Patent Publication Number: US-2020299963-A1

Title: Structural steel lintel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     See Application Data Sheet. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB) 
     Not applicable. 
     STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an improved building method and in particular to improvements in structural steel beam design for lintels in Low Rise Residential Buildings. 
     2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
     In residential building construction, there are a lot of different sized openings in external and internal walls. The openings are used to accommodate doorways, windows and accessways. The openings generally require a structural lintel to span over it and additional post supports either side as required to support the loading from the lintel. 
     Many different lintel types are used, including flat steel bars, structural angles and Tee section, as well as fabricated structural beam and plate for larger spans. 
     In brick veneer construction, a lintel is employed to span openings in single and double garages. The single car garage opening is generally under 3000 mm width and a structural steel T bar lintel  200  (see  FIGS. 1 and 4   b ) is deployed across the opening to support a double brick wall on top. The T lintel  82  is supported either side of the opening by double brick walls  84 , nominally 230 mm thick, comprising 230×76×110 mm wide bricks side by side. 
     In this application, the Tee lintel  82  is generally 200 mm wide with a vertically and centrally located steel plate  83 , the overall width of the brick wall does not change and when the brickwork is completed, both the inside of the garage wall and the outside of the building is complete and uniform. In some cases, the inside of the garage wall is cement rendered and at other times is left as face brick. 
     The application of T bars  82  as lintels is generally limited to lightly loaded openings and smaller spans, because the strength of the lintel is determined by the number of brick courses on top of the lintel, and the quality of the bond between the lintel and the brickwork. 
     Referring to  FIGS. 2 to 4   a , in more heavily loaded conditions and larger spans found in double garage openings, the lintels need to be designed as structural beams. These beams need to be fabricated, comprising a structural plate  92  on the base designed to carry the external brick, and is welded at points  93  to a structural beam  94 , normally in the shape of a C section, called a Parallel Flange Channel (PFC). In the resulting composite beam, the plate  92  is designed to carry external brick loads  96 , and the PFC  94  carries the internal wall, roof and first floor loads  98 . 
     The lintel is commonly called a PFC and plate 200 mm (width)×10 mm (thickness), and can be designed with wider plates and varying PFC depths to cater for a range of lintel applications. 
     When used in garage openings incorporating 230 mm wide brick walls, the PFC channel generally has a commercially available 200 mm wide by 10 mm thick structural steel hot rolled plate. In most applications, the fabricated lintel is hot dipped galvanised to comply with durability requirements in the Building Code. 
     The external brickwork rests on the protruding plate which is no thicker than the mortar course and this allows the external wall to be finished seamlessly with the rest of the external wall, to the underside of the roof eaves lining. The PFC and plate is all but concealed from the outside except for the edge of the plate and its underside exposed to the opening. 
     On the inside, however, the wall is difficult to finish with brick and the exposed beam is normally painted and invariably looks unfinished. There are a number of reasons why the inside wall cannot be finished with brickwork. Firstly, the PFC is located so that it can support the internal timber walls or brickwork subsequently installed on its top flange, which means the web of the PFC  94  is off centre from the centreline of the 200 mm wide steel plate  92  at its base. This eccentric positioning of the PFC relative to the plate  92  means that a brick cannot be installed to the inside of the PFC to be in line with the face of the internal wall. Secondly, the flange thickness of the PFC is larger than the mortar course thickness. Thirdly, the bottom flange of the PFC  94  is now combined with the thickness of the plate  92 , which means the bricks would now need to be cut to maintain the brick course above, which is extra work by the bricklayer, and lastly, the inside vertical dimension between the flanges of the PFC do not correspond to brick gauge, or the height of a uniform brick wall that will neatly fit between the beam flanges without cutting the bricks. 
     The present invention seeks to overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative. 
     It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides a lintel comprising a beam structure having a top flange and a bottom flange with a web extending therebetween, the beam having an internal depth extending from an internal surface of the top flange to an internal surface of the bottom flange, the internal depth being equal to the sum of the number of brick courses to be received between the top and bottom flanges multiplied by the depth of a brick plus the depth of mortar courses between the brick courses. 
     In one embodiment, the top and bottom flanges each have a thickness substantially equal to the depth of a mortar course. 
     In another embodiment, the web has a thickness not greater than the depth of a mortar course. 
     In another embodiment, the top flange is narrower than the bottom flange. 
     In another embodiment, the top flange is offset relative to the web. 
     In another embodiment, the top flange is centrally located relative to the web. 
     In another embodiment, the lintel further comprises spaced holes in the web at heights corresponding to the mortar courses. 
     In another embodiment, the width of the bottom flange is less than the sum of the widths of two bricks plus a vertical mortar joint between them. 
     In another embodiment, the top and bottom flanges have a thickness of 10 mm and the web has a thickness of no greater than 10 mm. 
     In another embodiment, the bottom flange width is 200 mm to 210 mm. 
     In another embodiment, the web is disposed to extend from corresponding aligned side edges of the top flange and the bottom flange. 
     In another embodiment, the further comprises spaced holes in the top flange 
     In another embodiment, the upper and lower flanges have a thickness of 5 mm. 
     In another embodiment, the bottom flange width is 100 mm. 
     In another embodiment, the beam has an external depth extending from an external surface of the top flange to an external surface of the bottom flange, the external depth being equal the sum of the number of brick courses to be received between the top and bottom flanges multiplied by the depth of a brick, plus the number of brick courses multiplied by a mortar course depth, plus the depth of the top flange. 
     The present invention also provides an assembly comprising the lintel of any one of the above and brick and mortar courses disposed between the internal surfaces. 
     In another embodiment, the lintel further comprises tie-down formations along the top surface of the top flange. 
     In another embodiment, the tie-down formations comprise lugs mounted in a spaced manner along the top surface. 
     In another embodiment, the lugs comprise upside down U-shaped rods with ends thereof mounted by welding to the top surface. 
     The invention also provides an assembly comprising the lintel of the above and metal straps fed through the tie-down formations, wherein ends of the straps can be attached to a timber plate or a roof truss. (the roof structure). 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a typical T-bar with bricks laid on it. 
         FIG. 2  is another sectional view of a typical PFC and plate section showing brickwork and open PFC to the inside of the wall. 
         FIG. 3  is a sectional view of a typical PFC and plate with external brickwork and timber wall on top of the PFC and open PFC. 
         FIG. 4A  is a sectional view of a typical PFC and plate section. 
         FIG. 4B  is a sectional view of a typical T-bar section. 
         FIG. 5  is a cross-sectional view of the proposed lintel of the invention according to a first embodiment with holes in the web for a  3  brick course configuration. 
         FIG. 6  is a cross-sectional view of the proposed lintel of the invention according to the first embodiment showing brickwork and the concealed lintel top flange and web. 
         FIG. 7  is a partial isometric perspective view of the lintel of the first embodiment showing the equi-spaced holes for a 3 course brick beam. 
         FIG. 8  is a partial isometric perspective view of the lintel of the first embodiment showing a typical configuration of a 3 course lintel, with several bricks of the first course laid, with a shear connector bedded in the first hole and a brick tie in the second hole in the first mortar course. 
         FIG. 9  is a cross-sectional view of the proposed lintel of the invention according to a second embodiment with a centrally located top flange of lesser width showing brickwork and the concealed lintel top flange and web. 
         FIG. 10  is a cross-sectional view of the proposed lintel according to the second embodiment. 
         FIG. 11( a )  is a cross-sectional view of a prior art structural angle lintel with bricks mounted thereon. 
         FIG. 11( b )  is a cross-sectional view of a C-section lintel according to another embodiment of the invention with bricks mounted thereon, this embodiment dimensioned to receive one course. 
         FIG. 11( c )  is a cross-sectional view of a C-section lintel with bricks mounted thereon according to another embodiment. 
         FIG. 11( d )  is a cross-sectional view. 
         FIG. 11( f )  is a perspective view of this lintel, this embodiment dimensioned to receive two courses. 
         FIG. 11( e )  is a cross-sectional view of a C-section lintel with bricks mounted thereon according to another embodiment, this embodiment dimensioned to receive three courses. 
         FIG. 12( a )  is a cross-sectional view of a lintel with bricks mounted thereon according to another embodiment. 
         FIG. 12( b )  is a cross-sectional view of this lintel, this embodiment dimensioned to receive two courses. 
         FIG. 12( c )  is a cross-section of a lintel with bricks mounted thereon according to another embodiment, this embodiment dimensioned to receive three courses, 
         FIGS. 13 ( a - c ) show a lintel according to another embodiment with spaced lugs along the upper flange where  FIG. 13( a )  is an end elevation view,  FIG. 13( b )  is a side elevation view, and  FIG. 13( c )  is a perspective view. 
         FIGS. 14 ( a - c ) show the lintel of  FIGS. 13 ( a - c ) in an example use where  FIG. 14( a )  is an end elevation view,  FIG. 14( b )  is a perspective view, and  FIG. 14( c )  is a close up end elevation view of the top portion of the lintel with a metal strap. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 5 and 7  show a structural lintel  10  according to a first preferred embodiment of the present invention. The lintel  10  is similarly shaped as an I-beam having a horizontal lower (or bottom) flange  12 , a horizontal upper (or top) flange  13  and a vertical web  14  extending therebetween. The flanges  12  and  13  are parallel with the web  14  extending therebetween. The flanges  12  and  13  and the web  14  form spaces  19   a  and  19   b,  at respective lateral sides of the web  14 . 
     Unlike a typical I-beam where the upper and lower flanges are similar in width, the upper flange  13  is narrower in width than the lower flange  12 . The edges of the upper flange  13  are disposed inwardly of the edges of the lower flange  12 —that is, the edges of the upper flange  13  do not extend past the respective edges of the lower flange  12  (as can be seen from the end view in  FIG. 5 ). 
     Further, the upper flange  13  is offset to one side of the web  14  as viewed from the cross-section. The space  19   a  to one side of the web  14  thus has more of the upper flange  13  forming it than the space  19   b  to the other side of the web  14 . 
     The upper and lower flanges  12  and  13  have a thickness of 10 mm and the web  14  also has a thickness of 10 mm, for reasons described below. 
     Referring to  FIG. 6 , the depth of the lintel  10  is determined by the height of the web  14 . The height of the web  14  is chosen such that the internal depth, being the distance between the facing internal surfaces  12   i  and  13   i  of the lower flange  12  and the upper flange  13  is equal to: 
       Number of brick courses (N)*Depth of each brick in mm (D)+(N−1)*Mortar Course Thickness in mm (M)
 
     Where N≥2 
     N is the number of brick courses, with a minimum of 2 courses. 
     D—Depth of each brick is typically 76 mm, but can vary 
     M—mortar course thickness is generally 10 mm. 
     The lowermost and uppermost brick courses abut against the internal surfaces  12   i  and  13   i  of the lower flange  12  and the upper flange  13  respectively, with mortar having a typical thickness of 10 mm therebetween. As the brick courses abut the flanges  12  and  13 , there is one less (N−1) number of mortar layers between the flanges  12  and  13 . Thus, only the depth of the mortar course between two courses of bricks are part of the calculation. 
     A standard brick course is equivalent to the depth of a brick (commonly 76 mm) plus a mortar course thickness generally of 10 mm, which equals 86 mm/course. The top flange  13  of the lintel is considered a mortar course. 
     The internal distance between the top and bottom flange  13  and  12  of the lintel  10  is equivalent to the number of courses (greater than or equal to 2), less the flange equivalent to a mortar course (10 mm). The distance between internal surfaces  12   i  and  13   i  for 2 course, 3 course and 4 course lintels are 162 mm (86 mm×2-10 mm), 248 mm (86 mm×3-10 mm) and 334 mm (86 mm×2-10 mm) respectively. 
     The overall depth of a lintel  10  is the distance between external faces of the lower and upper flanges. This is thus the distance between the internal surfaces noted above, plus the thicknesses (10 mm each) of the lower and upper flanges. For 2 course, 3 course and 4 course lintels, the overall depths are 182 mm, 268 mm and 354 mm respectively. 
       FIG. 6  shows an example of a 3 course depth lintel  10  with bricks  200  and mortar layers  210 . The lintel  10  comprises a series of spaced holes  17  formed along the web  14  which are at a height corresponding to the mortar layers  210 . 
     The space  19   a  is designated for the inside wall and the space  19   b  is for the outside wall. The top flange  13  has a width designed to allow a maximum brick overhang on the inside wall of 25 mm to comply with building regulations, as well as provide sufficient mortar cover to the edge of the flange  13  when the mortar joint between the brick under the flange and the brick above it, is ironed. 
     The part of the top flange  13  projecting partway onto the external brick skin  230  is designed to provide the maximum opportunity for the bricklayer to align the face brick to coursework by tilting the brick up or down with minimal interference from the top flange  13  on that side. The part way projecting flange also maximises the mortar bed width on the external side of the brick wall  230  for durability. The top flange thickness is the same as the mortar course, and is generally 10 mm. 
     The bottom flange  12  width is preferably 210 mm so that the brick course overhang of the plate each side is a maximum 10 mm and the holes through the brick are not visible along the side of the flange, however the more commonly available width is 200 mm. The bottom flange plate thickness is 10 mm. 
     Connecting the top flange  13  to the bottom flange  12  is a vertical and perpendicular web  14 . The web  14  is centrally located on the bottom flange  12 , which for a 210 mm wide flange gives a centreline distance of 105 mm from each edge of the flange. The web thickness is less than or equal to 10 mm, so when bricks are laid against each side the overall wall thickness of 230 mm can be obtained without cutting down the commonly available 110 wide brick. The web  14  is offset from the centre of the top flange  13  so that wall support, alignments and mortar cover to the flange sides is achieved. 
     Referring to  FIG. 8 , holes  17  are equi-spaced along the web and aligned centrally to the axis of the mortar course between brick courses. The holes are used for brick ties  31  access from front of the lintel to the back (from the space  19   a  to  19   b ), so the brick wall is tied together. Where required, shear connectors  32  are deployed in the holes  17  and into the mortar beds of the brickwork each side of the lintels so shear forces can be transferred from the beam  10  into the brickwork, increasing the overall strength of the lintel. 
     Referring to  FIGS. 9 and 10 , another aspect to the present invention is a lintel  10   b  with a centrally located orthogonal web  14  on a bottom flange  12 . The lower flange  12  is as wide as a brick-wall width less a small amount for brick overhang (generally 20 mm maximum) on each side. The lintel  10   b  includes a centrally located top flange  13  of lesser width than the bottom flange  12 . The width of the top flange  13  is sufficient to maximise the bricklaying access as well as the structural capacity of the beam as compared with prior art PFC and plate welded composite structural beams. 
     The lintel of the invention is sized to suit brick coursework, with flange thickness matching the mortar course thickness. The shape of the lintel enables brickwork to be installed both sides of the lintel to create a finished wall on each side. The top flange of the lintel is concealed within the brick mortar course. 
     The preferred embodiments of the invention provide an improved design for a structural garage lintel which:
         1. Has a number of lintels whereby each lintel depth measured between the bottom flange and the top flange matches the corresponding depth of two or more brick courses minus a mortar course.   2. Have a flange thickness in its preferred embodiment common to all lintel sizes and less than or equal to the generally accepted mortar course thickness of 10 mm.   3. Have beam strengths increased or decreased by varying the depth of the beam in multiples of brick coursing minus a mortar course between the flanges of the lintel   4. Standardise the top flange width of each lintel so that there is sufficient strength capacity to the beam and sufficient mortar cover to conceal its edges.   5. Has holes equi-spaced along the web corresponding in height with the mortar course of the brickwork, which can allow brick ties to be installed between the external and internal skin of brickwork.   6. Has holes equi-spaced in the web corresponding to the brick mortar coursing which can also be used to install a steel shear connector, which can be employed to improve the composite strength of the beam due to brickwork.   7. Doesn&#39;t need individual web stiffeners welded within the beam at locations where it supports other intersecting beam loads, and at the lintels support each side of the opening, due to direct loading and transfer of the loading into the brickwork sandwiched between the top and bottom flanges of the lintel.       

     The present invention aims to overcome the disadvantages of garage lintel technology by providing a structural lintel which combines all the construction advantages of a T bar lintel combined with the structural capacity of a steel beam. 
     The web thickness in the lintel beams in the examples are 10 mm, but this can be varied and can be thinner. The preferred maximum width is 10 mm, which is the perp mortar joint thickness between 2 off bricks laid side by side, giving a 230 mm wide wall. This wall is made from 2×110 mm wide bricks plus the central perp mortar joint between them (now replaced by the web of the beam). The web can be a little thicker and can be smaller if structurally adequate. Other example web thickness include 6.23 mm and 8 mm etc, the thickness governed by strength considerations and economy. 
     As mentioned above, the industry employs structural angles  140  as lintels as shown in  FIG. 11( a ) . 
       FIGS. 11( b )  to  FIG. 12  show structural angle lintel/brick assemblies and variations thereof that will be able to replace current industry lintels. 
     The lintel  10   c  comprises a C-section beam having a horizontal bottom flange  12 , a horizontal top flange  13  and a vertical web  14  extending between aligned side edges of the bottom flange  12  and the top flange  13 . The top flange  13  is narrower than the bottom flange  12 . The bottom flange width is generally 100 mm wide. The depth of the lintel  10   c  (height of the web  14 ) depends on the number of courses to be received as described below. The typical thickness of the lintel  10   c  is 5 mm. 
     The common dimensions of structural angles  140  used in the industry (bottom flange width in mm×web height in mm×flange/web thickness in mm) are 100×100×6 mm, 100×100×10 mm, 150×100×6 mm and 150×100×6 mm all in hot dipped galvanised, and supplied in a number of standard lengths to suit window and door openings. They are generally deployed in brick veneer construction, supporting the external brickwork over the openings. 
     Lintel  10   c - 1  is a one brick course depth lintel, which will replace the conventional 100×100×6 mm angle lintel  140 . Lintel  10   c - 2  is a two brick course depth lintel and lintel  10   c - 3  is a three brick course depth lintel. There is a thin mortar bed  210  on top of the bottom flange  12  of 5 mm below the lowermost brick course, and the top of the uppermost brick course will  200  will abut the underside of the top flange  13 . Mortar layers  210  are disposed between the brick courses. The brick course  200   b  on top of the uppermost brick course will have a 10 mm mortar course on the brick below, and a 5 mm thin bed mortar on top of the lintel top flange  13 . 
     The lintel is laid on top of the bricks either side of the window or doorway. The bricks laid within the lintel will have the 10 mm mortar course between the bricks (for two or more courses) as per the rest of the wall. However, when laid on top of the bottom flange, the mortar is only 5 mm thick. 
     The overall height depth of the lintel (between external surfaces of the top and bottom flange) for a single brick lintel will be 91 mm (5 mm bottom flange+5 mm thin mortar bed on top of bottom flange+76 mm brick depth+5 mm top flange). 
     The overall height/depth of the lintel (between external surfaces of the top and bottom flange) for a two course lintel will be 177 mm (5 mm bottom flange+5 mm thin mortar bed on top of bottom flange+76 mm brick depth+10 mm mortar course+76 mm brick depth+5 mm top flange). 
     The overall height/depth of the lintel (between external surfaces of the top and bottom flange) for a three course lintel will be 263 mm (177 mm above for two course lintel above+76 mm brick depth+10 mm mortar course). 
     Considering the bottom flange thickness+5 mm thin mortar bed on top of bottom flange comprises a 10 mm mortar course equivalent, the overall height of the lintels will be N×brick courses (one course=10 mm mortar+76 mm brick height plus=86 mm) plus 5 mm top flange thickness. So, a single brick course C-lintel will be 91 mm, 2 courses is 177 mm, 3 courses is 263 mm. 
     The top flange  13  further includes spaced holes  18  which will allow mortar filling and contribute positively to increased bonding between the lintel and the brick wall. The web  14  also includes holes  17  aligned centrally to the axis of the mortar course between brick courses, for the two or more brick course embodiments. 
       FIG. 12  shows lintels  10   d - 1  and  10   d - 2  which are similar to the lintels  10   c - 2  and  10   c - 3  respectively. The lintels  10   d  however have the top flange  13  extending past the other side of the web  14  and thus into the wall cavity in use. Because the minimum brick cavity is 25 mm, that is the maximum overhang of the top flange  13  for this design arrangement. 
     The C-section lintel  10   c  is the preferred design as it could be roll formed, whereas the lintel  10   d  would need to be a welded beam. 
     All these lintels will produce composite action, or increased capacity because of the laid brick interacting with the steel lintel. 
       FIG. 13  shows a structural lintel  10   f  according to another embodiment of the present invention. The lintel  10   f  is similarly shaped as the lintel  10   b  of  FIGS. 9 and 10 . The lintel  10   f  comprises an I-beam having a horizontal lower (or bottom) flange  12 , a horizontal upper (or top) flange  13  and a vertical web  14  extending therebetween. The top flange  13  is centrally located of lesser width than the bottom flange  12 . 
     The lintel  10   f  includes a plurality of lugs  29  mounted in a spaced manner along the top surface  33  of the upper flange  13 . The lugs  29  generally comprise upside down U-shaped rods or beams with ends thereof mounted by welding to the top surface  33 . The lugs  29  thus form tie-down formations with openings along the top surface  33 . The lugs  29  are aligned with the web  14 . 
       FIG. 14  shows an example use which is similar to that shown in  FIG. 6 , being a 3 course depth bricks  200 . Metal strapping  35  is passed through the opening of the lugs  29  by the brick layer, and the strapping  35  is pulled up between the bricks  220  as they are being laid along the top surface  33 , The upper ends of the strapping  35  are either turned over on top of a timber plate  37  and attached thereto or tied directly to a rafter of roof truss. 
     In prior art assemblies, there is nowhere to attach roof hold down straps except for folding the strap underneath a few brick courses immediately below the point of fixing, which is only a portion of the restraint required in some cases. 
     The lugs  29  with the strapping  35  effectively ties the roof structure to all the bricks as well as the beam lintel, across the garage opening for example, which solves a lot of hold down issues, especially for sheet roofs. The hold down means not only includes the brick dead weight but also the mass of the steel beam lintel. 
     The strap can be simply fed through the lugs by the bricklayer which is another advantage. 
     The strap upper ends can be fanned out along the timber plate so that each end of the strap can be spaced apart to reduce the span of the timber plate (between the hold down points) which means the timber plate size and strength can be maximised to hold down a roof structure that is fixed to it.