Incremental Hybrid Simulation Development Method for Large Scale Application EU-US-Asia Workshop on Hybrid Testing 5-6 October 2015 Xiaoyun Shao, Ph.D., PE Associate Professor Department of Civil and Construction Engineering Western Michigan University Kalamazoo, MI
Outline Background Hybrid testing in two NEESR projects Challenges associated with large-scale hybrid testing Incremental approach Developing hybrid testing methods Small-scale hybrid testing system Concluding remarks My thoughts on the five questions
Outline Background Hybrid testing in two NEESR projects Challenges associated with large-scale hybrid testing Incremental approach Developing hybrid testing methods Small-scale hybrid testing system Concluding remarks My thoughts on the five questions
NEES-Soft Project 1. NEES-Soft: Seismic Risk Reduction for Soft Story Woodframe Buildings PI : Dr. John W van de Lindt (Colorado State University ) Co_PIs : Dr. Weichiang Pang (Clemson University) Dr. Xiaoyun Shao (Western Michigan University) Dr. Michael Symans (Rensselaer Polytechnic Institute) Mikhail Gershfeld (California State Polytechnic University) Objectives: Experimentally validate 4 economical retrofit concepts (FEMA P807) 3 performance-based seismic retrofits (PBSR) Experimental program: Full-scale slow PSD hybrid teting at NEES@UB Full-scale shake table testing at NEES@UCSD
NEES-Soft Hybrid Testing Full-scale slow PSD hybrid testing @ UB-NEES facility Prototype: Full-scale three story residential building Evaluate the performances of different retrofits with the focus on the effects of the first story retrofits on upper stories Experimental substructure: Upper two stories (full-scale) Four actuators Translational & torsional Numerical substructure: First soft story with (4+3=7) various retrofits
NEES-RCFrame Project 2. NEESR: Near-collapse Performance of Existing Reinforced Concrete Frame Buildings PI : Dr. Mehrdad Sasani (Northeastern University) Co_PI : Dr. Xiaoyun Shao (Western Michigan University) Motivations: Collapse behavior requires system level analysis; current criteria based on element failure Structures subjected to 3D earthquake loading Goals: To determine the effects of triaxial as opposed to unidirectional seismic ground motions on column failure and collapse mechanism To develop reliable analytical modeling tools and methods for collapse analysis To develop system level acceptance criteria and procedures for collapse analysis Experimental program Geographically distributed hybrid simulation between NEES@UIUC and Northeastern
NEES-RCFrame Project ~5.3m
Challenges in Large-Scale Implementation NEES-Soft: first full-scale woodframe hybrid testing Verification of integration algorithms and numerical substructure models Verification of hybrid testing controller Large-scale specimen (costly and time-consuming to repair) Limited onsite development time @ NEES facility NEES-RCFrame: large-scale geographically distributed hybrid testing Verification of (internet) communication between the two sites between OpenSees and UI-Simcor Complex numerical model for RC frame collapse simulation
Outline Background Hybrid testing in two NEESR projects Challenges associated with large-scale hybrid testing Incremental approach Developing hybrid testing methods Small-scale hybrid testing system Concluding remarks My thoughts on the five questions
Incremental Approach 1. NEES-Soft: first full-scale woodframe hybrid testing Small-scale Mid - scale Full-scale Western Michigan Univ. (WMU) Univ. of Alabama (UA) Univ. of Buffalo (UB)
Hybrid Testing @ WMU SlowPSD HS controller Challenge: use a real time hybrid testing system for slow testing Double trigger strategy Slow the test rate Accurate force reading Ramping loading pattern 1 st trigger, fixed step 2 nd trigger, force reading Real time PSD HS controller Time delay compensation Smith s predictor Feed-forward (polynomial extrapolation) Integration algorithm Explicit Newmark Modified implicit Newmark (adopted in NEESSoft project) α operator splitting (α OS)
HS Testing @ WMU Displacement response of slow PSD HS @ WMU
Hybrid Testing @ UA Slow PSD HS Prototype structure Two-story stack wood shear wall frame Physical substructure First story shear wall Numerical substructure Second story shear wall Slow HS controller 20 times slow Integration step: 1/256 sec Real time controller step: 1/4096 sec RTHS Prototype structure Three-story Physical substructure First soft-story with and without damper retrofit Numerical substructure Upper two story RTHS controller Strong floor attachment Transverse support Same integration and real time controller step: 1/1024 sec Feed forward delay compensation
Hybrid Testing @ UA Displacement response of slow PSD HS @ UA
Hybrid Testing @ UB NEES Soft hybrid testing system @ UB
Hybrid Testing @ UB Phase 1: FEMA P807 economic retrofits Cross laminated timber (CLT) Distributed knee-braced retrofit (DKB) Inverted moment frame (IMF) Fluid viscous damper (FVD) Phase 2: Performance based seismic retrofits (PBSR) Shape memory alloy (SMA) Steel moment frame (SMF) Direct displacement design (DDD) procedure Shao, X., Pang, W., Griffith, C., Ziaei, E., and van de Lindt, J.W. (2015). Development of a Hybrid Simulation Controller for Full-Scale Experimental Investigation of Seismic Retrofits for Soft-Story Woodframe Buildings Earthquake Engineering and Structural Dynamics (under review). Pang, W., Shao, X., Ziaei, E., van de Lindt, J.W., and Griffith, C., (2014). Hybrid Simulation of Seismic Retrofits for Soft-Story Wood Frame Building. Part II: Numerical Simulation Development Earthquake Engineering and Structural Dynamics (under preparation). Jennings, E., van de Lindt, J., Ziaei, E., Bahmani, P., Park, S., Shao, X. Pang, W., Rammer, D., Mochizuki, G., and Open-loop collapse RTHS Gershfeld, M., (2014). Full-Scale Experimental Verification of Soft-Story-Only Retrofits Using Hybrid Testing. Journal of Earthquake Engineering (under preparation). Jennings, E., van de Lindt, J., Ziaei, E., Mochizuki, G., Pang, W., Shao, X. (2014). Retrofit of a Soft-Story Woodframe Building using SMA Devices with Full-Scale Hybrid Test Verification. Engineering Structures (under review).
Incremental Approach 2. NEES_RCFrame: Distributed Testing Small Scale distributed hybrid testing between WMU (US) & HIT (China)
Incremental Approach
Small-Scale Hybrid Testing System @ WMU Shore Western SC6000 2 channel, desktop enclosure 2.13 GHz processor Chassis 8-Slot PXI-1050 Chassis Real-time processor 2.53 GHz Dual Core PXI- 8108 Embedded Controller DAQ PXI-6229: 32 AI PXI-6221: 16 AI Connector Block SCB-68 Shielded I/O 10 Connector GPM HPS Block 380-480 V, 3 phase, 50/60 Hz power Local and remote control, 24 VDC control voltage High/low pressure controls Hybrid testing model: programmed in MATLAB/Simulink and deployed using NI-VeriStand Force: ±3240 lb at 3000 psi Stroke: ±3 in Servo valve: 10 gpm at 1000 psi Load cell: 2.5 kip Size: 3 ft x 3 ft Max. specimen LVDT mass: 500 lb Stroke: 10 in (227kg) Max. acceleration: Power supply 4g Max. displacement: converter: 115 ±3 volts in AC 15 volts DC Accelerometers Peak value: 4g 3 axes
Outline Background Hybrid testing in two NEESR projects Challenges associated with large-scale hybrid testing Incremental approach Developing hybrid testing methods Small-scale hybrid testing system Concluding remarks My thoughts on the five questions
Concluding remarks NEES-Soft project Hybrid testing of a full-scale wood frame building was successfully implemented to economically evaluate 7 different retrofits NEES-RC collapse project Geographically distributed test was performed (Implicit) Integration algorithm for complex numerical model and for collapse simulation requires further development Incremental approach seems to be a viable and efficient way for large-scale hybrid testing projects
Concluding remarks Objectives: accepting hybrid testing as a primary and economic testing method Process for planning and preparing Closely relate to the project objectives Validate at each preparing phase to ensure the functionality of each components (i.e. algorithms, controllers, specimen and hydraulic equipment) Assess accuracy/stability Before/after test: numerical verification During test: prepare for unstable test (safety mechanism)
Concluding remarks Objectives: accepting hybrid testing as a primary and economic testing method Model complexity Mostly shear-type building models for RTHS with nonlinear restoring force components Online model-updating Expand hysteresis model bank Using existing FEM analysis package Improve the acceptance Outreach to research communities (journal/conference papers, presentations) Share testing models online Prepare instructional documents (manuals, tutorials, etc.) Collaboration
Acknowledgement Workshop organization committee My students: Chelsea Griffith, Griffin Enyart, Adam Mueller, Chris Sawyer, Adnan Sanchez, Carlos Santana, Bilal Mohamed. Collaborators in the two NEESR projects Staffs at WMU, NEES@UB, NEES@UIUC and the Structural Engineering Laboratory @UA NSF and Office of Vice President for Research @ WMU