Download - Behavior and Design of Cast-in-Place Anchors under Simulated Seismic Loading (NEES-Anchor)
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Chadd Lane
Jian Zhao Assistant Professor
WisCamp Undergraduate Research
Summer 2009
University of Wisconsin Milwaukee
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Motivation:
Structural safety
Cracks in the cement, broken anchors,
or shifting of the beams.
Maximize structural safety
Saving time and money
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Behavior of anchor connections
Concrete cracking in tension
Current design regulations
Limited guidance
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How does one maximize structural safety with the number of anchors, anchor design, and location?
How does one disperse the weight of a
large beam evenly among all the anchors?
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Concrete Spall Cone—
Steel Breakage—
Anchor Pullout—
Bond Failure—
Edge Distance and Spacing Reduction—
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Spalled concrete— split, chip, or to break into smaller pieces
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A material can be loaded in:
a) compression b) tension c) shear
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Computer simulation failure rate of cement and anchors
Real life seismic loading simulation. Confirm computer simulationsHow the cement and anchors should look
when they fail. Understand the full nature of cement and
anchors. Calculations
How to disperse the weight of the large beam evenly amongst all anchors evenly
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One of the anchor bolts was fractured
The other bent under a combined tension and shear action.
The top layer of concrete spalled such that the hairpin, with an intention to help the anchor connection to resist shear, was displaced outside the anchor connection.
Note that the failure of the anchor connection might have contributed to the total collapse of the industrial building.
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The experimental tests include the
ongoing single-anchor tests at UWM
and the anchor group tests (to be
conducted at Illinois in 2010).
Anchors in every test group are
subjected to these loadings: tension
and shear
The loading frame shown right are
set for the various loading patterns.
Meanwhile
http://www.youtube.com/watch?v
=3z4YLUqOysI
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The anchor position is chosen to enable concrete
breakout failure.
The same configurations will be cast and tested
with various anchor reinforcements to explore
practical and effective reinforcement details that
can prevent the concrete breakout failure modes.
Headed bars and reinforcement cages are under
consideration.
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The single anchor tests will be simulated using
finite element models to optimize the anchor
reinforcement details.
The proposed design procedures will be
incorporated in the MathCAD programs.
Non-Seismic Anchor Design
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SteelTension
BreakoutTension
PulloutTension
BlowoutTension
SteelShear
BlowoutShear
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PCI
NZS
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Seismic Anchor Design
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SteelTension
BreakoutTension
PulloutTension
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ACI
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NZS
Euro
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Using the NEES facility at the University of Illinois.
Obtain detailed experimental - cyclic shear and
combined tension-shear.
Evaluate current seismic anchor design provisions and
develop new
design methodologies and the use of anchor
reinforcements.
Create fiber-based connection interface models.
Promote a timely transfer of knowledge
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This UWM project is being led by Dr. Zhao
Two graduate students Joshua Johnston and Derek
Petersen from UWM and one graduate student
from UC are working on the project.
Two undergraduate students Alice Muehlbauer
and Chadd Lane.
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Seismic behavior and design of cast-in-place anchors/studs using NSF NEES facility and local resources.
Anchor tests that simulate a combination of concrete breakout failure under shear and/or tension.
The focus will be also on the improvement of anchor behavior through using anchor reinforcements.
The research program will generate critical knowledge that advances the seismic design of anchor connections, as well as providing essential information for future revision of anchorage design regulations.
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Dr. Zhao and his team
WisCamp and McNair Staff and students
All other people that played a roll in this
great experience.