Thursday, May 31, 2012
Mechanical and Civil Engineering Seminar
Virtual Earthquake Engineering Laboratory (VEEL) in the era of parallel computers
In Ho Cho, Willis Research Fellow, University of Colorado at Boulder
By virtue of the remarkable advances in parallel computing technology, physically sound mechanisms and state information of entire system can now replace the macroscopic empirical models for describing nonlinear behavior of structures exposed to cyclic/seismic loadings. In VEEL originally launched in Caltech, the fixed-type multidirectional smeared crack model and tribology-inspired interlocking mechanisms play in concert to offer access to unprecedentedly realistic simulations of real-scale structures made of quasi-brittle materials. Also, the topological transition-based reinforcing bar model exploits systematic information to capture progressive compressive buckling of large-scale composite system. What lies behind all the aforementioned novel attempts is, of course, the problem-optimized parallel platform. In the talk, quantitative comparison of state-of-the-art parallel strategies (broadcasting, pipelined and look-ahead method) and its outcome shall be given, which successfully embraces the penalty method and banded nature, notably exhibiting the apparent super-linear speedup. Fascinating applications shall be also provided in the talk. Novelty of the simulations lies not only in the accurate nonlinear analysis of real-scale structures loaded by cyclic loadings, but also in the capability to reproduce localized damage on the large-scale structures, which appears to be closely tied to the random material properties over the entire domain introduced for the interlocking mechanism. The talk will be closed by providing the central idea of the ongoing project, for which we are extending VEEL, mainly following the central notion of multiscale analysis technique, in order to generate novel analytical vulnerability functions (i.e. probabilistic relationship between the seismic excitation and financial loss) of a large number of structures.