Submission Date: November 14, ,114 words (not including Title Page) plus words each = 4,114

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1 Joint-less Continuous Curved Steel Girder Structure Harold Fink, PE New York City Region New York State Department of Transportation st Street Long Island City, NY T) F) Richard Wenke, PE New York State Department of Transportation 50 Wolf Road Albany, NY T) F) Michael D. Liona, PE Hardesty and Hanover 1501 Broadway New York, NY T) F) Rasmin Kharva, PE Hardesty and Hanover 1501 Broadway New York, NY T) F) Harold Fink and Richard Wenke are the corresponding authors Submission Date: November 14, ,114 words (not including Title Page) plus words each = 4,114

2 ABSTRACT A new structure was designed to be fully joint-less to eliminate typical deck joints which are costly to maintain and are a main cause of superstructure and substructure deterioration. At a length of approximately 800 feet, this 4-span continuous curved steel girder bridge will be the longest fully jointless structure owned by NYSDOT when completed. Finite element modeling was used to determine the full range of thermal movements of the structure taking into account thermal gradients. Specific details were developed to accommodate these movements. The details included use of an asphalt pressure relief joint, sleeper slab and grade beams. Introduction The New York State Department of Transportation (NYSDOT) is progressing a series of construction contracts to address highway operational, structural, and safety deficiencies in the Kew Gardens Interchange of Queens, New York. This interchange contains several major highways including the Van Wyck Expressway (VWE), Union Turnpike (UTP), the Grand Central Parkway (GCP) and the Jackie Robinson Parkway (JRP). These facilities handle a combined traffic volume of over 250,000 vehicles each day. Due to the complexity of the Kew Gardens Interchange, the project is split into four construction contracts. The contract described herein is the second contract within the interchange and is designated as Contract 2A. This contract encompasses the segment of the Northbound Van Wyck Expressway (VWE) between Hoover Avenue and Jewel Avenue. The third planned contract, designated Contract 2B, includes the Southbound VWE and associated ramps. Hoover Ave. P a g e 1

3 Figure 1 Project Area The structures within Contracts 2A & 2B project limits are: Mainline -NB Van Wyck Expressway Viaduct (BIN C) -SB Van Wyck Expressway Viaduct (BIN ) Ramps -EB Union Turnpike/Jackie Robinson Parkway to NB Van Wyck Exp.- Ramp KB (BIN B) -SB Van Wyck Expressway to WB Union Turnpike- Ramp KA (BIN ) -EB Union Turnpike/Jackie Robinson merge to Ramp KB (BIN ) Figure 2 Aerial View Kew Gardens Interchange The Van Wyck Expressway Mainline Viaducts will be replaced on a new alignment, along with two ramp structures to the VWE. The superstructure of the merge to KB ramp will be replaced. The Mainline VWE approaches and Grand Central Parkway (GCP) connection ramps to the VWE will be replaced. The westbound Union Turnpike (UTP) at-grade ramp to the WB GCP will be replaced on a new alignment. The existing NYCDOT Arterial Maintenance Yard and existing MTA Jamaica Subway Yard access road which passes under the viaduct structures at the north abutment will be realigned. The geometric deficiencies, operational conditions, and load capacity of the structures will be improved as part of the project. P a g e 2

4 Existing and proposed structure The subject bridge for this paper is the NB VWE viaduct. Built in 1963, the existing viaduct is supported upon a series of steel plate girders and rolled stringers in an eighteen (18) span configuration with an overall length of 1329 feet. It handles two lanes of NB VWE traffic over the Kew Gardens Interchange. The extent of structural deterioration and need for improved highway geometrics require that the bridge be fully replaced. The proposed viaduct will be a four-span continuous steel plate girder, with span lengths of 192, 213, 213 and 179 for an overall length of approximately 800 feet. The structure profile has a vertical curve along with horizontal compound curvature of 1974 and 2959 radii. The concrete substructures are pile supported. Elastomeric bearings are used with expansion at the abutments, piers 1 and 3, with fixity provided at pier 2. Concrete shear blocks with steel guides have been provided at the piers and abutments for transverse seismic forces and to provide guiding of the superstructure. The proposed structure will feature improved highway geometry and carry three lanes with shoulders. Figure 3 Proposed Bridge Plan & Elevation View P a g e 3

5 Maintenance Concerns A main location of bridge deterioration occurs at deck joints. Joint problems lead to the introduction of water, debris and de-icing agents to the superstructure, bearings and substructure components at these locations, resulting in the premature deterioration of these components. The replacement costs of these components and the joint itself vary based upon the component types, span lengths and bridge location. The existing NB VWE handles 85,000 vehicles per day with an expected 98,000 in the future, with 10% truck traffic. Based on experience with similar roadways, NYSDOT has had maintenance concerns on similar structures that have used multi-cell modular joints. As such, NYSDOT requested that the structure be analyzed to determine if a joint-less alternative was feasible. The high traffic volume on the VWE Bridge and on the at-grade roadways crossed by the bridge makes future repairs/replacements of these components and the joint itself a major concern. By eliminating all joints along the deck and at the abutments, these concerns can be addressed. Joint-less Options Several existing joint-less options were reviewed. These included integral abutments, semi-integral abutments and joint-less deck details. With an overall span of 800, expansion length of 405 and curved structure the integral and semi-integral options were not deemed to be feasible for the NB VWE. Based on NYSDOT criteria, the allowed maximum expansion length of 165 and maximum curvature criteria were exceeded. Existing NYSDOT joint-less deck details were found to be applicable to expansion lengths in the range of up to only 200 with structures of less curvature. Additional analysis and development was required for the range of movements to be experienced by the NB VWE. Finite Element Analysis A finite element model of the superstructure was developed to analyze the structure movements through full thermal range based on AASHTO LRFD. The model included all primary members of the curved structure. In addition to the uniform thermal load cases, a temperature gradient of 20 degrees Fahrenheit was applied to each fascia to determine the thermal movements generated by this non-uniform heating distribution. Figure 4 Proposed Analytical Model P a g e 4

6 Some assumptions for the model are as listed: Assumed base construction temp is 68 deg. F Assumed Max. temperature is 120 deg. F as per (AASHTO LRFD 4th Edition, Table ) & applicable NYSDOT guidance for NYC Assumed Min. temperature is 0 deg. F as per (AASHTO LRFD 4th Edition, Table ) & applicable NYSDOT guidance for NYC Calculated Uniform Temperature Rise is 52 deg. F Calculated Uniform Temperature Fall is -68 deg. F Displacements are computed along and perpendicular to chord Cross slope and longitudinal slope were considered but were not included in the model Average coefficient of friction for the bond breaker pad material is 0.2 and for concrete to concrete is 0.6 per ACI Code. Analysis is based on average of 0.4 friction coefficient modeled as springs at the locations of approach slab to grade beam, wing wall and sleeper slab contact areas Assumed 20 deg. F temperature gradient to account for differential thermal exposure along fascias Longitudinal springs to represent pressure relief joint asphalt stiffness were obtained by increasing the estimated stiffness values by 20% from the average coefficient of friction Both lateral restraint at bearings and no lateral restraint at bearings (except fixed pier 2) were considered to determine max limits of transverse movements at approach slab ends. Output results The output of the thermal modeling demonstrated the longitudinal and transverse range of thermal movements to be experienced by the structure. The length of the structure produces mostly longitudinal movement, as expected, while the horizontal curvature of the structure introduces transverse displacements which need to be accounted for in the joint-less design. The gradient temperature applied, to the fascias of the structure demonstrated additional movement experienced in the transverse direction. Figure 5 Schematic View Showing Location For Tabulated Displacements P a g e 5

7 Thermal Displacements With Transverse Restraints Load Case Loc. Temperature Rise Temperature Fall Day Time Temp Change Day Time Temp Change Absolute Max Absolute Max West Face 20 Def F East Face 20 Def F Long. Disp. Trans. Disp Max(6,8) Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord in. in. in. in. in. in. in. in. in. in. South Approach Slab East Face Corner West Face Corner North Approach Slab East Face Corner West Face Corner Thermal Displacements without Transverse Restraints Load Case Loc. Temperature Rise Temperature Fall Day Time Temp Change Day Time Temp Change Absolute Max Absolute Max West Face 20 Def F East Face 20 Def F Long. Disp. Trans. Disp Max(6,8) Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Disp. Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord Along Chord Perp. To Chord in. in. in. in. in. in. in. in. in. in. South Approach Slab East Face Corner West Face Corner North Approach Slab East Face Corner West Face Corner Table 1 Summary of Thermal Displacements The maximum displacement range of longitudinal and transverse movements were found to be 3.75 and 1.32, respectively. These output results were used to develop the joint-less details. The model also provided force components generated at the joint-less details to determine the magnitude of frictional resistance developed by the deck approach slab to grade beam support interface. The force exerted back into the superstructure from the joint-less slab friction was found to be approximately 7% of the force imparted into the superstructure due to the elastomeric bearing stiffness resistance during temperature deformations. Final details The final configuration of the bridge eliminated all deck joints on the structure and at the abutments. A main concern was to allow for the longitudinal and transverse thermal movements with minimal friction between the contact points of the structure and approach supports to avoid binding and associated forces. The final details developed are shown in Figures 6 and 7. The deck slab was continued over the backwall and is supported upon longitudinal grade beams within the approach. This deck slab extension thus becomes the approach slab. P a g e 6

8 Figure 6 South Approach Slab Plan The use of longitudinal grade beams reduces the area of contact between the approach slab and this interface. This also allows better control on the construction tolerances of these interface points. To reduce frictional forces between the approach slab and longitudinal grade beam supports, the grade beams will receive a steel trowel finish and will be finished to match the profile and cross slope of the roadway. A 2-layer synthetic bond breaker sheet will be supplied between the grade beams and approach slab to reduce friction. Beyond the approach slab is an asphalt pressure relief joint that can contract and expand to handle the longitudinal movements. This pressure relief joint is supported on a sleeper slab which is also supported upon the longitudinal grade beams within the approach. P a g e 7

9 Figure 7 South Approach Slab Detail P a g e 8

10 The subgrade below the grade beams will utilize a select structural fill compacted to 95% standard proctor to address settlement at the approach grade beams. Weep holes and underdrains have been provided at the sleeper slab below the pressure relief joint to address potential water. To further reduce frictional concerns and binding, a 1 gap between the top of backwall and deck slab was provided to avoid friction and binding at this interface. This gap is filled with a compressible foam. To reduce potential friction/binding under the approach slab between the sub-base and approach slab, a 6 haunch of the slab between grade beam supports was provided. To address transverse movements the approach slab is cast above the wingwalls, with a bond breaker supplied, so as not to restrict transverse deformations. At the sleeper slab/wingwall location, a 2 transverse gap with compressible filler is supplied to alleviate potential stresses between the sleeper slab to the wingwalls if future slab movement occurs. The deck and abutment areas at the approach slab were provided with additional reinforcement to handle potential forces transmitted back through the joint-less system. Checks of the superstructure and substructure were performed to ensure potential forces generated by a failure of the joint could be handled by the structure. Conclusion In an effort to reduce maintenance of the proposed structure, NYSDOT will utilize the proposed details as a pilot program to ascertain its effectiveness. Typical NYSDOT joint-less details have been limited to shorter span, less curved bridges with expansion lengths of only up to 200. The proposed NB VWE bridge is curved and has an expansion length of 405 making it the longest, curved structure to be jointless for NYSDOT. The elimination of joints along the bridge has the potential to reduce deterioration of the structure. Their history with multi-cell modular joints on similar length structures with high traffic volumes has led to this pilot test. The pressure relief joint will require maintenance every 7 years or so but this is viewed as minor, routine maintenance which can be done quickly by a highway maintenance crew as compared to the more extensive work needed to repair or replace a multi-cell modular joint at this high traffic location. The project is currently in construction with the bridge to be in service in The contractor has been made aware that maintaining quality control during construction will be essential in order to reduce the potential frictional issues that could arise from improper installation of the proposed details. Thermal modeling of the curved structure revealed that transverse movements can be significant and need to be considered in joint design. A thermal gradient on the curved structure adds to the overall transverse movement and also requires consideration in joint design. As a test program, the tracking of the in-use results of the joint, its durability, effectiveness and the required maintenance cycles of the pressure relief joint will be compiled and reviewed. This information will allow NYSDOT to ascertain if implementing more joint-less details on longer span and curved structures is feasible. Acknowledgments: Zhi Wen, P.E., Hardesty and Hanover, New York, NY P a g e 9