Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Real-Time Hybrid Simulations P. Benson Shing University of California, San Diego
Better Known as the Pseudodynamic Test Method Early Work: Hakuno et al. (1969) Takanashi et al. (1974) Pseudodynamic:slow rate of loading; dynamic properties simulated numerically Institute of Industrial Science, University of Tokyo Hybrid:real-time testing; analytical substructuring;distributed testing and simulation; ……….
Pseudodynamic Test Method Update and Displacement Numerical solution of eqs. of motion Test Frame Advance to next time step: i = i + 1 Simple concept but requires care to execute. • Precision of displacement control. • Accumulation of experimental errors in numerical computation.
Experimental Error Accumulation Shing and Mahin (1982) Main source of systematic experimental errors: time-delay in servo-hydraulic loading apparatus
Computer Model Update and Numerical solution of eqs. of motion Advance to next time step: i = i + 1 Substructure Test Methods Dermitzakis and Mahin (1985) Test Frame
Computer Model Test Base Isolation Devices Computer Model Test Active/ Passive Dampers Needs for Real-Time Tests
General Framework for Hybrid Simulation Structural Partitioning
Coupled Subdomain Approach Implicit Scheme Explicit Scheme Magonette et al. (1998)
Computational Model Actuator Specimen Actuator Shake Table Dynamic Substructuring I Sivaselvan and Reinhorn (2004)
Dynamic Substructuring II Actual Equipment Tested Horiuchi et al. (2000) Bayer et al. (2005) Bursi et al. (2008) Actuator Shake Table Computational Model
Real-Time Hybrid Test Methods • Nakashima et al. (1992, 1999) • Horiuchi et al. (1996) • Tsai et al. • Darby et al. (1999) • Magonette et al. (1998) • Bayer et al. (2000) • Shing et al. (2002) • Wu et al. (2005, 2006) Explicit Integration Schemes Implicit-Explicit Coupled Field Analysis Implicit Integration Schemes
Convergence is guaranteed as long as is positive definite (Shing and Vannan 1991). Modified Newton Method • Number of iterations varies from time step to time step. • Increment size decreases as solution converges. Problems for Real-Time Tests:
Fixed Number of Iterations with Interpolation Shing et al. (2002)
Response Correction and Update Compatibility Equilibrium a-Method
System Configuration NEES@Colorado
Real-Time Substructure Test Platform Target PC –Real-Time Kernel OpenSEES Analytical Substructure Model Special Element SCRAMNet Card 1 Experimental Element/Substructure Actuators PID Controller SCRAMNet Card 2 Data-Acquisition Program Specimen Real-Time Processor
Issues in a Real-Time Test • Actuator time-lag caused by dynamics of servo-hydraulic system and test structure. • Communication delays among processors. • Accounting for real inertia and damping forces. • Convergence errors in numerical scheme. • Interaction of numerical computation with system dynamics.
Phase-Lag Compensation Methods PID with Feedforward Discrete Feedfordward Correction Phase-Lead Compensator
System Transfer Function (Linear System) • Consider dynamics of servo-hydraulic actuators and test structure. • Communication delays. • Error compensation schemes. • Interaction of numerical computation with physical system. Jung and Shing (2006)
Implicit Integration Scheme External Force Explicit Prediction Implicit Correction
Validation with Simulink Model Error Correction:
Update and Numerical solution of eqs. of motion Test Frame Advance to next time step: i = i + 1 Inertia Effect in Real-Time Tests +
Actual Test with Inertia Force Removal Mt/M = 4.7%
Nonlinear Structures (2-DOF, a-Method) Strain Hardening Strain Softening Convergence: has to be positive definite
Actuator Real-Time Substructure Test with a Single Column Test Column Analytical Model in OPENSEES
Test of a Zipper Frame Georgia Tech U. At Buffalo UC-Berkeley UC-San Diego/U. of Colorado Florida A&M
80% LA 22 200% LA 22 Test Results