Incremental Hybrid Simulation Development Method for Large‐Scale Application

EU-US-Asia Workshop on Hybrid Testing5-6 October 2015

Xiaoyun Shao, Ph.D., PEAssociate Professor

Department of Civil and Construction EngineeringWestern 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

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 Project

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 Project2. NEESR: Near-collapse Performance of Existing

Reinforced Concrete Frame BuildingsPI : 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 Approach1. NEES-Soft: first full-scale woodframe hybrid testing

Small-scale Mid - scale Full-scaleWestern Michigan Univ.

(WMU) Univ. of Alabama (UA) Univ. of Buffalo (UB)

Hybrid Testing @ WMU• Slow PSD‐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 

• 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)

1st trigger, fixed step2nd trigger, force reading

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– Same integration and real‐time 

controller step: 1/1024 sec– Feed‐forward delay 

compensationTransverse support

Strong floor attachment

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 seismicretrofits (PBSR)– Shape memory alloy (SMA)– Steel moment frame (SMF)– Direct displacement design

(DDD) procedure

• Open-loop collapse RTHS

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 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 Approach2. NEES_RCFrame: Distributed TestingSmall – Scale distributed hybrid testing between WMU (US) & HIT (China)

Incremental Approach

Small-Scale Hybrid Testing System @ WMU

• Size: 3 ft x 3 ft• Max. specimen mass: 500 lb

(227kg)• Max. acceleration: 4g• Max. displacement: ±3 in

• Force: ±3240 lb at 3000 psi• Stroke: ±3 in• Servo valve: 10 gpm at 1000 psi• Load cell: 2.5 kip

• 10 GPM HPS• 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

LVDT• Stroke: 10 in• Power supply

converter: 115 volts AC → 15 volts DC

Accelerometers• Peak value: 4g• 3 axes

Shore Western SC6000• 2 channel, desktop

enclosure• 2.13 GHz processor

Chassis• 8-Slot PXI-1050 ChassisReal-time processor• 2.53 GHz Dual Core PXI-

8108 Embedded ControllerDAQ• PXI-6229: 32 AI• PXI-6221: 16 AIConnector Block• SCB-68 Shielded I/O

Connector Block

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