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Adhesion factor: applications and limitations. Note
49A F
structures situated close to la"rge maples. Volumetric water variations are analysed and compared to rainfall deficits calculated for the period of monitoring and elevation profiles of the foundations. Observed damage is also compared to that according to a classification proposed by the BRE, England.
931368 Centrifugal testing of laterally loaded piles in sand Georgiadis, M; Anagnostopoulos, C; Saflekou, S Can Geotech d V29, N2, April 1992, P208-216 The response to lateral loading for model piles of three different diameters and flexural stiffnesses during centrifuge testing has been investigated. Pile head displacements and bending moments along the piles were measured and results compared to numerical predictions based on p-y relations of Reese et al, Scott, Murchison and O'Neill, and DnV. A new p-y relation for laterally loaded piles in cohesionless soils is suggested on the basis of this work. 931369 Lateral load tests to examine large-strain (seismic) behaviour of piles Naesgaard, E Can Geotech J V29, N2, April 1992, P245-252 In the Frazer River delta area on Canada's west coast, the combination of high potential seismicity and deep postglacial sediments makes the liquefaction of loose sands and differential settlement during a major earthquake a real possibility. Three different 406mm diameter piles (2 reinforced concrete shafts, one a concrete-filled steel pipe) have been tested under lateral, vertical, and moment loadings. The concrete piles failed with lateral pile head displacements of 300mm and 650mm and curvatures of 0.16 and 0.35rad/m respectively. The steel pipe withstood displacement and bending of 550mm and 0.08rad/m respectively. The stronger piles tolerate the greater lateral displacements. The flexibility of the concrete piles can be altered by changing the pitch of the spiral reinforcement. 931370 Adhesion factor: applications and limitations. Note Sladen, J A Can Geotech J V29, N2, April 1992, P322-326 The average ultimate shaft resistance of piles in clay is conventionally estimated by applying an empirically derived adhesion factor to the undrained shear strength of the soil. It is shown that this can have a theoretical basis, because horizontal stress at the interface and undrained shear strength are controlled by the same factors. The belief that mobilised strength is a fraction of the undrained shear strength is however erroneous. The danger of extrapolating adhesion factors beyond situations for which the empirical data were acquired is emphasised. 931371 Effect of loading history on the compression and uplift capacity of driven model piles in sand. Note Joshi, R C; Achari, G; Kaniraj, S R Can Geotech J I,'29, N2, April 1992, P334-341 Instrumented smooth cylindrical piles were driven into a bed of uniform sand prepared by raining. Load tests were carried out and the effects of pile slenderness and sand density on bearing capacity were also examined. Load transfer along the pile was studied at one value of L/D. Pile tip resistances were generally constant for L/D ratios of 20-33. Piles having a loading history showed significant decrease in bearing capacity
compared to untested piles. When piles were tested in compression following tension, end resistance was not mobilised until a certain pile movement had taken place, although side resistance was immediately mobilised. 931372 Discrete dement method for bearing capacity analysis Chang, C S; Chao, S J Comput Geotech V12, N4, 1991, P273-288 A DEM analysis for estimating bearing capacity of foundations is presented in which the soil mass is considered as blocks connected by elasto-plastic Winkler springs. Boundary stresses on the failure surface and ultimate capacity of shallow foundations can be obtained by considering the conditions of compatibility. The formulation of the method and examples of its use are presented. Effects of spring stiffness and mesh pattern on the results are investigated. The method is of particular use for foundations with unusual geometry and loading conditions. 931373 't-z' approach for cyclic axial loading analysis of single piles Chin, J T; Poulos, H G Comput Geotech V12, N4, 1991, P289-320 A simple, computationally efficient load transfer (t-z) approach is presented for the quasi-static cyclic response analysis of axially loaded single piles. Homogeneous, two layer or Gibson (modulus increasing linearly with depth) soil profiles are considered, with a hyperbolic t-z representation of the soil medium presented by the authors. Masing's criteria is incorporated to describe loading and unloading responses. The effects of cyclic loading are included in an approximate manner. Some numerical results illustrate the important parameters influencing single pile performance in a layered soil. Field measurements are provided for comparison. 931374 Rotational stiffness of shallow footings Melchers, B E Comput Geotech V13, NI, 1992, P21-35 Rotational characteristics of column bases depend on details of footing design, soil stiffness, and soil resistance. All of these will influence optimisation of economics, serviceability, and stability of structural frames. The ability to predict structural deformations under acceptable load levels is particularly important, but there has been only limited theoretical and experimental effort to this end. Moment-rotation tests have been carried out on an isolated footing under monotonic and load reversal conditions. Results are illustrated. A relatively simple theoretical model to predict rotation behaviour of simple pad footings on moment loading is developed on the basis of these results and earlier modelling attempts. 931375 Sensitivity analysis of laterally loaded piles by means of adjoint method. Technical note Budkowska, B B; Szymczak, C Comput Geotech V13, N1, 1992, P37-49 A sensitivity analysis is presented for laterally loaded piles on the basis of a one dimensional idealisation of a beam on a Winkler type foundation. The first variation of an arbitrary displacement and internal forces at a specified cross section due to some variation in the design variable (pile cross section, pile and soil material properties) are evaluated using the adjoint method. Numerical examples are presented and their accuracy discussed.
© 1993 Pergamon Press Ltd. Reproduction not permitted
structures situated close to la"rge maples. Volumetric water variations are analysed and compared to rainfall deficits calculated for the period of monitoring and elevation profiles of the foundations. Observed damage is also compared to that according to a classification proposed by the BRE, England.
931368 Centrifugal testing of laterally loaded piles in sand Georgiadis, M; Anagnostopoulos, C; Saflekou, S Can Geotech d V29, N2, April 1992, P208-216 The response to lateral loading for model piles of three different diameters and flexural stiffnesses during centrifuge testing has been investigated. Pile head displacements and bending moments along the piles were measured and results compared to numerical predictions based on p-y relations of Reese et al, Scott, Murchison and O'Neill, and DnV. A new p-y relation for laterally loaded piles in cohesionless soils is suggested on the basis of this work. 931369 Lateral load tests to examine large-strain (seismic) behaviour of piles Naesgaard, E Can Geotech J V29, N2, April 1992, P245-252 In the Frazer River delta area on Canada's west coast, the combination of high potential seismicity and deep postglacial sediments makes the liquefaction of loose sands and differential settlement during a major earthquake a real possibility. Three different 406mm diameter piles (2 reinforced concrete shafts, one a concrete-filled steel pipe) have been tested under lateral, vertical, and moment loadings. The concrete piles failed with lateral pile head displacements of 300mm and 650mm and curvatures of 0.16 and 0.35rad/m respectively. The steel pipe withstood displacement and bending of 550mm and 0.08rad/m respectively. The stronger piles tolerate the greater lateral displacements. The flexibility of the concrete piles can be altered by changing the pitch of the spiral reinforcement. 931370 Adhesion factor: applications and limitations. Note Sladen, J A Can Geotech J V29, N2, April 1992, P322-326 The average ultimate shaft resistance of piles in clay is conventionally estimated by applying an empirically derived adhesion factor to the undrained shear strength of the soil. It is shown that this can have a theoretical basis, because horizontal stress at the interface and undrained shear strength are controlled by the same factors. The belief that mobilised strength is a fraction of the undrained shear strength is however erroneous. The danger of extrapolating adhesion factors beyond situations for which the empirical data were acquired is emphasised. 931371 Effect of loading history on the compression and uplift capacity of driven model piles in sand. Note Joshi, R C; Achari, G; Kaniraj, S R Can Geotech J I,'29, N2, April 1992, P334-341 Instrumented smooth cylindrical piles were driven into a bed of uniform sand prepared by raining. Load tests were carried out and the effects of pile slenderness and sand density on bearing capacity were also examined. Load transfer along the pile was studied at one value of L/D. Pile tip resistances were generally constant for L/D ratios of 20-33. Piles having a loading history showed significant decrease in bearing capacity
compared to untested piles. When piles were tested in compression following tension, end resistance was not mobilised until a certain pile movement had taken place, although side resistance was immediately mobilised. 931372 Discrete dement method for bearing capacity analysis Chang, C S; Chao, S J Comput Geotech V12, N4, 1991, P273-288 A DEM analysis for estimating bearing capacity of foundations is presented in which the soil mass is considered as blocks connected by elasto-plastic Winkler springs. Boundary stresses on the failure surface and ultimate capacity of shallow foundations can be obtained by considering the conditions of compatibility. The formulation of the method and examples of its use are presented. Effects of spring stiffness and mesh pattern on the results are investigated. The method is of particular use for foundations with unusual geometry and loading conditions. 931373 't-z' approach for cyclic axial loading analysis of single piles Chin, J T; Poulos, H G Comput Geotech V12, N4, 1991, P289-320 A simple, computationally efficient load transfer (t-z) approach is presented for the quasi-static cyclic response analysis of axially loaded single piles. Homogeneous, two layer or Gibson (modulus increasing linearly with depth) soil profiles are considered, with a hyperbolic t-z representation of the soil medium presented by the authors. Masing's criteria is incorporated to describe loading and unloading responses. The effects of cyclic loading are included in an approximate manner. Some numerical results illustrate the important parameters influencing single pile performance in a layered soil. Field measurements are provided for comparison. 931374 Rotational stiffness of shallow footings Melchers, B E Comput Geotech V13, NI, 1992, P21-35 Rotational characteristics of column bases depend on details of footing design, soil stiffness, and soil resistance. All of these will influence optimisation of economics, serviceability, and stability of structural frames. The ability to predict structural deformations under acceptable load levels is particularly important, but there has been only limited theoretical and experimental effort to this end. Moment-rotation tests have been carried out on an isolated footing under monotonic and load reversal conditions. Results are illustrated. A relatively simple theoretical model to predict rotation behaviour of simple pad footings on moment loading is developed on the basis of these results and earlier modelling attempts. 931375 Sensitivity analysis of laterally loaded piles by means of adjoint method. Technical note Budkowska, B B; Szymczak, C Comput Geotech V13, N1, 1992, P37-49 A sensitivity analysis is presented for laterally loaded piles on the basis of a one dimensional idealisation of a beam on a Winkler type foundation. The first variation of an arbitrary displacement and internal forces at a specified cross section due to some variation in the design variable (pile cross section, pile and soil material properties) are evaluated using the adjoint method. Numerical examples are presented and their accuracy discussed.
© 1993 Pergamon Press Ltd. Reproduction not permitted