984 resultados para Diagrama HR


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The focus of highway runoff monitoring programs is on the identification of highway contributions to nonpoint source degradation of surface and groundwater quality. The results of such studies will assist the Iowa Department of Transportation (DOT) in the development of maintenance practices that will minimize the impact of highway transportation networks on water quality while at the same time maintaining public safety. Highway runoff monitoring research will be useful in developing a basis to address issues in environmental impact statements for future highway network expansions. Further, it will lead to optimization of cost effectiveness/environmental factors related to de-icing, weed and dust control, highway drainage, construction methods, etc. In this report, the authors present the data accumulated to date with a preliminary interpretation of the significance of the data. The report will discuss the site setup, operational aspects of data collection, and problems encountered. In addition, recommendations are included to optimize information gained from the study.

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Bridge deck and substructure deterioration due to the corrosive effects of deicing chemicals on reinforcing steel is a problem facing many transportation agencies. The main concern is protection of older bridges with uncoated reinforcing steel. Many different methods have been tried over the past years to repair bridge decks. The Iowa system of bridge deck rehabilitation has proven to be very effective. It consists of scarifying the deck surface, removing any deteriorated concrete, and overlaying with low slump dense concrete. Another rehabilitation method that has emerged is cathodic protection. It has been used for many years in the protection of underground pipelines and in 1973 was first installed on a bridge deck. Cathodic protection works by applying an external source of direct current to the embedded reinforcing steel, thereby changing the electrochemical process of corrosion. The corroding steel, which is anodic, is protected by changing it to a cathodic state. The technology involved in cathodic protection as applied to bridge decks has improved over the last 12 years. One company marketing new technology in cathodic protection systems is Raychem Corporation of Menlo Park, California. Their system utilizes a Ferex anode mesh that distributes the impressed direct current over the deck surface. Ferex mesh was selected because it seemed readily adaptable to the Iowa system of bridge deck rehabilitation. The bridge deck would be scarified, deteriorated concrete removed, Ferex anode mesh installed, and overlaid with low slump dense concrete. The Federal Highway Administration (FHWA) promotes cathodic protection under Demonstration Project No. 34, "Cathodic Protection for Reinforced Concrete Bridge Decks."

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During 1959, research was continued by the Agronomy Department in cooperation with the Iowa Highway Commission on vegetative establishment and erosion control on highway backslopes (Project 1010). The work was continued at previously established sites and also several new experiments were initiated during the year. The work will be discussed for each separate experiment and location in this report.

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Man’s never-ending search for better materials and construction methods and for techniques of analysis and design has overcome most of the early difficulties of bridge building. Scour of the stream bed, however, has remained a major cause of bridge failures ever since man learned to place piers and abutments in the stream in order to cross wide rivers. Considering the overall complexity of field conditions, it is not surprising that no generally accepted principles (not even rules of thumb) for the prediction of scour around bridge piers and abutments have evolved from field experience alone. The flow of individual streams exhibits a manifold variation, and great disparity exists among different rivers. The alignment, cross section, discharge, and slope of a stream must all be correlated with the scour phenomenon, and this in turn must be correlated with the characteristics of the bed material ranging from clays and fine silts to gravels and boulders. Finally, the effect of the shape of the obstruction itself-the pier or abutment-must be assessed. Since several of these factors are likely to vary with time to some degree, and since the scour phenomenon as well is inherently unsteady, sorting out the influence of each of the various factors is virtually impossible from field evidence alone. The experimental approach was chosen as the investigative method for this study, but with due recognition of the importance of field measurements and with the realization that the results must be interpreted so as to be compatible with the present-day theories of fluid mechanics and sediment transportation. This approach was chosen because, on the one hand, the factors affecting the scour phenomenon can be controlled in the laboratory to an extent that is not possible in the field, and, on the other hand, the model technique can be used to circumvent the present inadequate understanding of the phenomenon of the movement of sediment by flowing water. In order to obtain optimum results from the laboratory study, the program was arranged at the outset to include a related set of variables in each of several phases into which the whole problem was divided. The phases thus selected were : 1. Geometry of piers and abutments, 2. Hydraulics of the stream, 3. Characteristics of the sediment, 4. Geometry of channel shape and alignment.

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In the preparation of this compilation of drainage laws of Iowa, an attempt has been made to include those sections of the Code to which reference is frequently required by the State Highway Commission, Boards of Supervisors and County Engineers in the conduct of highway and road administration as it is affected by the Iowa drainage laws. Of necessity some Code provisions which have a bearing on the principal subject were omitted. Enactments of the 56th General Assembly which modify existing code sections have been included as part of the regular text of the Code sections included in this publication. THE USER IS CAUTIONED THAT THESE CODE SECTIONS, AS MODIFIED BY THE 56th GENERAL ASSEMBLY, ARE NOT A PART OF THE 1954 CODE OF IOWA AND ARE OFFICIAL ONLY INSOFAR AS THEY ARE PRINTED IN THE OFFICIAL PUBLICATION ACTS OF THE 56TH GENERAL ASSEMBLY. SINCE THE 57TH GENERAL ASSEMBLY IS IN SESSION DURING THE PRINTING OF THIS PUBLICATION, ENACTMENTS OF THAT BODY WHICH AMEND OR REPEAL SECTIONS SET OUT HEREIN ARE INCLUDED IN THE BACK OF THIS VOLUME ON THE PINK-COLORED PAPER. THE USER IS CAUTIONED IN USING THIS VOLUME TO REFER TO THE TABLE OF SECTIONS REPEALED OR AMENDED, ON THE PINK-COLORED PAPER AT THE BACK OF THIS VOLUME. This publication is offered with the hope and belief that it will prove to be of value and assistance to those concerned with the problems of administering a highway, road and drainage system.

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Water-surface-elevation profiles and peak discharges for the floods of July 12, 1972, March 19, 1979, and June 15, 1991, in the Turkey River Basin, northeast Iowa, are presented in this report. The profiles illustrate the 1979 and 1991 floods along the Turkey River in Fayette and Clayton Counties and along the Volga River in Clayton County; the 1991 flood along Roberts Creek in Clayton County and along Otter Creek in Fayette County; and the 1972 flood along the Turkey River in Winneshiek and Fayette Counties. Watersurface elevations for the flood of March 19, 1979, were collected by the Iowa Natural Resources Council. The June 15, 1991, flood on the Turkey River at Garber (station number 05412500) is the largest known flood-peak discharge at the streamflow-gaging station for the period 1902-95. The peak discharge for June 15, 1991, of 49,900 cubic feet per second was 1.4 times larger than the 100-year recurrence-interval discharge. The report provides information on flood stages and discharges and floodflow frequencies for streamflow-gaging stations in the Turkey River Basin using flood information collected during 1902-95. Information on temporary bench marks and reference points established in the Turkey River Basin during 1981, 1992, and 1996 also is included in the report. A flood history describes rainfall conditions for floods that occurred during 1922, 1947, 1972, 1979, and 1991.

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This report describes a short-term study undertaken to investigate the potential for using dense three-dimensional (3D) point clouds generated from light detection and ranging (LIDAR) and photogrammetry to assess roadway roughness. Spatially continuous roughness maps have potential for the identification of localized roughness features, which would be a significant improvement over traditional profiling methods. This report specifically illustrates the use of terrestrial laser scanning (TLS) and photogrammetry using a process known as structure from motion (SFM) to acquire point clouds and illustrates the use of these point clouds in evaluating road roughness. Five roadway sections were chosen for scanning and testing: three gravel road sections, one portland cement concrete (PCC) section, and one asphalt concrete (AC) section. To compare clouds obtained from terrestrial laser scanning and photogrammetry, the coordinates of the clouds for the same section on the same date were matched using open source computer code. The research indicates that the technologies described are very promising for evaluating road roughness. The major advantage of both technologies is the large amount of data collected, which allows the evaluation of the full surface. Additional research is needed to further develop the use of dense 3D point clouds for roadway assessment.

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This report is concerned with the prediction of the long-time creep and shrinkage behavior of concrete. It is divided into three main areas. l. The development of general prediction methods that can be used by a design engineer when specific experimental data are not available. 2. The development of prediction methods based on experimental data. These methods take advantage of equations developed in item l, and can be used to accurately predict creep and shrinkage after only 28 days of data collection. 3. Experimental verification of items l and 2, and the development of specific prediction equations for four sand-lightweight aggregate concretes tested in the experimental program. The general prediction equations and methods are developed in Chapter II. Standard Equations to estimate the creep of normal weight concrete (Eq. 9), sand-lightweight concrete (Eq. 12), and lightweight concrete (Eq. 15) are recommended. These equations are developed for standard conditions (see Sec. 2. 1) and correction factors required to convert creep coefficients obtained from equations 9, 12, and 15 to valid predictions for other conditions are given in Equations 17 through 23. The correction factors are shown graphically in Figs. 6 through 13. Similar equations and methods are developed for the prediction of the shrinkage of moist cured normal weight concrete (Eq. 30}, moist cured sand-lightweight concrete (Eq. 33}, and moist cured lightweight concrete (Eq. 36). For steam cured concrete the equations are Eq. 42 for normal weight concrete, and Eq. 45 for lightweight concrete. Correction factors are given in Equations 47 through 52 and Figs., 18 through 24. Chapter III summarizes and illustrates, by examples, the prediction methods developed in Chapter II. Chapters IV and V describe an experimental program in which specific prediction equations are developed for concretes made with Haydite manufactured by Hydraulic Press Brick Co. (Eqs. 53 and 54}, Haydite manufactured by Buildex Inc. (Eqs. 55 and 56), Haydite manufactured by The Cater-Waters Corp. (Eqs. 57 and 58}, and Idealite manufactured by Idealite Co. (Eqs. 59 and 60). General prediction equations are also developed from the data obtained in the experimental program (Eqs. 61 and 62) and are compared to similar equations developed in Chapter II. Creep and Shrinkage prediction methods based on 28 day experimental data are developed in Chapter VI. The methods are verified by comparing predicted and measured values of the long-time creep and shrinkage of specimens tested at the University of Iowa (see Chapters IV and V) and elsewhere. The accuracy obtained is shown to be superior to other similar methods available to the design engineer.

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General equations are presented for predicting loss of prestress and camber of both composite and non- composite prestressed concrete structures. Continuous time functins of all parameters needed to solve the equations are given, and sample results included. Computed prestress loss and camber are compared with experimental data for normal weight and lightweight concrete. Methods are also presented for predicting the effect of non-prestressed tension steel in reducing time-dependent loss of prestress and camber, and for the determination of short-time deflections of uncracked and cracked prestressed members. Comparisons with experimental results are indicated for these partially prestressed methods.

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Flood-elevation profiles and flood-peak discharges for floods during 1972, 1982, and 1987 in the Nishnabotna River basin are given in the report. The profiles are for the 1972 flood on the West and East Nishnabotna Rivers, the 1982 flood on Indian Creek, and the 1987 flood on the lower West Nishnabotna River. A flood history describes rainfall conditions and reported damages for floods occurring 1947, 1958, 1972, 1982, and 1987. Discharge for the 1982 flood on Indian Creek is 1.1 times larger than the 100-year recurrence interval discharge.

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Kirja-arvio

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This final report summarizes the activities of the archaeological surveys contract for primary roads, secondary roads, and urban systems. The contract is negotiated annually between the Iowa Department of Transportation and the University of Iowa. The information contained is composed of summaries abstracted from completed cultural resource reports on file with the Department of Transportation, the Office of Historic Preservation, and the Office of the State Archaeologist.

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This final report summarizes the activities of the archaeological surveys contract for primary roads, secondary roads, and urban systems. The contract is negotiated annually between the Iowa Department of Transportation and the University of Iowa. The information contained in this section of the report is composed of summaries abstracted from completed cultural resource reports on file with the Department of Transportation, the Office of Historic Preservation, and the Office of the State Archaeologist.

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Construction of an excellent network of primary highways across the State of Iowa has essentially been completed. The major task facing the Iowa Department of Transportation today is the maintenance and rehabilitation of that network. The most commonly utilized rehabilitation practice is asphalt concrete resurfacing. This practice will normally provide a good driving surface for at least 10 additional years. The major problem with asphalt concrete resurfacing is the reflection cracking from underlying cracks and joints in the portland cement concrete (PCC) pavement. Deterioration and spaling occur at these reflection cracks and are the limiting factor of the-effective life of the asphalt concrete resurfacing.

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The Engineering Research Institute at Iowa State University studied the organization and procedures for highway planning by all levels of government and the coordination among various state agencies and local governments in Iowa. Study information was derived from interviews, questionnaires, and a review of the literature. Representatives from state transportation or highway organizations in all states responded to questionnaires. Additionally, selected upper and intermediate level personnel from highway organizations in seven other states were interviewed and a visit was made to one state transportation department. Within Iowa, employees were interviewed in the Highway Commission, Office for Planning and Programming, Development Commission, Commerce Commission, Conservation Commission, and Highway Patrol. Nearly 600 officials of local governments in Iowa contributed factual data and opinions through questionnaires and interviews. Private citizens and consultants also provided input to the investigation through their responses to questionnaires. Twelve recommendations to improve highway planning in Iowa were formulated as a result of this study.