Bridges – Deck – Joint
Reexamination Certificate
1998-05-27
2003-12-30
Pezzuto, Robert E. (Department: 3671)
Bridges
Deck
Joint
C014S073000, C403S229000
Reexamination Certificate
active
06668412
ABSTRACT:
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to a subpanel system for bridge deck construction, and, more particularly, to a subpanel system that is prestressed in the transverse direction, and continuously connected in the longitudinal direction.
A great majority of bridges constructed in the United States utilize a concrete deck slab. A major disadvantage of utilizing concrete slabs is the deterioration of the concrete bridge deck and the need for rapid replacement of the deck. A number of different bridge constructions have been developed over the years for new bridge construction or for rehabilitation of deteriorated bridge decks.
A first of these construction systems is a full-depth, cast-in-place bridge deck system. This system involves the casting of the entire bridge deck in place utilizing wood forms constructed at the bridge construction site. The bridge deck is generally cast as a one piece full-depth structure. This type of construction system suffers from numerous serious disadvantages. First and foremost is the speed with which a bridge deck can be constructed. More specifically, creation of wood forms for the pouring of the bridge deck oftentimes is very labor intensive and time consuming. This is especially true in the edge portions of the bridges where an overhang extends beyond the edge of the nearest support girder or beam. In addition, due to the length of time required to install such forms and thereafter pour the concrete, the. forms generally are expensive to utilize. More specifically, they require great labor to set up the form and to thereafter remove the form from the bridge deck. In addition to speed and cost concerns, anytime the entire structure is poured in place, there can become serious questions of the quality of the entire bridge deck. As is apparent, the knowledge and skill of workmen in addition to various weather factors can affect the quality of the concrete poured throughout the transverse and longitudinal sections of the bridge deck. Additionally, such full-depth, cast-in-place systems oftentimes do not offer a realistic approach to rehabilitation of deteriorated bridge decks.
A second type of bridge deck system is the full-depth prefabricated deck system. As the name suggests, this involves entirely prefabricated deck panels which are positioned in place above bridge girders to form the deck system. There generally is little or no concrete pouring involved in constructing a bridge deck of this type. The main advantage associated with these prefabricated deck systems is that construction time is reduced, and the forming required for casting is eliminated. However, again, this type of system has serious drawbacks. First of all, because the entire depth is a prefabricated item, adjacent decks of the system are riot easily adjusted with respect to one another. Additionally, to create a smooth upper surface, substantial amounts of grinding are required between adjacent panels to increase the ride and quality of the bridge structure. Further, oftentimes it is necessary to longitudinally post-tension the prefabricated structures to control transverse joint cracking. Still furthermore, support beams and girders must have a special type of shear connector arrangement to fit into the pockets formed on the underside of the prefabricated bridge deck panels.
A still further type of bridge deck construction system involves a combination of a cast-in-place deck and a stay-in-place precast concrete panel. More specifically, most of these systems involve providing a thin solid precast prestressed panel to rest on top of the support beams or girders and to operate as a form for a cast-in-place layer placed on top of the prestressed panels. The panels are generally three to four inches in thickness and are produced in four to eight feet widths depending upon the available transportation and lifting equipment. The precast panels that form the base layer of such structure are butted against one another without any continuity between them. More specifically, nothing is utilized to connect the panels together as they rest adjacently on the reinforcing beams in both the transverse and longitudinal direction. This combination bridge If deck system suffers from numerous drawbacks. Although this system offers advantages in the form of prestressing in the individual panels themselves, the system still suffers from serious disadvantages. More specifically, because there is no way to support a prestressed concrete panel adjacent an edge girder to form a bridge overhang, it is still necessary to use forming structures adjacent the bridge edge to form such overhangs, thus resulting in the cost and labor intensive practices associated with such forms. Additionally, constructing a bridge deck can require the placement of numerous precast prestressed panels. More specifically, it could be required to place as many as three to four panels to transverse the width of the bridge structure with additional transverse rows necessary to cover the longitudinal length of the bridge. Each of these panels must be placed with precision, thus increasing the labor hours and costs of placing the panels. Additionally, a problem associated with precast prestressed concrete subpanels is reflective cracking during use. More specifically, it has been found that after travel over a bridge deck, cracks develop in the upper cast-in-place topping which outline the subdeck prestressed concrete panels. The reflective cracking is generally due to the lack of continuity in both the longitudinal and transverse directions. It has further been found that because of the lack of continuity between layers, if a bridge is to fail under loads, it will often fail adjacent a support girder or beam due to the shear stresses associated at such locations, caused by lack of continuity of the steel reinforcement at such locations.
A bridge deck construction is needed which alleviates the problems associated with the prior art as discussed above.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a bridge deck construction which is more cost-effective and simpler to construct.
Another object of the present invention is to provide a bridge deck construction which allows for excellent field quality in construction, and, further, offers long-term durability of the bridge deck.
A further object of this invention is to provide a bridge deck construction which eliminates the need for field forming to create deck overhangs.
A still further object of the invention is to create a bridge construction precast panel system which is able to support paving machine and construction loads in additional to self weight such that there is no need to support an overhang during the casting of a topping slab.
A still further object of the present invention is to provide a bridge deck construction which eliminates the need to handle a large number of pieces and the need to precisely position the subdeck panels onto the support beams or girders.
A still further object of the present invention is to provide a subdeck system that eliminates reflective cracking.
Another object of the present invention is to provide a bridge deck construction that does allow for significant flexibility in placement of shear connectors on beams or girders.
A still further object of the present invention is to provide a bridge deck system that has superior performance than conventional prestressed panel systems under cyclic load.
Another object of the present invention is to provide a bridge deck system which has immensely increased failure load capacity over the conventional subdeck prestressed panel systems.
A still further object of the present invention is to provide a precast panel which can. be crowned during forming such that the crowning will be achieved across the transverse direction of the bridge.
Accordingly, the present invention provides for a prestressed concrete panel for bridge construction including a first section hav
Badie Sameh Samir
Baishya Mantu C.
Tadros Maher K.
Addie Raymond W
Board of Regents of University of Nebraska
Pezzuto Robert E.
Shook Hardy & Bacon LLP
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