Tapered load plate for transferring loads between cast-in-place slabs

• US 8,381,470 B2
• Filed: 03/29/2010
• Issued: 02/26/2013
• Est. Priority Date: 09/13/2001
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Nigel K. Parkes, Russell Boxall
• Inventors: Boxall, Russell, Parkes, Nigel K.
• Primary Examiner(s): Gilbert, William
• Application Number:
  US12/749,148
• Publication Number:
  US 20100242401A1
• Time in Patent Office: 1,065 Days
• Field of Search: 523/93, 523/95, 523/96, 523/960.2, 523/960.4, 523/960.5, 523/960.7, 523/963.08, 524/02, 524/26, 524/35, 525/851, 526/77, 404/47, 404/51, 404/52, 404/55, 404/56, 404/57, 404/58, 404/59, 404 60- 67, 404134-136
• US Class Current: 52/396.02
• CPC Class Codes: E01C 11/14 Dowel assembly ; Design or construction of reinforcements in the area of joints coupling devices for prefabricated units E01C5/005; combined with characteristic packings E01C11/08 - E01C11/12; removable holders E01C23/045
• CPC Class Codes: E04B 1/483 Shear dowels to be embedded in concrete

Abstract

A tapered load plate transfers loads across a joint between adjacent concrete floor slabs. The top and bottom surfaces may taper from approximately 4 inches wide to a narrow substantially pointed end over a length of approximately 12 inches. The tapered load plate accommodates differential shrinkage of cast-in-place concrete slabs. The tapered load plate may comprise a main plate and at least one extension. When adjacent slabs move away from each other, the narrow end of the tapered load plate moves out of the void that it created in the slab thus allowing the slabs to move relative to one another in a direction parallel to the joint. Tapered load plates may be assembled into a load-plate basket with the direction of the taper alternating from one tapered load plate to the next to account for off-center saw cuts.

Claims

1. A system for restricting certain movement, accommodating certain other movement and transferring loads between a first concrete on-ground cast-in-place slab and a second concrete on-ground cast-in-place slab, the system comprising the slabs and further comprising:

a joint interposing the first and second slabs, at least the first slab having a substantially planar upper surface, at least a portion of the joint being initially defined by at least one of a crack, cut or a form oriented substantially perpendicular to the substantially planar upper surface of the first slab, wherein a longitudinal axis of the joint is formed by an intersection of the crack, cut or form and the upper surface of the first slab and wherein the joint is subject to opening through a range of joint opening dimensions and beyond;

a first tapered load plate and a second tapered load plate that each have a taper, protrude into the first and second slabs and have an extent across the joint such that the load plates span the joint and transfer between the first and second slabs a load applied to either of the slabs directed substantially perpendicular to the upper surface of the first slab;

the tapered load plates each having a width measured parallel to the longitudinal axis of the joint;

the width of each tapered load plate generally tapering from a relatively wide location in the extent of each plate across the joint to a relatively narrow portion such that, as the joint opens, a tapered gap opens between the load plate and the slab near the narrow end portion such that the slabs are allowed increasingly greater relative movement in the direction substantially parallel to the longitudinal axis of the joint; and

wherein the first and second tapered load plates are oriented such that for at least the range of joint opening dimensions, reduced width of one load plate at the narrowest width in the joint of the one load plate due to plate taper is compensated for by increased width of the other load plate in the joint due to opposing plate taper, such that for at least the range of joint opening dimensions, the combined widths of the first and second tapered load plates in the joint is consistently adequate for load transfer across the joint;

whereby the tapered load plates restrict relative movement between the first and second slabs in a direction substantially perpendicular to the upper surface of the first slab, allow the joint to open by allowing the first and second slabs to move away from each other in a direction substantially perpendicular to the joint, allow for increasingly greater relative movement in a direction substantially parallel to the longitudinal axis of the joint as the joint opens, and maintain consistently adequate load transfer across the joint;

at least one of the tapered load plates including a main plate portion and at least one extension, the main plate portion comprising a first end, a second end, and at least a first main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the first main plate portion side crossing the joint, and the at least one extension comprising at least a first extension side alongside the first main plate portion side.

2. The system of claim 1, wherein both the tapered load plates include main plate portions as in claim 1 and at least one extension also as described in claim 1.

3. The system of claim 1, wherein the tapered load plate that includes a main plate portion and at least one extension also includes a second extension, the main plate portion further comprising a second main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the second main plate portion side crossing the joint, and the second extension comprising at least a second extension side alongside the second main plate portion side.

4. The system of claim 3, wherein the main plate portion is steel and the at least one extension and the second extension include a material that is more compressible than the main plate portion.

5. The system of claim 1, further comprising a tapered-load-plate basket that positions the tapered load plates before the slabs are cast in place.

6. The system of claim 1 or claim 5, wherein the joint is a saw-cut control joint.

7. The system of claim 1, wherein the main plate portion of the tapered load plate having a main plate portion is steel and the extension includes a material that is more compressible than the main plate portion.

8. Apparatus for use in a system for transferring loads between a first concrete on-ground cast-in-place slab and a second concrete on-ground cast-in-place slab, the system comprising the first and second slabs and a joint interposing the first and second slabs, at least the first slab having a substantially planar upper surface, at least a portion of the joint being initially defined by at least one of a crack, cut or a form oriented substantially perpendicular to the substantially planar upper surface of the first slab, wherein a longitudinal axis of the joint is formed by an intersection of the crack, cut or form and the upper surface of the first slab and wherein the joint is subject to opening through a variety of joint opening dimensions;

the apparatus comprising;

a first tapered load plate and a second tapered load plate that each have a taper, protrude in use into the first and second slabs and have an extent in use across the joint such that the load plates span the joint and transfer between the first and second slabs a load applied to either of the slabs directed substantially perpendicular to the upper surface of the first slab;

the tapered load plates each having a width in use measured parallel to the longitudinal axis of the joint;

the width of each tapered load plate generally tapering from a relatively wide location in the extent of each plate across the joint to a relatively narrow portion;

whereby in use, as the joint opens, a tapered gap opens between the load plate and the slab near the narrow portion such that the slabs are allowed increasingly greater relative movement in the direction substantially parallel to the longitudinal axis of the joint; and

whereby in use the first and second tapered load plates are oriented such that as the joint opens, reduced width of one load plate at the narrowest width in the joint of the one load plate due to plate taper is compensated for by increased width of the other load plate in the joint due to opposing plate taper, such that as the joint opens, the combined widths of the first and second tapered load plates in the joint is substantially consistent for substantially consistent load transfer across the joint; and

whereby in use the tapered load plates restrict relative movement between the first and second slabs in a direction substantially perpendicular to the upper surface of the first slab, allow the joint to open by allowing the first and second slabs to move away from each other in a direction substantially perpendicular to the joint, allow for increasingly greater relative movement in a direction substantially parallel to the longitudinal axis of the joint as the joint opens, and maintain substantially consistent load transfer across the joint;

at least one of the tapered load plates including a main plate portion and at least one extension, the main plate portion comprising a first end, a second end, and at least a first main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the first main plate portion side crossing the joint, and the at least one extension comprising at least a first extension side alongside the first main plate portion side.

9. The system of claim 8, wherein both the tapered load plates include main plate portions as in claim 8 and at least one extension also as described in claim 8.

10. The system of claim 8, wherein the tapered load plate that includes a main plate portion and at least one extension also includes a second extension, the main plate portion further comprising a second main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the second main plate portion side crossing the joint, and the second extension comprising at least a second extension side alongside the second main plate portion side.

11. The system of claim 10, wherein the main plate portion is steel and the at least one extension and the second extension include a material that is more compressible than the main plate portion.

12. The system of claim 8, further comprising a tapered-load-plate basket that positions the tapered load plates before the slabs are cast in place.

13. The system of claim 8 or claim 12, wherein the joint is a saw-cut control joint.

14. The system of claim 8, wherein the main plate portion of the tapered load plate having a main plate portion is steel and the extension includes a material that is more compressible than the main plate portion.

15. Apparatus for transferring loads between a first concrete on-ground cast-in-place slab and a second concrete on-ground cast-in-place slab, the apparatus for use in a system, the system comprising:

a joint separating first and second slabs, at least a portion of the joint being initially defined by a partial depth saw cut that results in a crack below the saw cut, wherein a longitudinal axis of the partial depth portion of the joint formed by the saw cut is formed by an intersection of the saw cut and the upper surface of the first slab;

the apparatus comprising;

a first load plate and a second load plate that in use each protrude into the first and second slabs such that the load plates transfer between the first and second slabs a load applied to either of the slabs directed substantially perpendicular to the upper surface of the first slab;

whereby the load plates restrict relative movement between the first and second slabs in a direction substantially perpendicular to the upper surface of the first slab, and the load plates allow the joint to open by allowing the first and second slabs to move away from each other in a direction substantially perpendicular to the joint;

the load plates each having a width measured in use parallel to the longitudinal axis of the joint; and

wherein the width of each load plate generally tapers from a relatively wide portion near the joint to at least one relatively narrow end in at least one of the slabs such that, as the joint opens, the slabs are allowed increasingly greater relative movement in a direction substantially parallel to the longitudinal axis of the joint; and

wherein the tapered load plates define in use a cross section of tapered load plate material spanning the joint, and the cross section remains substantially constant between the saw cut being positioned on-center relative to the tapered load plates and the saw cut being, in at least one position of the saw cut, off-center relative to the tapered load plates;

at least one of the tapered load plates including a main plate portion and at least one extension, the main plate portion comprising a first end, a second end, and at least a first main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the first main plate portion side crossing the joint, and the at least one extension comprising at least a first extension side alongside the first main plate portion side.

16. The system of claim 15, wherein both the tapered load plates include main plate portions as in claim 15 and at least one extension also as described in claim 15.

17. The system of claim 15, wherein the tapered load plate that includes a main plate portion and at least one extension also includes a second extension, the main plate portion further comprising a second main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the second main plate portion side crossing the joint, and the second extension comprising at least a second extension side alongside the second main plate portion side.

18. The system of claim 15, further comprising a tapered-load-plate basket that positions the tapered load plates before the slabs are cast in place.

19. The system of claim 15 or claim 18, wherein the joint is a saw-cut control joint.

20. The system of claim 15, wherein the main plate portion of the tapered load plate having a main plate portion is steel and the extension includes a material that is more compressible than the main plate portion.

21. Apparatus for use in a system transferring loads between a first concrete on-ground cast-in-place slab and a second concrete on-ground cast-in-place slab, the system comprising the first and second slabs and a joint interposing the first and second slabs, at least the first slab having a substantially planar upper surface, at least a portion of the joint being initially defined by at least one of a crack, cut or a form oriented substantially perpendicular to the substantially planar upper surface of the first slab, wherein a longitudinal axis of the joint is formed by an intersection of the crack, cut or form and the upper surface of the first slab and wherein the joint is subject to opening through a variety of joint opening dimensions;

the apparatus comprising;

multiple first tapered load plates and multiple second tapered load plates, that each have a taper, protrude in use into the first and second slabs and have an extent in use across the joint such that the load plates span the joint and transfer between the first and second slabs a load applied to either of the slabs directed substantially perpendicular to the upper surface of the first slab;

the tapered load plates each having a width in use measured parallel to the longitudinal axis of the joint;

the width of each tapered load plate generally tapering from a relatively wide location in the extent of each plate across the joint to a relatively narrow portion; and

a tapered-load-plate basket that facilitates positioning the tapered load plates in the area of the joint before the slabs are cast in place;

whereby in use, as the joint opens, a tapered gap opens between the load plates and the slabs near the narrow portions of the plates such that the slabs are allowed increasingly greater relative movement in the direction substantially parallel to the longitudinal axis of the joint; and

whereby in use the multiple first and multiple second tapered load plates are oriented such that as the joint opens, reduced width of the first load plates at the narrowest width in the joint of the first load plates due to plate taper is compensated for by increased width of the second load plates in the joint due to opposing plate taper, such that as the joint opens, the combined widths of the multiple first and second tapered load plates in the joint is substantially consistent for load transfer across the joint; and

whereby in use the tapered load plates restrict relative movement between the first and second slabs in a direction substantially perpendicular to the upper surface of the first slab, allow the joint to open by allowing the first and second slabs to move away from each other in a direction substantially perpendicular to the joint, allow for increasingly greater relative movement in a direction substantially parallel to the longitudinal axis of the joint as the joint opens, and maintain substantially consistent load transfer across the joint;

at least one of the tapered load plates including a main plate portion and at least one extension, the main plate portion comprising a first end, a second end, and at least a first main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the first main plate portion side crossing the joint, and the at least one extension comprising at least a first extension side alongside the first main plate portion side.

22. The system of claim 21, wherein both the tapered load plates include main plate portions as in claim 21 and at least one extension also as described in claim 21.

23. The system of claim 21, wherein the tapered load plate that includes a main plate portion and at least one extension also includes a second extension, the main plate portion further comprising a second main plate portion side extending from between at least adjacent the first end and at least adjacent the second end, the second main plate portion side crossing the joint, and the second extension comprising at least a second extension side alongside the second main plate portion side.

24. The system of claim 21 or claim 23, wherein the joint is a saw-cut control joint.

25. The system of claim 21, further comprising a tapered-load-plate basket that positions the tapered load plates before the slabs are cast in place.

26. The system of claim 21, wherein the main plate portion of the tapered load plate having a main plate portion is steel and the extension includes a material that is more compressible than the main plate portion.