Chadd Lane

Jian Zhao Assistant Professor

WisCamp Undergraduate Research

Summer 2009

University of Wisconsin Milwaukee

Motivation:

Structural safety

Cracks in the cement, broken anchors,

or shifting of the beams.

Maximize structural safety

Saving time and money

Behavior of anchor connections

Concrete cracking in tension

Current design regulations

Limited guidance

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?

Concrete Spall Cone—

Steel Breakage—

Anchor Pullout—

Bond Failure—

Edge Distance and Spacing Reduction—

Spalled concrete— split, chip, or to break into smaller pieces

A material can be loaded in:

a) compression b) tension c) shear

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

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.

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

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.

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

0

10

20

30

40

50

60

70

80

SteelTension

BreakoutTension

PulloutTension

BlowoutTension

SteelShear

BlowoutShear

PryoutShear

Stre

ngth

(ki

ps)

ACI

PCI

NZS

Euro

Seismic Anchor Design

0

10

20

30

40

50

60

70

80

SteelTension

BreakoutTension

PulloutTension

BlowoutTension

SteelShear

BlowoutShear

PryoutShear

Str

eng

th (

kip

s)

ACI

PCI

NZS

Euro

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

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.

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.

Dr. Zhao and his team

WisCamp and McNair Staff and students

All other people that played a roll in this

great experience.