Structural Characterization of UHPC Waffle Bridge Deck and Connections, TR-614, 2014

The AASHTO strategic plan in 2005 for bridge engineering identified extending the service life of bridges and accelerating bridge construction as two of the grand challenges in bridge engineering. These challenges have the objective of producing safer and more economical bridges at a faster rate with a minimum service life of 75 years and reduced maintenance cost to serve the country’s infrastructure needs. Previous studies have shown that a prefabricated full-depth precast concrete deck system is an innovative technique that accelerates the rehabilitation process of a bridge deck, extending its service life with reduced user delays and community disruptions and lowering its life-cycle costs. Previous use of ultra-high performance concrete (UHPC) for bridge applications in the United States has been considered to be efficient and economical because of its superior structural characteristics and durability properties. Full-depth UHPC waffle deck panel systems have been developed over the past three years in Europe and the United States. Subsequently, a single span, 60-ft long and 33-ft wide prototype bridge with full-depth prefabricated UHPC waffle deck panels has been designed and built for a replacement bridge in Wapello County, Iowa. The structural performance characteristics and the constructability of the UHPC waffle deck system and its critical connections were studied through an experimental program at the structural laboratory of Iowa State University (ISU). Two prefabricated full-depth UHPC waffle deck (8 feet by 9 feet 9 inches by 8 inches) panels were connected to 24-ft long precast girders, and the system was tested under service, fatigue, overload, and ultimate loads. Three months after the completion of the bridge with waffle deck system, it was load tested under live loads in February 2012. The measured strain and deflection values were within the acceptable limits, validating the structural performance of the bridge deck. Based on the laboratory test results, observations, field testing of the prototype bridge, and experience gained from the sequence of construction events such as panel fabrication and casting of transverse and longitudinal joints, a prefabricated UHPC waffle deck system is found to be a viable option to achieve the goals of the AASHTO strategic plan.

An Adaptive Field Detection Method For Bridge Scour Monitoring Using Motion-Sensing Radio Transponders (RFIDs), TR-617, 2014

A comprehensive field detection method is proposed that is aimed at developing advanced capability for reliable monitoring, inspection and life estimation of bridge infrastructure. The goal is to utilize Motion-Sensing Radio Transponders (RFIDS) on fully adaptive bridge monitoring to minimize the problems inherent in human inspections of bridges. We developed a novel integrated condition-based maintenance (CBM) framework integrating transformative research in RFID sensors and sensing architecture, for in-situ scour monitoring, state-of-the-art computationally efficient multiscale modeling for scour assessment.

Galvanized Bridge Deck Reinforcing, HR-504, 1992

The deterioration of bridge decks due to steel corrosion is a problem encountered several years ago. This project, using galvanized reinforcement, began over twenty years ago. Since that time, epoxy coated reinforcement has become the specified material used in bridge decks. The decks researched in this project are located on 1-35 in Story County. They were constructed in 1967. The results from the testing done on this project show that galvanizing protects steel from corrosion due to deicing salts, resulting in less/no concrete deterioration.

Analysis of Safety Benefits for Shielding of Bridge Piers, 2009

The highway system in the State of Iowa includes many grade separation structures constructed to provide maximum safety and mobility to road users on intersecting roadways. However, these structures can present possible safety concerns for traffic passing underneath due to close proximity of piers and abutments. Shielding of these potential hazards has been a design consideration for many years. This study examines historical crash experience in the State of Iowa to address the advisability of shielding bridge piers and abutments as well as other structure support elements considering the offset from the traveled way. A survey of nine Midwestern states showed that six states had bridge pier shielding practices consistent with those in Iowa. Data used for the analyses include crash data (2001 to 2007) from the Iowa Department of Transportation (Iowa DOT), the Iowa DOT’s Geographic Information Management System (GIMS) structure and roadway data (2006) obtained from the Office of Transportation Data, and shielding and offset data for the bridges of interest. Additionally, original crash reports and the Iowa DOT video log were also utilized as needed. Grade-separated structures over high-speed, multilane divided Interstate and primary highways were selected for analysis, including 566 bridges over roadways with a speed limit of at least 45 mph. Bridges that met the criteria for inclusion in the study were identified for further analysis using crash data. The study also included economic analysis for possible shielding improvement.

Iowa Historic Property Study: Iowa-Illinois Memorial Bridge Carrying I-74 and U.S. 6 over Mississippi River between Bettendorf, Scott County, Iowa and Moline, Rock Island County, Illinois, 2012

The 1935 Iowa-Illinois Memorial Bridge is being documented at this time to fulfill the requirements of the Memorandum of Agreement regarding the removal of the Iowa-Illinois Memorial Bridge and the Iowana Farms Milk Company Building for the proposed improvements to Interstate 7 4 in Bettendorf, Iowa, and Moline, Illinois.1 The 1959 twin suspension bridge will be removed as well, but it was determined to be ineligible for the National Register of Historic Places. Discussion of the history of the 1959 twin span is included, however, in the current report as part of the overall history of the Iowa-Illinois Memorial Bridge. Fieldwork for the documentation occurred in November 2009 and October 2010 (Fig. 1). Limitations on photography included limited shoreline access on the Illinois side, making good views of the bridge from the south somewhat challenging. Also, photographs on the bridge deck were not possible because of interstate traffic and prohibitions on pedestrian traffic. Within the last few years, online primary sources have proliferated, along with historical materials regarding the Iowa-Illinois Memorial Bridge. Sources available online for this report included numerous historical photographs, as well as historical Davenport, Iowa, and U.S. newspapers that document the bridge planning and construction. Additional primary source material was found at the University of Iowa Libraries, the State Historical Society of Iowa in Iowa City, the Bettendorf Public Library, the Richardson-Sloane Special Collections Center at the Davenport Public Library, and the Iowa State University Special Collections in Ames.

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.

Iowa’s Bridge and Highway Climate Change and Extreme Weather Vulnerability Assessment Pilot, HEPN-707, 2015

The Iowa Department of Transportation (DOT) is responsible for approximately 4,100 bridges and structures that are a part of the state’s primary highway system, which includes the Interstate, US, and Iowa highway routes. A pilot study was conducted for six bridges in two Iowa river basins—the Cedar River Basin and the South Skunk River Basin—to develop a methodology to evaluate their vulnerability to climate change and extreme weather. The six bridges had been either closed or severely stressed by record streamflow within the past seven years. An innovative methodology was developed to generate streamflow scenarios given climate change projections. The methodology selected appropriate rainfall projection data to feed into a streamflow model that generated continuous peak annual streamflow series for 1960 through 2100, which were used as input to PeakFQ to estimate return intervals for floods. The methodology evaluated the plausibility of rainfall projections and credibility of streamflow simulation while remaining consistent with U.S. Geological Survey (USGS) protocol for estimating the return interval for floods. The results were conveyed in an innovative graph that combined historical and scenario-based design metrics for use in bridge vulnerability analysis and engineering design. The pilot results determined the annual peak streamflow response to climate change likely will be basin-size dependent, four of the six pilot study bridges would be exposed to increased frequency of extreme streamflow and would have higher frequency of overtopping, the proposed design for replacing the Interstate 35 bridges over the South Skunk River south of Ames, Iowa is resilient to climate change, and some Iowa DOT bridge design policies could be reviewed to consider incorporating climate change information.

A Generalized Model Study of Scour Around Bridge Piers and Abutments, HR-24, 1953

Four classes of variables are apparent in the problem of scour around bridge piers and abutments--geometry of piers and abutments, stream-flow characteristics, sediment characteristics, and geometry of site. The laboratory investigation, from its inception, has been divided into four phases based on these classes. In each phase the variables in three of the classes are held constant and those in the pertinent class are varied. To date, the first three phases have been studied. Typical scour bole patterns related to the geometry of the pier or abutment have been found. For equilibrium conditions of scour with uniform sand, the velocity of flow and the sand size do not appear to have any measurable effects on the depth of scour. This result is especially encouraging in the search for correlation between model and prototype since it would indicate that, primarily, only the depth of flow might be involved in the scale effect. The technique of model testing has been simplified, therefore, because rate of sediment transportation does not need to be scaled. Prior to the establishment of equilibrium conditions, however, depths of scour in excess of those for equilibrium conditions have been found. A concept of active scour as an imbalance between sediment transport capacity and rate of sediment supply has been used to explain the laboratory observations.

Live Load Deflections in a Prestressed Steel Beam Bridge, HR-74, 1963

This report describes the measurement of dynamic (live load) deflections in a 240' x 30' three span continuous prestressed steel bridge, skewed 30 degrees. The design assumptions and prestressing procedure are described briefly, and the instrumentation and loading are discussed. The actual deflections are presented in tabular form, and the deflections due to the design live load are calculated. The maximum deflections are presented as a ratio of the span length, and the further use of prestressed steel beams is recommended.

Detection of Steel Corrosion in Bridge Decks and Reinforced Concrete Pavement, HR-156, 1977

The Iowa Department of Transportation initiated this research to evaluate the reliability, benefit and application of the corrosion detection device. Through field testing prior to repair projects and inspection at the time of repair, the device was shown to be reliable. With the reliability established, twelve additional devices were purchased so that this evaluation procedure could be used routinely on all repair projects. The corrosion detection device was established as a means for determining concrete removal for repair. Removal of the concrete down to the top reinforcing steel is required for all areas exhibiting electrical potentials greater than 0.45 Volt. It was determined that the corrosion detection device was not applicable to membrane testing. The corrosion detection device has been used to evaluate corrosion of reinforcing steel in continuously reinforced concrete pavement.

Effects of Special Aggregate on Bridge Deck Overlay Frictional Properties, HR-205, 1986

The Iowa DOT has been using the "Iowa Method" thin bonded low-slump dense Portland Cement Concrete (PCC) bridge deck overlay for rehabilitation of delaminated decks since 1963. In time, continued use of studded tires will wear away the transverse grooved texture. The objective of this research was to evaluate the benefit of incorporating a hard durable aggregate into a dense PCC overlay to provide frictional property longevity. The project included three overlays on I-35 near Ankeny. The texture and friction properties of two overlays, one constructed with crushed granite and the other with crushed quartzite coarse aggregate, were compared to an overlay constructed with locally available crushed limestone. There were no construction problems resulting from the use of crushed granite or quartzite. There was no significant frictional property benefit from the crushed granite or crushed quartzite through six years.

Detection of Concrete Delamination by Infrared Thermography, HR-244, 1986

Iowa has approximately 1000 bridges that have been overlaid with a nominal 2" of portland cement concrete. A Delamtect survey of a sampling of the older overlaid bridges indicated delaminations in several of them. Eventually these bridges as well as those that have not received an overlay must be programmed for rehabilitation. Prior to rehabilitation the areas which are delaminated must be identified. There are currently two standard methods of determining delaminated areas in bridge decks; sounding with a metal object or a chain drag and sounding with an electro-mechanical sounding system (Delamtect). Sounding with a metal object or chain drag is time consuming and the accuracy is dependent on the ear of the operator and may be affected by traffic noise. The Delamtect requires less field time but the graphical traces require that data reduction be done in the office. A recently developed method of detecting delamination is infrared thermography. This method is based on the temperature difference between sound and delaminated concrete. A contract was negotiated with Donohue and Associates, Inc. of Sheboygan, Wisconsin, to survey 18 p.c. concrete overlaid bridge decks in Iowa using the infrared thermography method of detecting delaminations.

Design Methodology for Corrugated Metal Pipe Tiedowns, HR-332, Phase 1, 1993

Questionnaires were sent to transportation agencies in all 50 states in the U.S., to Puerto Rico, and all provinces in Canada asking about their experiences with uplift problems of - corrugated metal pipe (CMP). Responses were received from 52 agencies who reported 9 failures within the last 5 years. Some agencies also provided design standards for tiedowns to resist uplift. There was a wide variety in restraining forces used; for example for a pipe 6 feet in diameter, the resisting force ranged from 10 kips to 66 kips. These responses verified the earlier conclusion based on responses from Iowa county engineers that a potential uplift danger exists.when end restraint is not provided for CMP and that existing designs have an unclear theoretical or experimental basis. In an effort to develop more rational design standards, the longitudinal stiffness of three CMP ranging from 4 to 8 feet in diameter were measured in the laboratory. Because only three tests were conducted, a theoretical model to evaluate the stiffness of pipes of a variety of gages and corrugation geometries was also developed. The experimental results indicated a "stiffness" EI in the range of 9.11 x 10^5 k-in^2 to 34.43 x 10^5 k-in^2 for the three pipes with the larger diameter pipes having greater stiffness. The theoretical model developed conservatively estimates these stiffnesses.

Design Methodology for Corrugated Metal Pipe Tiedowns, HR-362, Phase II, 1995

This investigation is the final phase of a three part study whose overall objectives were to determine if a restraining force is required to prevent inlet uplift failures in corrugated metal pipe (CMP) installations, and to develop a procedure for calculating the required force when restraint is required. In the initial phase of the study (HR-306), the extent of the uplift problem in Iowa was determined and the forces acting on a CMP were quantified. In the second phase of the study (HR- 332), laboratory and field tests were conducted. Laboratory tests measured the longitudinal stiffness ofCMP and a full scale field test on a 3.05 m (10 ft) diameter CMP with 0.612 m (2 ft) of cover determined the soil-structure interaction in response to uplift forces. Reported herein are the tasks that were completed in the final phase of the study. In this phase, a buried 2.44 m (8 ft) CMP was tested with and without end-restraint and with various configurations of soil at the inlet end of the pipe. A total of four different soil configurations were tested; in all tests the soil cover was constant at 0.61 m (2 ft). Data from these tests were used to verify the finite element analysis model (FEA) that was developed in this phase of the research. Both experiments and analyses indicate that the primary soil contribution to uplift resistance occurs in the foreslope and that depth of soil cover does not affect the required tiedown force. Using the FEA, design charts were developed with which engineers can determine for a given situation if restraint force is required to prevent an uplift failure. If an engineer determines restraint is needed, the design charts provide the magnitude of the required force. The design charts are applicable to six gages of CMP for four flow conditions and two types of soil.

Investigation of High Density Polyethylene Pipe for Highway Applications, HR-373, Phase 1, 1996

In the past, culvert pipes were made only of corrugated metal or reinforced concrete. In recent years, several manufacturers have made pipe of lightweight plastic - for example, high density polyethylene (HDPE) - which is considered to be viscoelastic in its structural behavior. It appears that there are several highway applications in which HDPE pipe would be an economically favorable alternative. However, the newness of plastic pipe requires the evaluation of its performance, integrity, and durability; A review of the Iowa Department of Transportation Standard Specifications for Highway and Bridge Construction reveals limited information on the use of plastic pipe for state projects. The objective of this study was to review and evaluate the use of HDPE pipe in roadway applications. Structural performance, soil-structure interaction, and the sensitivity of the pipe to installation was investigated. Comprehensive computerized literature searches were undertaken to define the state-of-the-art in the design and use of HDPE pipe in highway applications. A questionnaire was developed and sent to all Iowa county engineers to learn of their use of HDPE pipe. Responses indicated that the majority of county engineers were aware of the product but were not confident in its ability to perform as well as conventional materials. Counties currently using HDPE pipe in general only use it in driveway crossings. Originally, we intended to survey states as to their usage of HDPE pipe. However, a few weeks after initiation of the project, it was learned that the Tennessee DOT was in the process of making a similar survey of state DOT's. Results of the Tennessee survey of states have been obtained and included in this report. In an effort to develop more confidence in the pipe's performance parameters, this research included laboratory tests to determine the ring and flexural stiffness of HDPE pipe provided by various manufacturers. Parallel plate tests verified all specimens were in compliance with ASTM specifications. Flexural testing revealed that pipe profile had a significant effect on the longitudinal stiffness and that strength could not be accurately predicted on the basis of diameter alone. Realizing that the soil around a buried HDPE pipe contributes to the pipe stiffness, the research team completed a limited series of tests on buried 3 ft-diameter HDPE pipe. The tests simulated the effects of truck wheel loads above the pipe and were conducted with two feet of cover. These tests indicated that the type and quality of backfill significantly influences the performance of HDPE pipe. The tests revealed that the soil envelope does significantly affect the performance of HDPE pipe in situ, and after a certain point, no additional strength is realized by increasing the quality of the backfill.