromsa z 1964 roku (por. Dodds i Martin, 2007;Basu, Salgado i Prezzi, 2008) dla gruntów spoistych przyj mu je się zazwyczaj wartość sztywności niezależną lub niemal niezależną od głębokości, a dla gruntów niespoistych za lepszy model uważa się funkcję liniowo rosnącą z głębokością, ewen tu alnie (dla pali) stałą poniżej głębokości 5 m (Kosecki, 2006). Omawiana przez Dembickiego oraz Tejchmana (1974) funkcyjna zależność dla poziomej sztywności podłoża C v = k h = k s ⋅ z/L v osiąga maksymalną wartość k s na dolnym końcu ścianki z = L v , co budzi wątpliwości. ...
... To verify the above approach, a laterally-loaded pile taken from [17] is analyzed. The pile of length L p = 20 m, cross-section radius r p = 0.3 m and modulus E p = 25 × 106 kN/m 2 is subjected to a lateral force F 0 = 300 kN and a moment M 0 = 100 kNm at the pile head. ...
... To verify the above approach, a laterally-loaded pile taken from [17] is analyzed. The pile of length p L =20 m, cross-section radius p r =0.3 m and modulus p E =25×106 kN/m 2 is subjected to a lateral force 0 A finite-element model of forty elements with equal length 0.5 m is used for the analysis. ...
... To verify the above approach, a laterally-loaded pile taken from [17] is analyzed. The pile of length p L =20 m, cross-section radius p r =0.3 m and modulus p E =25×106 kN/m 2 is subjected to a lateral force 0 F =300kN and a moment 0 M =100 kNm at the pile head. ...
A fuzzy finite element approach for static analysis of laterally loaded pile in multi-layer soil
with uncertain properties is presented. The finite element (FE) formulation is established
using a beam-on-two-parameter foundation model. Based on the developed FE model,
uncertainty propagation of the soil parameters to the pile response is evaluated by mean of
the α-cut strategy combined with a response surface based optimization technique. First
order Taylor's expansion representing the pile responses is used to find the binary
combinations of the fuzzy variables that result in extreme responses at an α-level. The exact
values of the extreme responses are then determined by direct FE analysis at the found
binary combinations of the fuzzy variables. The proposed approach is shown to be accurate
and computationally efficient.
... Qualitative descriptions for pile-soil system damages, considering soil failure, were prescribed based on the displacement limits to satisfy serviceability and ultimate failure criteria (Table 31.) [92]. The pile head deflection exceeds the tolerable head deflection. ...
... The pile head deflection exceeds the tolerable head deflection. If pile displacement remains within a certain level and no notable residual displacement appears, it is expected that a steady horizontal soil resistance to piles is maintained and nothing is going to happen in service [93] 0.025 pile diameters [92] 1% diameter of pile [93] Ultimate ...
... The soil resistive stresses attain the limit (yield) value over a substantial portion of the pile length so that plastic flow occurs within the soil mass resulting in large lateral deflections, translation or rotation of the pile [92] ...
The seismic assessment of bridges has been on ever-increasing demand owing to the crippling consequences of earthquakes on the integrity of the transportation networks of which the bridges are the most sensitive elements. It has been widely accepted that a priori assessment of vulnerability of a bridge to seismic damage helps towards critical pre-earthquake safety decisions regarding replacement or setting up appropriate retrofit strategy for the bridge with an objective of minimizing life and socio-economic losses during future earthquakes. This paper reviews the past studies on vulnerability assessment of various existing bridge types and configurations through the generation of analytical fragility curves and summarizes the various steps involved in different methodologies. Generation of fragility function is one of the key components of seismic vulnerability assessment. Past studies reveal that realistic fragility estimates are obtained through detailed analysis of bridge-foundation-soil system, reliable definition and quantification of damage states and identification of an optimal earthquake intensity measure corresponding to the particular bridge structural configuration and site-specific earthquake hazard.
... However, the piles do not only carry the axial force. The piles are often subjected to either monotonic or cyclic lateral loading due to different hazards, such as the impact of ships on bridge piers during berthing, wave and wind actions on offshore structures, and seismic wave motion on different buildings (Poulos, 1977;Basu et al., 2008;Heidari et al., 2013;Peng et al., 2010). ...
This paper proposes a method for the nonlinear analysis of laterally loaded single reinforced concrete piles based on the beam-onnonlinear- Winkler-foundation approach. A nonlinear fiber beam-column element is used to model the nonlinear behavior of a pile. The pile is divided into a series of segments, of which the cross section is assumed to be plane and normal to the longitudinal axis. The internal force of a segment is derived by integrating the nonlinear stress-strain relationships of all steel and concrete fibers within the cross section of the segment. The substructure technique is introduced to calculate the stiffness matrix of the segments. The nonlinear behavior of soils surrounding the pile is characterized by a modified strain wedge model. The results show that (1) the predicted results using the proposed method are consistent with the measurements for all three full-scale tested piles, and (2) updating the neutral axis of segments has a significant effect on the calculated lateral deflection; however, it has a slight effect on the calculated bending moment. Moreover, an empirical equation is derived from the numerical analyses for estimating the cracked flexural rigidity of bored piles subjected to lateral loading.
... Later in this paper, the soil parameters k and t in Eqs. (12), (13), (14) will be treated as fuzzy variable. ...
... The analytical solution of the deflection at the top for this case is 63.4802 mm [11], which is compared with finite-element analysis using four, eight and twenty equal-length elements in Tab. 1. Good agreement is obtained using even coarse finite-element mesh. The second example is adapted from [12]. A pile of length L p = 20 m, radius r p = 0.3 m and modulus E p = 25 × 106 kNm 2 is subjected to a lateral force The analytical solution for this case is obtained using the method proposed by Pham [13]. ...
... According to Eq. (12), it can be seen that the stiffness matrix is linear with respect to the soil parameters. Therefore, the fuzzy stiffness matrix can be expanded as ...
A fuzzy finite-element method for analysis of laterally loaded pile in multilayer soil with uncertain properties is presented. The finite-element formulation is established using a beam-on-two-parameter foundation model. Uncertainty propagation of the soil parameters to the pile response is evaluated by a perturbation technique. This approach requires a few number of classical finite-element equations to be solved and provides reasonable results. A comparison with vertex method is made in a numerical example.
