A bridge deck panel system using nonprestressed full-depth precast concrete bridge deck panels with continuous shear pockets was investigated. First, the research team performed conceptual improvement, design, detailing, and fabrication studies on a specific deck replacement system (System CD-2) previously proposed by NCHRP Project 12-65 researchers. Key improvements to the CD-2 deck panel system included modifications to the transverse joint coupler for ease of construction and the addition of a longitudinal staged-construction joint to expedite bridge deck replacement projects. Next, an experimental program was carried out to construct and perform service-level load testing on a full-size precast deck panel assemblage that incorporated the refinements. On the basis of static and cyclic loading test results, it was found that the modified CD-2 deck panel system as a whole performed satisfactorily with regard to AASHTO serviceability requirements.

Timber substructure bridges supported by three, four, or five piles were commonly used in Alabama in the past for secondary and county highway bridges. Because of the large number of such bridges in the state, the Alabama DOT recently developed a screening tool to assist its engineers in assessing the adequacy of bridge pile bents for extreme flood and scour events. The evaluation procedure employed in the screening tool is presented in this paper through the following sequence: (1) preliminary or general checks; (2) possible kick-out or plunging failure; (3) bent pile buckling failure; (4) transverse pushover failure from combined vertical gravity and lateral floodwater loadings; and (5) bent upstream pile beam-column failure from combined vertical gravity and lateral debris raft loadings. This paper discusses the theoretical background for the equations used to evaluate each failure mode in the timber screening tool, in addition to describing the flow of the screening process. (C) 2014 American Society of Civil Engineers.

Fatigue design provisions for stud shear connectors in the current AASHTO LRFD Bridge Design Specifications are based on the research conducted in the mid 1960s by Slutter and Fisher, who tested 44 push-out specimens to determine the fatigue life of the shear connector. An analysis of test data produced by Slutter and Fisher and an examination of the current AASHTO design provisions in comparison with their European and Japanese counterparts suggest that the AASHTO may significantly underestimate the fatigue life of stud shear connectors, especially in the range of fatigue behavior where most bridges are designed. A design example is presented that demonstrates that the required number of studs according to the AASHTO can be more than twice the number required by other design codes in Europe and Japan. A possible reason for this discrepancy is discussed.

Most bridges in Alabama that are over shallow bodies of water, including small creeks, wetlands, and marshes, were designed so that the bridge superstructure is supported on pile bents. During major flood events, excessive scour can occur at these bridge bent sites. Scour is the washing away of streambed material by the water channel flow. Hundreds of Alabama's bridges were designed and constructed without recognizing the impact of scour events on the bridge piers. To address this problem, the Alabama Department of Transportation (ALDOT) is currently assessing the scour susceptibility of its bridges, including an evaluation of the structural stability of these bridges for an estimated flood/scour event. It was determined in Phase I research work that the development of a screen was technically feasible, the primary parameters on which scour susceptibility depends were identified, and it was verified that these parameters were in ALDOT's databases, or could be estimated reasonably. In Phase II, a was developed to assess the adequacy of bridge pile bents for an estimated flood/scour event, and a user's guide that explained the proper use of the tool when evaluating the structural stability of the pile bents was created. The objective of the Phase III work was to expand, refine, and automate the developed in the previous phases. This report focuses on the automation of the screening tool. Visual Basic Studio 2005 was the software package (chosen in agreement with ALDOT engineers) used to automate the ST. The ST is a stand-alone computer program into which ALDOT engineers input bridge/site parameter values, and the program evaluates the stability of a critical pile or bent, or a set of bents, and outputs results regarding the adequacy of the bridge's stability. The ST evaluates the five most critical failure modes, which were identified in Phases I, II, and III as plunging, kick-out, buckling, and pushover failures, as well as failure of the upstream bent pile in a beam-column configuration. Tier-2 screening refinements and expansions, introduced in a sister Phase III report (Ramey et al., 2008), were also included in the automation of the ST.

A common design/construction procedure for highway bridges in Alabama is the use of steel HP piles driven to a firm stratum with a length above ground up to the level of a concrete bent cap which supports the bridge superstructure. The use of three, four, five, or six such piles in a row with the two end piles battered are very common bridge pile bents. Because of the large number of bridges in the state and the tendency to use standardized designs with pile bent substructures, the Alabama Department of Transportation recently developed a "screening tool" to assist its engineers in assessing the adequacy of bridge pile bents for extreme flood/scour events. The evaluation procedure employed in the screening tool is presented in macro and microfloodchart form in this paper, and basically moves through the following sequence: (1) preliminary or general checks such as the bridge bent being located in water with scour possible, etc.; (2) checking the bent piles for possible "kick-out" or plunging failure; (3) checking the bent piles for buckling failure; and (4) checking the bent for transverse (transverse to the bridge centerline) pushover failure from combined gravity and flood water loadings. The screening tool is a dynamic tool and is currently being automated, expanded in capabilities, simplified, and improved.

A common substructure for highway bridges over streams and creeks consists of a group of steel HP piles with a length above ground up to the level of a concrete bent cap, which supports the bridge superstructure. The use of three, four, five, or six such piles in a row with the two end piles battered constitutes a very common bridge bent configuration. In streams subject to significant flooding and scour, a critical load condition for these bents can be a gravity dead and live loading in conjunction with a horizontal flood water loading acting near the top of the bent. Such a loading may cause a pushover failure of the bent and, in turn, failure of the bridge. Pushover loads for such pile bents of various heights, bracing conditions, levels of gravity loading, and levels of scour are presented in this paper. A procedure is also presented for determining the maximum applied flood water loading acting on a bent, for determining the bent’s adequacy against a pushover failure.

A common design/construction procedure for highway bridges over marshes, small creeks, and streams is to have the bridge superstructure supported on pile bents. The focus of this article is to compare the relative lateral stiffness and pushover capacities of X-braced three-, four-, five-, and six-pile bents under combined gravity loadings and extreme flood/scour events. The relative performances of single-and two-story X-braced bents with and without a horizontal bracing strut at the bottom of the lower X-bracing were examined. Bent pushover capacities for the various combinations of the numbers of bent piles, bent heights, and X-bracing conditions previously described are presented in this paper.

A common design/construction procedure for highway bridges that are over marshes, small creeks, and shallow bodies of water is to have the bridge superstructure supported on pile bents. During major flood events, the volume and velocity of flood waters can cause considerable scouring to occur at the bents. As the elastic buckling capacity and stability of these bents vary inversely with the square of the bent height, a scour of 4.6 m (15 ft) at a bent that was originally 4.6 m (15 ft) in height will reduce its elastic buckling capacity by a factor of 4. Also the correct buckling load of such bents is somewhat questionable because of the unknown degree of fixity afforded by the soil at the pile ground line. This paper summarizes an investigation of the effect of the soil subgrade modulus on bridge pile bent buckling and pushover capacity. Analysis results indicate that bent pile buckling and pushover loads are not very sensitive to the soil subgrade modulus, k(0), unless the value of k(0) is very small, i.e., k(0) <= 1.36 N/cm(3) (5 lb/in.(3)). Also, the analyses indicate that complete pile fixity can be assumed at approximately 1.5 m (5 ft) below the ground line unless k(0) is very small, i.e., k(0) <= 1.36 N/cm(3) (5 lb/in.(3) ).

About two years ago, the Alabama Department of Transportation (ALDOT) increased its minimum bridge deck thickness to 178 mm (7 in.), and thus ALDOT’s deck thicknesses now range from 178 to 197 mm (7–7.75 in.). Even with the upgrade, ALDOT still utilizes the thinnest decks in the country. Thicker bridge decks are stiffer, stronger, and should provide a longer service life; however, they cost more and require a stronger and more costly support girder system. All of the parameters investigated in the parameter sensitivity study, with the exception of two (deck unit weight and initial cost), support increasing Alabama’s minimum bridge deck thickness. An increase in thickness from 178 to 203 mm (7–8 in.) would cause the deck unit weight to increase 287–575 N/m2 (6–12 psf), depending on whether the concrete is added to the top or the underside of the deck. This would increase the cost of the bridge deck around $2.15/m2 ($1.80/yd2), and would translate into an increase in deck initial cost of around 2–3%. However, increasing the deck thickness from 178 to 203 mm (7–8 in.) would also increase the deck service life, which would reduce the life-cycle cost of the deck/bridge.

Bridge deck rehabilitation via overlaying has been widely used in the colder regions of the United States but not in Alabama due to a warmer climate and nonuse of deicing salts on bridge decks. However, Alabama does have some experience with bonded deck overlays, and the purpose of this work is to document the performance of the overlays that were placed in Alabama prior to the Summer 2000. The service life performance of the Alabama Department of Transportation’s 19 bonded bridge deck overlays to date are as follows: • Thin (6.4 mm or 1/4 in.) urethane polymer concrete (four overlays) provided a service life of 3 years and left much to be desired before the 3 years. • Thin (9.5 mm or 3/8 in.) polyester polymer concrete (12 overlays) has provided highly variable performances. Four of the overlays had service lifes of less than 1 year. The remaining seven overlays are approximately 10 years old and continuing in service; however, most are near the end of their service life. • Thin (9.5 mm or 3/8 in.) epoxy co-polymer concrete (Flexogrid) (two overlays) has provided excellent performance. Both overlays are 8 years old and located on I-20 bridges and remain in excellent condition. • Thin (12.7–19.1 mm or 1/2–3/4 in.) asphaltic based NOVACHIP (one overlay) has been in service for 3 years. During this short period, it has and is continuing to perform in an excellent manner.

A companion paper reported on theoretical considerations associated with adding girder lines to rehabilitate highway bridge decks and superstructures. This article reports on practical, construction, and cost considerations associated with the addition of girder lines rehabilitation strategy. Results of the investigation indicate that adding longitudinal girders between the existing girders is a viable bridge superstructure rehabilitation strategy. The two primary merits of the strategy are (1) most of the work can be performed from the underside of the bridge, thus minimizing interference with traffic; and (2) the strategy strengthens and stiffens the deck/superstructure and, therefore, should significantly prolong the remaining service life of the existing girders and deck. The greatest drawback to the adding girder lines strategy is its high initial cost. Because of this high cost, the strategy is not recommended except in special cases.

The Alabama Department of Transportation (ALDOT) employs thinner decks on their highway bridges than almost all other states and countries, and unfortunately many of these decks are exhibiting significant levels of cracking and premature deterioration. Up until about two years ago, ALDOT deck depths ranged from 6 1/4 in. (159 mm) to 7 3/4 in. (197 mm), with the depth depending primarily on the girder spacing. Since that time, ALDOT has increased their minimum deck thickness to 7 in. (178 mm); however, they still employ thinner decks than most other highway agencies. As a first step in investigating bridge deck thickness and related deck design parameters, a survey questionnaire was prepared and sent to all state Departments of Transportation. Results of the survey indicate that the most common of the current design deck thickness in the United States is 8 in. (203 mm). Most states (61%) design-in an extra 1/2 in. (13 mm) of deck thickness to allow for future grinding, and most states (67%) do not employ a wearing surface on their decks. Other results of the survey questionnaire are presented and discussed.

Plastic shrinkage cracking of concrete bridge decks occurs when the water evaporation rate at the surface exceeds the bleeding rate of the freshly placed concrete. Also, the rate of early drying shrinkage after the concrete hardens is related to water evaporation rate due to weather conditions over a prolonged period of time. Thus, water evaporation rate values are of great interest when placing and curing concrete bridge decks. The American Concrete Institute (ACI) has published a water evaporation chart that aids in deciding if weather conditions will cause plastic shrinkage at the time of concrete placement. The chart, although developed for plastic concrete and plastic shrinkage, could be used in conjunction with relative humidity, temperature, and wind velocity data for different locations, times during a day, and times of the year, to provide an improved guideline for indicating appropriate weather-related curing requirements for bridge decks. This study identifies typical temperature, relative humidity, and wind-weather exposure conditions in Alabama for various months/seasons of the year and times of the day; it also evaluates, via the ACI 305 Surface Evaporation Chart, concrete-surface water evaporation rates for these typical Alabama weather exposure conditions. Based on these data and results, tentative bridge-deck curing requirement categories appropriate for Alabama are identified.

The Alabama Department of Transportation (ALDOT) has more than 4830 m of major Interstate bridges (three to five lanes wide) near downtown Birmingham, Alabama, that have significant levels of deck cracking and deterioration. The bridges are part of the Interstate 65 and Interstate 59 highway system through the city and are approximately 27 years old. It appears that deck cracking is primarily the result of (a) early drying and thermal shrinkage, (b) early concrete obstructed settlement, (c) thin and flexible decks, (d) light and flexible superstructures, and (e) heavy traffic volume and loadings. The deck condition versus age and the crack classification/width versus age curves are presented for three typical bridge decks, along with a photographic portrayal of the state of deck cracking and deterioration. Comparisons of experimental and theoretical load deflection behavior of two of the bridges are presented. The rehabilitation or replacement of the bridge decks that are approximately 55 740 M 2 is a matter of great concern to ALDOT. Actions the agency is currently taking and actions it plans to take are also presented.

A consideration that frequently receives too little attention in bridge design is durability. Probably the most important decisions made regarding the future durability/longevity of a bridge are made at the very beginning of the design process. These are upper department of transportation (DOT) management decisions regarding bridge design life, geometric parameters (e.g., number of lanes, shoulders, underneath clearances), average daily traffic, average daily truck traffic, design truck loading, material requirements, policing of overweight truck policies, preventative maintenance programs, and others. Thirteen actions are recommended in this article for consideration by DOT managers to enhance the durability/longevity of highway bridges. The actions are quite specific and are discussed in detail. They address design life and load considerations, geometric parameters, design traffic volumes, material requirements, training programs, and preventative maintenance programs. Changes in all or a number of the areas recommended could have a very significant positive impact on future bridge durability/longevity.

A factor that typically receives too little consideration in bridge work is durability, and the time to begin thinking about durability is at the beginning of the bridge planning and design phase. Once a bridge is designed and constructed, much of its eventual durability and longevity has been determined. Assessments of bridge durability performance were made based on data available in the literature along with a subset of the data available in the historical bridge records of the Alabama Department of Transportation. From these reviews it was determined that bridges in Alabama are currently providing service lives of approximately 55–60 years. A recent Federal Highway Administration edict that main artery highway bridges be designed for 75 year service life means that Alabama must improve the durability performance of its bridges. Improvements can best be made at the planning, structural design, and material selection stages, that is, in the design phase. Primary areas of focus in which to make changes and improvements can best be pinpointed by looking at durability performance of individual bridge subcomponents.

To gain a better understanding of how highway bridges in Alabama are performing in the area of durability/longevity, a review of the historical bridge records of the Alabama Department of Transportation was performed. Because of the large number of bridges, it was decided to select the subset of old bridges that were replaced during the 1980–93 period to evaluate their durability performance. Based on an analysis of this data subset, the most structurally deficient major component was the deck, followed by the substructure. The superstructure performed best. The worst performing subcomponents were the wearing surface, deck structure, curbs, expansion joints, abutment wings, and abutment backwall. The best performing subcomponents were the drains, rivet/bolt/weld connections, and piers or bents. The major reason for decks to fail functionally was the deck geometry. However, the structural condition of decks at the time of functional obsolescence was also near failure. The data indicated that simple span construction was superior to continuous span construction for enhancing durability. Simple spans excelled in performance in every component and subcomponent except for the curbs, columns of the bents or piers, and the alignment of members.

A design consideration that probably receives too little attention in bridge design and in concrete mixture design as well, is durability. One of the primary factors affecting concrete bridge durability is cracking. This cracking results primarily from thermal and drying shrinkage and from static and dynamic truck loadings. Structural designers have greater control of the ultimate cracking and durability performance of bridges than any other group. Specific actions are recommended in this article for the consideration of structural designers to mitigate concrete cracking and thus to enhance bridge durability. Most of the actions pertain to the deck, which is the bridge component that typically exhibits the greatest deterioration rate. An example illustrates dramatic improvements in bridge deck performance in the transverse direction for only a 2.54 cm (1 in.) increase in thickness. In the longitudinal direction, a 2.54 cm (1 in.) deck thickness increase also results in significant beneficial effects.

This article reports on the results of two actions that were taken to assess the nature, extent, and primary causes of highway bridge deterioration in Alabama. The first was a mail survey questionnaire that was sent to all state and county bridge maintenance engineers in the state. The questionnaire indicated that almost all engineers felt additional attention was needed at each phase of bridge evolution—planning, structural design/materials selection, construction, and maintenance—to enhance durability. Most of the group surveyed felt that concrete bridges (both prestressed and reinforced) were more durable, that support girders and bent caps were the better performing subcomponents, and that joint and bearing assemblies were the weakest performing elements. The second action was a detailed interview with Alabama Department of Transportation (ALDOT) bridge maintenance engineer in conjunction with site visits to numerous ALDOT bridges. The major types and causes of bridge deterioration identified during these visits were faulty deck joints, poor drainage, concrete cracking/spalling, faulty bearings, corrosion of structural steel, fatigue of structural steel, abutment erosion, foundation scour, and poor quality construction/inspection.

Because drying shrinkage cracking is a major source of bridge deck cracking, and because shrinkage compensating concrete (SCC) is known to substantially reduce shrinkage cracking, the use of SCC should be closely examined in an effort to increase the durability and service life of bridge decks. One of the concerns regarding the use of SCC is its more demanding construction requirements for placement time and for curing. This paper addresses relevant material and construction issues that have resulted in the successful use of SCC for bridge decks. The Ohio Turnpike Commission (OTC) has used SCC exclusively for its new and replacement bridge decks for the past 12 years, and they have been very satisfied with its performance to date. The OTC's evaluation of SCC is that it greatly mitigates shrinkage cracking. The OTC's requirements for SCC at the concrete plant, in-transit, and at the job site are included in this paper. The OTC's construction procedures are presented in the form of a chronological sequence of photographs illustrating the construction activities on a new SCC deck placement in 1994.