University of Iowa School of Library and Information Science newsletter. 1996-1997, no. 38.

Newsletter from the University of Iowa School of Library and Information Science.

Field Measurements of Ice Scraping Loads on Front Mounted Plow Blades, HR-374, 1997

Removal of ice from roads is of the more challenging task in winter highway maintenance. The best mechanical method is to use a truck with underbody plow blade, but such equipment is not available to all agencies charged with winter maintenance operations. While counties and cities often use motor graders to scrape ice, it would be of great benefit if front mounted plows could be used effectively for ice removal. To reveal and understand the factors that influence the performance of these plows, measurement of the forces experienced by the plow blades during ice scraping is desirable. This study explores the possibility of using accelerometers to determine the forces on a front-mounted plow when scraping ice. The plow was modeled by using a dynamic approach. The forces on the plow were to be determined by the measurement of the accelerations of the plow. Field tests were conducted using an "as is" front-mounted plow instrumented with accelerometers. The results of the field tests indicate that in terms of ice removal, the front-mounted plow is not favorable equipment. The major problem in this study is that the front mounted plow was not able to cut ice, and therefore experienced no significant scraping forces. However, the use of accelerometers seems to be promising for analyzing the vibration problems of the front-mounted plow.

Investigation of Two Bridge Alternatives for Low Volume Roads, Volume 1 of 2 Concept 1: Precast Steel Beam Units, HR-382, 1997

Recent reports have indicated that 23.5% of the nation's highway bridges are structurally deficient and 17.7% are functionally obsolete. A significant number of these bridges are on the Iowa secondary road system where over 86% of the rural bridge management responsibilities are assigned to the counties. Some of the bridges can be strengthened or otherwise rehabilitated, but many more are in need of immediate replacement. In a recent investigation (HR-365 "Evaluation of Bridge Replacement Alternatives for the County Bridge System") several types of replacement bridges that are currently being used on low volume roads were identified. It was also determined that a large number of counties (69%) have the ability and are interested in utilizing their own forces to design and construct short span bridges. In reviewing the results from HR-365, the research team developed one "new" bridge replacement concept and a modification of a replacement system currently being used. Both of these bridge replacement alternatives were investigated in this study, the results of which are presented in two volumes. This volume (Volume 1) presents the results of Concept 1 - Steel Beam Precast Units. Concept 2 - Modification of the Beam-in-Slab Bridge is presented in Volume 2. Concept 1, involves the fabrication of precast units (two steel beams connected by a concrete slab) by county work forces. Deck thickness is limited so that the units can be fabricated at one site and then transported to the bridge site where they are connected and the remaining portion of the deck placed. Since Concept 1 bridge is primarily intended for use on low-volume roads, the precast units can be constructed with new or used beams. In the experimental part of the investigation, there were three types of static load tests: small scale connector tests, "handling strength" tests, and service and overload tests of a model bridge. Three finite element models for analyzing the bridge in various states of construction were also developed. Small scale connector tests were completed to determine the best method of connecting the precast double-T (PCDT) units. "Handling strength" tests on an individual PCDT unit were performed to determine the strength and behavior of the precast unit in this configuration. The majority of the testing was completed on the model bridge [L=9,750 mm (32 ft), W=6,400 mm (21 ft)] which was fabricated using the precast units developed. Some of the variables investigated in the model bridge tests were number of connectors required to connect adjacent precast units, contribution of diaphragms to load distribution, influence of position of diaphragms on bridge strength and load distribution, and effect of cast-in-place portion of deck on load distribution. In addition to the service load tests, the bridge was also subjected to overload conditions. Using the finite element models developed, one can predict the behavior and strength of bridges similar to the laboratory model as well as design them. Concept 1 has successfully passed all laboratory testing; the next step is to field test it.

Vibratory Effects in Reinforced Portland Cement Concrete Pavement, MLR-97-2, 1997

A double mat of reinforcement steel consisting of No. 5 bars was placed in the longitudinal and transverse directions in a 26' wide, 10" thick pavement. The bars were placed on 12" centers with 2" of cover from the top and bottom surfaces. The special reinforcement is to provide additional strength in the pavement over an area of old coal mine tunnels. Auxiliary and standard paver vibrators were used to consolidate the concrete. There was concern that over-vibration could be occurring in some areas and also that a lack of consolidation may be occurring under the steel bars in some areas. A core evaluation study of the pavement was developed. The results showed that the consolidation and the air contents were satisfactory. Additional paving with reinforcement in the same area should use the same or similar method and amount of vibration as was used in the area evaluated in this study.

Guidelines for County Engineering Decisions, HR-369, 1997

There has been a great deal of concern by county engineers and supervisors over constrained budgets, lack of resources and a deteriorating infrastructure, as they affect the secondary road system in Iowa. In addition, public input and/or political pressure have been increasing over the years. This study was initiated to determine the most important issues facing counties and document the way in which various Iowa counties have been addressing those issues. The list of issues was developed through meetings of county engineers and supervisors in each of the Iowa Department of Transportation (DOT) regions around the state. Questionnaires were sent to all engineers and supervisors statewide asking them how the various issues (e.g. snow and ice removal policies, Level "B" roads, and so on) were handled in their respective counties. The responses were then compiled into this document. The subjects selected and used include: county policies, ordinances, resolutions; snow and ice removal policy; dust control; Level "B" roads; vacating roads; rural development; private entrance construction and maintenance; roadside management practices; right of way encroachments and easements; personnel matters, staff and organization; communicating information to citizens; supervisor/ engineer relations; and county leasing/purchasing practices.

Measurement of Ice Scraping Forces on Snow-Plow Underbody Blades, HR-372, 1997

In this study, several new cutting edges for removal of ice from the roadway were tested in a series of closed road tests. These new cutting edges consisted of a variety of serrated shapes. The study also included measurement of ice scraping forces by in-service trucks. These trucks were instrumented in a similar manner as the truck used in the closed-road tests. Results from the closed-road and in-service tests were analyzed by two parameters. The first parameter is the scraping effectiveness, which is defined as the average horizontal force experienced by a cutting edge. The amount of ice scraped from the roadway is directly proportional to the magnitude of the scraping effectiveness. Thus an increase in scraping effectiveness indicates an increase in the amount of ice being scraped from the roadway. The second parameter is force angle, which is defined as tan to the -1 power [vertical force/horizontal force]. A combination of a minimal force angle and a maximized scraping effectiveness represents a case in which the maximal amount of ice is being removed from the pavement without an exceptionally large vertical force. Results indicate that each cutting edge produced a maximal scraping effectiveness with a testing configuration of a 15 deg blade angle and a 23,000 lb. download force. Results also indicate that each cutting edge produced a minimal force angle with a testing configuration of a 15 deg blade angle and a 10,000 lb. download force. Results from the in-service trucks produced similar data and also similar trends within the data when compared to the results of the closed-road tests. This result is most important, as it suggests that the closed-road tests do provide an accurate measure of ice scraping forces for a given blade and configuration of that blade. Thus if the closed-road tests indicate that certain blades perform well, there is now excellent reason to conduct full scale tests of such blades.

Expansive Mineral Growth and Concrete Deterioration, HR-384, 1997

A significant question is: What role does newly-formed expansive mineral growth play in the premature deterioration of concrete? These minerals (ettringite and brucite) are formed in cement paste as a result of chemical reactions involving cement and coarse/fine aggregate. Petrographic observations and SEM/EDAX analysis were conducted in order to determine chemical and mineralogical changes in the aggregate and cement paste of samples taken from Iowa concrete highways that showed premature deterioration. Mechanisms involved in deterioration were investigated. A second objective was to investigate whether deicer solutions exacerbate the formation of expansive minerals and concrete deterioration. Magnesium in deicer solutions causes the most severe paste deterioration by forming non-cementitious magnesium silicate hydrate and brucite. Chloride in deicer solutions promotes decalcification of paste and alters ettringite to chloroaluminate. Calcium magnesium acetate (CMA) and magnesium acetate (Mg-acetate) produce the most deleterious effects on concrete, with calcium acetate (Ca-acetate) being much less severe.

Valistuneita arvauksia : talousennusteiden osuvuus 1997-2001

Kirjoitus perustuu vuosikokousesitelmään Kansantaloudellisessa Yhdistyksessä 21.3.2002.

L'aplicació dels nous plans d'estudi a l'escola de formació de professorat de la UB: un balanç (1992-1997)

En el presente artículo se realiza un balance, desde la perspectiva que otorgan los cinco años de su implantación, de los aspectos tanto positivos como negativos que han comportado los nuevos pianes de estudio de los seis títulos de magisterio. Se pone de relieve una serie de problemas que inciden tanto en el diseño de los planes como en su aplicación práctica, tales como la indefinición del perfil de maestro de cada título, el desequilibrio en algunos itinerarios curriculares, la infrautilización de la libre elección, la concentración de la demanda en las optativas, etc. También se destaca los aspectos positivos que se ha podido apreciar. Entre otros, se constata una mayor adecuación a las salidas profesionales, el nuevo diseño del Practicum y el gran potencial que la optatividad y la libre elección suponen para el alumnado que sepa utilizar los recursos que se ofrecen en este sentido.