Fastener for lightweight concrete panel and panel assembly

Abstract

The lightweight concrete panel is comprised of a thin concrete slab, a standard stud frame, optional insulation strips to increase its thermal performance for exterior wall applications, and specially engineered blind rivets or screws that connects the thin concrete slab to the metal frame. The specially engineered blind rivet has a protruding and shaped head that can act as an anchor when embedded in the hardened concrete slab and has an optional elastic cover in its embedded head to allow slight movement of the concrete slab. The engineered screw with an elastic cover can also be used as the connecting device that allow slight movement of the concrete slab.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lightweight concrete panel with a supporting steel frame and the device that connects the concrete facing to the steel frame.

2. Description of the Related Art

The following patents define the current state of the art:

Schilger, U.S. Pat. No. 4,602,467 describes a building panel with a supporting steel frame attached to a concrete slab. The attaching mechanism that connects the steel frame to the concrete slab is part of the stud members. The flange of one side of the stud member is punched and modified in various shapes intending to act as anchor when its entire side is embedded into the concrete slab. Because of the stud's flange embedment into the concrete, the panel is considered a composite panel where both the concrete layer and the steel frame plays important role on carrying load.

Schilger, U.S. Pat. No. 4,885,884 describes a building panel with a supporting steel frame attached to a concrete slab. The attaching mechanism that connects the steel frame to the concrete slab is part of the stud members. The attaching device of this panel is not one long section extending one whole side of the stud member like his earlier art U.S. Pat. No. 4,602,467. Instead, the multiple connecting devices are the intermittingly punched and bent portions in the C-section stud's flange. The punched and bent sections can be L-shaped, V-shaped, and T-shaped sections that run parallel to the stud member and extend into the concrete slab, acting as the connecting devices.

Ruiz, U.S. Pat. No. 6,151,858 has a similar concept as Schilger in U.S. Pat. No. 4,885,884. Ruiz's intermittingly punched and bent sections in the stud's flange have a different shape and bent direction. Ruiz's protruding L-shaped is narrower than Schilger and bent differently. Like Schilger's protruding sections, Ruiz's punched tabs are the connecting devices that are part of the stud member.

Bodnar, U.S. Pat. No. 4,909,007 has a similar concept as Schilger, U.S. Pat. No. 4,602,467. One entire side of the C-section stud is punched and bent into one L-shaped flange, forming one long integrated attaching device to be embedded into a concrete slab. The differences in Bodnar's art are the openings in the embedded L-shaped junction flange and the large opening in the stud web area. The openings in the embedded junction flange are claimed to enable material to flow through and form a stronger concrete in the local region. The large openings in the stud web are meant to limit the thermal conductivity from one side to the other through reducing the thermal pathway or steel area in the stud web.

There are three major problems that associate with all mentioned arts: first is that they will need specially designed machinery to create such special stud with integrated connecting mean; second is their poor thermal performance; and third is the meeting of the building code specifications. Generally, the cost of specially engineered machinery to produce such modified stud is expensive and prohibiting. The thermal performance of Ruiz's and Schilger's wall panels is poor due to the direct material contact between the stud flange and the exterior concrete slab. Metal has high temperature conductivity and the heat from the exterior concrete flows right though the metal material of the stud to the inside stud flange. Although Bodnar's opened web stud is an improvement in reducing thermal conductivity in the stud web, the cost of machinery that produces the openings in stud web is expensive and prohibiting due to its complex process. Bodnar's opened web stud is an improvement, but the bottom and top tracks in his steel frame still have solid web so the panel still has poor thermal performance in those areas of the panel. In load-bearing applications, Bodnar and Schilger's wall panel will not meet the current International Building Code specifications in many parts of the country and the world. Little is known about the composite action between the concrete slab and the steel frame in their design. There is no guidance in the code specifications to cover such panel constructions. Assuming any unique composite panel is tested and proven to have structural properties, the submitting of its data and getting it specified in the code specifications can be a very long and costly process. The wide adoption of any unique composite panel is very unlikely because code specifications are written to encompass a type of construction not of any specific product. Previous arts overlooked these three major issues. The present invention was developed to overcome these major problems inherent in all prior arts.

SUMMARY OF THE INVENTION

This invention is of a panel construction and the unique components that make it. The lightweight concrete panel is comprised of a thin concrete slab, a standard stud frame that can be load-bearing or non-load-bearing that is well studied and known to be in International Building Code specifications, optional insulation strips to increase its thermal performance for exterior wall applications, and unique blind rivet or screw that connects the thin concrete slab to the metal frame.

The standard steel studs in the supporting frame are manufactured by ordinary roll former or automated roll former with rivet or screw holes punched in stud flange. The optional insulation strip is ⅛″ to 1″ thick, extruded foam strip with adhesive backing. The insulating foam can be made from different materials to have the desired insulating properties. Some rigidity is preferred for easy handling during manufacturing process. The insulating strip can have marking or pre-punch holes that will align with the hole in the stud flange for easy installation. The specially designed blind rivet with extending body is the preferred connecting device that connects the concrete slab to the supporting steel frame. The steel stud frame can have steel shear bracing in the interior side of the frame to meet shear load requirements as specified in building code specifications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the basic construction of present invention with its components.

FIG. 2 illustrates the unique blind rivet as a separate connecting device that connects concrete slab to the steel frame.

FIG. 3 illustrates a cross-section of the blind rivet shown in FIG. 2.

FIG. 4 illustrates a cross-section of an exterior wall panel shown in FIG. 1 with its components.

FIG. 5 illustrates a cross-section of an interior panel where the insulating strip is unnecessary.

FIG. 6 illustrates a cross-section of an interior panel where a tampered head screw with elastic sleeve is the connecting device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an embodiment of the invention very well. The concrete panel (1) is comprised of a standard steel stud frame (20) with pre-punch holes (21) for concrete-to-stud connectors in each standard C-section stud (22), a thin ordinary concrete slab with steel mesh reinforcement or a very thin ECC (engineered cementitious composite) concrete with high amount of micro fibers as the primary reinforcement (10), optional insulating strips (30) made of various extrudable materials with high insulating property in exterior wall application, optional steel shear bracing (23) in the interior side of the frame (20) when load-bearing is required, and the specially designed blind rivet (40) as the preferred connecting device that connects the concrete slab (10) to the steel studs (22) of the steel frame (20).

The usage of standard shaped stud (22) of heavy gauge steel and size and steel shear bracing (23) in the steel frame (20) will allow the panel to meet the building code specifications readily and will require no specialized machinery or additional machine to modify the stud flange. The blind rivets or screws (40) attached to the standard studs are not designed to carry the bulk of the panel's shear load. The steel shear bracing (23) of the wall panel (1) is designed to be the main support in load-bearing applications. Also, in utilizing the standard stud frame system, one can use the latest labor-saving technology like automated roll forming technology from FRAMECAD Group (a New Zealand company) to improve in the stud frame manufacturing process at relatively low cost. The preferred manufacturing process would require an automated roll former that can cut to size both studs and tracks, and punch holes for rivets (40) in each stud. When this technology is applied, complexity of process and labor cost is greatly reduced.

The insulating strip (30) is designed to limit the thermal conductivity in the stud flange area. Its has the width of the stud flange, thickness between 1/16″ to 1″, made of various insulating materials, has adhesive backing, and has enough rigidity to counter the weight pressure of the concrete slab when the panel is lifted or moved. In exterior applications, this insulating strip will greatly increase the panel's thermal performance. The preferred strip (30) can be extruded rigid foam and has pre-punched holes or marking on strip surface for connector rivets (40) to go through.

The preferred concrete-to-steel connecting device in the embodied panel is the special designed blind rivet (40). The blind rivet (40) has a protruding and modified rivet head (41) that allows it to anchor in the concrete and has an optional rivet cover (43) over the rivet head (41). The protruding rivet head (41) can have various shapes that allow it to act as an anchor in the hardened concrete. The simplest rivet head (41) shape is of a cone shape as shown in FIG. 3 and FIG. 4. The rivet cover (43) is made from various thermal plastic or elastic materials such as silicon or rubber. The usage of various thermal plastic covers in steel anchor is a general practice to help reduce the steel corrosion and reduce a little of thermal conductivity between the steel body and the concrete. The protective cover (43) may not be necessary if the rivet head (41) is made of stainless steel and the concrete slab (10) is sufficiently restrained with steel mesh reinforcement in standard concrete. However, when the concrete slab (10) is made of ECC (engineered cementitious composite) concrete and has only micro-fiber as the primary means of reinforcement dry shrinkage of the concrete material causes the concrete slab (10) to shrink and move slightly. The rivet cover (43) is necessary and it must be made of an elastic material with the firmness and thickness to allow the concrete slab or plate (10) to move and reduce any internal stress of the concrete slab (10). If the shrinking concrete slab (10) is restrained the internal stress will crack concrete slab (10). This usage of elastic cover in any type of concrete anchor is novel and necessary to reduce internal stress of the concrete slab (10). The blind rivet (40) is the preferred connecting device because it has greater pull strength or holding strength and it is easier and faster to install. In cases, where the hold strength of connecting device is not critical and the concrete slab (10) has slight shrinkage movement, the modified head screw (50) with the elastic covering (51) can be used as illustrated in FIG. 6.

Claims

1. A lightweight and thermal efficient concrete panel comprising: (a) a concrete slab; (b) a standard metal stud frame with a plurality of parallel spaced apart steel stud members; (c) insulating strips with adhesive backing; and (d) specially engineered blind rivets or engineered screws with elastic cover as the concrete-to-frame connecting devices.

2. A lightweight and thermal efficient concrete panel according to claim 1 wherein the insulating strips with adhesive backing are made of any extrudable insulating material having thickness at least 1/16″ and width equal to or greater than the stud flange.

3. A lightweight and thermal efficient concrete panel according to claim 1 wherein the metal stud members of the standard metal stud frame are the standard C-section or U-section studs with pre-punched holes for blind rivets or screws to go through.

4. A lightweight and thermal efficient concrete panel according to claim 1 wherein the engineered blind rivet is made of any type of steel, has a protruding and shaped head to act as anchor embedded in the concrete slab, and has an optional elastic cover over its head that allows the concrete slab to move slightly.

5. A lightweight and thermal efficient concrete panel according to claim 1 wherein the engineered screw has an elastic cover over its embedded head to allow slight movement of the concrete slab.

6. A lightweight concrete panel comprising: (a) a concrete slab; (b) a standard metal stud frame with a plurality of parallel spaced apart steel stud members; and (c) specially engineered blind rivets or engineered screws with elastic covers as the concrete-to-frame connecting devices.

7. A lightweight concrete panel according to claim 6 wherein the metal stud members of the standard metal stud frame are the standard C-section or U-section studs with pre-punched holes for blind rivets or screws to go through.

8. A lightweight concrete panel according to claim 6 wherein the engineered blind rivet is made of any type of steel, has a protruding and shaped head to act as anchor embedded in the concrete slab, and has an optional elastic cover over its head that allow the concrete slab to move slightly.

9. A lightweight concrete panel according to claim 6 wherein the engineered screw has an elastic cover over its embedded head to allow slight movement of the concrete slab.

10. A steel blind rivet used as a concrete-to-steel frame connecting device wherein the rivet has a protruding and shaped head that acts as an anchor when the head is embedded in the concrete.

11. The blind rivet according to claim 10 wherein the rivet has an elastic cover over the embedded head to allow slight movement in the concrete slab.