university of california an...an optically-based sensor system for critical facilities post-event...

UNIVERSITY OF

CALIFORNIA

An Optically-based Sensor System for

Critical Facilities Post-Event Seismic

Structural Assessment

Floriana Petrone, PhD

Research Scientist

Lawrence Berkeley National Laboratory

David McCallen, Professor

University of Nevada, Reno

Lawrence Berkeley National Laboratory

October 24, 2018 NRC - Rockville (MD)

Agenda

Interstory Drift (ID)

Fundamental measure of building deformation adopted to assess structure

seismic performance (DOE: ASCE 43-05)

Physics of light used for direct broad-band measurements of ID:

Development of a Discrete Diode Position Sensor (DDPS)

Concept and Technology

Experimental Tests at 3 different scales

Testbed #1 (DDPS), Testbed #2 (2D Structure), Testbed #3 (3D Structure)

Model-based simulations of sensor system performance

Numerical tool for evaluating and predicting DDPS performance (design)

DDPS: Experimental Validation and Development of a Design Tool

DDPS Near-Real Time Android App

Development of a near-real time Android App

Transmit and display data to a smartphone for a very rapid determination of

structural ID after an earthquake event.

DOE Labs/Sites

Savannah River Los AlamosLivermore

Y-12

The availability of active and passive structural

monitoring systems is of primary importance for

enabling an efficient facility management

system in new and existing facilities.

Motivation – Risks for the DOE Enterprise and Critical

Infrastructure

ID: used as key parameter to assess building performance

Not-to-Exceed

Drift Limits

Limit

States

Damage

State Drift

Limits

The challenges of accurately measuring ID

Journal of Structural Engineering, Vol. 136, 2010

American Society of Civil Engineers

Journal of Structural Engineering, Vol. 139, 2013

American Society of Civil Engineers

Using Physics of light for DIRECT broad-band ID

measurement

Drift displacement

Laser

Position

Sensitive

Detector

Ref. – D. McCallen, “A Laser-Based System for Expedient Measurement of Vibratory Motions and Permanent Deformation in Civil

Infrastructure Systems” Lawrence Livermore National Laboratory concept paper, May 2013.

A staggered array of

discrete diodes

called DDPS

384 samplings/sec

“On-off”

switches

Diode Response to Incident Laser Light

0.45

0.40

0.35

0.30Diode voltage output

from laser sweep test

Diode Response

Volts

VTD34H

Photo DiodeActive

Diode Area

x Comparator Output

0.50

0.0

Volts

Sweeping laser beam

Diode

“off”

Diode

“on”

Diode

“off”

Threshold

a) b)

Array of diodes design to maximize measurement

accuracy

Agenda
















Testbed #1: Set-up and Objective

Objective: assess the inherent measurement performance of a DDPS, through the the

evaluation of the fundamental ability and resolution of the DDPS to measure TID(t), PID, and RID.

DDPS Motion table

LaserDiffractionoptic

Spread laserbeam

~300 cm

Actively controlled motion table

Roof

Floor

Testbed #1: Generation of Representative ID

Representative drifts were generated from detailed NL FEMs (40-story and 3-story buildings

were designed for UBC zone 3, and near-field strong motions were selected and applied, ID was

recorded)

40-story

3-story

Testbed #1: Results

Results: The DDPS demonstrated to provide accurate measurements of all key features of the

entire imposed drift waveform, with a drift measurement error of approximately 0.1 cm.

40-story

3-story

Waveforms

(TID)

Amplitude

f-content


Objective: evaluate the DDPS performance under more realistic structural dynamic conditions and

include the additional challenge of developing a correction to account for the local

structural member rotations at the mounting point of the laser.

Correcting for Laser Local Rotation

Vertical DDPS

Horizontal DDPS

Optical Beam Splitter

A

B

C

Laser

DDPS

DDPS

DriftD

LaserQ

RotationD ObservedD

VerticalD

H

W

El Centro Input Motion

DDPS sensor with impinging diffracted laser light

String encoder for drift measurement

Testbed #2: Results

Results: throughout the experiment, the DDPS exhibited an ability to accurately measure the

transient drift waveforms in terms of both frequency content and amplitude. Error was independent

of drift amplitude (<0.2 cm as expected from error analysis).

El Centro

Ground

Motion

Testbed #2: Results

Landers

Ground

Motion

Ref - McCallen, D., Petrone F., Coates, J., Repanich, N., (2017), "A Laser-Based Optical Sensor for Broad-Band Measurements of

Building Earthquake Drift", Earthquake Spectra, 33(4), pp. 1573-1598


Objective: validate a second generation, single-board, DDPS design and demonstrate sensor

performance at a scale more representative of actual building field conditions.

Diagnostics tower

a) b)

Frame withadded floor mass

N

SE

W

N

Original and New Sensor System

Single boardcomputer

Serial communication

Field ProgrammableGate Array (FPGA)

Main sensorboard

Photodiode array

Comparatorbank

6”

USB storage

Comparatorbank

Photodiodearray

FPGA

Photodiodethreshold

adjustment

Microcontrollermodule

Power in

Customsensor PCB

Aux. serial output Settings/configuration

Ethernet port

t1 t2 t3 t4

23 cm

Integrated Sensor on a

Single Board

Original sensor system with

Interconnected components

GEN 1

GEN 2

Testbed #3: El Centro 250%

Shake Table

Diagnostics Tower

Tensioned Cable

Tensioned

Cable

1/3 Scale Steel Building

String potentiometer for measuring cableextension and retraction

Laser DDPS

b)

a)a)

b)

Shake Table

Diagnostics Tower

Tensioned Cable

Tensioned

Cable

1/3 Scale Steel Building

String potentiometer for measuring cableextension and retraction

Laser DDPS

b)

a)a)

b)

Testbed #3: Results

a) b)

Floor 1 Drift

Floor 2 Drift

Floor 3 Drift

El Centro 250%

Ground Motion

DDPS vs Ground Truth DDPS “Error”

Max drift – 3.75%

Max error – 0.25% (amplitude indep.)

Ref - Petrone, F., McCallen, D., Buckle, I., Wu, S., (2018), "Direct Measurement of Building Transient and Residual Drift Using an

Optical Sensor System", Engineering Structures, Vol. 176, pp. 115-126.

Simulation of DDPS Performance for System Design

Computational

Model Experiment

Computational Model Attributes

ObservedDamping

Mode 1 Mode 2 Mode 3

1.8%1.13 Sec0.86 Hz

0.33 Sec3.03 Hz

0.11 Sec9.09 Hz

We wanted to develop a predicting capability of the sensor system, without relying just on

experiments on different types of structures.

Simulation of DDPS Performance for system design

Experiment

Experiment

Without rotation correction With rotation correction

Without rotation correction With rotation correction

Agenda
















Application to DOE Facilities

Develop understanding of

facility specific drifts

Force Level

Inter-Story Drift Ratio

1.2%

(plastic hinge) 3.0%

(ultimate capacity)0.6%

(yield point)

Accurately and rapidly

measure facility drifts

Moving forward, the ultimate vision for the DDPS system is to provide the data necessary

for a very rapid determination of structural drifts immediately after an earthquake. This

data would provide critical, unprecedented, information to activate emergency response and

continuity of operations in critical facilities.

Confirm as-built performance

Inform continuity of operations

Indicate where to inspect

Inform damage potential

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