SCEC Award Number 18103 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Development of a numerical nonlinear soil module to expand the capabilities of the SCEC BroadBand Platform
Name Organization
Pedro Arduino University of Washington Luis Bonilla Universite Paris-Est (France) Ertugrul Taciroglu University of California, Los Angeles Mahdi Taiebat University of British Columbia (Canada)
Other Participants
SCEC Priorities 4a, 4b, 4c SCEC Groups CS, EFP, CSEP
Report Due Date 03/15/2019 Date Report Submitted 04/30/2019
Project Abstract
This project aims to extend the capabilities of the SCEC Broad Band Platform (BBP) to include the inelastic response of soft soil layers near the surface. For this purpose, BBP is coupled with a finite element (FE) tool that incorporates robust nonlinear constitutive models for soils. Existing OpenSees FE libraries are used to represent the domain soft soil layers, and the Borja-Amies bounding surface constitutive model is used to represent the inelastic/hysteretic behavior of surface soils. The model is based on sound mechanics principles, and is well described mathematically and algorithmically. The required model parameters can be calibrated using field or laboratory data, as well as empirical relations that are deemed to have sound physical meanings both for engineers and seismologists. The resulting finite element soil column is added to the BBP workflow and an option is included into its standard operation mode allowing the user to perform a nonlinear analysis with minimal additional input data.
Intellectual Merit Propagation of seismic waves in soils is a complex phenomenon requiring advanced models to capture the response of harder geological units and advanced material models to represent the inelastic response of the upper soft soil layers. Extensive work has been—and continues to be—carried out in the development and validation of numerical tools for the simulation of synthetic motions in hard geological units. Full utilization of such tools by the broader earthquake engineering community is not possible unless their capabilities are extended to include wave propagation in soft inelastic soil layers. This requires the use of finite element/difference platforms featuring advanced constitutive models to represent the wave propagation in inelastic soils and coupling to existing broadband earthquake generation tools.
In this context, this project aims contribute in this line of work by extending the capabilities of the SCEC Broad Band Platform (BBP) to include the nonlinear response of soft soil layers near the surface. The upgraded tool with proper validation could be very useful for the estimation of synthetic ground motions.
Broader Impacts This project stimulated the creation of an independent teaching module on bounding surface plasticity and kinematic hardening. For this purpose, several educational matlab scripts were created including a variety of loading conditions. One PhD student worked in the implementation of the constitutive model and development of finite element tool and another was in charge of upgrading the BBP tool. One master student has continued working on simulations using the upgraded BBP tool.
This project adheres to the initiative for a Technical Activity Group to coordinate SCEC research on nonlinear shallow crust effects. In this context, this project prompted cooperation and coordinated research activities between project 18020 led by Domniki Asimaki and our group. The Asimaki group used the same constitutive model but implemented in the Hercules framework.
Exemplary Figure Figure 2
Caption: 1D-3C OpenSees finite element mesh and simulation results for simple wavelet signal
Credits: P. Arduino, E. Taciroglu, F. Bonilla and M. Taiebat