Repair and Strengthening of Corroded Structures

Methods and systems are disclosed for easily and cost-effectively repairing and/or reinforcing damaged and/or underwater structures. In these methods, special FRP panels with protruding profiles are fabricated and additional reinforcement elements, in various desired orientations, are attached to the panels by special universal attachment devices. The reinforced panels are placed at a distance from the damaged structure, and the annular space between the structure and the panels is filled with curable materials such as concrete, grout, epoxy-grout, etc.

TECHNICAL FIELD

This application relates generally to the repair and/or reinforcement of structures. More specifically, this application relates to an easy and cost-effective method for repairing and/or reinforcing damaged and/or underwater structures.

DETAILED DESCRIPTION

While the present disclosure is described with reference to several illustrative embodiments described herein, it should be clear that the present disclosure should not be limited to such embodiments. Therefore, the description of the embodiments provided herein is illustrative of the present disclosure and should not limit the scope of the disclosure as claimed.

Many structures in marine and coastal environments corrode and require repair and strengthening. These repairs become very challenging when the structure is submerged in water or if it is on the underside of a pier or deck where the close proximity to the high water elevation makes the repair challenging and costly. There are also cases, for example, the repair of a bridge beam or girder that crosses over a road, where a fast repair is preferred or required to minimize traffic disruption. The methods disclosed here are very quick and economical and lead to speedy repairs with minimal disruption of service.

There are several shortcomings with the existing repair methods, some of which are listed below:

The disclosed methods overcome the above shortcomings. Throughout this document, the term “FRP” refers to Fiber Reinforced Polymer materials and, in particular, to tows, rovings and/or sheets or chopped, woven, stitched, etc. fabrics of glass, carbon, Kevlar, basalt, nylon and other similar fibers impregnated fully or partially with a “Resin” such as polyesters, vinyl esters, epoxies, polyurea, etc. Throughout this document the term “Concrete” or “Grout” (used interchangeably) refers to a mix of sand, gravel, cement, water and other additives (e.g. for underwater application) to create a concrete-like material. The term includes all methods of application of this material, be it applying by hand, a trowel, pumping, the tremie method, spraying, shotcreting or guniting it pneumatically as is commonly used in the industry. The term also includes any concrete-like material with high compressive strength where the matrix or binder is a material other than cement; such materials can include polymers and Resins. These are referred to as “Epoxy Grout” in the industry. Concrete or grout can also be lightweight and of the expansive and/or non-shrink type. “Tie Wire” refers to flexible wires that offer little structural value but are commonly used by ironworkers to hold (i.e. tie) different reinforcing materials together so that they do not get displaced while concrete is being placed.

In various embodiments, panels made from non-corroding materials may be manufactured before repair. These panels can be modular and connected in the field along their edges to make a much larger panel covering a large portion of a seawall that is to be repaired. The panels can be made from any material, such as PVC, plastics, HDPE, etc. The preferred material is Fiber Reinforced Polymer (FRP), which can be reinforced with various fibers such as glass, carbon, basalt, Kevlar, and the like. FRP has the added benefit that the panel itself becomes a structural reinforcing element, whereas the other materials, e.g. PVC, HDPE, etc. that are significantly weaker than FRP in tension, mostly serve as a formwork without significant contribution to resisting the loads from the earth and the existing corroded wall.

FIG. 1 illustrates an example embodiment of panel 100. As shown in this figure, panel 100 is placed at a distance from a damaged concrete, steel, or timber wall 145. Panel 100 consists of a flat exterior face 110. On the opposite side of face 110 (on the interior face), there are protruding elements such as the example T profiles 120. Many other shapes of protruding elements may be used with similar results. Panel 100 itself can be made with FRP with fibers of glass, carbon, etc., running along the length of the panel and/or perpendicular to that direction. These fibers may be incorporated in any or all segments of the panel, e.g. the flat portion of Panel 100, and the legs (web and flange) of the protruding T profiles. These fibers result in a panel that may be calculated and designed for each separate application to have desired flexural, axial, shear, and torsional strength. The engineers can calculate and design the amount and direction of the fibers, including the orientation angle of the fibers and the type of resin, e.g. epoxy, vinyl ester, polyester, etc., to achieve the optimum strength in each direction with minimal waste. The panels may also be manufactured using the pultrusion process; this allows a higher fiber to resin ratio which increases the strength of the panel. This procedure also eliminates any air bubbles or voids in the panel, which improves its durability.

In various embodiments, separate additional reinforcing elements may be added to supplement the strength of panels 100. For example, steel or FRP reinforcing bars 140 are attached to the interior face of the panel by supporting elements 130 and/or 135, which are connected to two or one protruding elements 120, respectively. As will be discussed later, the reinforcing bars 140 may be attached to the protruding elements 120 in any desired orientation with respect to, and within any distance from, the protruding elements 120.

The supporting elements 130 may be made of metals, plastics, or other non-corroding materials. They may be, for example, about 1 to 4 inches long and snap in place. One such supporting element 130 may be provided every 4 to 6 feet along the protruding elements 120. The reinforcing elements 140 can be easily snapped into these supporting elements 130 before or after the panel is assembled and installed. As shown in FIG. 1, panel 100 and its additional reinforcements are mounted at a calculated distance from surface 148 of the corroded wall 145. The annular space between panel 100 and surface 148 will ultimately be filled with concrete, grout, epoxy-grout, resin, or any other desired material. The reinforcement process will be concluded when the filling material is cured.

In some embodiments, the additional reinforcing elements 140 may be placed between the stems of the protruding T profiles 120. This placement choice has the advantage of “hiding” these reinforcing elements 140 within the overall panel thickness and making the profile of the repaired wall thinner. Various bar holder elements 130 may be designed for this purpose, including some that can be tied to or pinned through the stems of the protruding elements 120.

A convenient width for the panels 100 is about 3 to 4 feet. Like standard plywood sheets, this suggested width is just wide enough for a worker to hold with both arms stretched. FRP panels 100 may be manufactured using the pultrusion process. This process allows panels 100 to be manufactured in a continuous manner. A long manufactured panel may be cut to any length in the plant before shipment. These panels can also be cut with a table saw or rotary saw in the field to desired lengths. However, it is preferred to have a panel long enough to cover the full height of the seawall being repaired without the need to splice it along the length.

In the short direction, the 3-4 ft wide panels 100 are connected along their width. One method, illustrated in FIG. 2, is to use connectors 160 in the shape of the letter “H” to slip over the edges of two adjacent panels 100. These connectors 160 can be made with PVC, other plastics, FRP, etc. An adhesive such as an epoxy or a sealant material may be applied to the inner surfaces of the connectors 160 to create a watertight and strong connection between the two adjacent panels 100. Connectors 160 can also be manufactured with gaskets (including water-activated ones), rubber, etc. embedded in them, so once they are connected to panels 100, they create a watertight joint.

Connectors 160 may also be made in various shapes and angles. For example, FIG. 3 shows a connector 161 in a 90-degree configuration. The ends of panels 100 are inserted into the openings of connector 161, which can be filled with a sealant or adhesive 162. In some embodiments, mechanical stoppers such as bolts, pins, screws, and rivets 170 may also be used to secure panels 100 to the connectors 160 or 161. Connector 161 allows the repair assembly to turn around a corner and traverse the same shape as the structure being repaired.

FIG. 4 shows a more typical assembly of many panels 100. After installation, only the outside surface of the panels and the connectors 160 will be visible. The view of the opposite side (i.e. inside face), which will be closest to the structure being repaired, includes the protruding T profiles 120, the attachment or supporting elements 130 and 135, and the reinforcement elements attached to the supporting elements.

Before or after panels 100 are installed, additional reinforcing elements may be added to the panels to strengthen them beyond their original design and built-in strength. FIG. 4 shows several panels 100 connected by connectors 160. Each panel 100 includes reinforcing elements, for example reinforcing elements 210 in the vertical direction and reinforcing elements 220 in the horizontal direction. These elements can be made of any material, but preferably a lightweight and non-corroding material such as carbon or glass FRP. For example, tows of carbon and glass fiber saturated with resin may be embedded in the panels 100 during their initial manufacturing to give them the desired strength, as calculated by the project engineers.

Panels 100 are connected and secured to the host structure with, for example, anchor bolts such as non-corroding J bolts. The desired portion of the face of the structure being repaired may be covered with an assembly of panels like those shown in FIG. 4. Spacers can be used to define the necessary stand-off distance between the structure and the assembly of these panels 100. The edges of the annular space between the panels and the structure are sealed to prevent leakage of the concrete. Next, the annular space is filled with concrete, grout, epoxy-grout, etc. The top and edges of the concrete that remain exposed can also be sealed with epoxy, paint, or other impervious products to seal the concrete completely and prevent moisture ingress into the concrete.

The repaired structure is fully protected from moisture and oxygen, bringing the corrosion rate to a near halt and prolonging the structure's service life. The strength of panels 100, as reinforcement for the concrete, results in a strong reinforced concrete structural element that can be designed to resist any desired level of flexural, shear, axial, and torsional loads.

In yet another embodiment illustrated in FIG. 5, the sheet pile or bulkhead 300 is made of steel, concrete, or timber. In many applications, these sheet piles 300 are so severely corroded that they have lost nearly all their strength and cannot support the weight and pressure of the soil, fluids, or traffic behind them. New piles 310 made of timber, concrete, or steel can be driven in front of the old sheet pile 300 at a desired calculated distance from the face of the sheet pile 300.

Reinforcement panels 340 are positioned between piles 310 and sheet pile 300 in the horizontal direction such that the panels 340 span from one pile 310 to the adjacent pile 310 and their T profiles 330 run in the horizontal direction along the length of the seawall. The visible sides of panels 340 typically rest against piles 310 to provide a reaction force when panels 340 are loaded by the soil or filling materials such as concrete. For example, if the spacing between piles 310 is 15 feet (center to center of piles) and the wall height is 8 feet, 3-ft wide×15-ft long panels 340 can be used for the repair. The end of each panel 340 is supported by the piles 310. In this case, three 3-ft wide panels are needed to cover the 8-ft height of the wall. One 3′×15′ panel runs from the elevation of the top of the wall (sea level) to 3 feet below that; the other 3-ft wide panel is placed directly below it and covers the wall elevation from 3 feet below the sea level to 6 feet below the sea level. The third 3-ft wide panel will be split lengthwise into a 1-ft and a 2-ft wide panel. The 2-ft wide piece will be used to cover the elevation from 6 feet below the sea level to 8 feet below the sea level. In another embodiment, 3′×15′ panels may be lengthwise overlapped, as will be discussed with regard to FIG. 11, in which case there will be no need to split the last panel.

As previously discussed, supporting elements 130, 135, or the like may be used to attach the additional reinforcing elements, such as rebars, to panels 340 in the desired positions and orientations based on the strength requirements of the retrofit system and the engineering calculations. In the example cited above, the loads from the soil cause flexural (bending) on the panels, with the panels having a span length of 15 feet. In various embodiments, other types of reinforcing elements can also be added in any desired direction to resist shear, torsion, and other loads.

Once the panels 340 and the reinforcing bars are in place, the edges of the installation are sealed and the annular space is filled with concrete, grout, or epoxy-grout 350. The top edge of the concrete 350 can also be sealed with epoxy or other impervious products to prevent moisture and oxygen from entering the system from the top. The new solution not only provides significant strength to resist all the loads from the corroded seawall 300 but also panels 340, in combination with the concrete 350, produce an impervious protective layer for the corroded seawall 300. As we expect from a thin layer of paint to protect a steel structure from corrosion, this new protective layer will deprive the host sheet pile 300 from moisture and oxygen and brings the corrosion rate to insignificantly low levels. This new system can be easily installed underwater without the need for coffer dams. These benefits offer significant cost advantages for the disclosed repair system compared to conventional painting or other repair techniques.

For simplicity, in most of the above examples, flexural strength is provided by the panels supplemented by longitudinal reinforcement 510, shown in FIG. 6; however, reinforcement elements can be provided and embedded in these panels in all directions, such as the shear reinforcement 520 in FIG. 6. These bars can also be held in position using clips, fasteners, bar holders, adhesives, and the like.

To attach additional reinforcement elements, such as rebars, to the panels in any direction and coordination, supporting elements may be designed as depicted in FIGS. 7A and 7B. FIG. 7A illustrates a supporting element 700 for installation between two protruding T profiles of the panels. Supporting element 700 has a base 710, a stem 720, and a receiving component 730. In this example embodiment, supporting element 700 is manufactured in one piece and can be installed between two adjacent protruding T profiles in two different positions. Using its base 710, the supporting element 700 may be attached to any two adjacent T profiles via two parallel sides of its base 710 or be turned 90 degrees around its A-A′ axis and be attached via its other two parallel sides. This allows the rebar to attach to the panel either in the direction of the T profiles or perpendicular to the direction of the T profiles. If base 710 is manufactured to have more than two pairs of parallel sides, such as a hexagon or octagon, the rebar in the receiving component 730 can be attached to the T profiles in multiple orientations and angles.

FIG. 7B illustrates another supporting element 770, for the installation of a reinforcement element on a single T profile of the panels. Supporting element 770 has a base 740, an adjustable stem 750, and a receiving component 760. In this example embodiment, supporting element 770 is manufactured such that multi-part stem 750 can change its length and its parts can rotate with respect to each other. While, in contrast to supporting element 700, the base 740 of supporting element 770 can only be attached to a T profile in one way, the length of stem 750 can be adjusted and the receiving component 760 can rotate as desired to attach a rebar to a panel at any distance from the panel and any angle with respect to the panel's T profiles.

In other embodiments, the proposed technique may be used to repair corroded decks in ports and piers. Rebuilding these structures from below the deck is very challenging and costly, especially when the crew has little headroom from the high water to the bottom of the deck.

The concrete slab (deck) and beam 400 in FIG. 8 are assumed to be corroded and require strengthening and repair. Multiple panels 410, which have protruding profiles 450, can be connected with connector elements 420 along their edges and corners to create a mold that is the same shape but slightly larger than the cross-section of deck 400 and can encompass the structure 400. Reinforcing elements such as rebars 430 (in transverse direction) and 440 (in longitudinal direction) can be attached to these panels.

This assembly can be taken to the underside of deck 400 on a barge and lifted up to fit around the corroded structure 400. Anchor bolts and other means (not shown) can be used to securely hold this assembly in place while concrete or epoxy-grout or grout is pumped in the annular space between the assembly and the structure 400. The grout can be pumped from ports inserted in the shell or from holes drilled through the top deck; such holes will be later patched and filled with concrete.

The above solution makes the repairs significantly more cost-effective than using heavier plywood and timber to build the formwork and remove them after the casting of concrete. Moreover, this solution offers the added benefit that the impervious panels will protect the host structure permanently from exposure to salt water and will significantly prolong the service life of the host structure. Furthermore, the panels themselves are structural reinforcing elements and add significant strength to the host structure.

Similar to the ports and piers where the above repair solution can be beneficial for decks, bridges often get damaged by over-height trucks hitting the girders. There are also times when it is required to strengthen the bridge so it can resist more (heavier) loads. These tasks require the closure of traffic lanes as the crew spends days and weeks building scaffolding under the bridge to repair the bridge from below. This causes high costs, loss of time to the traveling public, and safety risk concerns to the owners when barricades have to be erected and traffic must be controlled or diverted. A solution similar to that of FIG. 8 may be implemented for these bridges. By preparing the reinforcing shell in advance, the actual repair (installation) can be completed in a few hours at nighttime, with minimum disruption of service to the travelers. In current repair methods, the surface of the damaged bridge girder must be patched first to be made smooth. This itself is a time-consuming task that causes significant delays. In contrast, when using the disclosed methods, it is preferred to have a rough or unfinished surface, which saves the time to prepare the surface.

The advantages of these panels and their design, which includes protruding profiles, cannot be overlooked. The protruding profiles offer several unique features, whether they are in the shape of T, L, V, or other shapes per design requirements:

The large contact surface of profiles that get cast in concrete results in a significant contribution of the panels to the flexural strength of the repaired structure. For example, it is assumed that panel 650 has a tensile strength of 30,000 psi and a cross-sectional area (sum of the T profiles and the flat plate) of 4 square inches. When panel 650 is used in a repair as described above, the panel will provide a tensile force of:

If the reinforcing bars between the protrusions have a total cross-sectional area of 1.5 square inches and a tensile strength of 60,000 psi, these bars also provide a tensile force of:

The total tensile force in this system will be:

This total tension force will be balanced by the compression force in concrete, and the resulting couple is the flexural capacity of this system. It is evident that the panel itself contributes significantly to the flexural strength of the system. In this example, (120/210) or over 57% of the strength of the system is from the contribution of the panel itself and only 43% from the reinforcing bars.

If desired, the interior surface of the panels can be made rough to improve its bonding to concrete and its contribution to the load-carrying capacity of the system. For most applications, it is preferred that the exterior (i.e., exposed) surface of the panels be smooth. However, that surface can also be made rough, for example, if painting or application of other coatings (e.g., stucco and the like) requires a rough surface. The exterior surface can also be embossed with architectural design features, patterns, etc., such as flowers, geometrical patterns, and the like to give them a more appealing finish.

FIG. 10 illustrates a simplified cross-sectional view of a reinforced wall, where panels 1000 are placed in front of the damaged wall 1010 and concrete or grout 1020 is poured in the annular space between them and allowed to cure. In such a scenario, the plane between damaged wall 1010 and filler material 1020 will be the most susceptible to failure due to shear forces. In general, all planes parallel to this plane are susceptible to failure due to shear forces. To remedy this danger, in various embodiments shear-transfer mechanisms and shear connectors, such as anchor bolts 1030 are used to connect panels 1000 to the cured filler materials 1020 and to the damaged wall 1010. The number, positions, and other details of shear bolts 1030 are all calculated by design engineers. Shear connectors 1030 are generally perpendicular to the flat surface 1040 of panels 1000 and the surface of wall 1010 and are strongly anchored in wall 1010.

In some embodiments, in lieu of using any kind of connectors 160, the adjacent panels may be partially overlapped, for example, for 3 or 4 inches, and nothing more needs to be done. In other embodiments, sealant, epoxy, resin, or any other kind of adhesives may be applied to the overlapped area of the panels. In yet other embodiments, more esthetically pleasing connections may be formed by fabricating a depressed strip, for example, 4 inches wide, along one edge of the panels so that when the panels are overlapped, all panels stay on a single flat plane. Sealants may or may not be applied over this depressed region before the edge of the next panel overlaps this region to create a flush and watertight overlapping joint. The overlapped regions may additionally be secured together with adhesives or mechanical fasteners. FIG. 11 illustrates two panels 1110 and 1112 being joined by overlapping them, using a depression on one side of each panel.

Changes can be made to the claimed invention in light of the above Detailed Description. While the above description details certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the above appears in text, the claimed invention can be practiced in many ways. Details of the system may vary considerably in its implementation details, while still being encompassed by the claimed invention disclosed herein.

Particular terminology used when describing certain features or aspects of the disclosure should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the disclosure with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the claimed invention to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms.

The above specification, examples, and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. While the present disclosure has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this disclosure is not limited to the disclosed embodiments, but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.