Long-Term Structural Movement, HR-275, 1986

This report describes the field application of the tilt sensing method for monitoring movement of the Black Hawk and Karl King Bridges. The study objectives were: to design a data acquisition system for tilt sensing equipment utilizing a telephone telemetry system; to monitor possible movement of the main span pier, Pier No. 2, on the Black Hawk Bridge in Lansing and the possible long-term movement of Pier No. 4 on the Karl King Bridge in Fort Dodge; and to assess the feasibility, reliability, and accuracy of the instrumentation system used in this study.

Use of Longitudinal Subdrains in the 3R Program, HR-509, Progress Report #2, 1981

The main consideration for base construction under the pavement, in the design of Iowa's interstate, was structural capacity. The material was dense graded with the aim of supporting the pavement and distributing the load as it is transferred to the underlying grade. The drainage characteristics of the base was apparently not given adequate consideration. On jointed portland cement concrete pavement, the water that is trapped immediately beneath the pavement causes severe problems. The traffic causes rapid movement of the water resulting in the hydraulic pressures or "pumping" (movement and redeposit of base fine material), further resulting in faulting between individual slabs. The objective of this evaluation is to determine if longitudinal subdrains are effective in preventing or reducing pumping, faulting and related deterioration. Results suggest that, based upon the flow from the outlets observed during periodic checks and evidence of water flow at the outlets, it appears that to date the subdrains are effective in draining the subbase and subgrade. Because of the limited data available at this time, however, the pavement condition and faulting results are inconclusive.

Importance of polyethylene thickness in total shoulder arthroplasty: a finite element analysis.

BACKGROUND: Articular surfaces reconstruction is essential in total shoulder arthroplasty. Because of the limited glenoid bone support, thin glenoid component could improve anatomical reconstruction, but adverse mechanical effects might appear. METHODS: With a numerical musculoskeletal shoulder model, we analysed and compared three values of thickness of a typical all-polyethylene glenoid component: 2, 4 (reference) and 6mm. A loaded movement of abduction in the scapular plane was simulated. We evaluated the humeral head translation, the muscle moment arms, the joint force, the articular contact pattern, and the polyethylene and cement stress. Findings Decreasing polyethylene thickness from 6 to 2mm slightly increased humeral head translation and muscle moment arms. This induced a small decreased of the joint reaction force, but important increase of stress within the polyethylene and the cement mantel. Interpretation The reference thickness of 4mm seems a good compromise to avoid stress concentration and joint stuffing.

Evaluation of Brisco Scour Monitors, HR-551, 1993

Two Brisco Scour Monitors were installed on pier MS1 of the Mississippi River at Burlington in August 1991. No problems were encountered during the installation. The monitors consist of a probe resting on the river bottom fastened to a cable that wraps around a reel. An electrical system monitors the movement of the reel which transmits to a digital readout which shows whether scour has occurred. The intent was to monitor the digital readout twice a year during a four-year evaluation period. The scour monitor digital readouts malfunctioned frequently due to electrical storms. The scour monitor performance was completely unacceptable.

Determination of Tension Crack Development in Plastic P.C. Concrete with Retarding Admixtures, MLR-86-12, 1987

Bridge deck cracking occasionally occurs during construction for any number of reasons. Improper design, concrete placement or deck curing can result in cracks. One contributing factor toward cracking may be dead load deflections induced during concrete placement. For both continuous and non-continuous bridges, specific placement sequences are required to minimize harmful deflections in previously placed sections. Set retarding admixtures are also used to keep previously placed concrete plastic until the pour is completed. The problem is--at what point does movement of the concrete cause permanent damage to the deck. The study evaluated the time to crack formation relationship for mixes with low and high dosages of set retarding admixtures currently approved for use in Iowa state and county projects.

Use of Longitudinal Subdrains in the 3R Program, Progress Report 1, HR-509, 1980

The main consideration for base construction under the pavement, in the design of Iowa's interstate, was structural capacity. The material was dense graded with the aim of supporting the pavement and distributing the load as it is transferred to the underlying grade. The drainage characteristics of the base was apparently not given adequate consideration. On jointed portland cement concrete pavement, the water that is trapped immediately beneath the pavement causes severe problems. The traffic causes rapid movement of the water resulting in the hydraulic pressures or "pumping" (movement and redeposit of base fine material), further resulting in faulting between individual slabs. The objective of this evaluation is to determine if longitudinal subdrains are effective in preventing or reducing pumping, faulting and related deterioration. Results suggest that, based upon the flow from the outlets observed during periodic checks and evidence of water flow at the outlets, it appears that to date the subdrains are effective in draining the subbase and subgrade. Because of the limited data available at this time, however, the pavement condition and faulting results are inconclusive.

Use of Longitudinal Subdrains in the 3R Program, Final Report, HR-509, 1981

Construction of the interstate highway system began in 1956. This U.S. network of highway consists of more than 41,000 miles with 790 miles in Iowa. There have been many benefits of the controlled access roadway, but probably the most significant is the improved safety for the motorist. In Iowa, we have always endeavored to utilize quality locally available materials in our construction using the most economical or cost effective methods. Obviously when the effort is to build a cost effective system, there will be some portions of the network that will not perform as well as expected. In the design of our interstate, the main consideration for base construction under the pavement was structural capacity. The material was dense graded with the aim of supporting the pavement and distributing the load as it is transferred to the underlying grade. The drainage characteristic of the base was apparently not given adequate consideration. On jointed portland cement concrete (pcc) pavement, the water that is trapped immediately beneath the pavement causes severe problems. The traffic causes rapid movement of the water resulting in the hydraulic pressures or "pumping" (movement and redeposit of base fine material) resulting in faulting between individual slabs. Recognizing the need for maintaining this large national highway network, the Federal Highway Administration has initiated a funding program for resurfacing, restoration and rehabilitation (3R). Many miles of the system are more than 20 years old and in need of major maintenance. This new 3R Program necessitated a complete inventory of the Iowa interstate system to establish priorities and to identify those sections in need of immediate remedial treatments.

Dynamic Deflections for Determining Structural Rating of Flexible Pavements, HR-178, 1979

The Road Rater is a dynamic deflection measuring apparatus for flexible base pavements. The Road Rater replaces the Benkelman Beam which was last used by the Iowa DOT in 1977. Road Rater test results correlate reasonably well (correlation coefficient = 0.83) with Benkelman Beam test data. The basic differences between the Road Rater and Benkelman Beam are as follows: 1. The Benkelman Beam uses a static 18,000 lb. load while the Road Rater uses a dynamic 800 to 2,000 lb. loading. 2. The Road Rater tests much faster and more economically than the Benkelman Beam. 3. The Road Rater better simulates a moving truck than the Benkelman Beam. The basic operating principle of the Road Rater is to impart a dynamic loading and measure the resultant movement of the pavement with velocity sensors. This data, when properly adjusted for temperature by use of a nomograph included in this report, can be used to determine pavement life expectancy and estimate overlay thickness required. Road Rater testing will be conducted in the spring, when pavements are in their weakest condition, until seasonal correction factors can be developed. The Road Rater does not have sufficient ram weight to effectively evaluate load carrying capacity of rigid pavements. All rigid pavements react similarly to Road Rater testing and generally deflect from 0.65 to 1.30 mils. Research will be contined to evaluate rigid pavements with the Road Rater, however. The Road Rater has proven to be a reliable, troublefree pavement evaluation machine. The deflection apparatus was originally front-mounted,but was rear-mounted during the winter of 1977-78. Since that time, van handling has greatly improved, and front suspension parts are no longer overstressed due to improper weight distribution.

Distribution of arm velocity and frequency of arm usage during daily activity: objective outcome evaluation after shoulder surgery.

In clinical settings, functional evaluation of shoulder movement is primarily based on what the patient thinks he/she is able to do rather than what he/she is actually performing. We proposed a new approach for shoulder assessment based on inertial sensors to monitor arm movement in the daily routine. The detection of movement of the humerus relative to the trunk was first validated in a laboratory setting (sensitivity>95%, specificity>97%). Then, 41 control subjects and 21 patients suffering from a rotator cuff tear were evaluated (before and after surgery) using clinical questionnaires and a one-day measurement of arm movement. The quantity of movement was estimated with the movement frequency and its symmetry index (SIFr). The quality of movement was assessed using the Kolmogorov-Smirnov distance (KS) between the cumulative distribution of the arm velocity for controls and the same distribution for each patient. SIFr presented differences between patients and controls at 3 month follow-up (p<0.05) while KS showed differences also after 6 months (p<0.01). SIFr illustrated a change in dominance due to the disorder whereas KS, which appeared independent of the dominance and occupation, showed a change in movement velocity. Both parameters were correlated to clinical scores (R(2) reaching 0.5). This approach provides clinicians with new objective parameters for evaluating the functional ability of the shoulder in daily conditions, which could be useful for outcome assessment after surgery.

The estimation of PMP and PMF on alpine basins in Switzerland

This paper presents a very fine grid hydrological model based on the spatiotemporal repartition of precipitation and on the topography. The goal is to estimate the flood on a catchment area, using a Probable Maximum Precipitation (PMP) leading to a Probable Maximum Flood (PMF). The spatiotemporal distribution of the precipitation was realized using six clouds modeled by the advection-diffusion equation. The equation shows the movement of the clouds over the terrain and also gives the evolution of the rain intensity in time. This hydrological modeling is followed by a hydraulic modeling of the surface and subterranean flows, done considering the factors that contribute to the hydrological cycle, such as the infiltration, the exfiltration and the snowmelt. This model was applied to several Swiss basins using measured rain, with results showing a good correlation between the simulated and observed flows. This good correlation proves that the model is valid and gives us the confidence that the results can be extrapolated to phenomena of extreme rainfall of PMP type. In this article we present some results obtained using a PMP rainfall and the developed model.

Rapid Replacement of Bridge Deck Expansion Joints Study – Phase I, RB33-013, 2014

Bridge deck expansion joints are used to allow for movement of the bridge deck due to thermal expansion, dynamics loading, and other factors. More recently, expansion joints have also been utilized to prevent the passage of winter de-icing chemicals and other corrosives applied to bridge decks from penetrating and damaging substructure components of the bridge. Expansion joints are often one of the first components of a bridge deck to fail and repairing or replacing expansion joints are essential to extending the life of any bridge. In the Phase I study, the research team focused on the current means and methods of repairing and replacing bridge deck expansion joints. Research team members visited with Iowa Department of Transportation (DOT) Bridge Crew Leaders to document methods of maintaining and repairing bridge deck expansion joints. Active joint replacement projects around Iowa were observed to document the means of replacing expansion joints that were beyond repair, as well as, to identify bottlenecks in the construction process that could be modified to decrease the length of expansion joint replacement projects. After maintenance and replacement strategies had been identified, a workshop was held at the Iowa State Institute for Transportation to develop ideas to better maintain and replace expansion joints. Maintenance strategies were included in the discussion as a way to extend the useful life of a joint, thus decreasing the number of joints replaced in a year and reducing the traffic disruptions.

Effects of Cement on Moisture Migration in Concrete, Phase A, Laboratory Study of Moisture Migration in Hardened Cement Paste, HR-141, 1972

The Columbus Laboratories of Battelle Memorial Institute is currently conducting a study of the effect of cement on moisture migration in concrete as related to the problem of D-cracking of portland cement concrete pavements. The study began on December 31, 1970, and is planned as a 3-year program. The work plan, approved by the policy committee of the members of the Iowa, Kansas, and Missouri highway departments and the Federal Highway Administration, is composed of four parts. The first phase (A) of the investigation concerned the movement of moisture into and from hardened cement pastes and the dimensional changes accompanying the moisture changes. Small slab specimens of hardened neat cement pastes were prepared from 32 different cements which were prepared at the same water/cement ratio and hydrated to the same maturity factor.

Design, Fabrication, and Operation of the Pavement Crack Monitor Gauge, HR-1054, 1990

A mechanical gauge was developed to monitor the movement of crack or joint openings in portland cement concrete structures, in general, and portland cement concrete pavements in particular. Designed to be inexpensive and simple to operate, this gauge is capable of recording maximum, minimum, and instantaneous crack or joint openings. Specific recommendations were made for recording minimum and maximum pavement temperature over the monitoring period. The report was written as a set of guidelines for design, fabrication, installation, and operation of the gauge as well as the temperature measuring device.

Evaluation of Unbonded Ultrathin Whitetopping of Brick Streets, TR-466, 2006

Many cities in Iowa have retained the original brick street surfaces in downtown areas and in older residential areas as the base for modern driving surfaces. The original brick surfaces were not built to handle current and future traffic loadings. In recent years, these surfaces have tended to shift and become uneven, creating problems with safety. Asphaltic concrete overlays have been the typical rehabilitation technique in these situations. This has proven to be a successful rehabilitation technique in some cases; in other cases, the combination of movement of the brick and flexibility of the asphalt has proven to accentuate the original problems. Most of the existing literature on rehabilitation of brick streets shows the use of asphaltic concrete. Other rehabilitation methods include reconstruction of the brick surface and strengthening of the surface by placing asphaltic concrete or portland cement concrete, along with sand, underneath the brick layers. To date, little if anything has been done in the area of using portland cement concrete as an overlay of the brick surfaces. This final report documents the planning, construction, and performance of unbonded ultrathin whitetopping rehabilitation of a brick street in Oskaloosa, Iowa, in 2001. It also reports on a similar project in Des Moines that was constructed two years later in 2003.

Importance and evolution of sexual dimorphism in different families of Collembola (Hexapoda)

A bibliographic revision of sexual dimorphism in different families of Collembola was performed in order to determine the most common patterns in each group. We list several examples of the sexual dimorphism in different families of Collembola, which illustrate from some of the smallest differences between males and females to major differences between both sexes in some families. We show different cases of sexual dimorphism in Spinactaletes, Sminthurides, and the remarkable morphology of Guthriella muskegis. It seems that most of the cases of strong sexual dimorphism are related to aquatic habitats or behaviour still not fully understood. Species belonging to primarily aquatic families (fresh water or marine water) have the most evolved morphology, where males have clasping antennae to attach the females in order to avoid loosing them with the movement of the water.