This invention relates to the construction of multi-story buildings and, in particular, to the use of Stacked Structural Steel Wall Trusses that are interconnected in three dimensions with other modular construction elements to enable the rapid construction of multi-story buildings with improved quality of construction over that found in traditional multi-story building construction techniques.
There are a number of problems associated with the construction of multi-story buildings using the traditional construction techniques of Poured Concrete frame buildings, Pre-Cast Concrete frame buildings, conventional Structural Steel frame buildings, conventional Wood Frame buildings and Masonry construction as described in more detail below. Multi-story buildings constructed with these traditional construction techniques are built in the traditional manner of field craftsmen applying construction materials (dimensional lumber, thin gauge steel members, individual structural steel members) or hardscape materials (cinder block, brick, concrete) to first fabricate the frame of the multi-story dwelling on a foundation at the building site according to a set of architectural plans. While there are few architectural, structural, or dimensional limitations, these construction techniques require a sequential, craft-based, field building format, where item A must be completed before item B can begin, and in turn, item B must then be completed before item C can begin and so on. For example, the ground level walls must be completed before the installation of utilities on the ground level can begin, the second level walls must be completed before substantial work on upper floor walls can begin, and the first floor walls on the building must be framed before finishes can be applied to the first floor walls. While these methods of construction have worked for many years, there are inherent inefficiencies in these methods that result in significant time, cost, and quality penalties.
Traditional construction techniques involve a lengthy process and, therefore, result in construction activity of extended duration. In addition, the finish work is accomplished only after the structural work is completed.
This in situ fabrication results in a lack of quality, is prone to errors, and requires the workers to innovate with respect to the interconnection of utilities, thereby resulting in inconsistency in implementation.
Much of the work done is at the mercy of local weather conditions which can delay schedules and damage materials.
The materials and supplies are mostly hand carried, piece-by-piece, into and within the building during construction, which is an inefficient process.
It is common to have 12- to 30-month construction schedules in the traditional construction of a multi-story building, especially when brick or cinder block construction is used, since these materials inherently limit the daily rise of the walls.
The process is labor intensive, and it is frequently difficult to locate workers of the desired skill level.
There is typically a wide diversity in the quality of building materials that are available and the skills of the workers performing the construction tasks.
Supervision and quality control in traditional multi-story building is non-uniform.
Advantages of traditional construction techniques are that these multi-story buildings can be built to any size or layout that is desired within the limitations of the structural capabilities of the framing material. Multi-story buildings can easily be built with the architectural features, room size, and layout being determined by the architect, builder, and/or owner. Other advantages of traditional multi-story building construction techniques are:
However, this construction process, especially early on, is highly dependent on weather conditions and most often can only occur during daylight hours. An interruption in the flow of construction caused by one of the subcontractors has a ripple effect in that each subcontractor must await the completion of another subcontractor's work before they can begin their work. Furthermore, operating in a field environment is detrimental to maintaining the quality of the construction because it is difficult using portable hand tools to precisely cut and assemble framing material into walls and various finish elements with precise tolerances. It is often difficult in multi-story building construction to find a sufficient number of skilled workmen who can craft a structure of high quality at very reasonable costs. The quality suffers and there is also a significant amount of waste, since the materials must be handled at least two to three times between shipment from the factory or mill to being delivered to the individual job site, and there are many steps of additional material handling on the job site. There is excess labor and significant breakage as a result of this repetitive handling of materials. In addition, typically there aren't people at individual job sites all day to receive materials, so materials and supplies are exposed to the possibility of theft and bad weather. Surplus materials, unless they represent a significant quantity, are discarded since the value of salvaged materials does not offset the cost involved to salvage these materials.
In many areas of the world, population growth is greatly exceeding the growth of available housing. Therefore, one of the primary building construction problems in the world is the ability to very rapidly build large quantities of housing to address the growing deficit. This problem is compounded by limited amounts of skilled labor at a reasonable cost. Traditional construction techniques are not responding to the existing and growing housing shortage, and new means of producing housing in very large quantities effectively and quickly are in great demand.
Thus, traditional construction techniques fail to deliver the quality and speed of construction that is desirable. In many locations, these impediments result in a severe shortage of multi-story buildings and a commensurate lack of available quality buildings.
The present method and apparatus of Constructing Multi-Story Buildings Using Stacked Structural Steel Wall Trusses (also termed “Stacked Wall Truss Construction” herein) has broad application worldwide. The major attributes of the present Stacked Wall Truss Construction are their ability to be used in a huge diversity of building products, with high quality, with a decreased need for skilled labor, at low cost, that can be built in a timely fashion, where an exceedingly high rate of aggregate production to address the present and growing deficits of housing can all be achieved.
The Stacked Wall Truss Construction is a novel design of stacking structural steel Wall Truss Frames, which are structurally either moment frames or braced frames (termed “Wall Truss” herein) where provisions for the installation of coordinated Floor Modules are provided. Unlike many forms of traditional construction, the floors of the multi-story building do not separate the walls at each level of the building. The walls are created with stacking modular elements to form a vertically continuous structure, and the floors are supported by the Floor Shelf at predetermined elevations that facilitate structural connections among the elements and which also provide efficient Utility Interconnect Locations to connect all required plumbing and electrical systems of the building.
The Floor Module provides a solid surface on top of which the Topping Slab of concrete is poured which fills the space between the Floor Module and the Wall Trusses. The Floor Module includes a Capping Track which caps and encloses the ends of the Floor Module. The Topping Slab also fills the void between the Wall Trusses and the Floor Module, since the Capping Track in combination with the Floor Shelves form a pocket into which the concrete poured for the Topping Slab can flow to create an integral structure (floor slab anchor) that locks the Floor Module to the Wall Trusses.
In the present Stacked Wall Truss Construction, the building is really a structural steel frame without the use of stacking individual or independent columns. Vertical Vierendeel trusses including vertical members of tube steel are used, thereby the construction process involves stacking Wall Trusses, not individual columns. An inner “Mating Member” can be placed hanging out the bottom of each truss (or out of the top of the truss below) such that, when that Wall Truss is crane hoisted up into position, the Mating Member enables the truss to be perfectly positioned on top of the installed Wall Truss below, and the Mating Member also immediately holds the Wall Truss being installed in place as the Mating Member sticks into the column above and column below, typically to an extent of 2 or 3 feet and, as such, the Wall Truss being installed cannot lay over. The Wall Truss is immediately stable upon dropping it into position, and the positioning is near perfect without effort. All Wall Trusses are manufactured to precise dimensional consistency, so assembly of the multi-story building is “Lego™ like,” with identical pieces aligning with one another. So Wall Trusses, not individual columns, are stacked. This is different than customary structural steel design, and the floors of the multi-story building are also not interposed between the vertically stacked wall trusses, so this is not like poured-in-place concrete construction or other conventional building methods.
As shown in
Unlike traditional Vierendeel trusses, the horizontal chords or Wall Truss Beams 111-114 and 121-124 do not span the entire length of the Wall Truss 100 and cap the individual Wall Truss Columns 101-105, but instead the Wall Truss Columns 101-105 extend beyond the top and bottom horizontal chords, such that the chords interconnect the Wall Truss Columns 101-105 in a segmented manner. Thus, the horizontal chords do not provide the vertical load carrying capacity, but function to secure and brace the vertical Wall Truss Columns 101-105 to enable them to carry vertical loads and to provide shear capacity for the Wall Truss 100.
The Wall Truss 100 shown in
Floor Shelves 141-144 are placed on the top surface of the top horizontal Wall Truss Beams 111-114, and may be tack welded in place to hold them in place until the Wall Truss 100 above is installed, which can optionally be used to sandwich the Floor Shelves 141-144 between the top horizontal beam of a lower Wall Truss 100 and a bottom horizontal beam of a Wall Truss placed on top of this Wall Truss as shown in
The Stacked Wall Truss Construction as illustrated in
The Stacked Wall Truss Construction enables the construction of multi-story buildings in a highly modular manner because, in addition to the modular Wall Trusses 100, the modular Floor Modules 161, 162, shown in
Traditional Types of Multi-Story Building Construction
There are several traditional types of multi-story building construction: Poured Concrete frame buildings, Pre-Cast Concrete frame buildings, conventional Structural Steel building frames, conventional wood frame buildings, and Masonry construction.
Poured Concrete Frame Buildings: In most parts of the world, poured-in-place concrete frame buildings are the norm. For each successive floor, columns are poured, a beam is poured on top of the columns to link the columns together, and then a floor is formed and poured on top of the beams and spanning between them to form a monolithic concrete frame. Vertical and shear loads from above are transmitted through the concrete floors downward to columns, beams, and floors in the structure below. This structure takes advantage of the huge compressive capacity of concrete in that, using the third floor as an example with a 20-story building, the vertical compressive loads and the shear loads associated with wind and earthquake of the 17 floors of the building above bear directly on and get transferred through the concrete third floor to the second floor below. Vertical reinforcing steel is placed, typically sticking up and out of columns to extend through beams and floors and into the columns above to provide for vertically continuous tensile strength, which the concrete by itself does not have. Tensile strength is a part of developing required shear strength in the frame of the concrete building.
Pre-Cast Concrete Frame Buildings: Concrete can be pre-cast into 2D or 3D shapes as a means to construct the frame of a structure. These are hoisted into position on the building and affixed together, most commonly via welding steel that spans from an embedded plate in one pre-cast member to a similar embedment in the adjacent pre-cast member. The pre-cast sections have the required structural capacity for vertical loads and shear, as do the connections between the pre-cast sections. Pre-cast frames can include columns, or else the vertical loads would be designed to be carried in wall sections.
Conventional Structural Steel Building Frames: Structural steel has enabled building construction to heights not formerly possible. Steel is a very high strength material, and has considerable strength in both tension and compression (unlike concrete which has just high compressive strength without reinforcing steel). With this high strength material, columns are customarily provided, most often at a significant spacing between them to create column-free open space on floors, and very importantly these columns stack on top of each other and are directly connected together. A continuous vertical load path results where loads transfer from column to column down through the building. This is totally different than the poured concrete frame where the columns are not continuous, as each floor separated them. Horizontal beams are provided that affix to columns, and these beams brace the columns, create shear capacity in the overall frame, and support floors by transferring the floor weight over to the columns. As buildings get tall, the columns get big, and the beam sizes need to grow to stabilize the vertical columns and to create shear capacity in the overall frame of the tall building. This works well. We are all familiar with the look of a structural steel framed building and the “heavy” scale of the column and beam framework, and the resultant ability to build high, wide open floor plans and also to create broad, open window sections in exterior walls.
Conventional Wood Frame: This building architecture became common when trees were sawn into dimensional lumber of consistent sizes. This enabled wood framing to proliferate in areas where forests are common.
Masonry Construction: Perhaps one of the oldest construction techniques is Masonry construction. Making bricks and then laying the bricks into walls is not only a historic practice but remains a common practice in modern construction. Masonry walls are used to create load bearing walls, where loads from above are supported by the masonry, and masonry walls are also utilized in non-load bearing configurations such as the in-fill walls of a poured concrete frame building. Masonry can develop relatively high compressive strength including both the bricks and mortar, but (unreinforced) masonry is a low strength material in tension. Accordingly, there are limitations in the application of Masonry construction; further, masonry is laid by hand so quality and appearance are inherently prone to variability.
Another distinction in types of multi-story construction is the use of trusses. This building component can be found in all four traditional types of multi-story building construction, and it is further described in the next section.
Basic Truss Technology
The Wall Truss 100 can be fabricated using either braced frames or moment frames from a structural standpoint. Shear loads in a braced frame are carried by bracing members; shear loads in moment frames are carried by the moment capacity of the connections between the members of the frame. In the present Stacked Wall Truss Construction, the Wall Trusses 100 are demonstrated using a Vierendeel truss configuration. Basic truss technology and Vierendeel truss characteristics are described below.
In engineering, a classic truss is a structure that consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object. A “two-force member” is a structural component where force is applied to only two points. Although this rigorous definition allows the members that form a truss to have any shape and be interconnected in any stable configuration, trusses typically comprise five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes. In this typical context, external forces and reactions to those forces are considered to act only at the nodes and result in forces in the members which are either tensile or compressive. For straight members, moments (torques) are explicitly excluded because, and only because, all the joints in a truss are treated as revolutes, as is necessary for the links to be two-force members.
A traditional planar truss is one where all the members and nodes lie within a two-dimensional plane, while a space truss has members and nodes extending into three dimensions. The top beams in a truss are called top chords and are typically in compression, the bottom beams are called bottom chords and are typically in tension, the interior beams are called webs, and the areas inside the webs are called panels. A truss consists of typically straight members connected at joints, traditionally termed panel points. Trusses are typically geometric figures that do not change shape when the lengths of the sides are fixed and are commonly composed of triangles because of the structural stability of that shape and design. A triangle is the simplest comparison, but both the angles and the lengths of a four-sided figure must be fixed for it to retain its shape.
A truss can be thought of as a beam where the web consists of a series of separate members instead of a continuous plate. In the truss, the lower horizontal member (the bottom chord) and the upper horizontal member (the top chord) carry tension and compression, fulfilling the same function as the flanges of an I-beam. Which chord carries tension and which carries compression depends on the overall direction of bending.
A variation of the planar truss is the Vierendeel truss which is a structure where the members are not triangulated but form rectangular openings and is a frame with fixed joints that are capable of transferring and resisting bending moments. Vierendeel trusses are rigidly-jointed trusses having only vertical members interconnected by the top and bottom chords which connect to a side of the vertical members which face adjacent vertical members and at a location a predetermined distance below the top of the vertical members. The chords are normally parallel or near parallel. Elements in Vierendeel trusses are subjected to bending, axial force, and shear, unlike conventional trusses with diagonal web members where the members are primarily designed for axial loads. As such, it does not fit the strict definition of a truss (since it contains non-two-force members); regular trusses comprise members that are commonly assumed to have pinned joints, with the implication that no moments exist at the jointed ends. The utility of this type of structure in buildings is that a large amount of the exterior envelope remains unobstructed and can be used for fenestration and door openings as shown in
Concrete Technology
Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement which hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as fondants. In Portland cement concrete (and other hydraulic cement concretes), when the aggregate is mixed together with the dry cement and water, they form a fluid mass that is easily molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix which binds all the materials together into a durable stone-like material. Often, additives (such as pozzolans or super plasticizers) are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials (such as rebar) embedded to provide tensile strength, yielding reinforced concrete. Thus, concrete can be poured into a form or column and will conform to the shape of the form, hardening in place to lock the elements in a durable stone-like material.
Stacked Wall Truss Construction
In this structure, each Wall Truss 1-4, as shown in
A sequential set of images to illustrate the construction method using the Wall Trusses of the present invention comprises
As shown in
Floor Modules
Floor Cross-Section
Roof
In the multi-story residential building application described herein,
Foundation
11F illustrate a mechanism that can be used to transition from the customary poured concrete foundation 170 and 171 (in
The distinction between the present Stacked Wall Truss Construction and the prior art grows with the design and construction of the floors and horizontal components of the building frame. The prior art structural steel frame had substantial horizontal beams framing into the individual steel columns, while the present Stacked Wall Truss Construction does not. By placing vertical Wall Trusses in an orthogonal arrangement, vertical Wall Truss Columns of the Wall Trusses that are perpendicular to one another are affixed together, thereby preventing “lay-over” of each Wall Truss in the opposite direction to its plane. So unlike traditional structural steel building construction that requires heavy steel beams to restrain horizontal movement of the individual steel columns, and to provide a frame with shear capacity, the geometry of the Stacked Wall Truss Construction of orthogonally positioned vertical Wall Trusses connected at their ends and also on Wall Truss Columns not on the end inherently controls and stabilizes the Wall Truss Column movement that would otherwise occur in plan view. Therefore, no heavy steel beams or customary individual column/beam structure is necessary to create a braced frame or Special Moment Frame. Instead, a dispersion of smaller Wall Truss Columns (as small as 6″×6″ in a 14-story building) is created and a dispersion of shear elements is created by virtue of a large number of Wall Trusses that each provide shear capacity, going both plan directions, resulting in an adequate level of aggregated shear capacity without the development of shear capacity in the classic individual steel column/beam frame.
The distinction grows further with the installed floors, which are Floor Modules of light gauge steel or joist types that are preassembled into a coordinated assembly that sits on top of the Floor Shelf located near the top of the Wall Trusses. The Floor Shelf is a tray for the Floor Modules. So when the Wall Trusses are installed on a particular floor of a building, a continuous Floor Shelf has been created in hallways, rooms, apartment units, and outdoor balcony areas such that the Floor Modules of the pre-made hallways, rooms, apartment units, and outdoor balcony areas can be lifted with the crane (where these pre-made Floor Modules are staged for assembly in close proximity to the crane) and they are quickly and efficiently dropped into place. There is no need to make a connection to the building frame before the crane can let go as the Floor Modules just rest on the Floor Shelf with no need for precise positioning. All these Floor Modules sit on a perimeter Floor Shelf of a given building area, and a gap is typically provided on 4 sides to enable easy positioning of the Floor Module, so just drop the Floor Module on the Floor Shelf and move on. Later, by hand or otherwise, the Floor Modules can be moved a bit one way or the other as needed by an inch or two to achieve desired alignment. It requires little skill and is difficult to install incorrectly. Then a concrete Topping Slab is poured on top of the Floor Modules to create a fireproof, soundproof, structural diaphragm, which can also be polished to be the finished floor surface. The resultant floors are implemented without a thick concrete slab capable of spanning across rooms as is present in the traditional poured-in-place concrete building, and also without the heavy individual steel column/beam frame as in classic structural steel construction.
From a structural steel design standpoint, the Wall Trusses can either be a “braced frame” or a “Moment Frame or Special Moment Frame.” As a braced frame, a diagonal piece of steel or other brace is installed in at least one bay of each Wall Truss. The diagonal functions as a shear brace in that Wall Truss, greatly increasing its capacity to resist folding in the direction of the Wall Truss. A Special Moment frame is created when, by virtue of just the geometry of the Wall Truss and its members and their connection together, the Wall Truss has shear capacity to resist laying over in the direction of the Wall Truss and functions with the inherent shear capacity of a Vierendeel Truss. Moment Frames flex in the cycle loading of earthquakes and with wind loading, as opposed to just being a rigid braced frame; therefore, Moment Frames tend to perform better and are preferred in tall multi-story buildings and in high seismic load areas. Both implementations work, and the architecture and design engineering of the present art can be either.
The Thin Concrete Wall Panel of the preferred embodiment of the multi-story building is either poured against the pre-made Wall Truss in an on-site forming system, or they are fabricated as another pre-made assembly that is simply affixed to the Wall Trusses. Either way, in the preferred embodiment of the present art, when you hoist a wall frame, it consists of the structural elements, installed utilities, walls, wall finishes, etc. There is no requirement to return to place hand laid brick as in-fill as is done in the traditional poured-in-place concrete buildings today. Hoist the Wall Trusses, place the Floor Modules, pour the Topping Slabs, connect the utilities that have been preinstalled in the Modular Elements at the Utility Interconnect Locations, then move onward and upward.
The present Stacked Wall Truss Constructions and their use in the construction of multi-story buildings departs from the traditional methods of constructing multi-story buildings by the use of prefabricated modular Wall Trusses that are interconnected in three dimensions to enable the rapid completion of building construction with improved quality of construction over that found in traditional multi-story building construction. Further, additional Modular Elements including Floor Modules and Kitchen Modules compliment the Wall Trusses to create a fully modular program of building construction that can be quickly and efficiently accomplished. The resultant building is really a structural steel frame without the use of traditional, heavy, individual stacking columns and beams, since the vertical Wall Trusses create smaller continuous vertical steel elements by virtue of the design configuration and vertical assembly of the Wall Trusses, thereby building construction becomes a process of stacking Wall Trusses, not individual, heavy steel columns and beams. An inner Wall Truss Column Mating Member can be placed hanging out of the bottom of each Wall Truss or sticking out of the top of lower Wall Trusses to enable a Wall Truss placement to be near perfectly positioned on top of the installed Wall Truss below.
Filing Document | Filing Date | Country | Kind |
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PCT/US2017/013902 | 1/18/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/146838 | 8/31/2017 | WO | A |
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5012622 | Sato | May 1991 | A |
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8720154 | Horne | May 2014 | B1 |
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1 174 724 | Mar 1959 | FR |
WO 2013086638 | Jun 2013 | WO |
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20190048573 A1 | Feb 2019 | US |
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62298054 | Feb 2016 | US |