8 resultados para Narrative construction of museums

em Iowa Publications Online (IPO) - State Library, State of Iowa (Iowa), United States


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Report on a review of the funding for construction of the Lewis and Clark Interpretive Center at Lewis and Clark State Park in Monona County for the period February 25, 1999 through December 31, 2008

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The use of a high range water reducer in bridge floors was initiated by an Iowa Highway Research Board project (HR-192) in 1977 for two basic reasons. One was to determine the feasibility of using a high range water reducer (HRWR) in bridge floor concrete using conventional concrete proportioning, transporting and finishing equipment. The second was to determine the performance and protective qualities against chloride intrusion of a dense concrete bridge floor by de-icing agents used on Iowa's highways during winter months. This project was basically intended to overcome some problems that developed in the original research project. The problems alluded to are the time limits from batching to finishing; use of a different type of finishing machine; need for supplemental vibration on the surface of the concrete during the screeding operation and difficulty of texturing. The use of a double oscillating screed finishing machine worked well and supplemental vibration on one of the screeds was not needed. The limit of 45 minutes from batching the concrete to placement on the deck was verified. This is a maximum when the HRWR is introduced at the batch plant. The problem of texturing was not solved completely but is similar to our problems on the dense "Iowa System" overlay used on bridge deck repair projects. This project reinforced some earlier doubts about using truck transit mixers for mixing and transporting concrete containing HRWR when introduced at the batch plant.

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The Rock Island Centennial Bridge spanning the Mississippi River between Rock Island, Illinois and Davenport, Iowa was opened to traffic on July 12, 1940. It is a thoroughly modern, four-lane highway bridge, adequate in every respect for present day high speed passenger and transport traffic. The structure is ideally situated to provide rapid transit between the business districts of Rock Island and Davenport and serves not only the local or shuttle traffic in the Tri-City Area, but also heavy through motor travel on U.S. Highways 67 and 150. The Centennial Bridge is notable in several respects. The main spans are box girder rib tied arches, a type rather unusual in America and permitting simplicity in design with pleasing appearance. The Centennial Bridge is the only bridge across the Mississippi providing for four lanes of traffic with separation of traffic in each direction. It is a toll bridge operating alongside a free bridge and has the lowest rates of toll of any toll bridge on the Mississippi River. It was financed entirely by the City of Rock Island with no obligation on the taxpayers; there was no federal or state participation in the financing. But perhaps the most outstanding feature of the new bridge is its great need. A few remarks on the communities served by the new structure, the services rendered, and some statistics on cross-river traffic in the Tri-City Area will emphasize the reasons for constructing the Centennial Bridge.

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Reconstruction of bridge approach slabs which have failed due to a loss of support from embankment fill consolidation or erosion can be particularly challenging in urban areas where lane closures must be minimized. Precast prestressed concrete pavement is a potential solution for rapid bridge approach slab reconstruction which uses prefabricated pavement panels that can be installed and opened to traffic quickly. To evaluate this solution, the Iowa Department of Transportation constructed a precast prestressed approach slab demonstration project on Highway 60 near Sheldon, Iowa in August/September 2006. Two approach slabs at either end of a new bridge were constructed using precast prestressed concrete panels. This report documents the successful development, design, and construction of the precast prestressed concrete bridge approach slabs on Highway 60. The report discusses the challenges and issues that were faced during the project and presents recommendations for future implementation of this innovative construction technique.

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Use of bridge deck overlays is important in maximizing bridge service life. Overlays can replace the deteriorated part of the deck, thus extending the bridge life. Even though overlay construction avoids the construction of a whole new bridge deck, construction still takes significant time in re-opening the bridge to traffic. Current processes and practices are time-consuming and multiple opportunities may exist to reduce overall construction time by modifying construction requirements and/or materials utilized. Reducing the construction time could have an effect on reducing the socioeconomic costs associated with bridge deck rehabilitation and the inconvenience caused to travelers. This work included three major tasks with literature review, field investigation, and laboratory testing. Overlay concrete mix used for present construction takes long curing hours and therefore an investigation was carried out to find fast-curing concrete mixes that could reduce construction time. Several fast-cuing concrete mixes were found and suggested for further evaluation. An on-going overlay construction project was observed and documented. Through these observations, several opportunities were suggested where small modifications in the process could lead to significant time savings. With current standards of the removal depth of substrate concrete in Iowa, it takes long hours for the removal process. Four different laboratory tests were performed with different loading conditions to determine the necessary substrate concrete removal depth for a proper bond between the substrate concrete and the new overlay concrete. Several parameters, such as failure load, bond stress, and stiffness, were compared for four different concrete removal depths. Through the results and observations of this investigation several conclusions were made which could reduce bridge deck overlay construction time.

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State Highway Departments and local street and road agencies are currently faced with aging highway systems and a need to extend the life of some of the pavements. The agency engineer should have the opportunity to explore the use of multiple surface types in the selection of a preferred rehabilitation strategy. This study was designed to look at the portland cement concrete overlay alternative and especially the design of overlays for existing composite (portland cement and asphaltic cement concrete) pavements. Existing design procedures for portland cement concrete overlays deal primarily with an existing asphaltic concrete pavement with an underlying granular base or stabilized base. This study reviewed those design methods and moved to the development of a design for overlays of composite pavements. It deals directly with existing portland cement concrete pavements that have been overlaid with successive asphaltic concrete overlays and are in need of another overlay due to poor performance of the existing surface. The results of this study provide the engineer with a way to use existing deflection technology coupled with materials testing and a combination of existing overlay design methods to determine the design thickness of the portland cement concrete overlay. The design methodology provides guidance for the engineer, from the evaluation of the existing pavement condition through the construction of the overlay. It also provides a structural analysis of various joint and widening patterns on the performance of such designs. This work provides the engineer with a portland cement concrete overlay solution to composite pavements or conventional asphaltic concrete pavements that are in need of surface rehabilitation.

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The need to construct bridges that last longer, are less expensive, and take less time to build has increased. The importance of accelerated bridge construction (ABC) technologies has been realized by the Federal Highway Administration (FHWA) and the Iowa Department of Transportation (DOT) Office of Bridges and Structures. This project is another in a series of ABC bridge projects undertaken by the Iowa DOT. Buena Vista County, Iowa, with the assistance of the Iowa Department of Transportation (DOT) and the Bridge Engineering Center (BEC) at Iowa State University, constructed a two-lane single-span precast box girder bridge, using rapid construction techniques. The design involved the use of precast, pretensioned components for the bridge superstructure, substructure, and backwalls. This application and demonstration represents an important step in the development and advancement of these techniques in Iowa as well as nationwide. Prior funding for the design and construction of this bridge (including materials) was obtained through the FHWA Innovative Bridge Research and Deployment (IBRD) Program. The Iowa Highway Research Board (IHRB) provided additional funding to test and evaluate the bridge. This project directly addresses the IBRD goal of demonstrating (and documenting) the effectiveness of innovative materials and construction techniques for the construction of new bridge structures. Evaluation of performance was formulated through comparisons with design assumptions and recognized codes and standards including American Association of State Highway and Transportation Officials (AASHTO) specifications.

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This research project was initiated in 1988 to study the effectiveness of four different construction techniques for establishing a stable base on a granular surfaced roadway. After base stabilization, the roadway was then seal coated, eliminating dust problems associated with granular surfaced roads. When monies become available, the roadway can be surfaced with a more permanent structure. A 2.8 mile section of the Horseshoe Road in Dubuque County was divided into four divisions for the study. This report discusses the procedures used during construction of these different divisions. Problems and possible solutions have been analyzed to better understand the capabilities of the materials and construction techniques used on the project.