Abstract:
A hybrid framed curtain wall panel is used to prevent inter-floor fire propagation from both the interior and exterior, featuring the combined use of three different infill materials for three different functions. The first infill is a continuous exterior fire-resistant thin pane for providing an aesthetic element and for preventing exterior inter-floor fire propagation. The second infill is a small band of fire-resistant material, such as mineral wool panel infill, located at the slab edge for preventing interior inter-floor fire propagation. The third infill is a structural infill, such as composite foam panel infill, to provide a light-weight material with excellent thermal insulation value.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention is related to the building envelope system design applicable to an exterior wall panel design for preventing inter-floor fire propagation from both the interior and exterior. 
       BACKGROUND OF THE INVENTION 
       [0002]    An exterior wall is formed by multiple wall units joined and sealed between two adjacent wall units in both horizontal and vertical directions. The major functions of an exterior wall include the aesthetic design provided by the project architect and the interior environmental protection design provided by the exterior wall system designer or supplier. It is well recognized in the industry that a product known as composite foam panel (CFP) has a superior strength to weight ratio as well as thermal insulation value. A CFP comprises two thin structural skins with structural foam sandwiched in between the two skins. The most popular skin material is thin gauge steel or aluminum coil cold-rolled into the panel side joint profile. The CFP is produced by either a foamed-in-place or a laminating process. 
         [0003]    Due to the good insulation value provided by the foam core, significant solar gain on the exterior skin may result in a significant temperature differential between the two skins, resulting in two potential aesthetic problems known as thermal blistering caused by interface air pockets within the foam core and thermal rippling due to thermal stress. 
         [0004]    In addition, the structural foam core is a combustible material. Even if fire retardant is added to the foam system, a separate fire barrier using noncombustible material behind the foam panel must be installed to stop inter-floor fire propagation. There are also composite panels available in today&#39;s market using a noncombustible core material known as mineral wool panel (MWP), comprising a mineral wool core bonded to two noncombustible structural skins such as thin steel skins for stopping inter-floor fire propagation. However, MWP is inferior to CFP in many aspects, including: (1) MWP is heavier; (2) MWP is weaker in structural strength; (3) MWP has a lower thermal insulation value; (4) the mineral wool core in MWP is water-absorbent, requiring a more elaborate sealing method along the panel side joint and the panel butt joint; (5) the exterior aesthetic features of MWP are more limited and often not compatible with a desirable CFP, therefore, it is rare to use both CFP and MWP on the same elevation. 
         [0005]    It is desirable for a panel design to stop inter-floor fire propagation that incorporates the performance advantages of both CFP and MWP without the problems of both CFP and MWP. 
       SUMMARY OF THE INVENTION 
       [0006]    Preferred aspects of the invention provide a hybrid framed wall panel by glazing into the panel frame a wall panel having three different types of infills (1) an exterior aesthetic and fire-resistant or non-combustible infill, (2) a first interior fire-resistant infill, such as MWP infill or an inorganic foam material disclosed in U.S. Pat. No. 9,365,457 (the entire content of which being hereby incorporated by reference), at the slab edge location, and (3) a second interior structural infill such as CFP infill at the remaining locations within the wall panel. It will become apparent from the following description of the preferred aspects of the present invention that the hybrid framed wall panel will stop inter-floor fire propagation without many of the problems of CFP and MWP. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate aspects of the invention and, together with the description, serve to explain the principles of the invention. 
           [0008]      FIG. 1  shows the front (exterior) view of a typical hybrid framed wall panel of the present invention. 
           [0009]      FIG. 2  shows one embodiment of the cross-section taken along Line  2 - 2  of  FIG. 1 . 
           [0010]      FIG. 3  shows one embodiment of the cross-section taken along Line  3 - 3  of  FIG. 1 . 
           [0011]      FIG. 4  shows one embodiment of the cross-section taken along Line  4 - 4  of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]      FIG. 1  shows the front (exterior) view of a typical hybrid framed wall panel  10  of the present invention. The panel frame is formed from a head frame member  11 , two jamb frame members  12 , and a sill frame member  13 . A wall panel having a continuous fire-resistant exterior infill  14  is glazed into the panel frame. With respect to the fire-resistant exterior infill  14 , the term “continuous” means that fire-resistant material covers the entire area of the wall panel that is exposed to the exterior. 
         [0013]      FIG. 2  shows one embodiment of the cross-section taken along Line  2 - 2  of  FIG. 1  for an erected hybrid framed wall panel. As shown, the head frame member  11  and the sill frame member  13  are for the preferred airloop system. A short piece of an interior MWP infill  15  is located near the edge of a floor slab  17  and butted against inter-floor fire safing  18 . Two interior CFP infills  16   a  and  16   b  are butted with the MWP infill  15  to form butt joints  19  to complete the interior infill structure. The interior butt joints  19  are air sealed with noncombustible caulking such as silicone caulking. If a fire started under the floor slab  17 , the CFP infill  16   a  could catch on fire. However, interior inter-floor fire propagation will be stopped by the combination of the MWP infill  15  and the fire safing  18 . If a fire extends to the exterior side of the building due to a broken window below the sill panel frame  13 , exterior inter-floor fire propagation is prevented by the continuous fire-resistant or noncombustible exterior infill  14 . When an airloop system is used as shown, the air space between the panel frame and the infill are open to the exterior air. Therefore, any moisture that infiltrates into the core of the MWP infill  15  during a rain storm will be quickly dried out after the storm. 
         [0014]    Because the continuous exterior infill  14  conceals the butt joints  19  from exterior view, the exterior aesthetic problem for the mixed usage of CFP and MWP infills is solved. Due to the combination of a relatively small area of MWP infill  15  and a relatively large area of CFP infills  16   a  and  16   b,  the advantages of light weight and good thermal insulation value of CFP are largely kept. Further, no additional interior fire barrier behind the CFP infills  16   a  and  16   b  is required to stop interior fire propagation. Therefore, a significant cost saving can be achieved if the interior skin surfaces of the CFP infills  16   a  and  16   b  are used as the finished interior wall surface. The butt joints  19  may be hidden in the spandrel area. Alternatively, the butt joints  19  may be hidden from interior view by glazing in a continuous fire-resistant interior infill (not shown), similar to the exterior infill  14 , behind the MWP infill  15  and the CFP infills  16   a  and  16   b.  With respect to this continuous interior infill, the term “continuous” means that the fire-resistant material covers the entire area of the wall panel that is exposed to the interior. 
         [0015]    The location of the MWP infill  15  depends on the location of the floor slab. Therefore, although  FIG. 2  depicts an embodiment with the MWP infill  15  in the center of the wall panel, the MWP infill in other embodiments may be located elsewhere in the wall panel for placement at the edge of a floor slab. 
         [0016]      FIG. 3  shows one embodiment of the cross-section taken along Line  3 - 3  of  FIG. 1 . As shown, the jamb panel frame members  12  of an airloop system are strong structural members more than adequate to support the combination of the exterior infill  14  and the interior MWP infill  15  spanning between the two jamb panel frame members  12 . In a common curtain wall grid line design, the panel width is the minimum panel dimension, typically 48″ (1.22 m). Even though the structural strength of the MWP infill  15  is much less than that of the CFP infill  16   a  or  16   b,  it is more than adequate to span the width direction. Therefore, the structural problem of using an MWP is obviated. 
         [0017]      FIG. 4  shows one embodiment of the cross-section taken along Line  4 - 4  of  FIG. 1 . This cross-section is similar to that shown in  FIG. 3 , except the strong CFP infill  16   b  is shown instead of the MWP infill  15  shown in  FIG. 3 . 
         [0018]    Even though a typical airloop panel frame is used in illustrating the present invention, some of the design features can be used in other systems to achieve the function of stopping inter-floor fire propagation. 
         [0019]    Nothing in the above description is meant to limit the present invention to any specific materials, geometry, or orientation of elements. Many modifications are contemplated within the scope of the present invention and will be apparent to those skilled in the art. The embodiments described herein were presented by way of example only and should not be used to limit the scope of the invention. For example, other fire-resistant infills, such as the inorganic foam materials described in U.S. Pat. No. 9,365,457, may be used in place of the MWP infill used in the above-described embodiments and shown in the figures. 
         [0020]    The present invention is also directed to the following clauses. 
         [0021]    Clause 1: A hybrid framed curtain wall panel comprising: an exterior fire-resistant infill; a first interior infill comprising a band of fire resistant infill, the first interior infill being located for placement at the edge of a floor slab; and a second interior infill comprising a structural infill. 
         [0022]    Clause 2: The hybrid framed curtain wall panel of clause 1, wherein the exterior fire-resistant infill comprises a continuous fire-resistant thin pane. 
         [0023]    Clause 3: The hybrid framed curtain wall panel of any of clauses 1 or 2, wherein the band of fire resistant infill of the first interior infill comprises a mineral wool panel infill. 
         [0024]    Clause 4: The hybrid framed curtain wall panel of any of clauses 1-3, wherein the band of fire resistant infill of the first interior infill comprises an inorganic foam material. 
         [0025]    Clause 5: The hybrid framed curtain wall panel of clause 4, wherein the inorganic foam material is formed by a low-temperature process that comprises mixing a glass and a cement to form a raw material of inorganic foam material, forming a gas inside the raw material of inorganic foam material by a foaming agent, and forming an inorganic foam material made from the glass and the cement. 
         [0026]    Clause 6: The hybrid framed curtain wall panel of any of clauses 1-5, wherein the structural infill of the second interior infill comprises a composite foam panel infill. 
         [0027]    Clause 7: The hybrid framed curtain wall panel of any of clauses 1-6 further comprising a fourth infill, wherein the fourth infill comprises a continuous interior fire-resistant infill. 
         [0028]    Clause 8: The hybrid framed curtain wall panel of any of clauses 1-7, wherein the first interior infill and the second interior infill are sealingly adjoined. 
         [0029]    Clause 9: The hybrid framed curtain wall panel of any of clauses 1-8, wherein the first interior infill and the second interior infill are adjoined with silicone. 
         [0030]    Clause 10: The hybrid framed curtain wall panel of any of clauses 1-9, wherein a floor slab is adjoined to an inter-floor fire safing and wherein the first interior infill is adjoined to the inter-floor fire safing.