Seismic joint seal

Abstract

The present invention is a seismic joint seal comprising a support plate, a channel assembly, and a deck plate. It is used to join bridge segments to each other or to an abutment. The invention has a curved deck plate that rides along a complementarily-curved support plate to accommodate movements that result from seismic events.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to joints for connecting segments of a bridge.

2. General Background

Joints of various types have been developed to connect roadway bridge segments to each other and to abutments. In the past, these joints were only designed to accommodate the differential displacement and rotation that occur during ordinary service conditions, and were not designed to withstand the effects of significant seismic events. Instead, the joints were simply repaired or replaced after an earthquake, with the bridge typically inoperable until the repairs could be made.

But many bridges are so important that they must remain passable even after a significant seismic event. Thus, seismic joints have been developed to accommodate the great displacement (both longitudinal and transverse) and rotation that results from an earthquake.

The present invention is an improved seismic joint that has robust performance and that does not cause significant discomfort to drivers.

SUMMARY OF THE INVENTION

The present invention is a seismic joint seal comprising a support plate, a channel assembly, and a deck plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is side cross-sectional view of a seismic joint seal according to an embodiment of the present invention.

FIG. 2 is a top view of a channel assembly for a seismic joint seal according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a channel assembly for a seismic joint seal according to an embodiment of the present invention.

FIG. 4 is a side view of a channel assembly for a seismic joint seal according to an embodiment of the present invention.

FIG. 5 is a close-up of the indicated area of FIG. 4.

FIG. 6 is a top view of a series of seismic joint seals according to an embodiment of the present invention.

FIGS. 7a-7g show an exemplary construction sequence for a seismic joint seal according to an embodiment of the present invention.

FIGS. 8a-8b depict the movement of a seismic joint seal according to an embodiment of the present invention during a seismic event.

DETAILED DESCRIPTION

The present invention is a seismic joint seal comprising a support plate, a channel assembly, and a deck plate. It is used to join bridge segments to each other or to an abutment.

As shown in FIGS. 1, 7a-7g, and 8a-8b, the present invention can be used on a bridge deck 10 to join a first bridge segment 20 with a second bridge segment 30. It can also can be used to join a bridge segment to an abutment.

The bridge segments 20, 30 are modified by creating a blockout area 22, 32 in each, as shown best in FIGS. 7a-7g. Mild steel reinforcement 24, 34 is then placed in the blockout area. See FIG. 7a. Concrete 26, 36 is poured in the blockout areas 22, 32 after placement of the steel frames 24, 34. Preferably self-consolidating concrete is used, although standard concrete may be used as well. Also, a gutter 28 may be placed on one of the bridge segments to catch water that leaks between the support plate 40 and the deck plate 80. See FIG. 1. A gap 38 of varying width lies between the bridge segments 20, 30.

The support plate 40 is secured by means of shear studs 42. See FIGS. 1, 7b, 7c, 7f, 7g, 8a, and 8b. The support plate 40 also may have ventilation holes to prevent the formation of air cavities during construction.

The support plate 40 is curved in a convex manner so as to mate with the concave sliding deck plate 80. As explained further below, the complementary curvature of the support plate 40 and the deck plate 80 offers a number of advantages over the prior art. Of course, the curvature of the support plate 40 and deck plate 80 may vary without departing from the scope of this patent.

The purpose of the support plate 40 is to provide a structure upon which the deck plate 80 may slide and move. In one embodiment, it is made of steel or equivalent material, with an approximate thickness of at least 25 mm.

The channel assembly 50 is built into the second blockout area 32 and is used to secure one end of the deck plate 80. See FIGS. 1, 2, 3, 4, It is formed by steel plates, namely structural steel plates 56 and stiffener steel plates 54, which are placed along in parallel to the roadway along the channel assembly 50. See FIGS. 1, 2, 3, and 4. The channel assembly is secured to the blockout area 32 by anchor studs 52.

The spring assembly 60 is fitted within the channel assembly 50. See FIGS. 1, 2, 3, and 4. The spring assembly 60 rotatably secures one end of the deck plate 80, with the other end free to slide along the support plate 40. See FIG. 1. The spring assembly 60 comprises two high strength bolts 62, 63 that are fitted through the deck plate 80 and into the channel assembly 50, two slotted nuts 64, 65 that secure the bolts 62, 63, and an alternating series of elastomeric washers 66 and steel washers 68. See FIGS. 1, 2, 3, 4, and 5. The spring assembly 60 is pre-tensioned so that the deck plate 80 maintains its proper position. The elastomeric washers 66 are essential elements of the joint since they secure the deck plate in case of a bridge settlement, bearing failure, or seismic event.

A bridge deck seal 70 is placed between the deck plate 80 and the second bridge segment 30. See FIG. 1. This deck seal 70 prevents the flow of water into the joint. It includes a silicone seal 72 or equivalent on top of polyethylene foam 76, with an underlying neoprene support sheet 76 that runs the length of the channel assembly 50. This neoprene sheet 76 facilitates stress distribution and thus improves the bearing of the deck plate 80.

To protect against corrosion, all metal parts of the assembly are either painted with inorganic zinc-rich primer or hot dip galvanized. Also, the channel assembly 50, bolts, 62, 63 and joints between deck plates may be sealed with a silicon-based sealant.

The deck plate 80 is rotatably attached at one end to the channel assembly 50, but is free to move at the other end, along the support plate 40. See FIGS. 1, 7a-7g, 8a-8b. The deck plate 80 has freedom of movement in all directions (longitudinal, transversal, vertical, and rotational), and thus can accommodate seismic events and remain drivable. The deck plate 80 will move during both seismic events and ordinary service conditions, but will obviously is subject to greater movement during seismic events. FIGS. 8a and 8b depict the longitudinal movement of the deck plate 80 relative to the support plate 40.

The deck plate 80 is tapered on its underside, with its free end thinner than the end that is rotatably secured to the channel assembly 50. See FIGS. 1, 7a-7g, 8a-8b. In one embodiment, the deck plate is 12 mm thick at its free end, and has a taper ratio of 30:1 or better from the thicker end to the narrow end. This results in a 12 mm gap or bump between the deck plate 80 and the support plate. The deck plate may have grooves 82 on its top surface for greater traction, and traction welds (not shown) may be used for portions of the deck plate that are too thin for grooves 82. Except for the grooves 82 or the traction welds, the top of the deck plate 80 is flat.

A critical aspect of the invention is the relationship between the deck plate 80 and the support plate 40. In the present invention, the underside of the deck plate 80 is concave, and the top side of the support plate 40 is convex. See FIG. 1. The deck plate 80 and support plate 40 have complementary curvatures, so that they mate with each other. As the deck plate 80 moves longitudinally, it rides along the convex surface of the support plate. This results in a minor rotation of the deck plate about the transverse axis, which translates to an approximately 2 mm rise or fall of the deck plate at its pinned end. This does not pose a problem to joint performance, since the uneven stress distribution at the pinned side is very small, and can be absorbed by the neoprene sheet and the elastomeric springs. Because the top of the deck plate is flat and the initial 12 mm bump at the tip of the free end of the deck plate 80 is lower than that of the horizontal tangent of the support plate 40, the joint of the present invention does not exhibit the “ramp up” feature of earlier joints. More particularly, the present invention provides a significantly smoother driving surface than joints in which the undersurface of the deck plate and the top surface of the support plate are planar. This is because the interface at the free end of the deck plate remains constant in the present invention despite longitudinal movements, while the interface can change in earlier, planar-mating-surface joints as a result of longitudinal movement. For instance, with planar-mating-surface joints, a “v” or depression is formed and deepened as the deck plate moves away from the support plate, but with the present invention the interface remains relatively constant notwithstanding longitudinal movements.

An exemplary construction sequence is depicted in FIGS. 7a-7g. In this example, the first step is preparing the blockout areas 22, 32, and then placing the mild steel reinforcement 24, 34 within the blockout areas 22, 32. See FIG. 7a. Next, the support plate 40, channel assembly 50, and deck plate 80 are temporarily installed so that each component be properly positioned relative to the others. See FIG. 7b. Then the deck plate 80 is removed and self-consolidating concrete is poured at the free end of the joint. See FIG. 7c. The deck plate 80 is then reinstalled, see FIG. 7d, and self-consolidating concrete is poured in the pinned end, as shown in FIG. 7e. The gutter can then be installed, and the bolts and pins tightened as necessary. See FIG. 7f. Finally, a deck overlay 90 is placed adjacent to the pinned end of the joint, and silicone can be used to seal the joint. See FIG. 7g. This sequence is exemplary only, and other sequences can be used without departing from the scope of this patent.

Typically, each lane or half-lane will have its own channel assembly 50 containing a plurality of spring assemblies, thereby creating a modular joint that can be more easily installed and repaired. See FIGS. 2 and 3. The deck plate 80 will also typically have the same width as the channel assembly 50, making the entire unit modular. A number of such modules could be combined to create a multilane joint. See FIG. 6.

One skilled in the art will appreciate that the present invention can be practiced by other than the preferred embodiments, which are presented for purposes of illustration and not of limitation.

Claims

1.) A seismic joint seal for joining a bridge segment to another bridge segment or to an abutment, comprising:

a support plate having a curved top surface and a substantially planar bottom surface, said support plate fixedly attached to a first bridge segment; and

a deck plate having a curved bottom surface, said deck plate attached to a second bridge segment, and said curved bottom surface of said deck plate slidably resting on said curved top surface of said support plate.

2.) The seismic joint seal according to claim 1, wherein said curved top surface is convex, and said curved bottom surface is concave.

3.) The seismic joint according to claim 1, additionally comprising a channel assembly for attaching said deck plate to a bridge segment.

4.) The seismic joint according to claim 3, wherein said channel assembly comprises a spring assembly with elastomeric washers.

5.) The seismic joint according to claim 4, wherein said channel assembly comprises a spring assembly with alternating elastomeric washers and steel washers.

6.) The seismic joint according to claim 5, additionally comprising a support sheet between the channel assembly and the deck plate.

7.) The seismic joint according to claim 6, wherein the support sheet is made of neoprene.

8.) A method of seismically sealing a bridge joint, comprising:

attaching a support plate with a curved top surface to a first bridge segment; and

attaching a deck plate with a curved bottom surface to a second bridge segment, so that said curved bottom surface slidably rests on said curved top surface.

9.) The method according to claim 2, wherein said curved top surface is convex and said curved bottom surface is concave.

10.) A seismically protected bridge, comprising a first bridge segment joined to a second bridge segment or to an abutment by a joint seal according to claim 1, 2, 3, 4, 5, 6, or 7.

11.) A seismic joint seal for joining a bridge segment to another bridge segment or to an abutment, comprising:

a support plate having a top surface, said support plate fixedly attached to a first bridge segment;

a deck plate having a bottom surface, said deck plate attached to a second bridge segment, and said bottom surface of said deck plate slidably resting on said top surface of said support plate to form an interface; and

means for ensuring that as said deck plate moves longitudinally relative to said support place the interface remains substantially constant.

12.) The seismic joint according to claim 11, wherein said means for ensuring that as said deck plate moves longitudinally relative to said support place the interface remains substantially constant comprises a curved bottom surface and a curved top surface.

13.) The seismic joint according to claim 12, wherein said top surface is convex and said bottom surface is concave.

14.) A kit for creating a seismic bridge joint, comprising a deck plate with a curved bottom surface and a support plate with a curved top surface.

15.) The kit according to claim 14, wherein said bottom surface is convex and said top surface is concave.

16.) A seismically-protected bridge, comprising at least one support plate and a plurality of modular channel assemblies and deck plates, wherein the support plate has a curved upper surface, and the deck plates have a curved lower surface.

17.) The bridge according to claim 16, wherein the upper surface is concave and the lower surface is convex.

18.) A seismic joint seal for joining a bridge segment to another bridge segment or to an abutment, comprising:

a support plate having a support plate top surface and a support plate bottom surface, said support plate fixedly attached to a first bridge segment;

a deck plate having a deck plate top surface and a deck plate bottom surface, said deck plate attached to a second bridge segment;

wherein said support plate top surface is not parallel to said support plate bottom surface, and wherein said deck plate top surface is not parallel to said deck plate bottom surface.

19.) The seismic joint according to claim 4, wherein said channel assembly is protected from liquid by a deck seal.

20.) The seismic joint according to claim 19, wherein said deck seal is placed between said first bridge segment and said deck plate.