Full-Depth Precast Concrete Bridge Deck Panel Systems (2008)

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5The use of full-depth precast concrete deck panels in high- way bridges in the United States started as early as 1965. The motive for switching to this construction system was a desire to shorten deck construction time in rehabilitation projects in areas with high traffic volumes, where road closures have high costs and cause major inconvenience to the public. Since then, design engineers have realized that there are significant advan- tages to this construction system not only for rehabilitation projects, but also for new construction, due to the relatively fast construction speed and because the higher quality of precast decks reduces maintenance costs and increases service life. This chapter summarizes the information gleaned from a review of the literature and a national survey. The survey was sent to highway agencies in the United States and Canada and to members of the PCI Committee on Bridges and the TRB Concrete Bridges Committee. The goal of this summary is not to report on all of the bridges built with full-depth pre- cast panels, but to show the diversity of the connections between panels and between panels and superstructure. The survey and results are provided in Appendix A, which also provides information collected from the literature review. Several bridges were constructed using full-depth precast panels prior to 1973 (9, 10). Among them were the Pintala Creek Bridge, Montgomery County, Alabama; the Kosciuszko Bridge, Brooklyn–Queens Expressway, New York; the Big Blue River Bridge, Kingstown, Indiana; and the Bean Blossom Creek Bridge, Bloomington, Indiana. Biswas reports that these structures have generally performed well; however, some structures have exhibited partial failures at panel to panel joints (10). These bridges have the following common fea- tures: (a) the deck-girder systems are primarily noncompos- ite, (b) the spans do not have skews or superelevations, (c) most projects involved new construction rather than reha- bilitation, (d) fewer geometric fit-up problems have been experienced with new construction than with replacement decks, and (e) a full-depth precast panel deck system was used for both temporary and permanent bridges. Since 1974, significant advances have been made in the construction of bridge decks built with full-depth precast concrete deck panels. The following sections provide infor- mation on the connection details and grout material used in these bridges. More information can be found in Appendix A and in reports by Anderson and others (9–26). Panel to Superstructure Connection Most of the bridges built during this period were made composite with the superstructure. This was achieved by extending steel shear studs or structural steel channels into the precast deck through prefabricated pockets. The spacing between pockets ranged from 18 in. to 24 in. (457 to 610 mm), and the number of studs per pocket ranged from 4 to 12. In some cases, one stud per row was used, as in the three-span bridge over the Delaware River between Sullivan County, New York, and Wayne County, Pennsylvania (Figure 1). In other cases, as many as four studs per row were used, as in the I-80 overpass project in Oakland, California (Figure 2). As an alternative to steel shear studs, standard channel sec- tions welded to the top flange of the stringer beam were used, such as in the experimental bridge in Amsterdam, New York (13), shown in Figure 3. Although the experimental study showed that the channel welded sections performed well, their use was limited because of the relatively high labor cost. On the same experimental bridge, a bolted connection was also used, as shown in Figure 4; in this connection, the pan- els were first placed using steel shims for leveling. After the holes for the bolts were drilled in the top flange of the steel girder through the sleeves in the panels, high-strength bolts were fastened. Full tension in the bolts could not, however, be achieved because of concerns the precast slab would break as a result of the excessive tensioning. This connection detail was not used on any subsequent projects. In most of the projects built during this period, the panels were supported on the girders using steel shims, and a 1 in. to C H A P T E R 2 Background and Literature Review

6Figure 1. Deck/superstructure connection details of the Delaware River bridge. Figure 2. Panel dimensions and cross section of the I-80 overpass project, Oakland, California. Figure 3. Welded channel section detail used in the New York Thruway experimental bridge.

2 in. (25 mm to 50 mm) high haunch was provided between the precast panel and the girders. Once the grout filling the haunch achieved design strength, full bearing of the precast panels on the supporting girders could be expected, eliminating any pos- sible stress concentrations in the panels. Many details were used to form dams for the grout, such as the light-gauge side forms that were used on the Queen Elizabeth Way–Welland River Bridge in Ontario, Canada, as shown in Figure 5, and the elastomeric strips used on the Clark’s Summit Bridge on the Pennsylvania Turnpike, as shown in Figure 6. In both cases, tie anchors, bolted on the bottom surface of the panels, were used to secure the grout dam against leakage. As shown in Figure 7, leveling screws were used to adjust the panel elevation. Two screws per panel were typically used at every girderline. These screws were designed to support the panel weight and expected construction loads. After the grout that filled the haunches and pockets gained strength, the screws were removed or were flame cut. Transverse Panel to Panel Connection The transverse edges of the precast panels were usually provided with shear keys, which play an important role in the service performance of the finished deck. The shear key must be designed to protect adjacent panels from relative vertical movement and to transfer the traffic load from one panel to the next without failure of the panel to panel joint. Under traffic load, a panel to panel joint experiences two types of forces: (a) a vertical shear force that tries to break the bond between the panel and the grout filling the joint, and (b) a bending moment that puts the top half of the joint in com- pression and the bottom half in tension. The following two types of shear keys have typically been used with full-depth precast concrete panels: • Nongrouted match-cast shear key (see Figure 8). This type of shear key was used with longitudinal posttensioning on the Bloomington Bridge in Indiana. Thin Neoprene sheets were installed between adjacent panels to avoid high stress concentrations. Although match casting can be achieved in a controlled fabrication environment, such as in a precast concrete plant, it was difficult to achieve a perfect match in the field as a result of construction tolerances and the nec- essary elevation adjustment of the panels. After 5 years of service, cracking and spalling was observed in the concrete at the panel joints, which eventually led to leakage prob- lems at the joints (17). 7 Figure 4. Bolted detail used in the New York Thruway experimental bridge. 1/4" (6 mm) dia. tie-rod at block out Light-guage side forms bolted at 4'-0" (1220 mm) on center Figure 5. Grout dam built using light-gauge side forms (Queen Elizabeth Way–Welland River bridge, Ontario, Canada). Epoxy mortar Insert andbolt Elastomeric strip Bridge tie-anchor Figure 6. Grout dam built using elastomeric strips (Clark’s Summit bridge, Pennsylvania Turnpike)

• Grouted female-to-female joints. With this type of joint, grout was used to fill the joint between adjacent panels. Inclined surfaces were provided in the shear key detail to enhance the vertical shear strength of the joint. Vertical shear forces applied at the joint were thus resisted by bear- ing and bond between the grout and the panel. The shear key was recessed at the top to create a relatively wide gap that allowed casting the grout in the joint. Figure 9 shows some of the shear key details for bridge decks built since 1973. With grouted joints, a form must be provided at the bot- tom surface of the panels to protect the grout from leaking during casting. The following two methods of forming have been used: • Polyethylene backer rods are placed in the tight space be- tween panels at the bottom of the joint, as shown in Figure 10. This detail has been used for a very long time by many highway authorities. Although this detail does not require any construction work to be done from below, it has been reported that, as a result of fabrication and construction tolerances, joints in some cases ended up partially full, as shown in Figure 10 (21, 22, 23). Partially filled grouted joints cause high stress concentrations at the panel edges, especially if longitudinal posttensioning is applied, and ini- tiate cracking close to the bottom surface of the panels. • Wood forming is installed from under the panel, as shown in Figure 11. In this detail, a gap of 1 to 3 in. (25 to 76 mm) is maintained between adjacent panels, and wood forms are installed from under the panel. The forms are hung from the top surface of the precast panels using threaded rods and nuts. This detail usually results in a full-height grouted joint with excellent performance (21, 22). This technique allows the joint to be completely filled with grout, but it requires access from below for form erection and removal. The bond between the grout and the shear key surface can be significantly enhanced by roughening the surface of the shear key (23). This has been found to be extremely important when connecting precast panels that have no longitudinal posttensioning. The roughening can be achieved by sand- blasting, followed by a thorough washing. This operation can be done either in the precast plant before the panels are shipped or at the bridge site before the panels are installed. Roughening can also be achieved during panel fabrication by painting the side forms with a retarding agent. After removing the side forms, the shear key is washed with water under high pressure so that the aggregate in the concrete will be exposed, creating a uniformly roughened surface. This concept was used by Texas DOT on precast concrete panels for tied-arch bridges, as shown in Figure 12. The findings from the literature review of the performance of the transverse panel to panel connection can be summa- rized as follows: • The nongrouted match-cast shear key joint detail was used on a small number of projects and had unsatisfactory per- formance; cracking and spalling of the concrete was noticed after a bridge was in service for a short period of time. • Joints made with polyethylene backer rods have performed satisfactorily in most cases, especially when longitudinal posttensioning is provided on the deck. • The use of wood forming has recently become more com- mon than the use of polyethylene backer rods. 8 Figure 7. Leveling screw detail. Polyurethane sealant 1/16" Neoprene sheet Figure 8. Nongrouted match-cast joint.

9(a) Trapezoidal-shape shear key detail used in the Pedro Creek Bridge, Alaska (b) Semi-circle shear key detail used in the George Washington Memorial Parkway Bridges, Washington DC (c) V-Shape shear key detail used in the Skyline Drive Bridge, Omaha, Nebraska (d) Rectangular shear key detail used in the Delaware River Bridge, New York 2” 3” 1” Figure 9. Shear key details for various grouted female-to-female joints. LOOSE TOLERANCETIGHT TOLERANCEJOINT AS DESIGNED GROUT 1 1/2" 1/2" GROUT GROUT JOINT PACKING JOINT PACKING Figure 10. Effect of tight and loose tolerances on panel-to-panel joints. Figure 11. Wood forming of the panel-to-panel joint used in the tied-arch bridges, Texas.

10 Figure 12. Exposed aggregate roughened surface used on the tied-arch bridges, Texas. Figure 13. Nonreinforced panel-to-panel connection used on bridges by Alaska DOT. Longitudinal Reinforcement Longitudinal reinforcement in deck slabs is used to dis- tribute the concentrated live load in the longitudinal direc- tion. It is also used to resist the negative bending moment due to superimposed dead and live loads at the intermediate sup- ports of continuous span bridges. For deck slabs made with full-depth precast panels, splicing this reinforcement at the transverse joint between panels is a challenge for design engi- neers for the following reasons: • The panels are relatively narrow, measuring 8 to 10 ft. Therefore, a wide concrete closure joint (2 to 3 ft) is needed if the longitudinal reinforcement splices are to be lapped. This would require wood forming under the panels and an extended period of time for curing. • The longitudinal reinforcement is spliced at the transverse grouted joint between panels that is considered the weakest link in the system. Great care thus has to be taken in detail- ing the splice connection to maintain the construction feasibility and avoid leakage at the joint during the service life of the deck. • Splicing the longitudinal reinforcement requires a high level of quality control during fabrication to guarantee that the spliced bars will match within a very small tolerance. • Splicing the longitudinal reinforcement requires creating pockets and/or modifying the side form of the panels, which increases the fabrication cost. As a result, a few highway agencies, such as the Alaska DOT and the New Hampshire DOT, have opted not to splice the longitudinal reinforcement on simply supported span bridges. Figure 13 shows the transverse joint of the precast deck system that has recently been used on the Dalton and Pedro Creek bridges on Route FAP 65 in Alaska. Although Alaska DOT design engineers have reported that there is no significant cracking or leakage at the joints, the reader should note that the average daily traffic on these bridges is very low compared with bridges in metropolitan areas. Most highway agencies prefer to provide some type of rein- forcement across the transverse joints. Various methods have been used in the past to provide and splice the longitudinal reinforcement, including the following four methods: • A lap splice was used in the full-depth precast concrete deck panel system on the rehabilitation project involving struc- ture C-437 of the county road over I-80 to Wanship, Utah, as shown in Figure 14. In this project, the design engineer allowed the use of threaded couplers at the face of the trans- verse joints to simplify the side forms used in fabrication. • U-shaped pin bars were used on the Castlewood Canyon Bridge in Colorado. Figure 15 shows the U-shaped pin bars where they are overlapped and confined with rectangular stirrups.

11 Figure 14. Lap splicing of longitudinal reinforcement used on Structure C-437, Wanship, Utah. • Spiral confinement has been developed to reduce the lap splice length and give higher construction flexibility for the spliced connection (2, 3, and 5). Figure 16 shows the spliced connection where a loose bar confined with high- strength spiral is used. This detail reduces the lap splice length by about 40% to 50% and helps in simplifying the fabrication of the panel because no bars extend outside the transverse edges of the panel. • Longitudinal posttensioning has been used on the major- ity of bridges built with full-depth precast panels during the past 30 years. It puts the transverse panel-to-panel joints under compression, which eliminates the tensile stresses resulting from a live load. The amount of postten- sioning stress on the concrete after seating losses used in bridge decks ranges from 150 to 250 psi (1.03 to 1.72 MPa). Longitudinal posttensioning is typically conducted after the transverse panel-to-panel joints are grouted and cured, but before the deck-girder connection is locked. This pro- cedure guarantees that all of the posttensioning force is applied to the precast deck. In most cases, high-strength threaded rods uniformly distributed between girderlines are used. The threaded rods are fed through galvanized or polyethylene ducts that are provided in the panels during fabrication. Figure 17 shows the posttensioning details that were used on Bridge 4 on Route 75 in Sangamon County, Illinois. Longitudinal posttensioning can be provided in stages and coupled as shown in Figure 17. After the threaded rods are postten- sioned and secured, the ducts are grouted with nonshrink grout to protect the threaded rods from corrosion. Figure 15. Continuity detail over the cross piers used on Castlewood Canyon bridge, Colorado.

Recently, longitudinal posttensioning concentrated at the girderlines has been used on the Skyline Drive Bridge in Omaha, Nebraska. Figure 18 shows a cross section of the bridge at a girderline. The posttensioning consists of 16.5 in. (12.7 mm) diameter, 270 ksi (1.86 GPa) low-relaxation strands. The strands are fed into open channels created over the girderlines, and a special end panel that houses the anchorage device is used, as shown in Figure 18. Grout Material Several grout materials have been used to fill the shear pock- ets and the transverse joints between adjacent panels. Some of these materials are commercial products, while others have been developed by state highway agencies. The properties common to all types of grout are: (a) relatively high strength (2,000 to 4,000 psi) at young age (1 to 24 hours), (b) very small shrinkage deformation, (c) superior bonding with hardened concrete sur- faces, and (d) low permeability. In conducting the literature review, the researchers noticed that most state highway agencies specify the properties required for the grout material, rather than a certain type of grout material. The contractor therefore has to assume responsibility for choosing the type of grout material and then secure the approval of the highway agency. The following sections provide a summary of the most common types of grout that have been used with full-depth precast panels. Information is also included about some of the recent research that has compared the performance of various types of grout. Commercial Products Various commercial types of grout material have been used with full-depth precast concrete deck, such as: Set 45, 12 2" 6" + 1 /4 " * * 3 3/ 4" 4 1/ 8" #7 splice bar, 2'-2 1/2" long 2'-3" 4" OD, 1" pitch, 27" long, 1/4" diameter wire Figure 16. Panel-to-panel connection using spiral confinement. Figure 17. Posttensioning detail used on Bridge-4 constructed on Route 75, Sangamon County, Illinois.

Set 45 Hot Weather (HW), Set Grout, EMACO 2020, SS Mortar, Masterflow 928, 747 Rapid Setting Grout, S Grout, and Sonogrout 10K. A comparison of the physical and mechanical properties of some of these products is given in Chapter 3. In a recent study by Issa et al. (23), the researchers studied the behavior of female-to-female joint details using Set 45, Set 45 HW, Set Grout, and EMACO 2020. The joint was tested for direct vertical shear, direct tension, and flexure. A total of 36 specimens were tested. The compressive strength of the elements that represented the precast panels was about 6,250 to 6,500 psi (43 to 45 MPa). For all specimens, the joint sur- faces were sandblasted and thoroughly cleaned. There was no reinforcement crossing the interface between the joint and the precast panel. In addition to the full-scale testing of the joint, the permeability and shrinkage properties of the grout- ing material were determined in accordance with ASTM C1202-97 and ASTM C157, respectively. The findings of that experimental program can be sum- marized as follows: • The shear, tensile, and flexural strength of joints made with EMACO 2020 were the highest among all types of grouting material. • The shear, tensile, and flexural strength of joints made with Set Grout were higher than those made with Set 45 and Set 45 HW. • Failure of specimens made with EMACO 2020 occurred away from the joint in the precast panels, while failure of the specimens made with Set Grout occurred simultane- ously through the joint and in the precast panels. For spec- imens made with Set 45 and Set 45 HW, failure occurred through the joint. • Moisture and carbonation at the joint surface adversely affected the bond and strength of joints made with Set 45. • EMACO 2020 and Set 45 set very quickly, which necessi- tates fast mixing and installation. • EMACO 2020 was significantly less permeable and showed much lower shrinkage deformation compared with other grout materials. Noncommercial Grout Material The noncommercial grout materials presented in this sec- tion were used for projects with regular construction sched- ules, where the bridge was closed for an extended period of time, and where the grout needed an extended period of con- tinuous curing (at least 7 days). Hydraulic Cement Concrete Hydraulic cement concrete (HCC) mixes were used on some of the bridges built before 1972. The specifications for these mixes contained a minimum concrete strength of 4,000 psi (27.6 MPa), relatively high slump (about 6 in., or 153 mm), and a maximum aggregate size of 0.5 in. (12.7 mm). Latex-Modified Concrete Latex-modified concrete (LMC) mixes are different from HCC mixes in that a latex admixture is added to the mix. The latex forms a thin film on the aggregate surface, which enhances the bond between the paste and the aggregate and results in high compressive strength and a less permeable concrete mix. 13 Figure 18. Longitudinal posttensioning concentrated at girder lines used on the Skyline Drive bridge, Omaha, Nebraska.

Many state highway agencies have developed their own LMC mix. The following are the specifications for the LMC mix that has been developed and used by the Virginia DOT (24, 25). Portland cement III 7 bags, 658 lb/yd3 (388 kg/m3) (minimum): Water (maximum): 2.5 gal/bag of cement Water/cement ratio: 0.35 to 0.40 Styrene butadiene latex 3.5 gal/bag of cement admixture: Air content: 3 to 7% Slump (measured 4.5 4 to 6 in. (100 to 200 mm) minutes after discharge): Cement/sand/aggregate 1.0/2.5/2.0 by weight: Menkulasi and Roberts-Wollman (26) conducted an ex- perimental investigation using two types of grout material— LMC and Set 45 HW; angular pea gravel filler was added to both types. The test included only direct shear specimens that simulated precast concrete panels supported on prestressed concrete girders, as shown in Figure 19. Three specimens with different amounts of reinforcement crossing the interface were used: no reinforcement, reinforcement with No. 4 (No. 13 metric) bar, and reinforcement with No. 5 (16) bar. The height of the haunch used in all specimens was 1.0 in. (25.4 mm). The investigation revealed that specimens made with Set 45 HW and LMC had almost the same shear capacity when no or only a small amount of shear reinforcement was present. However, at high amounts of shear reinforcement, the specimens made with Set 45 HW showed higher strength than those made with LMC. The researchers were in favor of using Set 45 HW over LMC as the recommended grout material. The investigation also showed that changing the height of the haunch from 1.0 to 3.0 in. (25.4 to 76 mm) had almost no effect on the shear capacity of the specimens made with Set 45 HW grout. Type K Cement Concrete Mix Type K cement concrete mix was used on the Skyline Bridge in Omaha, Nebraska, to fill the longitudinal open channels that house the posttensioned cables (6). The concrete mix had a specified concrete strength of 4,000 psi (27.6 MPa), and only Type K cement was used in the mix. The concrete mix had no fly ash, and the maximum aggregate size was 3⁄8 in. (9.5 mm). Type K cement is an expansive cement that contains anhy- drous calcium aluminate, which when mixed with water forms a paste that increases in volume significantly more than portland cement paste does during the early hydrating period that occurs after setting. History of the Shear Connector Spacing Limits of the AASHTO LRFD Design Specifications Creating a composite action between the precast deck and the supporting girders has been one of the challenges facing the engineers designing precast concrete panel decks. Inter- mediate pockets over the girderlines have to be created in the panel to accommodate the shear connectors extending from the supporting girders into the precast deck. In addition, the shear connectors have to be clustered in groups lined up with these pockets. Forming the shear pocket typically slows the panel fabrica- tion process and eventually raises the fabrication cost. There- fore, design engineers try to space the shear connectors as far as the specifications allow them. The AASHTO Standard Spec- ifications for Highway Bridges (27) and the AASHTO LRFD Bridge Construction Specifications (8) state that the spacing between the shear connectors for steel or concrete girders should not exceed 24 in. (610 mm). The following discussion provides a brief summary of the history of this limit in the specifications. The first composite concrete slab on a steel I-beam bridge in the United States was constructed in the early to mid 1930s in Iowa. A composite bridge design example, prepared as part of a paper by Newmark and Siess in accordance with the third (1941) edition of the American Association of State Highway Officials (AASHO) Standard Specifications for Highway Bridges, states “the spacing of the shear connectors shall be not more than 3 to 4 times the depth of the slab” (28). While this limit did not appear in the AASHO provisions, it appears to have been used as a convention or rule of thumb. Newmark and Siess recognized that while these connectors are generally 14 Figure 19. Push-off test specimen from Salvis (19).

only designed to transfer horizontal shear, they also play a role in preventing the separation of the beam and the slab. The 2 ft maximum limit on shear connector spacing, or pitch, first appeared in the fourth edition of the AASHO Stan- dard Specifications for Highway Bridges (1944). This require- ment appears without commentary, which was typical of that era, and the source of this change was not given. A 1953 paper by Viest and Siess contains a discussion of why mechanical connectors are needed (29). Their argu- ments include (a) to prevent relative movement (either hor- izontal or vertical) between the beam and the slab during all loading levels up to ultimate, and (b) to transfer horizontal shear from the slab to the beam. The discussion that supports these roles for shear connectors is primarily directed at ensuring linear-elastic behavior of the composite system. Viest and Siess returned to this subject in a 1954 paper that reports conclusions based on their experimental results and in- cludes design recommendations (30). It should be noted that these experiments were carried out using the channel-type shear connectors that were conventional at the time. Although they did not comment on the origin of the 24 in. (610 mm) maximum connector spacing in the AASHO provisions, the experimental results support retaining the limit. The testing considered connector spacing of 18 in. (457 mm) and 36 in. (914 mm). While the 18 in. (457 mm) spaced connectors performed as necessary, the 36 in. spaced connector specimens experienced lift-off between connectors under load in the ex- periments. This result motivated the authors to recommend that “the maximum spacing of channel shear connectors be not greater than four times the thickness of the slab, but in no case greater than 24 inches.” Further investigation has revealed that when the headed stud shear connector became available to the steel bridge con- struction industry in the late 1950s, the steel industry people relied on Viest and Siess to help formulate the design provi- sions for these connectors that were eventually incorporated into the AASHTO specifications in the early 1960s. Based on their previous work, Viest and Siess again recommended a limit of 24 in. (610 mm) maximum spacing for these provi- sions. This timeframe also coincides with industry acceptance of precast/prestressed concrete girders as an alternative to steel girders for highway bridge construction. The effect of the number of studs per cluster and the num- ber of clusters per specimen was studied by Issa et al. in 2003 (31). In that research, quarter- and full-scale push-off speci- mens were made with various configurations. The researchers concluded that the increase in ultimate strength of a cluster of studs was not linearly proportional to the number of studs. The researchers stated that, for all specimens, an initial slip- page of about 0.02 in. was noticed before the studs started to initiate the composite action, and that shear failure was recorded at the stud base. The failure was accompanied by local cracking and crushing of the concrete close to the stud base. Once the concrete at the stud base was crushed, the stud lost its bearing support and started to act as a partial cantilever, which led to shear failure at the base. It was also reported that the ultimate capacity of a cluster of studs determined by Equa- tion 6.10.10.4.3-1 of the AASHTO LRFD specifications was overestimated by as much as 22% in some specimens. This conclusion was drawn based on testing of push-off specimens and was not confirmed by any full-scale beam test. On the Interstate 39/90 Door Creek project, the Wisconsin DOT has used a precast deck panel system, where a 48 in. (1220 mm) spacing of clustered studs was used (32). The decision to violate the maximum spacing limit given by the AASHTO LRFD specifications was based on the experimental investigation conducted by Markowski, where a half-scale composite beam was tested (32). One-half of the beam length had studs at 24 in. (610 mm) spacing, and the other half had studs at 48 in. (1220 mm) spacing. The test results have shown that full composite action was achieved under full service load, and no signs of stiffness deterioration were noticed after applying 2,000,000 cycles of repeated loading. The beam con- tinued to show full composite action when it was overloaded beyond the service load level; however, Markowski could not test the beam at ultimate because of the limited capacity of the loading frame. Summary of the Literature Review Panel to Panel Connection • Female-to-female joints (i.e., shear key details) filled with cast-in-place nonshrink grout provide superior perfor- mance compared with match-cast, male-to-female joints. Sharp corners of the shear key enhance the shear transfer across the joint. • The design criteria for a successful joint detail include no cracks under repeated service loads and no water leakage. • Various methods were used in the past to provide and splice the panel-to-panel longitudinal reinforcement: • Although longitudinal posttensioning, which puts the joint in compression and secures it against leakage, increases the cost of the deck system, it was used with the majority of full-depth precast concrete deck panel systems. • U-shaped pin bars and/or lap splice details require a wide joint and/or a thick precast panel to provide for the required lap splice length and concrete cover. Panel to Girder Connection • The majority of full-depth precast concrete deck panel sys- tems were used on steel girders. – Typically, headed steel studs are used to compositely connect the girder with the deck. 15

– Two sizes of steel studs are typically used—3⁄4 in. and 7⁄8 in. (19 mm and 22 mm). – Recently, one successful attempt was made to extend the shear pocket spacing to 48 in. (1220 mm). • A very limited amount of research was conducted on the panel to concrete girder connection. – Practically, it is very difficult to cluster the vertical shear reinforcement of the concrete girder to match the shear pockets of the deck panel. – Some attempts have recently been made to separate the vertical shear reinforcement from the horizontal shear reinforcement. 16