Transcript Presentation by Valentin Shustov 20 June, 2007 https://central.nees.org/activities/index.php?facility=UCSD • The latest research activities at CSUN culminated in the innovative building technology called the.

Presentation
by Valentin Shustov
20 June, 2007
https://central.nees.org/activities/index.php?facility=UCSD
• The latest research activities at CSUN culminated in the
innovative building technology called the Earthquake
Protector. Its research, supported by NSF, Award No.
0618183, and entitled “SGER: Testing of a New Line of
Seismic Base Isolators” is both analytical and experimental.
For the Final Report to NSF, click on
https://central.nees.org/data/get/NEES-20060283/Public/REPORT.pdf
• The reported research contains a lot of novelties including but
not limited to the very concept of earthquake protection,
metrics of building performance, physical and virtual
experiments, hardware, software and, of course, conclusions.
• Software for analytical research called Earthquake
Performance Evaluation Tool (EPET) enables virtual
experiments on buildings with and without Earthquake
Protectors. On demand, all virtual experiments are animated.
• Major building earthquake performance evaluation parameter
for the testing is the Seismic Performance Ratio.
Building models are the primary measuring tool in all experiments.
Physical model
Mathematical model
For assessment or comparison of
the anticipated building
performance, the Story
Performance Rating R will be
used as a major criterion:
v
R=
ve
(1)
•
where v = un - un-1 is an actual or
calculated inter-story drift;
• ve is an inter-story drift at the
assumed elastic limit of horizontal
deformation.
The ultimate allowable value of R will
occur when
R = Rw =
vu
ve
(2)
• where Quality Factor Rw is
understood as the ratio of the
ultimate allowable story drift
vu that can be tolerated by the
structure without a collapse to
the maximum elastic story drift
ve.
• The case R < 1 relates to a
purely elastic performance of
the structure.
• The case 1 < R < Rw defines
how far the structure extends
into the plastic range.
• The case R > Rw means a
possibility of either collapse of
the story or occurrence of
other life threatening damage
that will not, necessarily, result
in losing full value of the
structure.
• Ratio R/Rw is the Seismic
Performance Ratio which
controls the anticipated
physical losses due to seismic
exposure of the building
structure.
• The anticipated damage due to
a seismic exposure is defined
by the Damage Ratio D.R. that
may be related to R/Rw.
http://www.ecs.csun.edu/~shustov/000-EPF.html
http://www.ecs.csun.edu/~shustov/EP-2004-1.htm
http://www.ecs.csun.edu/~shustov/001-EPF-03.html
http://www.ecs.csun.edu/~shustov/EP-2005.htm
Main technical characteristics of
the facility:
• Platen
7.6 m x 12.2 m
• Stroke
0.75 m
•
•
•
•
Frequency
Peak velocity
Force capacity
Vertical payload
0-20 Hz
1.8 m/s
6.8 MN
20 MN
Performance testing of Earthquake Protectors took place at the UC San
Diego Large High Performance Outdoor Shake Table (LHPOST).
LHPOST is a participant of the George E. Brown Jr. Network for
Earthquake Simulation (NEES).
• Three 1/8th–scaled down building
models of identical design were tested
on the shake table, namely: 6-story,
12-story and 18-story ones.
• Those models were kinematically
equivalent to the real building
prototypes which meant they would
deflect horizontally the same way
under the same horizontal excitation.
• The “prestressing” concept of design
was chosen to increase the models’
structural redundancy while preserving
their visual sensitivity to any kind of
lateral excitations.
• Earthquake Protector or EP (U.S. • Unlike the active, hybrid or
Patent pending) is a system of
semi-active structural control
structural elements resting on a
hardware, it looks,
building footing and underpinning a
apparently, simple and selfbuilding superstructure.
sufficient .
• This system, generically called base
isolation, is intended to shield the
building superstructure against
lateral impacts of strong
earthquakes.
• To withstand the real earthquake
time-histories, the models of
earthquake protectors had to have
full scale horizontal dimensions.
Each EP comprises:
• a column stub 7 resting upon a
•
Three properly configured
spherical bearing 9 mounted
race pads 1, 2 and 3
centrically on the upper pad 3
mounted one over another
with the top end of the column
with the lower pad 1 resting
stub being framed rigidly into
on the footing.
the supported superstructure 8.
•
Two circular-cylinder-shaped
segmented slide tracks 4 and
5 which are sagged down,
located between adjacent
race pads and containing
freely revolving parallel
cylindrical rollers 6 with their
axes being set horizontal and
mutually orthogonal.
• Assembly of four Earthquake
Protectors in the process of
assembly:
• The 6-story building model
supported on four Earthquake
Protectors:
http://www.ecs.csun.edu/~shustov/EP-2006.htm
Ground acceleration mitigation factor Fmit , that is the most simple performance
parameter chosen for comparison with the field records, may be determined
as a ratio of the maximum recorded horizontal acceleration on the ground
(or on the shake table platen) to the maximum recorded horizontal
acceleration on the building (or on the model structure).
Superstructure
Bearing type
with fundamental and its isolated
period Tf
period Ti
Earthquake
Mitigation
Factor Fmit
6-story building
model, Tf = 0.6s
Earthquake
Protector, Ti = 5s
300% Northridge
Jan.17, 1994
4.78
12-story building
model, Tf = 1.2s
Earthquake
Protector, Ti = 5s
100% Northridge
Jan.17, 1994
2.63
18-story building
model, Tf = 1.8s
Earthquake
Protector, Ti = 5s
120% Northridge
Jan.17, 1994
2.77
See http://www.ecs.csun.edu/~shustov/Topic4.htm
Bearing Type
Earthquake
Mitigation
Factor Fmit
Santa Ana River
Bridge
Lead-rubber
Whittier Narrows
Oct. 1, 1987
0.28
Sierra Point
Overpass
Lead-rubber
Loma Prieta
Oct. 17, 1989
0.22
LA County Fire
Command Facility
High-damping
rubber
Northridge
Jan.17, 1994
0.54
USC Teaching
Hospital
Rubber/Leadrubber
Northridge
Jan.17, 1994
0.89 – 1.76
Rockwell Intl.
Headquarters
Lead-rubber
Northridge
Jan.17, 1994
0.53
3-story Residence
Building
Spring &
Viscodamper
Northridge
Jan.17, 1994
0.70
Facility
See http://www.ecs.csun.edu/~shustov/Topic2.htm
1 - LA County Fire Command Facility
2 - USC Teaching Hospital
3 - 3-story Residence Building
4 - Rockwell Intl. Headquarters
The software development source code: http://epet.space3d.biz/EPET_DEV.zip.
•
•
Software for analytical research called Earthquake Performance Evaluation
Tool (EPET) enables virtual experiments on buildings with and without
Earthquake Protectors. On demand, all virtual experiments are animated.
Major building fitness evaluation parameter for the testing is the Seismic
Performance Ratio R/Rw .
• Quantitative performance evaluation of a virtual building structure
during a virtual earthquake excitation is done with the help of the nth
story Seismic Performance Ratio R/Rw (or SPR):
•
•
•
•
SPR = vn/Rwnven
There will be the following three basic situations:
0 < SPR < 1
Acceptable performance of a story, called: GOOD.
1 < SPR < 1.5
Possibility of structural failure, called: FAILURE.
1.5 < SPR
Structural collapse, called: СOLLAPSE.
(3)
DAMAGE
INDEX
0
1
2
3
4
DAMAGE
CATEGORY
No damage
Slight
Considerable
Severe
Collapse
SPR = R/Rw
< 0.167
0.167 – 0.5
0.5 – 1.0
1.0 - 1.5
> 1.5
D.R. (%)
< 0.14
0.14 - 3.75
3.75 – 30.00
30.00 – 100
> 100
http://www.ecs.csun.edu/~shustov/TEST_8_LARGE.wmv
EXPERIMENTAL STORY DRIFTS of 6-STORY BUILDING MODELS (cm)
FLOOR
NUMBER
Cone© maximum
velocity = 16.96 cm/s
Cone© maximum
velocity = 46.63 cm/s
Cone© maximum
velocity = 89.48 cm/s
Fixed base
On EP
Fixed base
On EP
Fixed base
On EP
6th
1.23
0.26
2.39
0.37
4.96
0.54
5th
2.82
0.25
6.46
0.39
6.90
0.62
4th
2.22
0.38
5.83
0.54
7.15
0.81
3rd
3.22
0.31
8.65
0.47
11.66
0.73
2nd
2.97
0.31
7.17
0.47
11.4
0.72
1st
2.12
0.24
4.29
0.37
13.46
0.59
Ave. drift
mitigation
8.38
13.18
13.82
STORY DAMAGE INDEX and DAMAGE CATEGORY for 6-STORY
BUILDING MODELS at SHAKE TABLE TESTING
FLOOR
NUMBER
Cone© maximum
velocity = 16.96 cm/s
Cone© maximum
velocity = 46.63 cm/s
Cone© maximum
velocity = 89.48 cm/s
Fixed base
On EP
Fixed base
On EP
Fixed base
On EP
6th
1
slight
0
2
0
4
1
no damage
considerable
no damage
collapse
slight
5th
3
0
4
0
4
1
severe
no damage
collapse
no damage
collapse
slight
2
0
4
1
4
1
considerable
no damage
collapse
slight
collapse
slight
4th
3rd
2nd
1st
3
0
4
0
4
1
severe
no damage
collapse
no damage
collapse
slight
2
0
4
0
4
1
considerable
no damage
collapse
no damage
collapse
slight
2
0
3
0
4
1
considerable
no damage
severe
no damage
collapse
slight
http://www.ecs.csun.edu/~shustov/TEST_5_LARGE.wmv
http://www.ecs.csun.edu/~shustov/TEST_6_LARGE.wmv
FLOOR
NUMBER
COMPARATIVE INDEX OF EARTHQUAKE PERFORMANCE FOR 6STORY BUILDING MODELS on: Earthquake Protector vs. Fixed base
Cone© maximum
velocity = 16.96 cm/s
Cone© maximum
velocity = 46.63 cm/s
Cone© maximum
velocity = 89.48 cm/s
6th
0-1
0-2
1-4
5th
0-3
0-4
1-4
4th
0-2
1-4
1-4
3rd
0-3
0-4
1-4
2nd
0-2
0-4
1-4
1st
0-2
0-3
1-4
Damage Index: 0 – no damage; 1 – slight; 2 – considerable; 3 – severe; 4 - collapse
•
•
•
•

Shake table experiments with
Earthquake Protectors performed on
the scaled-down building models were
a full success.
The stronger an earthquake the better
Earthquake Protector’s mitigating
performance.
Taking ground acceleration mitigation
factor Fmit as a criterion for
performance comparison of different
types of base isolators, Earthquake
Protector is, at least, five times more
effectively than any of the field-tested
seismic base isolator in California.
Earthquake Protector is simple,
inexpensive to build and applicable to
any size of the building structure.
Earthquake Performance Evaluation
Tool (EPET) can accurately predict
earthquake performance of a building,
with or without Earthquake Protector,
up to the point of its virtual state of
“severe damage”.