Load transfer system
View Patent ↗A new two-step construction method for foundations or any structure using steel rebar by covering said rebar with cured concrete or welding smaller rebar to the main rebar prior to being placed into service. This is to obtain advantages over common construction methods by changing the construction sequence and making an efficient system for load transfer. This is done by forming undulating steel bars or concrete on the load bearing rebar prior to placing into service. These can be inserted into borings, trenches, or forms along with granular fill and grout pipes to build designed structures. The grout can be injected at the time of installation, or at a later time. The grout could be additional Portland cement concrete or lower strength grout to complete the structure. The primary advantage is to have full strength steel and concrete in a structure without waiting for the concrete to cure.
1 . A method for constructing steel reinforced structural elements consisting of first modifying steel rebars by placing concrete on said rebars and allowing the concrete to cure prior to placing the modified rebars into service in an excavation or confined space; wherein said rebars with the cured concrete have undulating shape that alternates from a minimum covered zone that transitions to a maximum covered zone which transitions back to a minimum covered zone with said undulations repeating along a length of the rebars and leaving a portion of said rebars unmodified; the minimum covered zone has a concrete cover thickness of at least 1.5 inches and the maximum covered zone has a concrete cover that is at least 1.5 times of the thickness of the concrete cover of the minimum cover zone, and the transition between the minimum and maximum covered zone has a slope at an angle between 20 and 45 degrees as measured from an alignment of the rebar within the concrete; prior to placing the modified rebars into service, the concrete is allowed to cure to a minimum unconfined compressive strength of 2000 pounds per square inch (PSI) then said modified rebar may be placed into service; wherein the second step of constructing the structural elements is to place the modified rebar in the excavation or other confined space and then surrounding the modified rebar with granular fill material to completely fill a space between the modified rebars and the limits of the excavation or confined space, the granular fill consisting of sand, gravel, cobbles, boulders, and possibly demolition concrete or slag from metal refining to completely fill the space between the modified rebars and the excavation or other confined space prior to grouting, then to complete the structural elements the modified rebars include a grouting system to grout the entire surrounding space to ensure that the granular fill and the modified rebar will function as a complete structural element; and connecting the unmodified portion of the rebars with other structures including at least one of a pile cap, grade beam, structural foundations, structural slabs, walls, columns, or tie back anchors.
2 . The method of claim 1 wherein said modified rebars, granular fill, and the grouting system consisting of pipes spaced to ensure uniform grouting.
3 . The method of claim 1 , wherein the concrete cover includes the undulating shape on a portion of the modified rebars.
4 . The method of claim 1 , wherein a concrete form is placed in the excavation or confined space first and then said modified rebars are placed in the excavation and then Portland cement concrete is then poured around the modified rebars.
5 . The method of claim 1 , wherein the grout system is lowered into the excavation along with the modified rebars then the remainder of the hole is filled with granular fill which is then grouted by pumping grout through the grout pipes using fast setting polymer, or other grout capable of locking the granular fill in-place.
6 . The method of claim 2 , wherein the structural elements are comprised of multiple modified rebars tied in two directions to form a lattice.
7 . The method of claim 1 , wherein splicing modified steel rebars where it is necessary, the unmodified portion of each modified rebar may be joined to the next modified rebar by casting unmodified end portions of each of the rebars with concrete in shapes that allow for the ends of each modified rebar to interlock with the next modified rebar with minimum overlap, this can be accomplished through the use of additional rebars spliced alongside a load bearing rebar and cast together in concrete in the undulations leading up to the splicing end of the modified rebar thus making it possible for multiple rebars to be formed into multiple interlocking fingers at the end of the first rebar such that the next rebar which has been cast with a complementary set of molded fingers designed to fit snugly into the spaces between the fingers of the first rebar and in the case of each rebar prior to casting the ends, the rebars are bent around a tight curve as determined by the diameter size of bar and anticipated load at a connecting point, to ensure that the fingers of each rebar will remain in close contact with the fingers of the next rebar then the two concrete covered rebars shall be enclosed in a containment vessel such that any remaining void space can be grouted to hold the ends in-place so that the load on the first rebar can be efficiently transmitted to the second rebar.