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Earthquakes threaten humanity globally in complex ways that mainly include various socioeconomic consequences of life and property losses. Resilience against seismic risks is of high importance in the modern world and needs to be sustainable. Sustainable earthquake resilience (SER) from the perspective of structural engineering means equipping the built environment with appropriate aseismic systems. Shape memory alloys (SMAs) are a class of advanced materials well suited for fulfilling the SER demand of the built environment. This article explores how this capability can be realized by the innovative SMA-based superelasticity-assisted slider (SSS), recently proposed for next-generation seismic protection of structures. The versatility of SSS is first discussed as a critical advantage for an effective SER. Alternative configurations and implementation styles of the system are presented, and other advantageous features of this high-tech isolation system (IS) are studied. Results of shaking table experiments, focused on investigating the expected usefulness of SSS for seismic protection in hospitals and conducted at the structural earthquake engineering laboratory of the University of Bonab, are then reported. SSS is compared with currently used ISs, and it is shown that SSS provides the required SER for the built environments and outperforms other ISs by benefitting from the pioneered utilization of SMAs in a novel approach.

The low-strain dynamic behavior of Leda clays is investigated using resonant column (RC) and bender element (BE) tests. Four undisturbed, lightly overconsolidated Leda clay samples, collected from two sites near the St. Lawrence River valley, are tested at different strains, confining stresses, and frequencies. To evaluate the effect of excitation frequency, simultaneous measurements of shear wave velocity using RC and BE tests are performed. The results show that the samples from the different sites behave differently. The high sensitivity of the Leda clays does not have a significant effect on the modulus degradation curves. However, the measured degradation curves are similar to those of soft clays with high plasticity, which is contrary to the expected behavior of these low plasticity ([I.sub.p] = 6.2-20) specimens. Likewise, the measured damping ratios are on the lower end of the typical values reported for soils of high plasticity. Low values of damping ratio make the amplification of small seismic events more likely in Leda clay deposits. The difference in the shear wave velocity measurements from RC and BE tests ranges from 17% to 26% depending on the confinement, likely because of the strong influence of P-waves observed in the BE tests for these soils. Key words: shear modulus, damping ratio, shear wave velocity, seismic characterization, dynamic properties, soil testing. Le comportement dynamique a faible deformation des argiles Leda est etudie a l'aide d'essais de colonne resonante (RC) et d'elements plies (BE). Quatre echantillons d'argile Leda non perturbes et legerement surconsolides, preleves sur deux sites pres de la vallee du fleuve Saint-Laurent, sont testes a differentes contraintes, contraintes de confinement et frequences. Pour evaluer l'effet de la frequence d'excitation, des mesures simultanees de la vitesse de l'onde de cisaillement sont effectuees au moyen d'essais RC et BE. Les resultats montrent que les echantillons provenant des differents sites se comportent differemment. La sensibilite elevee des argiles Leda n'a pas d'effet significatif sur les courbes de degradation du module. Cependant, les courbes de degradation mesurees sont similaires a celles des argiles molles a plasticite elevee, ce qui est contraire au comportement attendu de ces eprouvettes a faible plasticite ([I.sub.p] = 6,2-20). De meme, les rapports d'amortissement mesures se situent dans la partie inferieure des valeurs typiques rapportees pour les sols ayant une plasticite elevee. Les faibles valeurs du rapport d'amortissement rendent l'amplification des petits evenements sismiques plus probable dans les depots d'argile a Leda. La difference entre les mesures de vitesse des ondes de cisaillement des essais RC et BE varie de 17 a 26 % selon le confinement, probablement en raison de la forte influence des ondes P observee dans les essais BE pour ces sols. [Traduit par la Redaction] Mots-cles : module de cisaillement, rapport d'amortissement, vitesse des ondes de cisaillement, caracterisation sismique, proprietes dynamiques, essais de sol., Introduction The Canadian Highway Bridge Design Code (CSA Group 2019) and National Building Code of Canada (NRCC 2015) have recently standardized the provisions of seismic design of infrastructures in which [...]

A nonlinear analysis framework for laterally loaded piles is presented that is as accurate as equivalent three- dimensional nonlinear finite element analysis, but computationally one order of magnitude faster. The nonlinear behavior of sands and clays are account for by using hyperbolic modulus-reduction relationships. These nonlinear-elastic constitutive models are used to calculate the reduced modulus at different points in the soil based on the soil strains induced by lateral pile displacement. The reduced modulus at different points in the soil domain are spatially integrated to calculate the reduced soil resistance parameters associated with the differential equation governing the lateral pile displacement. The differential equations governing the lateral displacements of pile and soil under equilibrium are obtained by applying the principle of virtual work to a continuum-based pile-soil system. These coupled differential equations are solved using the one-dimensional finite difference method following an iterative algorithm. The accuracy of the analysis is verified against equivalent three- dimensional nonlinear finite element analysis, and the validity of the analysis in predicting the field response is checked by comparisons with multiple pile load test results. Parametric studies are performed to gain insights into the lateral pile response. Key words: pile, lateral load, nonlinear elastic soil, principle of virtual work, finite difference. Le document propose un cadre d'analyse non lineaire pour les pieux charges lateralement, dont la precision est egale a celle de l'analyse tridimensionnelle non lineaire equivalente par elements finis, mais qui est plus rapide d'un ordre de grandeur sur le plan du calcul. On y prend en compte le comportement non lineaire des sables et des argiles en utilisant des relations de reduction de module hyperbolique. Pour calculer le module reduit en differents points du sol, on utilise ces modeles constitutifs non lineaires-elastiques en se basant sur les contraintes du sol induites par le deplacement lateral des pieux. Ils sont integres dans l'espace pour calculer les parametres de resistance reduite du sol associes a l'equation differentielle regissant le deplacement lateral des pieux. La difference entre les equations differentielles regissant les deplacements lateraux des pieux et du sol en equilibre est obtenue en appliquant le principe du travail virtuel a un systeme continu pieux-sol. Pour resoudre ces equations differentielles couplees, on utilise la methode des differences finies unidimensionnelles selon un algorithme iteratif. Elles sont ensuite verifiees par rapport a une analyse tridimensionnelle non lineaire equivalente par elements finis et la validite de l'analyse pour prevoir la reponse du terrain est verifiee par des comparaisons avec de nombreux resultats de tests de charge de pieux. On effectue des analyses parametriques pour obtenir des informations sur la reponse laterale des pieux. [Traduit par la Redaction] Mots-cles: pieu, chargement lateral, sol elastique non lineaire, principe du travail virtuel, difference finie., Introduction The options commonly available to engineers for analysis of laterally loaded piles are the p-y method (Matlock 1970; Reese et al. 1975; O'Neill and Murchison 1983) and the three-dimensional [...]

Adequate prediction of surrounding ground movement during braced excavation is critically important as excessive soil movement damages adjacent structures. The magnitudes and patterns of ground movement and wall deflection largely depend on excavation parameters like thickness of diaphragm wall, wall embedment depth, strut locations and soil parameters such as soil strength, compressibility and creep parameter. In the present paper a thorough, parametric study has been conducted using finite element (FE) analysis to address the influence of various parameters on deformation characteristics of braced excavation in soft clayey deposits. The importance of correct estimation of soil parameters for braced excavation design is also documented. The analysis of typical braced excavations in soft clay is carried out using PLAXIS 2D software where soft soil creep constitutive model is used. On the basis of numerical study a handy design guideline is recommended. Further multivariate regression models are developed incorporating various important excavation parameters for the adequate prediction of maximum wall and ground displacement along with wall and ground surface deformation profile. Here large numbers of data reported in case histories and generated artificially from FE analysis are used for formation of regression equations. The proposed model is validated comparing results from literatures not used for the development of the model. [ABSTRACT FROM AUTHOR]

The traditional method for analysis and design of laterally loaded piles with non-circular cross-sections such as rectangular, H-shaped, and X-shaped piles involves the simplification of converting the non-circular pile to a circular pile with equivalent second moment of inertia. A rigorous semi-analytical method is developed for calculating the response for laterally loaded piles with arbitrary non-circular cross-sections in multi-layered elastic soil without using any simplification regarding the shape of the pile cross-section. The governing differential equations for the pile–soil system are obtained using the principle of virtual work. The soil displacements around the pile are described as products of separable functions that are compatible with horizontal pile movement. As a result, the three-dimensional (3 D) boundary value problem (BVP) is described by a fourth-order linear ordinary differential equation (ODE) governing horizontal pile displacement and second-order partial differential equations (PDEs) governing soil displacements. New solution techniques for the ODE and PDEs are proposed, and the accuracy of the present method is verified by comparing the predicted pile and soil responses with the corresponding results of equivalent 3 D finite element method. The effects of pile cross-section shape and lateral loading direction on the pile and soil responses are highlighted through a series of parametric analyses. [ABSTRACT FROM AUTHOR]