CONCRETE MEMBER SHEAR TRANSFER BRACKET

Abstract

A structure is disclosed for mechanically coupling a new concrete member to an existing concrete member to enable transfer of loads such as shear loads from the existing wall to the new wall. In examples, the mechanical structure includes a base which may be affixed to the existing member by a connective interface. A top a segment of the structure is spaced from, and connected to, the base by a number of diagonal segments. The diagonal and top segments of the bracket embed within the new concrete member during fabrication of the new concrete to transfer loads from the existing to the new concrete. A number of such brackets, of varying configurations, may be used depending on the layout of the new and existing members, and the magnitude of the loads to be transferred.

Claims

1. A structure for reinforcing an existing member with a new member, comprising: a base affixed to the existing member; diagonal segments extending at an angle from the base; and a top segment connected to each of the diagonal segments, wherein the base, diagonal segments and top segment are embedded in the new member.

2. The structure of claim 1, further comprising a connective interface for connecting the base to the existing member.

3. The structure of claim 1, wherein the diagonal segments are provided at an angle less than 90 off of the base.

4. The structure of claim 1, wherein the base is wider than the diagonal segments.

5. The structure of claim 1, wherein the base, diagonal segments and top segment define one or more openings in the structure.

6. The structure of claim 5, further comprising steel rebar embedded within the new member and extending through the openings.

7. A structure for reinforcing an existing member with a new member, comprising: a base affixed to the existing member; diagonal segments extending from the base; and a top segment connected to each of the diagonal segments, the diagonal segments spaced from each other to define one or more enclosed openings between the base, diagonal segments and top segment, and wherein the base, diagonal segments and top segment are embedded in the new member.

8. The structure of claim 7, wherein the base, diagonal segments and top segment protruded orthogonally from a surface of the existing member to which the base is attached.

9. The structure of claim 7, further comprising reinforcing rods embedded in the new member, extending through the enclosed openings.

10. The structure of claim 7, wherein the base and top segment are parallel to each other, and the diagonal segments extend at an oblique angle between the base and top segment.

11. The structure of claim 10, wherein first and second diagonal segments extend between the base and top segment at opposite angles

12. The structure of claim 7, further comprising a connective interface for connecting the base to the existing member.

13. The structure of claim 7, wherein the top section and diagonal segments have the same thickness.

14. The structure of claim 7, wherein the top section and diagonal segments have different thicknesses.

15. A structure for reinforcing a first concrete slab with a second concrete slab, comprising: a base affixed to the first concrete slab; diagonal segments extending from the base; and a top segment connected to each of the diagonal segments, the diagonal segments spaced from each other to define one or more enclosed openings between the base, diagonal segments and top segment, and wherein the base, diagonal segments and top segment are embedded in the second concrete slab.

16. The structure of claim 15, wherein the base, diagonal segments and top segment protruded orthogonally from a surface of the first concrete slab to which the base is attached.

17. The structure of claim 15, further comprising reinforcing rods embedded in the second concrete slab, extending through the enclosed openings.

18. The structure of claim 15, wherein the base and top segment are parallel to each other, and the diagonal segments extend at an oblique angle between the base and top segment.

19. The structure of claim 18, wherein first and second diagonal segments extend between the base and top segment at opposite angles

20. The structure of claim 15, further comprising a connective interface for connecting the base to the first concrete slab.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a top view of a bracket according to embodiments of the present technology.

[0004] FIG. 2 is a front view of a bracket according to embodiments of the present technology.

[0005] FIG. 3 is an end view of a bracket according to embodiments of the present technology.

[0006] FIGS. 4 and 5 are top and end views of a bracket according to alternative embodiments of the present technology.

[0007] FIG. 5A is an end view of a bracket according to a further alternative embodiment of the present technology.

[0008] FIGS. 6 and 7 are top and end views of a bracket according to alternative embodiments of the present technology.

[0009] FIGS. 8 and 9 are top and end views of a bracket according to alternative embodiments of the present technology.

[0010] FIGS. 10 and 11 are top and end views of a bracket according to alternative embodiments of the present technology.

[0011] FIG. 12 is an exploded top view of a bracket, a connective interface and an existing concrete member according to embodiments of the present technology.

[0012] FIG. 13 is a top view of a bracket affixed to an existing concrete member by a connective interface according to embodiments of the present technology.

[0013] FIG. 14 is a perspective view of a bracket affixed to an existing concrete member by a connective interface according to embodiments of the present technology.

[0014] FIG. 15 is a top view of a bracket affixed to an existing concrete member and buried within a new reinforcing concrete according to embodiments of the present technology.

[0015] FIG. 16 is a perspective view of a bracket affixed to an existing concrete member and buried within a new reinforcing concrete member according to embodiments of the present technology.

[0016] FIG. 17 is a perspective view of shear forces shared between existing and new concrete members affixed to each other by a bracket according to embodiments of the present technology.

[0017] FIG. 18 is a graph of stress vs. strain of a pair of concrete walls affixed to each other by bracket according to embodiments of the present technology.

[0018] FIGS. 19-26 are front views of sections of a new concrete member including various configurations of brackets according to embodiments of the present technology.

DETAILED DESCRIPTION

[0019] The present technology, roughly described, relates to seismically retrofitting, or otherwise reinforcing, existing concrete members. In particular, the present technology includes a structure for mechanically coupling a new concrete member to an existing concrete member to enable transfer of loads such as shear loads from the existing member to the new member. In embodiments, the mechanical structure, referred to herein as a bracket, includes a base which may be affixed to the existing concrete by a connective interface, which in examples may comprise an industrial epoxy. A top a segment of the bracket is spaced from, and connected to, the base by a number of diagonal segments. The diagonal and top segments of the bracket embed within the new concrete member during fabrication of the new concrete member to transfer loads from the existing to the new concrete member. A number of such brackets, of varying configurations, may be used depending on the layout of the new and existing concrete members, and the magnitude of the loads to be transferred.

[0020] It is understood that the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art. Indeed, the invention is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to those of ordinary skill in the art that the present invention may be practiced without such specific details.

[0021] The terms top and bottom, upper and lower and vertical and horizontal as may be used herein are by way of example and illustrative purposes only, and are not meant to limit the description of the invention inasmuch as the referenced item can be exchanged in position and orientation. Also, as used herein, the terms substantially and/or about mean that the specified dimension or parameter may be varied within an acceptable manufacturing tolerance for a given application. In one embodiment, the acceptable manufacturing tolerance is 2.5%.

[0022] FIGS. 1, 2 and 3 are top, front and end views, respectively, of a structure in the form of a bracket 100 according to embodiments of the present technology. The bracket 100 may comprise a number of diagonal segments 102 affixed to a top segment 104. In the embodiment shown, the bracket 100 comprises a first set of diagonal segments 102 slanted in the first direction, and a second set of diagonal segments slanted in a second, opposed direction. The diagonal segments 102 may be integrally formed with the top segment 104. However, the diagonal segments 102 may be affixed to the top segment 104 in further embodiments, as by welding bolting and/or gluing.

[0023] The diagonal segments in each set will slant from a point at which they join the top segment 104 toward an end of the top segment 104 to which they are closest. Thus, the diagonal segments on a left side (from the perspective of FIG. 1) of centerline, CL, will slant from their connection point at top segment 104 to the left (i.e., toward a first end 104a of top segment 104). The diagonal segments on a right side (from the perspective of FIG. 1) of centerline, CL, will slant from their connection point at top segment 104 to the right (i.e., toward a second end 104b of top segment 104).

[0024] The given slant of the diagonal segments 102 may assist in transferring shear loads from an existing to a new concrete member as explained below. The amount of the slant may be varied depending on the magnitude of the load to be transferred. In embodiments, the diagonal segments 102 may form a variety of positive and negative angles, , with the top segment 104. These angles may range between 60 and 90, and more optimally between 75 and 80. It is understood that the diagonal segments may form other angles in further embodiments. As noted, in embodiments, the diagonal segments 102 may form a right angle off of the top segment 104. In such embodiments, the segments 102 may still be referred to herein as diagonal segments despite not extending at an oblique angle from the top segment 104.

[0025] In one example, the top segment 104 may have a length, l, ranging between 1 to 6 feet, such as for example 2 feet. The top segment 104 may have a depth, d, of 1 to 6 inches, such as for example 3 inches. And the top segment 104 may have a width, w, of 2 to 8 inches, such as for example 4 inches. It is understood that the length, width and depth of the top segment 104 may vary outside of those ranges in further embodiments.

[0026] Each of the diagonal segments 102 may be the same length as each other, and may be between 2 and 12 inches long, such as for example 6 inches long. The diagonal segments 102 may have the same depth as a top segment 104, and may have a thickness, t, of 1 to 6 inches, such as for example 3 inches. The diagonal segments may have a cross-sectional area of approximately of approximately 0.20 to 3 square inches, for example 0.40 inches squared. Each of these dimensions and the cross-sectional area of the diagonal segments 102 may vary outside of those ranges in further embodiments.

[0027] The diagonal segments in a given set may be spaced from each other 6 to 12 inches, such as for example 8 inches. The distance between the two diagonal segments nearest the centerline, CL, may be 6 to 12 inches, such as for example 8 inches, at the point at which they attach to the top segment 104. In the embodiment shown in FIG. 1, there are two diagonal segments in each of the first and second sets of oppositely slanting diagonal segments. Is understood that a single bracket 100 may have more or less diagonal segments in each set of oppositely slanting diagonal segments in further embodiments.

[0028] While FIGS. 1-3 show a particular configuration of the bracket 100, it is understood at the bracket 100 may have a wide variety of different configurations in further embodiments. For example, in the embodiment shown in FIG. 1, the diagonal segments 102 nearest the ends 104a and 104b attach to the top segment 104 at points which are spaced inward from the ends 104a and 104b. In a further embodiment shown in the top and end views of FIGS. 4 and 5, the diagonal segments nearest the ends 104a and 104b may attach to the top segment 104 at ends 104a and 104b.

[0029] In embodiments, the top segment 104 and diagonal segments 102 may have a constant depth, d, from the bases (i.e., lower ends) of the diagonal segments 102 to the top surface of segment 104, as shown for example in FIGS. 3 and 5. In a further embodiment, the depth may vary from the bases of the diagonal segments 102 to the top surface of segment 104. For example, FIG. 5A shows an embodiment where the depth, d.sub.1, of the bracket 100 at the bases of diagonal segment 102 is greater than the depth, d.sub.2, of the bracket 100 at the top surface of the segment 104.

[0030] In a further embodiment shown in FIGS. 6 and 7, the top segment 104 may have a T-shape, including a wider section 104c at its top surface as compared to the remainder of the depth of the bracket 100.

[0031] In the embodiments shown in FIGS. 1-7, the lower ends of the diagonal segments 102 are freestanding. In a further embodiment shown in FIGS. 8-11, the bracket 100 may further include a base 110 connecting each of the diagonal segments 102 to each other. FIGS. 8-9 show an embodiment where the base 110 is wider than the diagonal segments 102 and top segment 104. In such embodiments, the base may for example range between 6 inches and 12 inches, and may for example be 8 inches, though it may be lesser or greater than that range in further embodiments. FIGS. 10-11 show an embodiment where the base 110 has the same depth as the diagonal and top segments 102, 104.

[0032] With base 110, openings 112 are defined in the bracket 100 between adjacent diagonal segments 102, and the top segment 104 and the base 110. The base 110 may be integrally formed on the diagonal segments 102. Alternatively, the base 110 may be affixed to the diagonal segments, for example by bolting and/or gluing. In embodiments, a lower surface of the base 110 may be parallel to an upper surface of the top segment 104.

[0033] In embodiments, the bracket 100 may be formed of a rigid material such as a carbon fiber reinforced polymer (CFRP). It may be formed of a variety of other fibers, including glass and natural fibers. As one example, the bracket may be formed of a unidirectional carbon fibers, such as used in carbon fiber fabric, such as model number CSS-CUCF11 from Simpson Strong-Tie, headquartered in Pleasanton, Calif. The carbon fiber or fabric may be laminated and/or saturated with a high strength, high modulus epoxy or other resin, such as for example a composite strengthening system (CSS) provided by Simpson Strong-Tie under model numbers CSS-ES or CSS-UES. The bracket 100 may further be formed of a variety of other materials including various resins, such as epoxy, vinyl-ester, polyester and other materials. The bracket 100 may be formed in a unitary structure in a single process so that the base 110, diagonal segment 102 and top segment 104 are integrally formed together.

[0034] FIG. 12 shows a top exploded view of a bracket 100 to be affixed to an existing concrete member 150. The bracket 100 may be affixed to the wall 150 using a connective interface 140. The existing concrete member 150 may have various thicknesses such as for example 4 to 8 inches. The connective interface 140 may for example be bidirectional CFRP, though other chemical and composite materials are contemplated. Where a bidirectional CFRP is used, it may be saturated with an epoxy or other resin and applied directly to the existing concrete slab 150. Thereafter, the bracket 100 may be pressed against and bonded to the interface 140 with a lower surface of the base 110 in direct contact with the interface 140 to provide a high strength connection of the bracket 100 to the existing concrete 150, as shown in the top view of FIG. 13 and the perspective view of FIG. 14.

[0035] As noted in the Background section, one disadvantage to conventional systems is the requirement of having to prepare the existing concrete member to receive a reinforcing layer of concrete. Such preparation may for example include having to drill through the existing concrete member, requiring extra preparation steps and disrupting occupants of a building with noise and vibration. The method of affixing the bracket 100 to the existing concrete member 150 using the interface 140 has an advantage that reduced preparation of the concrete member 150 is required, such as surface grinding and/or a power washing of the existing concrete member 150 surface.

[0036] Referring now to the top view of FIG. 15 and the perspective view of FIG. 16, once the bracket 100 is mounted to the existing member 150, a new concrete member 160 may be formed against the existing member 150, with the bracket 100 embedded within the new concrete member 160. The new concrete member 160 may for example be 6 to 18 inches thick, such as for example 12 inches thick, though it may be thinner or thicker than that in further embodiments.

[0037] During the formation of the new member 160, reinforcing structures such as steel rebar dowels 162 may be inserted into the new member 160. The steel rebar 162 may be inserted vertically to fit through one or more of the openings 112 before the concrete of new member 160 sets. The steel rebar 162 may alternatively or additionally be provided within the new member 160 horizontally, above and/or below the bracket 100.

[0038] The bracket 100 is effective at transferring and dissipating loads on the existing concrete member 150 into the new member 160. For example, during seismic activity, the existing member 150 may undergo shear forces in the directions of arrows F.sub.E. Those shear forces are significantly reduced as a result of the bracket 100, which transfers a portion of those shear forces into the new member 160 as indicated by arrows F.sub.N. The steel rebar 162 also cooperates with the bracket 100 to add structural rigidity to the new concrete member 160 and facilitate the transfer of shear loads from the existing member 150 to the new member 160.

[0039] FIG. 18 is a graph showing an example test of the bracket 100, showing the response of a bracket 100 in transferring shear loads between an existing member 150 and a new member 160 including the bracket 100. In actual fabricated uses of the present bracket, the new member 160 may be formed right up against the existing member 150. However, in this example test, the new member was spaced slightly from the existing member to ensure that all measured transferred shear loads were as a result of the bracket 100. In this example test, the shear load was increased from zero to a peak load of about 70,000 pounds, with the load increasing at a rate of 500 pounds per second. As shown, the bracket 100 was effective in elastically responding to loads of up to about 66,000 pounds. As noted, in actual use, the response of the bracket 100 would be higher given the contact of the new and existing members.

[0040] FIGS. 19-26 show various uses of a bracket 100 attached to an existing member 150 and embedded within a new reinforcing member 160. Each of the figures show a number of sections of new member 160, and a number of brackets 100 in each of the sections. It is understood that the number of brackets 100 shown in each section is a way of example only, and may vary depending on the length of the member sections, the length of the bracket 100 and/or the anticipated shear loads.

[0041] FIG. 19 shows a number of sections 166 of new member 160. Each member section 166 includes a number of brackets 100 (one of which is numbered) provided horizontally in each member section 166, with each bracket residing in the same horizontal plane. Where multiple brackets 100 are provided next to each other in a horizontal plane, the brackets 100 may be spaced from each other for example 1 to 10 feet, though they may be spaced from each other a greater or lesser amount in further embodiments.

[0042] FIG. 19 shows the brackets 100 completely contained within each section 166 of new member 160. FIG. 20 shows some of the brackets 100 extending between adjacent sections 166 of the new member 160. In such embodiments, a first section 166 of member 160 may be formed with a boundary bracket 100 partially embedded in the first section. A second section 166 of member 160 may subsequently be formed embedding the remainder of the boundary bracket 100.

[0043] FIGS. 21 and 22 illustrate an example where each section 166 may include multiple horizontal rows of brackets 100. While two such rows are shown, it is understood that there may be more than two rows in further embodiments. FIG. 21 illustrates an embodiment where brackets in the respective rows are aligned with each other. As noted above, rebar 162 may be fit vertically down through openings 112 formed in each of the brackets 100. Aligning the brackets makes it easy to fit the rebar down through openings 112. However, the brackets 100 in respective rows may be offset with respect to each other, as shown in FIG. 22. In such embodiments, the offset may be controlled so that rebar 162 may still fit vertically down through openings 112 of the brackets 100 in different rows.

[0044] In embodiments described above, the brackets 100 may be provided horizontally (i.e., perpendicular to the direction of the gravitational force). However, the brackets 100 may be provided in other orientations in further embodiments. FIG. 23 illustrates an example where brackets 100 are mounted within sections 166 at some nonzero angle with respect to horizontal. This angle may be any nonzero angle. In FIG. 23, all the brackets in each of the sections 166 are provided at the same angle. FIG. 24 illustrates an embodiment where the brackets 100 are angled in different directions. The brackets 100 may be angled in different directions within each section 166 as shown. Alternatively, all angles within one section 166 may be the same angle, and all sections in the next adjacent sections 166 may be at a different angle. Where the brackets 100 are provided at different angles, the brackets may be provided at positive and negative angles of each other (as shown in FIG. 24), or at a variety of different angles with respect to each other.

[0045] FIGS. 25 and 26 show a further embodiment where the brackets 100 are provided vertically (i.e., parallel to the direction of the gravitational force). The brackets 100 may be spaced from each other horizontally by distance of 1 to 5 feet, though the spacing between brackets 100 may be greater or lesser than that in further embodiments. FIG. 25 shows a single row of vertically oriented brackets 100. There may be multiple rows of vertical brackets in further embodiments. For example, FIG. 26 shows two rows of vertical brackets. The brackets in the respective rows may be vertically aligned with each other or offset (as shown). In a further embodiment, a section 166 may include horizontally oriented brackets, vertically oriented brackets and/or brackets at some oblique angle.

[0046] The foregoing detailed description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.