Abstract: Final design of the replacement orthotropic deck panels for the rehabilitation of the Williamsburg Bridge in New York City was based on laboratory fatigue tests of a full-scale prototype and an as-built orthotropic deck panel carried out at Lehigh University in the latter 1990s. The tests focused on determining and comparing the fatigue resistance of two different welded rib-to-diaphragm connection details that were recommended in the 1994 AASHTO LRFD Bridge Design Specifications and an alternative proposed by Steinman. The test on the prototype panel demonstrated that the fatigue resistance of the alternative detail was superior and influenced additional design changes that were incorporated into the replacement panels installed on the southern inner and outer roadways. Subsequent tests on the as-built panel further confirmed that the fatigue resistance of the alternative detail was superior and demonstrated that the additional design changes were also beneficial. Static and dynamic tests revealed the complex behavior of the orthotropic deck panels and demonstrated the effectiveness of retrofit and repair options at cracked connections. An assessment of fatigue resistance based on fracture mechanics models provided theoretical correlation. This research has led to the revision of design specifications for steel orthotropic decks first provided in the 2000 Interim AASHTO LRFD Specifications.

Abstract: A patient support apparatus includes a base, a frame coupled to the base, and a deck coupled to the frame. The frame includes a storage portion. The deck includes a head section, a seat section and first and second laterally spaced apart outer leg support sections adjacent the seat section. The seat section and the first and second outer leg support sections being configured to define a central opening therebetween. The apparatus also includes a removable center leg support configured for movement between a first position located within the central opening and coupled to the deck to provide a portion of the deck and a second storage position detached from the deck and located in the storage portion of the frame and below the deck.

Abstract: A new concrete bridge in the Municipality of Wotton, Quebec, Canada, was constructed using fibre-reinforced polymer (FRP) bars as reinforcement for the deck slab. The new bridge is a girder type with four main girders simply supported over a span of 30.60 m. One half of the concrete deck slab was reinforced with carbon and glass FRP bars, and the other half with conventional steel bars. The design of the reinforced concrete deck slab was made according to sections 8 and 16 of the new Canadian Highway Bridge Design Code. The bridge was well instrumented at critical locations for long-term internal temperature and strain data collection using fibre optic sensors. The construction of the bridge was completed and the bridge opened for traffic in October 2001. The bridge was then tested for service performance using standard truckloads. Design, construction details, and the results of the field test and 1 year of remote monitoring are discussed. Under the same real service and environmental conditions, very si...

Abstract: The research presented herein describes the development of durable link slabs for jointless bridge decks based on strainhardening cementitious composite - engineered cementitious composite (ECC). Specifically the superior ductility of ECC was utilized to accommodate bridge deck deformations imposed by girder deflection, concrete shrinkage, and temperature variations, providing a cost-effective solution to a number of deterioration problems associated with bridge deck joints. Current design concept of link slabs was first examined to form the basis of design for ECC link slabs. Microstructurally optimized ECC material, with good workability and satisfactory mechanical properties was then developed. After the material design, the shrinkage, shrinkage crack resistance and the freeze-thaw behavior of the pre-selected mix proportion was investigated and revealed excellent for the durability concern. Improved design of ECC link slab/concrete deck slab interface was confirmed in numerical analysis and further strengthened by excellent reinforcement pullout and shear stud pushout behavior in ECC. Based on the above findings, monotonic and subsequent cyclic tests of full-scale ECC link slab specimens were performed and compared with those of a conventional concrete link slab. It was revealed that the inherent tight crack width control of ECC decouples the dependency of crack width on the amount of reinforcement. This decoupling allows the simultaneous achievement of structural need (lower flexural stiffness of the link slab approaching the behavior of a hinge) and durability need (crack width control) of the link slab. Overall investigation supports the contention that durable jointless concrete bridge decks may be designed and constructed with ECC link slabs. Finally, a simple design guideline is presented.

Abstract: During a flood, a bridge may be partially or entirely submerged by the flow and the subsequent loading of fluid plays a major role in assessing the vulnerability of the structure. We have performed laboratory experiments to quantify the hydrodynamic loading on a bridge deck with rectangular cross section. We measured the time-varying hydrodynamic forces acting on the obstacle for various submergences and Deck Froude numbers. The experimental results have been analyzed via dimensional analysis and relationships between time-averaged force coefficients (drag, lift, and moment coefficients), the Deck Froude number and geometrical parameters of the problem are discussed and compared against relevant literature. Due to the presence of a free surface, force coefficients can be either larger (by more than a factor of 2) or lower than the corresponding values of the unbounded domain. The experimental drag coefficients are then compared with the results obtained by the momentum equation.

Abstract: Many bridges in the state of Indiana have been identified to have cracking in the concrete deck. Cracking has been identified in the negative and positive moment regions of bridges on both the top and bottom surfaces and can appear before or shortly after the opening of the structure to live loads. Significant crack widths and various degrees of cracking exist in different bridge systems including both concrete and steel superstructures. This research project was divided into five phases to determine the factors affecting transverse and longitudinal bridge deck cracking, as well as, to develop design recommendations that minimize or prevent these types of bridge deck cracking. The research focused on the design and construction of new bridge decks. However, an overview of overlay cracking is also presented. The first phase was a field evaluation to investigate the scope of the problem. Using the information gathered from the first phase, the second phase instrumented a typical bridge structure to provide an understanding of the behavior of transverse cracks in a concrete bridge deck. With the findings from the previous two phases, the third phase conducted a laboratory investigation to study the effects of shrinkage and restraint of a concrete deck and to determine the contribution of stay-in-place steel forms to the formation of transverse cracking. The fourth phase evaluated the effect of formwork type on restrained shrinkage. In the final phase, the effect of reinforcing bar spacings and epoxy thickness on crack width and spacings were evaluated. Based on the research investigation, transverse deck cracking is caused by restrained shrinkage of the concrete deck while longitudinal cracking is caused by a combination of factors including restrained shrinkage and a construction detail that turns the leg of an angle used to support stay-in-place formwork into the deck. Design and construction recommendations are provided to minimize transverse, longitudinal, and overlay map cracking.

Abstract: This paper describes recent developments and new applications in the field of numerical simulation for nonlinear ship motions using the Large Amplitude Motion Program (LAMP), following up on our 1997 paper (Shin, et al. 1997). The objective of LAMP’s development is to develop an analysis tool for highly realistic prediction of wave loads and behavior for a ship in severe seas. This approach is based on physics and does not rely on statistical information gathered from model tests or existing ships, so it is expected to be especially useful for new ship types. The kernel of LAMP is panel-based potential flow solution of the ship-wave hydrodynamic problem with many numerical options, including a recently-added Rankine singularity model with a damping beach and an option to rapidly compute the perturbation potential using pre-computed Impulse Response Function (IRF) potentials. The paper describes important implementation details for these and other computational options added since 1997. The LAMP System is structured so that numerical or empirical models of other systems or effects can be directly incorporated into the time domain ship motions and load calculations using a series of optional features. One such feature is a multi-level green-water-on-deck model including a finite-volume solution of 3-D shallow water flow over the deck. This model can be used for analyzing ship behavior with water on deck and loads caused by green-water-on-deck. Numerical results illustrate the effect of green-water-on-deck on the pitch motion and vertical bending moment of a cruiser in head seas and on the roll behavior of a fishing vessel. Another feature involves anti-roll fin and tank systems, including an integrated anti-roll tank model that solves for fluid motion in a U-tube tank concurrently with the wave-body hydrodynamics. The paper evaluates the use of passive anti-roll tanks to mitigate parametric roll resonance. Recent development has focused on applying LAMP to unconventional ships, multi-hull high-speed displacement ships, and non-ship-like configurations. Results are presented from studies for an advanced Naval hull form, a trimaran, and a semi-submersible platform.

Abstract: Early age cracking on concrete bridge decks has been experienced by many state departments of transportation (DOTs). In Colorado the cracking problem on newly constructed bridge decks has not been completely solved. In this study, the extent and causes of the cracking problem were investigated, and necessary changes to alleviate the cracking problem were identified. To achieve these goals, current Colorado Department of Transportation (CDOT) practice was reviewed and compared with other DOTs practices for construction of bridge decks. A database analysis of field inspection results was performed. Presently, 18% of newly constructed bridge decks in Colorado have no early cracking problem, and the rest (82%) have various degrees of cracking problems. The results of the database analysis were then confirmed by field inspections conducted on nine newly constructed bridge decks. An extensive literature review was performed. Past research activities in Colorado were reviewed, current CDOT practices for controlling the bridge deck cracking problem were assessed, and recommendations to alleviate the cracking problem were identified. From the literature survey and previous research studies, the causes of cracking in newly constructed bridges can be categorized as material, design, construction, and environmental factors. High early age shrinkage of concrete is a major contributor among the adverse material factors. The cracking can also be a direct result of several structural design factors. Based on the results of field inspections, the cracks typically form above supporting members, such as girders or piers, and have large and uniform spacing. This is a result of tensile stresses from negative bending moments in the deck above supports. The construction and environmental factors (such as wind speed, temperature, and curing procedures) greatly affect the shrinkage of the concrete. Due to very limited information regarding deck curing or placement conditions, it has not been possible to determine the specific impact of these factors on early age deck cracking of the inspected bridges. Recommendations to reduce the cracking problem in newly constructed bridges in terms of materials, design, and construction factors are presented. Based on findings of Research Report No. CDOT-DTD-R-2001-11, new concrete mix designs Class H and Class HT have been implemented in the 2003 CDOT Standard Specifications for Road and Bridge Construction. Most of the recommendations for construction of bridge decks have also been implemented in the 2003 CDOT specifications. The study recommendations for the structural design factors of bridge decks should also be implemented in CDOT Bridge Guidelines.

Abstract: A method and apparatus using foam forms for poured concrete roof and floor decks for on-site concrete structural joists is shown that may be integrated into the concrete deck formed by the forms or otherwise used as structural supports. Greater joist strength results from providing a communication channel in the forms between an opening in C channel metal studs used in such panel forms and a space between piers that forms the main concrete beam portion of a finished concrete structural joist. By providing such flow of concrete, when the joist is completed, the concrete structural joint is stronger because the concrete is disposed inside of the C channel studs and continuously between the inside of the C channel studs and the main concrete beam portion. The concrete thereby interlocks the C channels to the main concrete portion of beam.

Abstract: The corrosion protection service life extension provided by epoxy-coated reinforcement (ECR) was determined by comparing ECR and bare steel bars from 10 Virginia bridge decks built between 1981 and 1995. The objective was to determine the corrosion protection service life time extension provided by ECR field specimens with various degrees of coating adhesion: disbonded, partially disbonded, and wholly bonded coatings. The size and length distributions of cracks in Virginia bridge decks were investigated to assess the frequency and severity of cracks. Correlation of cracks with chloride penetration was used to characterize the influence of cracking on deck deterioration. Cracks influence the rate of chloride penetration, but the frequency and width distributions of cracks indicate that cracks are not likely to shorten the overall service life of most bridge decks in Virginia. Altogether, 141 drilled cores, 102 mm (4 in.) in diameter, were employed in this study. For each of the decks built with ECR, 10 to 12 cores were drilled through a top reinforcing bar adjacent to the previous study core locations. In addition, approximately 3 cores were drilled through a top reinforcing bar at a surface crack location. Laboratory testing involved nondestructive monitoring using advanced electrochemical techniques to periodically assess the corrosion state of the steel bars during cyclic exposure to chloride-rich solution over 36 months of treatment. Time of corrosion initiation and time of cracking (where applicable), as well as chloride content of the concrete before and after treatment, were used in the analysis. Analysis of the epoxy coating after treatment showed the presence of micro cracks in the surface of some coatings, and moisture uptake and glass transition temperatures, as related to curing of the coatings, were investigated. Less than 25% of all Virginia bridge decks built under specifications in place since 1981 is projected to corrode sufficiently to require rehabilitation within 100 years, regardless of bar type. The corrosion service life extension attributable to ECR in bridge decks was found to be approximately 5 years beyond that of bare steel and, therefore, ECR is not a cost-effective method of corrosion prevention for bridge decks. Deleting the requirement for ECR in decks would save Virginia approximately $845,000 per year.

Abstract: Composite beam or joist and slab systems typically provide the most efficient design alternative in steel frame construction, and indeed it is one of these systems that make steel an economically attractive alternative to concrete framed structures. Composite beam specification requirements and design aids are given in the American Institute of Steel Construction (AISC) Load and Resistance Factor Design (LRFD) Manual. The LRFD composite beam design procedure results in designs that are typically 10-15 percent more economical than those obtained using the AISC allowable stress design (ASD) procedure. The efficiency of composite beam design using LRFD procedures has, in the authors' opinions, been the primary motivating factor for the use of the LRFD specification to date. The design strength and stiffness of composite beams depends on the shear connection behavior. The strength of the shear connectors may be reduced because of the influence of the steel deck geometry. An empirical expression for this reduction was developed by evaluating results of composite beam tests in which the deck ribs were oriented perpendicular to the steel beam. A reduced stud strength is obtained by multiplying the stud reduction factor, SRF, by the nominal strength of a shear stud, Qn. The expression for the nominal stud strength, which has been incorporated in the AISC LRFD specification and is the basis for the tabular values given in the AISC ASD specification, is given by:

Abstract: A deck system employing a plurality of substantially hidden fasteners to couple the floor boards of the deck to the joists. Each hidden fastener is rigidly coupled to a respective joist and positioned between a pair of adjacent floorboards. Each fastener forms a mating relationship with specially configured sides of the boards to thereby rigidly couple the boards to the joists.

Abstract: A fastener for securing deck boards to a support structure without the need for driving screws or nails through the deck boards. The fastener includes two horizontal flanges that fit into slots cut into the sides of adjacent deck boards, a center hole for securing the fastener to the support structure and deformable, resilient elements that bridge the gap between adjacent deck boards during fastening yet compress inward when the boards swell and expand.

Abstract: A decking system, decking components and an installed deck for use on a support structure. The decking system comprises hollow profile planking units having anchor flanges on opposite edges that cooperate with an anchor structure to form a deck or platform. The flanges and the anchor units are shaped and configured to closely interact and form an installed platform structure. The planks comprise an extruded thermoplastic wood fiber composite having an internal structure sufficient to withstand installation, engineering forces placed on the installed platform, weathering and use. The anchor structures have a shape that conforms to the anchor flanges on the decking profiles to hold the deck in place.

Abstract: The water on deck caused on a restrained ship model without forward speed in head waves is studied experimentally by using a transient-test technique. A single watershipping event is induced by the wave packet, and the severity of the interaction is controlled by the wave-packet steepness. Three different bow geometries are considered. Two of them are analytical hull forms, and the last is the ESSO-Osaka tanker. The models are equipped with a transparent-material deck to study the flow-field evolution by image analysis. A vertical wall is placed at a certain distance from the forward perpendicular to mimic the presence of deck structures. Velocity of the shipped water along the deck, pressure field on the deck, and horizontal impact force on the wall are measured. The main fluid-dynamic aspects of the green-water phenomenon are highlighted. For the tested cases, water shipping starts always with the free surface exceeding the freeboard, plunging onto the deck, and forming complex cavities entrapping air inside. The geometry of the air cavity depends on the hull form and the wave steepness. Then the water propagates along the deck. In general, the water front is strongly three dimensional because of the water entering along the deck contour. The interaction of the shipped water with the vertical structure consists of impact, run up-run down cycle, and backward plunging of the water onto the deck, still wetted. The evolution of the pressure field follows that of the water front. Pressure peaks are associated with the impact against the vertical wall, and by the backward plunging of the water on the deck, at the end of the run up-run down cycle of the water. It is shown that both these stages can be of importance from the structural point of view.

Abstract: A mower deck having movable chamber gate members that permit the deck to selectively operate in either a discharge or mulching mode of operation. The deck includes a control structure that operates the gate members to permit the operator to quickly and easily switch between the discharge mode and the mulching mode while mowing.

Abstract: A stretcher includes an elongated base having a head end and a foot end, a plurality of floor-engaging casters rotatably mounted to the base, a radiolucent upper deck, head and foot end hydraulic cylinders coupled to the base adjacent to the head and foot ends thereof, and head and foot end connectors for coupling the head and foot end hydraulic cylinders to the head and foot ends of the upper deck. The head and foot end connectors secure the upper deck to the base while allowing (a) movement of the upper deck between a low position and a high position, (aa) translation of the upper deck toward the foot end of the base, and (aaa) rotation of the upper deck to a Trendelenberg position or to a reverse Trendelenberg position. The head end and foot end hydraulic cylinders are spaced apart to define a central imaging region above the base between the hydraulic cylinders which is free of structure that would interfere with imaging. The stretcher further includes a base, a pair of front wheel assemblies coupled to the base, a pair of rear wheel assemblies coupled to the base, a deck coupled to the base, a pair of armboards coupled to the deck, each armboard positioned to overlie a respective one of the pair of front wheel assemblies, and a pair of handles coupled to the deck, each handle positioned to overlie a respective one of the pair of rear wheel assemblies. In a preferred embodiment the deck includes a transversely-extending cross bar, with armboards pivotally coupled thereto.

Abstract: The demand for the development of efficient and durable bridge decks is a priority for most of the highway authorities worldwide. This paper summarizes the results of an experimental program designed to study the behavior of an innovative glass fiber reinforced polymer (GFRP) bridge deck recently patented in Canada. The deck consisted of a number of triangular filament wound tubes bonded with epoxy resin. GFRP plates were adhered to the top and bottom of the tubes to create one modular unit. The experimental program, described in this paper, discusses the evolution of two generations of the bridge deck. In the first generation, three prototype specimens were tested to failure, and their performance was analyzed. Based on the behavior observed, a second generation of bridge decks was fabricated and tested. The performance was evaluated based on load capacity, mode of failure, deflection at service load level, and strain behavior. All decks tested exceeded the requirements to support HS30 design truck loads specified by AASHTO with a margin of safety. This paper also presents an analytical model, based on Classical Laminate Theory to predict the load-deflection behavior of the FRP decks up to service load level. In all cases the model predicted the deck behavior very well.

Abstract: A modular structure construction and repair system for use in new bridge construction and old bridge repair. The invention comprises a plurality of prefabricated modules which have a plurality of longitudinally extending beams and deck portions molded thereto. The modules are positioned over a plurality of girders so that longitudinal joints are formed above the girder. In the repair of an old bridge, an old section of the bridge deck is removed, and the modules are positioned on the existing girders. The modules are attached to the girders such that a shear connection is provided therebetween. Precompression may also be applied to clamp the sides of adjacent deck portions together. Various embodiments disclose this precompression and the shear connections.

Abstract: The most popular type of bridge in service today is the concrete deck on steel-girder composite bridge. A finite-element model is built to analyze the superstructure of this type of bridge under working load conditions. The deflections along a test bridge are computed by using this method; the results obtained are close to the experimental data. The concrete deck of the bridge is analyzed using nonlinear finite elements, of which the analytical procedure is described in detail. A comparison is also made between this method and the traditional transformed area method.

Abstract: A treadmill (10) includes a frame on which are mounted transverse forward and rearward roller assemblies (14, 16). An endless belt (18) is trained about the forward and rearward roller assemblies. A deck (20) is positioned between the upper run of the belt and the frame. The rearward portion of the deck (20) is mounted to the frame by a pivot connection (24) to allow pivoting of the deck about an axis transversely to the length of the deck. Elongate springs (26) of adjustable stiffness are mounted either along the sides of the frame to underlie the side margins of the deck, or transversely of the deck, to support the deck in conjunction with the pivot connection (24) and to absorb impact loads imparted on the deck by the user.

Abstract: This paper presents a probabilistic approach for predicting the chloride contamination of concrete and reinforcing steel corrosion, which takes into account the uncertainty associated with the analytical models of chloride transport, corrosion initiation, as well as damage accumulation, material properties, structural dimensions, and applied environmental and mechanical loads. The proposed approach is illustrated on an aging reinforced concrete bridge deck that has been exposed to chlorides from deicing salts for forty years. An extensive non-destructive and destructive evaluation of the corrosion-damaged deck was undertaken. The field survey data showed a considerable level of variability in all parameters measured with coefficients of variation ranging from 34% for the concrete cover depth to 86% for the diffusion coefficient. The distributions of the chloride concentration at the level of the top reinforcement mat and the time for its corrosion initiation were generated using Monte Carlo Simulation. The simulated results were very close to the field data, which illustrates the prediction capabilities of probabilistic methods as opposed to deterministic methods.

Abstract: A very lightweight tubular building element for the construction of reinforced concrete floors and roofs; providing the formwork for the casting in place of the structural concrete and a high quality finished ceiling at the same time. It is a single component that can be installed easily and efficiently without heavy equipment or special craftsmanship; afterward the component is not removed, but stays permanently integrated in the concrete floor or roof. It forms a deck that is impervious, eliminating cumbersome cleaning during construction and leakage afterward, saving the common need of a costly waterproofing membrane over the slab. The formwork deck, composed of a plurality of the invention component, weighs less than four (4) pounds per square foot; and a single component for a common 15 feet span weighs less than 30 pounds, which can be easily handled by only one laborer. Furthermore, in forming the concrete, the plurality of this component creates hidden closed air spaces in the slab that saves concrete, reduces the overall weight of the building and provides better thermal insulation in comparison with a conventional solid concrete slab of same span, thickness and strength.

Abstract: A storage rack has upright columns supporting vertically cambered beams having step box or channel shapes accommodating a generally horizontal deck for carrying pallets and product loads. The beams have upward cambers or convex curvatures that increase the load carrying capacity of the rack.

Abstract: Deploying an offshore oil and gas production platform comprises placing a buoyant equipment deck on a buoyant pontoon so that elongated legs on the pontoon, each comprising a buoyant float, extend movably through respective openings in the deck. Chains extending from winches on the deck are reeved through fairleads on the pontoon and connected back to the deck. The chains are tightened to secure the deck to the pontoon for conjoint movement to an offshore location. The chains are loosened and the pontoon and leg floats ballasted so that the pontoon and leg floats sink below the floating deck. The chains are then re-tightened until pawls on the leg floats engage the deck. The buoyancy of at least one of the pontoon and leg floats is increased so that the deck is thereby raised above the surface of the water. The chains are connected to mooring lines around an offshore well site, and the raised deck and submerged pontoon are maintained in a selected position over the site with the winches.

Abstract: A prestressed or post-tensioned composite structural system for bridge floors, road beds, pedestrian walkways, building floors, building walls, or similar structural elements. The structural system comprises a composite structure comprising an unfilled grating as a base component, and a prestressed, post-tensioned reinforced concrete slab as a top component. The base grating component is preferably a plurality of main bearing bars without any distribution bars or tertiary bars. The upper portions of the main bearing bars are embedded in the concrete component permitting horizontal shear transfer and creating a composite deck structure which maximizes the use of tensile strength of steel and the compressive strength of concrete.

Abstract: This paper presents a probabilistic approach to predicting the chloride contamination of concrete and reinforcing steel corrosion and takes into account the uncertainty associated with eh analytical models of chloride transport, corrosion initiation as well as damage accumulation, material properties, structural dimensions and applied environmental and mechanical loads. The proposed approach is illustrated on an aging reinforced concrete bridge deck that has been exposed to chlorides from deicing salts for forty years. An extensive non-destructive and destructive evaluation of the corrosion-damaged deck was undertaken. The field survey data showed a considerable level of variability in all parameters measured with coefficients of variation ranging from 34% for the concrete cover depth to 86% for the diffusion coefficient. The distributions of the chloride concentration at the level of top reinforcement mat and the time of its corrosion initiation were generated using Monte Carlo Simulation. The simulated results were very close to the field data which illustrates the prediction capabilities of probabilistic methods as opposed to deterministic methods.

Abstract: As ground-penetrating radar (GPR) is increasingly used for assessing the condition of bridge decks, quantifying and controlling the quality of GPR measures becomes an important challenge. A methodology developed to assess the accuracy of deck condition measures is presented, and its use in a case study involving real data is demonstrated. The latter are generated during GPR applications on a large bridge deck and are processed with a commercial image-processing algorithm. The measures extracted from the processed GPR data are the rebar reflection amplitude and the dielectric constant of the deck material. The accuracy of the GPR assessments is evaluated by comparing core data (ground truth) with the GPR measures. The methodology uses appropriate statistical characteristic curves for quality control. It is based on a use of data to plot the probabilities of true detection versus false detection. Image interpretation requires using a threshold value (typically established from experience) selected to optimize true and false detection rates. The results of the case study indicate that rebar reflection data detect defects of the bridge decks at a 75% true detection rate with a 15% false detection rate. The dielectric data generated during field testing appear not to adequately represent the condition of the bridge deck because of the presence of latex-modified concrete overlay. The details of this finding and important conclusions are presented and discussed.