Patent Publication Number: US-2021180310-A1

Title: Building construction system with split precast horizontal floor supports

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is continuation-in-part of PCT patent application number PCT/US19/48058, filed Aug. 26, 2019, titled Simplified Precast Concrete System with Rapid Assembly Formwork, which claims priority to U.S. patent application Ser. No. 16/122,064, filed on Sep. 5, 2018, issued as U.S. Pat. No. 10,260,224 on Apr. 16, 2019, titled Simplified Precast Concrete System with Rapid Assembly Formwork, which in turn is a continuation-in-part of U.S. application Ser. No. 15/858,589, filed on Dec. 29, 2017, issued as U.S. Pat. No. 10,094,101 on Oct. 9, 2018, titled Precast Concrete System with Rapid Assembly Formwork. 
    
    
     FIELD 
     This invention relates to the field of building construction and more particularly to a system for the rapid construction of buildings using precast structure to support and reinforce cast-in-place concrete. 
     BACKGROUND 
     The construction material of choice for modern multi-story structures is concrete. Concrete is a durable material, able to be formed into floors, walls, and columns. 
     Conventional cast-in-place concrete construction relies on the use of labor-intensive, time-consuming, bulky, built-in-place formwork that must be erected for each wall and column. The formwork takes up space that could be used for moving around the site in the floor below, and does so for the duration of the construction. This process alone is time-consuming. After the formwork is placed, concrete is poured  within the forms. This concrete is allowed to partially cure, then the formwork is removed and after twenty-eight days, the concrete can bear its full load. The result of these delays is the slow the speed of construction. 
     Given the time-consuming nature of cast-in-place concrete, the concept of casting off-site arose, with the pre-cast concrete pieces being assembled on-site. While this can speed up construction, the resulting structure lacks the strength of a cast-in-place building due to weak connectivity. Expanding the size of the precast pieces can address the weaknesses caused by assembling discrete elements, but the resulting larger pieces complicate transportation. 
     What is needed is a system for constructing a building that combines the strength and continuity of cast-in-place construction with the rapid assembly of precast construction, while minimizing transportation difficulties caused by moving large precast pieces. 
     SUMMARY 
     The disclosed building construction system with split precast horizontal floor supports combines the strength and ease of construction of pre-cast concrete, with ease of transportation of cast-in-place concrete. The system avoids the requirement of casting difficult shapes by breaking the complex T-shape sections of prior patents into separate flat pieces. 
     The formwork for flat pieces is simpler than that of complex items that include both long and wide components. For examine, T-shapes and cross-shapes are hard to cast and difficult to transport because these shapes do not sit flat, and thus must be supported at their ends.  
     Instead of this complex casting and transport, the slabs are separated into shapes that can later be placed around the columns. This simulates the strength of a fully-precast system, while reducing the precast costs and transportation costs. 
     Specifically, the columns are formed as a single precast unit, the resulting column spanning multiple floors. The columns are precast in a series, with gaps for cast-in-place concrete to flow through, creating a solid, unified structure. 
     By forming precast columns that span multiple floors, construction of the building is simplified because each column unit is plumbed as it is set, creating a column that is plumb (vertical) across multiple floors. 
     The preferred column unit length—during transportation—height during construction—is three floors, or thirteen meters. This ideal dimension is reached assuming an interior height of three meters, plus is three rebar gaps of 0.3 meters each, totaling to thirteen meters. This length of thirteen meters is the standard length of a trailer, thus simplifying transportation. 
     Each column segment of a column is separated by a floor gap, across which bridging rebar connects the column segments. 
     This is the point at which the vertical columns must transition to the horizontal floors. To help carry the load between the floor and columns, a mirrored, split central member is used. The central member splits into two or more central member components. The central member components are placed on top of each column segment, partially surrounding the exposed bridging rebar.  
     Steel bars run continuously through each half of the column cap, also protruding outward at least one development length in all four horizontal directions. 
     The precast column cap mitigates severe shear stresses around columns by diffusing the stresses to a larger area while transferring moments between adjoining bays. Each half is primarily rectangular in shape, with a cut-out of a smaller rectangle near interior edge. The cutout, or gap, allows steel to pass between the precast column cap halves, the cap resting on the column segment below. 
     Steel stirrups embedded in the central member protrude upwards. The stirrups surround the cast-in-place rebar, creating a continuous rebar connection across the central members through to adjacent structure. 
     After placement of the central members, temporary structures are used to support spanning members. The spanning members are preferably a perforated, grid-shaped structure to reduce weight, appearing similar to a waffle. The cavities of the spanning member are optionally filled with foam fillers before concrete is poured. When the cavities are filled, the resulting structure requires less concrete, but maintains the bulk of its strength. 
     With the rebar placed, and concrete is poured over the entire floor. Special care is taken to ensure concrete flows into the floor gaps between column segments, ensuring that the bridging rebar is surrounded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:  
         FIG. 1  illustrates a first isometric view of the building construction system with split precast horizontal floor supports. 
         FIG. 2  illustrates a second isometric view of the building construction system with split precast horizontal floor supports. 
         FIG. 3  illustrates a view during assembly of the building construction system with split precast horizontal floor supports. 
         FIG. 4  illustrates a cross-sectional view of the building construction system with split precast horizontal floor supports. 
         FIG. 5  illustrates an isometric view showing column placement of the building construction system with split precast horizontal floor supports. 
         FIG. 6  illustrates an isometric view showing multiple placed columns of the building construction system with split precast horizontal floor supports. 
         FIG. 7  illustrates an isometric view showing a spanning member of the building construction system with split precast horizontal floor supports. 
         FIG. 8  illustrates an isometric view showing a structure ready for the cast-in-place concrete of the building construction system with split precast horizontal floor supports. 
         FIG. 9  illustrates a detail view of the columns with central members of the building construction system with split precast horizontal floor supports. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures.  
     Referring to  FIGS. 1 and 2 , a first and second isometric views of the building construction system with split precast horizontal floor supports are shown. 
     The hybrid concrete structure with C-shaped central member  1  includes a base member  10  at the foundation elevation. The base member  10  is topped with a column  12  that is broken into multiple column segments  14 . Crossing the floor gap  17  between each column segment  14  is bridging rebar  16 . The columns  12  are precast in units with multiple column segments  14 , including the bridging rebar  16 . Thus, when a column  12  is placed and plumbed, multiple floors are ready for construction, rather than only a single floor. 
     The top of each column segment  14  optionally includes a locking protrusion  18  to aid in integration of the columns  12  and the cast-in-place concrete  80  (see  FIG. 4 ). 
     The central member  30  is formed from one or more central member components  32 . The central member components  32  are preferably C-shaped, allowing the central member components  32  to surround the floor gap  17 , while still resting against the lower column segment  14 . 
     Each central member component  32  includes a column gap  40  formed by two or more component arms  38 . The combination of column gaps  40 , when the central member components  32  are placed, creates a central member recess  36 . 
     The column member components  32  meet at a central member joint  34 . 
     The central members  30  include rebar stirrups  50  to surround cast-in-place rebar  54 . Further included is central member rebar  52  that extends outward, helping to create a unitary structure.  
     Referring to  FIG. 3 , a view during assembly of the building construction system with split precast horizontal floor supports is shown. 
     The hybrid concrete structure with C-shaped central member  1  includes temporary formwork used during construction. 
     The spanning member  60  is temporarily supported by a collapsible tower  100 . Spaces between the spanning members  60  are enclosed from beneath by rotating formwork panels  110 , lifted into place by rotating with respect to support rod  116  and a combination of fixed hooks  112  and slideable hooks  114 . 
     Also visible is a column segment  14  with a central member  30  formed from two central member components  32 . 
     Referring to  FIG. 4 , a cross-sectional view of the building construction system with split precast horizontal floor supports is shown. 
     In this figure, the cast-in-place concrete  80  has been poured, creating the unitary structure. 
     The cast-in-place concrete  80  now surrounds the bridging rebar  16 , and has covered and surrounded the central members  30  and the spanning member  60 . 
     In this embodiment, the spanning member  60  includes multiple cavities  64 , each filled with an optional foam cavity filler  66  that prevents the cast-in-place concrete  80  from flowing into the cavities  64 . This reduces the amount of cast-in-place concrete  80  that is needed, without decreasing the resulting strength. 
     The spanning member  60  is optionally topped with rebar mesh  68 , further adding strength to the hybrid concrete structure with C-shaped central member  1 . 
     Referring to  FIG. 5 , an isometric view showing column placement of the building construction system with split precast horizontal floor supports is shown. 
     Shown are base members  10 , topped with columns  12  formed from column segments  14 . 
     Referring to  FIG. 6 , an isometric view showing multiple placed columns of the building construction system with split precast horizontal floor supports is shown. 
     Again shown are base members  10 , now all topped with columns  12 . 
     Referring to  FIG. 7 , an isometric view showing a spanning member of the building construction system with split precast horizontal floor supports is shown. 
     The spanning member  60  is shown supported by a collapsible tower  100 , the spanning member  60  placed between column segments  14  set atop base members  10 . 
     Referring to  FIG. 8 , an isometric view showing a structure ready for the cast-in-place concrete of the building construction system with split precast horizontal floor supports is shown. 
     This view shows many spanning members  60  between a multiplicity of columns  12 . 
     Referring to  FIG. 9 , a detail view of the columns with central members of the building construction system with split precast horizontal floor supports is shown.  
     The central members  30  are shown after placement on the column segments  14  of the columns  12 , with the rebar stirrups  50  and central member rebar  52  extending upward and outward. 
     Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
     It is believed that the system and method as described and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction, and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.