19 resultados para Process system value
Resumo:
Recent reports indicate that of the over 25,000 bridges in Iowa, slightly over 7,000 (29%) are either structurally deficient or functionally obsolete. While many of these bridges may be strengthened or rehabilitated, some simply need to be replaced. Before implementing one of these options, one should consider performing a diagnostic load test on the structure to more accurately assess its load carrying capacity. Frequently, diagnostic load tests reveal strength and serviceability characteristics that exceed the predicted codified parameters. Usually, codified parameters are very conservative in predicting lateral load distribution characteristics and the influence of other structural attributes. As a result, the predicted rating factors are typically conservative. In cases where theoretical calculations show a structural deficiency, it may be very beneficial to apply a "tool" that utilizes a more accurate theoretical model which incorporates field-test data. At a minimum, this approach results in more accurate load ratings and many times results in increased rating factors. Bridge Diagnostics, Inc. (BDI) developed hardware and software that are specially designed for performing bridge ratings based on data obtained from physical testing. To evaluate the BDI system, the research team performed diagnostic load tests on seven "typical" bridge structures: three steel-girder bridges with concrete decks, two concrete slab bridges, and two steel-girder bridges with timber decks. In addition, a steel-girder bridge with a concrete deck previously tested and modeled by BDI was investigated for model verification purposes. The tests were performed by attaching strain transducers on the bridges at critical locations to measure strains resulting from truck loading positioned at various locations on the bridge. The field test results were used to develop and validate analytical rating models. Based on the experimental and analytical results, it was determined that bridge tests could be conducted relatively easy, that accurate models could be generated with the BDI software, and that the load ratings, in general, were greater than the ratings, obtained using the codified LFD Method (according to AASHTO Standard Specifications for Highway Bridges).
Resumo:
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."
Resumo:
The Transportation Facilities Manual provides a system of identifying and coding existing streets and highways and of recording data pertaining to these facilities. This manual is part 1 and together with the other two documents may be used in connection with the preparation of comprehensive and special planning an urban research studies of all kinds. Particular emphasis was placed on the updating of collected information so that basic inventories pertaining to the planning process can be kept current without undue effort or cost.
Resumo:
My job today as chief justice is to inform you and all Iowans of the condition of the Iowa Judicial Branch. The judicial branch is accountable to do its work so that Iowans can see the value of its fair and impartial courts. It is accountable every day for the resources it is given and the important responsibilities with which it has been entrusted. We best meet these obligations by becoming the best court system we can be. I am honored to report the progress the judicial branch has made towards becoming the best court system in the nation and the value of this progress for all Iowans. Both my grandfathers were carpenters. Like others who build with their hands, they could look at their work at the end of the day and see progress since the beginning of the day. Building Iowa’s court system consistent with its goals may not reveal progress at the end of every day as easily as the work of a carpenter. It is a long, careful process that requires the hands of many, working every day. But, certain days do come along when progress can be seen and our goals are closer within reach. Again this year, the goals of the judicial branch are to: Protect Iowa’s children; Provide full-time access to justice; Operate an efficient, full-service court system; Provide faster and less costly resolution of legal disputes; Remain open and transparent; and Provide fair and impartial justice for all.