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Axial compression of footings in cohesionless soils. I: load-settlement behavior / Sami O. Akbas in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1562–1574 Titre : Axial compression of footings in cohesionless soils. I: load-settlement behavior Type de document : texte imprimé Auteurs : Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur Année de publication : 2009 Article en page(s) : pp. 1562–1574 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : FootingsLoad  testsFoundation  settlementCohesionless  soilsSoil  compression Résumé : The results of 167 full-scale field load tests were used to examine several issues related to the load-displacement behavior of footings in cohesionless soils under axial compression loading, including (1) method to interpret the “failure load” from the load-settlement curves; (2) correlations among interpreted loads and settlements; and (3) generalized load-settlement behavior. The L1-L2 method was found to be more appropriate than the “tangent intersection” and “10% of the footing width” methods for interpreting the failure load. The interpreted loads and displacements indicate that footing load-settlement behavior is less elastic and more nonlinear than that of drilled foundations. The results show that the footing behavior will be beyond the elastic limit for designs where a traditional factor of safety between 2 and 3 is used. A normalized curve was developed by approximating the load-settlement curve for each load test in the database by hyperbolic fitting, and the uncertainty in this curve was quantified. This normalized curve can be used in footing design that considers capacity and settlement together. Where possible or warranted, the normalized curve can be subdivided as a function of initial soil modulus. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000135 [article] Axial compression of footings in cohesionless soils. I: load-settlement behavior [texte imprimé] / Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur . - 2009 . - pp. 1562–1574. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1562–1574 Mots-clés : FootingsLoad  testsFoundation  settlementCohesionless  soilsSoil  compression Résumé : The results of 167 full-scale field load tests were used to examine several issues related to the load-displacement behavior of footings in cohesionless soils under axial compression loading, including (1) method to interpret the “failure load” from the load-settlement curves; (2) correlations among interpreted loads and settlements; and (3) generalized load-settlement behavior. The L1-L2 method was found to be more appropriate than the “tangent intersection” and “10% of the footing width” methods for interpreting the failure load. The interpreted loads and displacements indicate that footing load-settlement behavior is less elastic and more nonlinear than that of drilled foundations. The results show that the footing behavior will be beyond the elastic limit for designs where a traditional factor of safety between 2 and 3 is used. A normalized curve was developed by approximating the load-settlement curve for each load test in the database by hyperbolic fitting, and the uncertainty in this curve was quantified. This normalized curve can be used in footing design that considers capacity and settlement together. Where possible or warranted, the normalized curve can be subdivided as a function of initial soil modulus. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000135

Axial compression of footings in cohesionless soils. II: bearing capacity / Sami O. Akbas in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1575–1582 Titre : Axial compression of footings in cohesionless soils. II: bearing capacity Type de document : texte imprimé Auteurs : Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur Année de publication : 2009 Article en page(s) : pp. 1575–1582 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : FootingsLoad  testsFoundation  settlementCohesionless  soilsSoil  compressionLoad  bearing  capacity Résumé : An extensive database of full-scale field load tests was used to examine the bearing capacity for footings in cohesionless soils. Each load test curve was evaluated consistently to determine the interpreted failure load (i.e., bearing capacity) using the L1-L2 method. This test value then was compared with the theoretical bearing capacity, computed primarily using the basic Vesić model. The comparisons show that, for footing widths B>1 m , the field results agree very well with the Vesić predictions. However, for B<1 m , the results indicated a relationship between B and the predicted-to-measured bearing capacity ratio. Accordingly, a simple modification was made to the bearing capacity equation, and the resulting predictions are very good. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000136 [article] Axial compression of footings in cohesionless soils. II: bearing capacity [texte imprimé] / Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur . - 2009 . - pp. 1575–1582. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1575–1582 Mots-clés : FootingsLoad  testsFoundation  settlementCohesionless  soilsSoil  compressionLoad  bearing  capacity Résumé : An extensive database of full-scale field load tests was used to examine the bearing capacity for footings in cohesionless soils. Each load test curve was evaluated consistently to determine the interpreted failure load (i.e., bearing capacity) using the L1-L2 method. This test value then was compared with the theoretical bearing capacity, computed primarily using the basic Vesić model. The comparisons show that, for footing widths B>1 m , the field results agree very well with the Vesić predictions. However, for B<1 m , the results indicated a relationship between B and the predicted-to-measured bearing capacity ratio. Accordingly, a simple modification was made to the bearing capacity equation, and the resulting predictions are very good. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000136

Reliability-based design approach for differential settlement of footings on cohesionless soils / Sami O. Akbas in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 12 (Décembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1779–1788 Titre : Reliability-based design approach for differential settlement of footings on cohesionless soils Type de document : texte imprimé Auteurs : Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur Année de publication : 2010 Article en page(s) : pp. 1779–1788 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : FootingsCohesionless  soilsReliabilityFoundation  settlementDifferential  settlement Résumé : A probabilistic method is presented to estimate the differential settlements of footings on cohesionless soils, considering the uncertainties in both the load and capacity sides of the design equation. A random field approach is employed to characterize the inherent soil variability. This method is first compared to typical limit values from the literature to denote critical combinations of design parameters that can lead to exceedance of tolerable differential settlements. Then, reliability-based design equations are developed for the serviceability limit state (SLS) design of footings on cohesionless soils. The key parameters controlling the SLS are the allowable angular distortion, site variability, and footing spacing. The results are given in a straightforward design format and indicate that currently suggested deformation factors (resistance factors for SLS) equal to 1.0 are likely to be unconservative for most design situations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000127 [article] Reliability-based design approach for differential settlement of footings on cohesionless soils [texte imprimé] / Sami O. Akbas, Auteur ; Fred H. Kulhawy, Auteur . - 2010 . - pp. 1779–1788. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1779–1788 Mots-clés : FootingsCohesionless  soilsReliabilityFoundation  settlementDifferential  settlement Résumé : A probabilistic method is presented to estimate the differential settlements of footings on cohesionless soils, considering the uncertainties in both the load and capacity sides of the design equation. A random field approach is employed to characterize the inherent soil variability. This method is first compared to typical limit values from the literature to denote critical combinations of design parameters that can lead to exceedance of tolerable differential settlements. Then, reliability-based design equations are developed for the serviceability limit state (SLS) design of footings on cohesionless soils. The key parameters controlling the SLS are the allowable angular distortion, site variability, and footing spacing. The results are given in a straightforward design format and indicate that currently suggested deformation factors (resistance factors for SLS) equal to 1.0 are likely to be unconservative for most design situations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000127