International Benchmark on Numerical Simulations for 1D, Nonlinear Site Response (PRENOLIN): Verification Phase Based on Canonical Cases

Julie Régnier;Luis‐Fabian Bonilla;Pierre‐Yves Bard;Etienne Bertrand;Fabrice Hollender;Hiroshi Kawase;Deborah Sicilia;Pedro Arduino;Angelo Amorosi;Domniki Asimaki;Daniela Boldini;Long Chen;Anna Chiaradonna;Florent DeMartin;Marco Ebrille;Ahmed Elgamal;Gaetano Falcone;Evelyne Foerster;Sebastiano Foti;Evangelia Garini;George Gazetas;Céline Gélis;Alborz Ghofrani;Amalia Giannakou;James R. Gingery;Nathalie Glinsky;Joseph Harmon;Youssef Hashash;Susumu Iai;Boris Jeremić;Steve Kramer;Stavroula Kontoe;Jozef Kristek;Giuseppe Lanzo;Annamaria di Lernia;Fernando Lopez‐Caballero;Marianne Marot;Graeme McAllister;E. Diego Mercerat;Peter Moczo;Silvana Montoya‐Noguera;Michael Musgrove;Alex Nieto‐Ferro;Alessandro Pagliaroli;Federico Pisanò;Aneta Richterova;Suwal Sajana;Maria Paola Santisi d'Avila;Jian Shi;Francesco Silvestri;Mahdi Taiebat;Giuseppe Tropeano;Luca Verrucci;Kohei Watanabe

2016-01-01

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Abstract

PREdiction of NOn‐LINear soil behavior (PRENOLIN) is an international benchmark aiming to test multiple numerical simulation codes that are capable of predicting nonlinear seismic site response with various constitutive models. One of the objectives of this project is the assessment of the uncertainties associated with nonlinear simulation of 1D site effects. A first verification phase (i.e., comparison between numerical codes on simple idealistic cases) will be followed by a validation phase, comparing the predictions of such numerical estimations with actual strong‐motion recordings obtained at well‐known sites. The benchmark presently involves 21 teams and 23 different computational codes. We present here the main results of the verification phase dealing with simple cases. Three different idealized soil profiles were tested over a wide range of shear strains with different input motions and different boundary conditions at the sediment/bedrock interface. A first iteration focusing on the elastic and viscoelastic cases was proved to be useful to ensure a common understanding and to identify numerical issues before pursuing the nonlinear modeling. Besides minor mistakes in the implementation of input parameters and output units, the initial discrepancies between the numerical results can be attributed to (1) different understanding of the expression “input motion” in different communities, and (2) different implementations of material damping and possible numerical energy dissipation. The second round of computations thus allowed a convergence of all teams to the Haskell–Thomson analytical solution in elastic and viscoelastic cases. For nonlinear computations, we investigate the epistemic uncertainties related only to wave propagation modeling using different nonlinear constitutive models. Such epistemic uncertainties are shown to increase with the strain level and to reach values around 0.2 (log10 scale) for a peak ground acceleration of 5  m/s2 at the base of the soil column, which may be reduced by almost 50% when the various constitutive models used the same shear strength and damping implementation.