Support system for concrete column formwork and related bracket

Formwork for erecting a crown on a top end of a structural concrete column of a highway bridge is supported by a pair of vertically positioned elongated jack-screws. Lower ends of these jack-screws are threaded respectively into adjusting nuts seated on outer ends of respective horizontal arms of a pair of brackets. Each bracket includes an upright support member. These members are attached respectively to opposite sides of the column. The vertical location of the formwork attached to an upper end of a jack-screw may be adjusted up or down by selective rotation of the adjusting nut into which that jackscrew is assembled.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates generally to support systems for concrete formwork and more particularly to a support system and related bracket for formwork for casing a crown on a top end of a concrete structural column of a highway bridge.

2. Prior Art

As is well known, use of concrete as a building material concurrently requires formwork to hold and shape just poured concrete until that concrete is sufficiently cured to allow removal of the formwork. Until formwork removal, the curing concrete and formwork must be secured by a formwork support system.

One early concrete formwork support system is disclosed in U.S. Pat. No. 3,504,879. This system includes a bracket attachable to a side to a structural column of a building under construction to support the formwork needed for casting an above floor of the building. This bracket has a vertical tubular body formed with internal threading for disposition of a vertically positioned jack screw. An upper end of the jack-screw has an internal bore to rotatably receive a pin attached to a bottom side of a horizontally positioned, channel-shaped support head. Extending horizontally inward from the body is a pair of spaced apart upper and lower projections. These projections include respective passages to receive a pair of mounting bolts that extend outward from the column. Attached to an outer end of the upper projection is a horizontally positioned roller.

For use, the bracket is attached to the column using the mounting bolts. A bottom beam of the formwork then is positioned in the support head, and the formwork raised to a desired location by rotating the jack-screw. When the concrete poured onto the formwork has set, the formwork may be lowered by rotating the jack-screw in a reverse direction until the formwork beam rests on the bracket roller. The formwork then may be rolled out from under the now semi- cured concrete floor above.

A further bracket for a concrete formwork support system is disclosed in U.S. Pat. No. 3,863,877. This bracket comprises a column-attached support part and a movable jack part. The jack part then includes a base plate that operatively carrying a vertically positioned jack- screw. On an upper end of the jack-screw is a frame that supports a pair of rollers. Each roller has a cylindrical traction section and connecting spool-shaped flange. Attached to respective side edges of the jack part base plate is pair of inward facing channels. Slidably disposed in these channels are respective side edges of a pair of spaced apart shelf arms of the bracket support part. The arms in turn are attached to respective top edges of a pair of triangular shaped gusset plates that then are attached to a vertically positioned backing plate. This backing plate is prepared to be attached to a side of a structural column of a building under construction.

A laterally adjustable bracket for shoring concrete formwork is set out in U.S. Pat. No. 3,967,806. This bracket includes a horizontally positioned, angle-shaped arm having an inner end joined to a vertically positioned end plate attachable to a side of a concrete column of a building under construction. This bracket further includes a vertically positioned plate member formed with an inverted L-shaped opening for disposition of the angle-shape arm. Attached to an outer side of the plate are spaced apart, upper and lower projections of a jack-screw unit having a vertical cylindrical portion to operatively receive a jack-screw. A support head is attached to a top end of the jack-screw. On an outer end of the upper projection is a pair of spaced apart lugs to hold ends of a shaft for a horizontally positioned roller. The plate member and attached jack- screw unit may slide laterally along the bracket angle arm until the support head is properly aligned with the formwork above. The location of the plate member and jack-screw unit then are secured in place by inward threading of a fastener carried by one of a pair of spaced apart ears on the plate member. These ears are positioned on respective sides of a vertical leg of the angle arm.

Other examples of formwork support systems are disclosed in U.S. Pat. Nos. 3,797,794; 3,815,858; 3,900,179; and 4,768,939.

SUMMARY OF THE INVENTION

A support system of this invention for supporting formwork needed for forming a crown on a top of a concrete column of a highway bridge includes a pair of brackets attached respectively to opposite sides of the column. Each bracket includes an upright having a pair of upper openings for selective disposition of an end of a threaded rod that extends through a tube embedded in the column. Nuts threaded onto the rod ends then compressively secure the brackets to the column. Each bracket further includes an outward extending arm supported in part by an angularly positioned pair of braces that extends from a lower end of the bracket upright to an outer end of the bracket arm. Carried on the outer end of the arm is an adjusting nut to receive a threaded lower end of a vertically positioned jack-screw. An upper end of each jack-screw operatively connects to the formwork above to hold the crown formwork in place until concrete contained by this formwork is sufficiently cured to permit removal of the formwork and supporting structure.

The support system and related brackets of the invention provide several advantages over like support systems known or in use.

A first advantage is that system only requires two brackets to support the formwork above.

A second advantage is that the lateral location of either bracket as attached to a column may be adjusted depending on which pair of openings is selected for disposition of the threaded rod carried by the column. The lateral position of the point for attaching the jack-screw to the formwork also is considered when selecting the bracket opening pair for insertion. Once selected, then only one nut threaded onto the rod end is required to secure that bracket to that side the column. Note that the threaded rod and brackets are reusable.

A last advantage is that the bracket structure may be fabricated using ready available steel structural shapes. By using selective shaped steel members, the brackets may be easily configured to support substantial weight.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A system for supporting formwork needed to form of a crown on a top end of a concrete column of a highway bridge is shown generally inFIG. 1and designated10. The system10includes a pair of brackets12,14attached to opposite sides16,18of a concrete column20. Since the structure of each bracket12,14is the same, only the bracket12is described in detail. Like reference numbers are used to identify like structure.

The bracket12is defined by an upright22having an inner and outer wall24,26and sidewalls28. As best seen inFIG. 5, each sidewall28is inwardly offset from side edges30of the inner and outer walls24,26. Additionally, an inner partition32positioned parallel to and between the sidewalls28connects the inner and outer walls24,26. As seen inFIGS. 2 and 3, bottom ends34of the inner wall24and the partition32extend below bottom ends36of the outer wall26and the sidewalls28. A pair of horizontally spaced apart oblong-shaped mounting holes is formed in the inner wall24on either side of the partition32just above the inner wall bottom end34.

In an upper portion40of the inner wall24and the outer wall26are two pairs of horizontally spaced apart and horizontally aligned openings42. Extending between the inner and outer walls24,26in alignment with each opening pair is a tube44. An inside diameter of each tube44is greater than a diameter of the openings42. Attached to top ends46of the inner and outer walls24,26and sidewalls28is a top plate48.

Attached to the upright outer wall26is an inner end49of an arm50. This arm50extends horizontally outward and is defined by two spaced apart channel members52. Attached to outer ends54of the channel members52is an end plate56. A jack-screw plate58then is attached to top surfaces60of top flanges62of the arm channel members52adjacent to the end plate56.

To enhance the connection between the arm inner end49and the upright outer wall26, a pair of reinforcing plates66is attached respectively to side edges68of the channel member top flanges62and bottom flanges70and to the upright outer wall26. Note that top and bottom edges72of each reinforcing plate66extend respectively above and below the channel member top flange62and bottom flange70. Additionally, the fixed position of the arm50is enhanced by a pair of spaced apart, angularly positioned tubular braces76. Upper ends78of these braces76are attached one each to a bottom surface80of each channel member bottom flange70while lower ends82of the braces76are attached to the upright outer wall26. Carried between the channel members52in alignment with an opening84in the jack-screw plate58is a vertically positioned jack-screw tube88. Note that a bottom end90of the tube88extends below the bottom surface80of the channel member bottom flanges70.

For use as seen inFIG. 1, the brackets12,14are positioned on respective sides16,18of the column20. During forming of the column20, a tube92has been embedded in the column20for disposition of a threaded rod93. Outer ends94of the rod93then extend beyond the column sides16,18. One each of the rod ends94is inserted into one of the pair of aligned openings42in each bracket upright22. Selection of which pair of aligned openings42to use for rod end insertion depends on the desired location of each bracket12,14since the tube92may not be centered in the column20. Mechanically positioning of the brackets12,14is facilitated by operative use of a lifting lug96attached to the top plate48on each bracket upright22. This lifting lug96is positioned to vertically align with a center of gravity of each bracket12,14.

Once in place, the brackets12,14are compressively secured to the column20by nuts98threaded on the respective ends94of the rod93. Additionally, the bottom end34of each bracket inner wall24is secured to the column20by an anchor bolt (not shown) inserted into the column20through one of the openings38. Next, a bottom end100of a jack-screw102is inserted through in each jack-screw plate opening84so that this bottom end100fits into the respective tube88located below the jack-screw plate58. Each jack-screw102then is held vertically in place by a jack-screw nut104assembled on that jack-screw102as the nut104seats of the bracket jack-screw plate58. The vertical location of a top end (not shown) of each jack-screw102may be adjusted by rotation of the nut104for selective attachment to the column crown formwork above (not shown). Once attached, the system10may support the formwork and uncured concrete poured into the formwork for casing the crown.

The system10, as its use is described above, supports working loads of 200,000 pounds with a safety factor of 500,000 pounds. To meet this requirement the brackets12,14are made using selective structural steel shapes. For example, the inner and outer walls24,26and the inner partition32of each bracket upright22are integrally formed as flanges and a web of a 10 in. structural steel H-beam106having a weight of 77 pounds/linear foot. The bracket sidewalls28then are made from ½ in. thick steel plate. The arm channel member52are 6 in. structural steel channels having a weight of 13 pounds/linear foot. Lastly, the braces76are made from 2 in.×4 in.× 3/16 in. thick steel tubes. These structural members106,28,32, and76then are welded together.

While an embodiment, uses, and advantages of this invention have been shown and discussed, it should be understood that this invention is limited only by the scope of the claims. Those skilled in the art will appreciate that various modifications and changes may be made without departing from the scope and spirit of the invention, and these modifications and changes may result in farther uses and advantages.