Description
and Abstracts
of REU Projects for Summer 2007
TITLE:
Analysis of a Testing Method Used to Determine Solubilization
Characteristics of Aqueous Nonylphenol Ethoxylate
Abstract: Phenanthrene was added to aqueous nonylphenol
ethoxylate surfactant and the partition coefficient
of chemical dissolved in the micelle to aqueous chemical
was calculated from UV spectrophotometry analysis
of samples. A comparison was made between the partition
coefficient and the average number of ethoxylate groups
on the nonylphenols forming micelles in solution.
The method of analysis, a best-fit of the spectra
of standards to that of samples, showed an apparent
trend between ethoxylate average and partition coefficient
where, in fact, no trend existed. This apparent trend
appeared when a standard used for comparison was assumed
to be completely micellar and in fact the chemical
was not completely dissolved in the micelle, with
some aqueous chemical present and skewing calculated
micellar concentrations for samples. An analysis of
standards has been prepared to determine if an apparent
trend will be created with the standard being used.
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TITLE: Shake Table Tests to
Demonstrate the Nonlinear Dynamic Response of Timber
Frames with Different Connections
Abstract: Despite the increased use of steel as a
building material, timber is still a popular construction
material. Although timber has been used for many centuries,
the advent of more complicated building schemes including
shear walls, trusses, and aesthetic structures requires
an advanced effort to maximize the understanding,
performance, and safety of timber-based structures.
Therefore, the main objective of this experiment is
to demonstrate the nonlinear response of timber structures
under dynamic loading. The purpose of this objective
is to develop a test bed and teaching demonstration
of nonlinear dynamics. This exploration focuses on
the nonlinearities that develop at the connections
of two simple timber systems, the inverted-T and the
frame. Special attention is given to the connections
within the frame since the literature agrees that
connections between timber members are the most important
governing factors of its behavior. This experiment
intends to explore the response of L-plates, mending
plates, and nails to a shake table’s excitation
force. To accomplish this task, an improvement to
the timber research of Sugeng (2006) is considered,
following his accelerometer-shake table methodology
while adding displacement data with the aid of video
cameras. The results from this study confirm the presence
of nonlinearities in the twelve tested specimens.
The specimens with L-plates, nails, or the combination
therein exhibited hardening behavior while those with
mending plates, L-plates/mending plates, or nails/mending
plates had softening trends. The nonlinearities in
this study match those in Sugeng’s research,
with the exception of the L-plate and L-plate/nail
specimens. Deformation diagrams were obtained using
frame by frame analysis of each testing sequence (Figure
3.1.1). The lateral stiffness approximations from
the gathered data (Figure 3.2.1, 3.2.2) agree with
the processed deformation diagrams (Figure 3.1.1):
the nail joint is the loosest while the L-plate/mending
plate is the stiffest. The small size of the designed
specimens makes this an excellent teaching application,
provided fabrication errors can be avoided.
TITLE: Properties of OHD L-50
Stabilized Soils
Abstract: An acceptable soil subbase is resistant
to volume change and shear. Some soils are naturally
good urban material, but in Oklahoma where fine grained
soils are predominant, additives must be used to form
suitable subbase. Prior research allowed the American
Society for Testing and Materials (ASTM) to develop
a standard for evaluating the effectiveness of additives
used throughout the USA. Using the ASTM standard (insert
standard #) the Oklahoma Department of Transportation
developed the shorter OHDL-50 standard for use in
Oklahoma. The core of this standard is a soil stabilization
table. This soil stabilization table provides suggested
additive amount for approximately seven AASHTO Standard
M145 soil types (A-1 through A-7). Three of these
soil types require a traditional mix design for most
additives because of special concerns or non-approved
chemical sources. Suggested additives include lime
(hydrated and quick lime), Portland cement (PC), fly
ash (FA), and cement kiln dust (CKD). A problem with
the OHDL-50 standard is that soils under the same
AASHTO classification have been observed to act differently
to the recommended additive amounts. Because the development
of the OHDL-50 was based on experience and assumptions
in the field, there are possibilities for error in
some soil and additive combinations. Errors in additive
amounts can cause the subbase to be stabilized inadequately.
Several soils from the same AASHTO types will be included
in experiments to measure the variation in strength
gain and ensure standards are met. The purpose of
the proposed research is to evaluate soils classified
in the same AASHTO set to determine if the OHDL-50
table standard sufficiently determines stabilization
type and amount, or if there is another consideration
besides classification, that must be taken into account
before stabilization begins. This project utilized
soils from throughout Oklahoma that have been extensively
characterized and found to fall within the same classification;
specifically groups A-6 and A-7-6. Harvard Miniature
tests have been produced to calibrate a standard proctor
curve and used as unconfined compressive test samples.
Lime, CKD and FA were added in different percentages
by weight and compacted to 95% of the dry density
and close to the optimum moisture content. The pH
of each of the stabilized soils were measured and
recorded. To ensure accuracy and repeatability, unconfined
tests were conducted in sets of five and the increase
in strength from the addition of the stabilizer was
recorded. The Atterberg limits, more specifically
the liquid and plastic limits, were determined using
the liquid limit device and kneading/rolling. After
all tests were completed the results were analyzed
to make certain that they met or exceeded the strength
requirements called for in ASTM Dxxxx, of an increase
in strength of 50 psi. Findings validated that soils
within the same AASHTO classification do not behave
the same, or as predicted by the OHDL-50 standard.
Suggestions will be made to optimize the OHDL-50 with
findings from this project. Further research entails
finding the reason why soils under the same AASHTO
classification do not behave the same as predicted.
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TITLE: Metal Contamination
in Volunteer Wetlands
Abstract: Little is known about the effects metal
contamination has on plants living in volunteer wetlands.
The aim of this study was to lay the ground work so
that in the future we could assess the extent to which
settled organic matter and dead macrophytes affected
metal accumulation in volunteer wetlands. We set out
to determine the consequences hydrology and water
saturation may have on our samples. We found that
the organic matter in all three types of wetlands
we sampled were similar. In addition, we found that
organic matter collected in both flooded and saturated
zones of these wetlands were also comparable.
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TITLE: Compressive Strength
Analysis of Class F Fly Ash
Abstract: The research focuses on analyzing how
mechanically activating fly ash of five different
samples of Class F fly ash. The fly ash will be ground
for a period if 0, 30 and 120 minutes. The grinding
will affect the workability and cementitious value
of the fly ash when it is used as an admixture in
aggregates to enhance strength properties. The research
will apply compressive strength tests to 20 samples
of 42 different batches. The compressive strength
data will be compared to 6 samples of Class C fly
ash previously researched.
The batches are organized in a matrix to ensure organization
in scheduling compression tests on sample cylinders.
Each sample of Class F fly ash (denoted Sample A,
Sample B, Sample C, Sample D, Sample E) was ground
for 0, 30, and 120 minutes. Then 20%, 40% and 60%
of fly ash is added to the mix along with Portland
cement. For clarification the batches where organized
in this manner: Sample A, 20% added volume, and ground
for 30 minutes. The concrete is placed in plastic
cylindrical molds and left in a climate controlled
curing chamber. The compressive strength tests where
administered following ASTM standards (1, 7, 14, 28,
and 56 days). Three samples from each batch were chosen,
with respect to the day the concrete was batched,
and were tested for compressive strength. The concrete
cylinders were completely brought to failure and values
of pounds per square inch were recorded. The compressive
strengths will be compared to 100% PCC samples for
comparison. The data from this research will provide
insight into the strength of Class F fly ash. In high
sight, this research will aid the improvement of the
current fly ash classification system. During the
course of the research 42 batches were completed,
15,000 lbs of concrete and 840 samples were made.
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TITLE: Pullout Resistance of
Multiple Reinforcements in MSE Walls
Abstract: Standard practice for the compaction of
the backfill soil near the facing of an MSE wall or
embankment is to use lightweight compaction equipment
to prevent excessive facing deformation. Complications
due to compaction using heavy equipment near the facing
could also include misalignment or structural damage
of the wall facing and overstressing of the reinforcement
layers. However, inadequate compaction near the facing
could result in later settlement or appearance of
voids behind the facing.
Little research has been reported in the literature
to quantify the effects of loosely compacted soil
behind the facing on the stability and serviceability
of MSE walls at the end of construction. In this study,
the influence of inadequate compaction effort near
the facing on the construction performance of idealized
wrapped-face MSE wall models is investigated using
a numerical simulation approach. It is shown that
inadequate backfill compaction within 1 m of the wall
facing could increase the wall lateral displacement
by about 40% and the reinforcement strains by about
90% compared to the response of an otherwise identical
(i.e. control) wall model constructed with uniform
compaction throughout the backfill. This effect was
found to be more significant for higher quality backfills
with greater friction angle values and less stiff
reinforcement materials. Results of this study on
idealized wrapped-face wall models highlight the importance
of proper soil compaction and quality control near
the facing of MSE walls and offer example quantitative
increases that could be expected in the out-of-alignment
and reinforcement loads in these MSE structures.
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TITLE: Investigation of Shearing
Capacity of Prestressed Concrete Girders Designed
According to the Quarter-Point Rule
Abstract: Shear capacity of prestressed concrete
girders estimated using the AASHTO specification in
the early and mid 1970s were based on the quarter-point
rule. Since then, the specification has become more
conservative. There is concern that some of the beams
designed using the old methodology are not up to specification
according to the new design codes.
The purpose of this study is to find out if this is
true or not. A real-world beam that was designed and
constructed when these techniques were in use will
be analyzed using current design codes to find the
estimated shear capacity. Afterwards, the beam will
be subjected to destructive testing in order to find
the true shear capacity.
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TITLE: Assessing the Relationship
Between Composition of Riparian Vegetation Stream
Morphology and Stability
Abstract: Streams and their associated ecosystems
have great ecological and societal importance, yet
they are increasingly altered and destroyed by anthropogenic
disturbances. Riparian vegetation is known to interact
with the stream by stabilizing banks against erosion,
collecting sediment in flood waters, moderating light
and temperature of waters, and providing nutrients
and habitat that support diverse ecosystems. This
work analyzes plant life-forms and density in the
entire riparian region and relates this to stream
morphology and stability. A new vegetation assessment
is developed to quantify structural (or spatial) density
of these life forms. Only two streams were studied,
so there is not sufficient data for conclusive results.
Stream morphology did not differ between the streams.
An estimate of stream stability, or predicted erosion,
was found to relate with both stream density and structural
life-form diversity. This result is consistent with
previous findings and provides some validation for
the new vegetation assessment.
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TITLE: Influence of Spatial
Distribution of Riparian Zones on Low-order Streams
Abstract: Although many physical characteristics
of an ecosystem define a stream’s form; one
that has received little attention in the current
literature is the distribution and form of a riparian
zone. The question explored in this project is whether
the spatial distribution patterns of riparian vegetation
affect the geomorphologic structure of a stream. Many
may observe that the riparian zone certainly does
have an impact upon the stream, in particular the
effects of the riparian zone’s ability to filter
non-point source water pollutants. However, the question
that is being asked is whether the vegetation of this
zone is enough to affect the state of the stream and
possibly even its form. The root systems of the vegetation
of these zones has an ability to absorb the energy
from shear stresses acting upon the stream banks caused
by flowing water. It is therefore hypothesized that
increased distribution of forested riparian zones
results in a more constant stream form for low order
streams.
This hypothesis was tested in the following manner.
First reaches along two streams were selected for
the study by determining where the spatial distribution
of the riparian zone is similar on each bank, but
different among the stream reaches. Longitudinal and
cross-sectional profiles were then surveyed at the
upstream end of the designated reach of stream, in
the middle of the reach, and then at the downstream
end of the reach. This survey data was then used to
determine stream form and the Rosgen classification
(Rosgen, 1994, 1996). This data combined with a Bank
Erodibility Hazard Index (BEHI) is a partial indicator
of stream channel stability. Autocorrelations were
then be used to determine the influences of the distribution
of forested riparian zones on stream form and state.
It was determined that forested, riparian vegetation
distribution has a greater effect on the stream state,
especially of the stream banks, than specific, quantifiable
effects on stream form.
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TITLE: Hydraulic Behavior
of Colloidal Silver-Enhanced Ceramic Water Purifiers
Abstract: Each year unsafe drinking water results
in the deaths of 1.7 million people around the world.
In an effort to supply a sustainable source of safe
water to developing nations, Potters for Peace has
developed an inexpensive, low-tech, colloidal silver-enhanced
ceramic water purifier. Made with a mix of terra-cotta
clay and a combustible material, such as sawdust,
and coated with colloidal silver, these simple pots
have been proven to effectively eliminate approximately
99.88% of most water born disease agents. However,
specific hydraulic characteristics of these filters
are currently unknown. The purpose of this project
is to understand the hydraulic behavior of the ceramic
water purifier through a combination of laboratory
and numerical experiments. Through the use of advanced
pressure transducers, the flow through several pots
will be analyzed, thus allowing for calibration of
the hydraulic conductivity. These results can then
be used to observe the differences related to the
fabrication of the filters. When coupled with a transport
model, the hydraulic model can be used to analyze
the impacts of water quality, such as turbidity, on
the hydraulic performance of the filters. In addition
to this, the effects resulting from the application
of various arsenic and fluoride removing substances
to the interior surfaces of the filters can also be
evaluated.
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TITLE: Timber
Joints with Dynamic Loading
Abstract: Observe the joint behavior in timber single-degree-of-freedom
models to study nonlinearity, to increase the database
for nonlinear timber joint response. Find which joint
produces the best response under dynamic loading.
Study joints that are fast, easy, and cheap to use:
nails, L-plates, and mending plates. Also, model a
truss using OpenSees, subject it to similar cyclic
loading, and compare hysteretic response of the joints
from OpenSees and from the experimental SDOF models
in order to show that small models can be representative
of larger structures.
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TITLE: Sustainable
Solutions for Arsenic and Fluoride Removal in Developing
Countries
Abstract: According to the World Health Organization
(WHO), there are currently 1.1 billion people who
do not have access to safe drinking water. The UN
Millennium Development Goal on water and sanitation
aims to “Reduce by half the proportion of people
without sustainable access to safe drinking water”,
by the year 2015 (UN, 2007). Since there are an estimated
2 billion people living on less than $1 US per day,
simple, cost effective, sustainable solutions are
needed to provide safe drinking water and reach the
UN Millennium Development Goals (WHO, 2007).
Two contaminants which contribute to unsafe drinking
water are fluoride and arsenic. This study looked
into the effectiveness of several adsorbents at removing
arsenic and fluoride from water. The adsorbents explored
were cattle bone char, fish bone char, corn husks
and rice husks, all of which are often locally available
and reproducible in developing countries. This study
also investigated the possibility that adding these
materials to the bottom of clay pots, which act as
microbial water filters from the Potters for Peace
organization, would aid in the removal of fluoride
and arsenic. Batch tests were conducted to determine
the effectiveness of the adsorbents at removing fluoride
and arsenic (V), separately. Column studies were then
run to determine removal break through and saturation
points. This study also looked into scale up issues
that could occur when the adsorbents were put in a
layer on the bottom of the clay pots.
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TITLE:Teaching Demonstration
for Nonlinear Dynamics Using Timber Joints
The focus of the research and the results herein
explores the response of timber joints to cyclic loading.
Using a shake table and and 2 tri-axial accelerometers,
one can see the non-linearities present in these joints.
The purpose in researching these structures is twofold.
The first is to find an inexpensive teaching demonstration
for non-linearities in structural dynamics. The second
is to create a test bed for structural health monitoring
systems and algorithms. The timber frames that hold
the joints in question must be easy to produce and
single degree of freedom to satisfy both purposes.
The research found that both inverted Tframes and
square frames are relatively easy to manufacture and
relatively inexpensive though neither are sufficient
to restrict the range of motion to a single degree.
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