Claims:We claim:

1. An undercut anchor system (50) for mechanically mounting, supporting, and holding dry-clad stones on building structures, said undercut anchor system comprising:

• a profiled back clip (10) fixed to a dry-clad stone panel/slab (S);

• said back clip (10) having a cantilever portion projecting out from and connected to the base thereof by a bridge;

• an undercut fastener (12) tightened in an undercut (Uc) already made in said stone panel/slab (S) to positively lock said back clip (10) therein for mounting of said stone panel/slab (S) free of expansion force and stresses therein;

• a profiled transome (20) to be tightened on said building structure for mounting said dry-clad stone panel/slab (S) thereon to keep;

• said transome (20) having a lower hook support extending from the hook base connected to the base plate of said transome (20) for supporting the cantilever portion of said back clip (10) thereon, and the base plate of said transome (20) having a projection extending parallel to the hook base thereof;

• a pair of fasteners (F) tightened through said transome (20) for fitting thereof in said building structure;

wherein said back clip (10) and said transome (20) are configured for aligning the projection of said transome (10) with the bridge of said back clip (10) and to support the stone panel/slab (S) thereon; and the one end of said cantilever portion of said back clip (10) is supported between the hook support (HS) and the projection of said transome (20).

2. The undercut anchor system (50) as claimed in claim 1, wherein said back clip (10) is supported on said transome (20) directly tightened on said building structure.

3. The undercut anchor system (50) as claimed in claim 1, wherein said back clip (10) fitted with a stone panel/slab (S) is supported on said transome (20) indirectly tightened on said building structure by tightening the base plate of said transome (20) by a fastener (22) on a subframe (Fr) having the bracket (B) thereof fitted on said building structure by means of the fastener (F).

4. The undercut anchor system (50) as claimed in claim 1, wherein said back clip (10) fitted with a stone panel/slab (S) is supported on said transome (20) is tightened on the wall of said building structure.

5. The undercut anchor system (50) as claimed in claim 4, wherein the fastener (22) side open end of each consecutive transome (20) is facing upwards to fully support the weight of the respective stone panel/slab (S1, S2) fitted with said back clips (20) in turn supported on a respective transome (20) for a secure mounting, supporting and holding of said stone panels/slabs (S1, S2) on the ceiling of said building structure.

6. The undercut anchor system (50) as claimed in claim 1, wherein said back clip (10) fitted with a stone panel/slab (S) is supported on said transome (20) is tightened on the ceiling of said building structure.

7. The undercut anchor system (50) as claimed in claim 5, wherein the fastener (22) side open end of each consecutive transome (20) is facing away from each other to facilitate the sliding of said back clips (20) fitted with a stone panel/slab (S) on the respective transome (20) for a secure mounting, supporting, and holding of said stone panels/slabs (S1, S2) on the ceiling of said building structure.

8. The undercut anchor system (50) as claimed in claim 1, wherein said back clip (10) and said transome (20) are made from respective extruded aluminium sections configured to be safe against the stresses developed therein due to the weight of said stone panel/slab and causing the axial tension, bending, shear and a combination therein.

9. The undercut anchor system (50) as claimed in claim 8, wherein said back clip (10) and said transome (20) are made from the virgin or recycled aluminium material.

10. The undercut anchor system (50) as claimed in claim 8, wherein said aluminium material is aluminium alloy 6063 T6.

Dated this 07th day of May 2021.

Digitally signed.

(SANJAY KESHARWANI)
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA-2043. , Description:FIELD OF INVENTION

The present invention relates to stone fixing on building structures. In particular, the present invention relates to a mechanical anchor system for fixing stone slabs/panels on building structures. More particularly, the present invention relates to a lightweight undercut anchor system for mechanically mounting, supporting, and holding dry-clad stone slabs/panels on building structures.

BACKGROUND OF THE INVENTION

Natural stone is the oldest building material known to the mankind. Stone structures have stood tall for ages and the use of dimensioned stones in the architecture has evolved over time. Stones resonate well with the nature. Stones have class and durability, which make them an exciting material to work on for civil engineers, architects, designers, and planners. However, in the current climate conditions, stone has been marginalized due to bad quality of stone selection and lack of design information, which causes inaccurately produced/dimensioned stones, poor quality of fixing and inadequate cost-planning thereof.

STONE CLADDING

Stone has a versatile use in architecture, being the only building material that has multiple functions, e.g., as a structural member, finishing material as well aesthetic material. The oldest known structures used stones as a structural material. Stones have been an integral part of the architectures of almost all civilizations. It is particularly important to design a stone-fixing system which is safe and easy in install and which demonstrates enhanced quality of stone-fixing and retains the natural properties of the stones.
DRY CLADDING

Dry-clad stone walls were developed to protect structural walls and ceilings by keeping them dry. Dry-clad stones also imparts a high-level aesthetic characteristic and thus demonstrates undisputed advantages of heat insulation and sound proofing.

The dry-clad stone mounting is done by mechanically securing stones without any adhesive for installation thereof.

This system functions by securing and supporting the stone slabs by undercut fasteners fixed in the undercuts made in the stone panels/slabs and directly or indirectly mounted on walls and/or ceilings via anchor fasteners.

The applicant specializes in designing stone-cladding systems as per the design/architectural requirements of different building structures and which are developed to execute such projects for diverse purposes.

The applicant’s project execution experience in such dry-clad stone fixing systems has enabled them to develop innovative stone-cladding systems, which are quite relevant to the modern building structures.

The stone panels/slabs mounted on the walls and/or ceiling of the building structure are subjected to a variety of loads and stresses. Accordingly, the structure for mounting these stone panels/slabs is exposed to varying wind loads and dead loads due to different size of stone panels of the dry-cladding.

Therefore, there is an existing need of an improved stone-fixing system, which is simple and ingenious to overcome the disadvantages associated with the present-day stone fixing systems and uses thinner stone panels/slabs.
OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a lightweight undercut anchor system for mechanically mounting and supporting dry-clad stones on building structures.

Another object of the present invention is to provide a simple undercut anchor system for mechanical mounting and supporting of such dry-clad stones on building structures.

Still another object of the present invention is to provide an undercut anchor system which is easy to mechanically mount and support the dry-clad stone panels/slabs on building structures.

Yet another object of the present invention is to provide a simple undercut anchor system, which ensures a positive locking for mechanically mounted and supported dry-clad stone panels/slabs on building structures.

A further object of the present invention is to provide an undercut anchor system, which is free of expansion and stresses during mechanical mounting and supporting of dry-clad stone panels/slabs on building structures.

A still further object of the present invention is to provide an undercut anchor system, which facilitates thinner stone panels/slabs to be mechanically mounted and supported on building structures.

A yet further object of the present invention is to provide an undercut anchor system, which allows different types of stones to be mechanically mounted and supported in dry-clad stones on building structures.
A yet another object of the present invention is to provide an undercut anchor system, which allows the stones with varying bending tolerances to be mechanically mounted and supported in dry-clad stones on building structures.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

DESCRIPTION OF THE INVENTION

The idea underlying the present invention is to provide a simple and lightweight undercut anchor system, which is easy to be used for mechanical mounting and supporting of dry-clad stone panels/slabs on building structures. In this undercut technique, a blind hole with an expanded base is drilled into the backside of stone panel/slab. Subsequently, the undercut anchor bolt/fastener is inserted therein to guarantee a positive-locking of the back clip of the undercut anchor system on the stone panel/slab for ensuring a secure attachment thereof, free of expansion force and stresses developed therein. Once the stone panel/slab is fitted with the back clip of the undercut anchor system, it is mounted directly on the wall or ceiling of the building structure supported on the transome thereof.

These undercut anchors system can also be indirectly fixed to a subframe system fixed via brackets thereof the wall or ceiling of the building structure.

This undercut anchor system can be configured by considering the stone variations and bending tolerances in detail. The undercut anchor system is technically superior and substantially reduces the thickness of stone and is therefore lightweight and substantially reduces the cavities therebetween.
The undercut anchor system configured in accordance with the present invention, for mechanically mounting, supporting and securely holding dry-clad stone panels/slabs, minimizes the cavity between the adjacent stone slabs/panels to optimize the space availability in modern building structures. This undercut anchor system is particularly suitable for the interiors, e.g. wall and ceilings of modern building structures.

The undercut anchor system configured in accordance with the present invention is more versatile than the conventional dry-clad stone mounting systems because it facilitates to directly or indirectly mount, support and hold dry-clad stone panels/slabs on the building structures.

The undercut anchor system configured in accordance with the present invention uses recyclable material, such as extruded aluminium sections, which can be fully reused. This undercut anchor system can also be made by using recycled aluminium as well as virgin aluminium.

The undercut anchor system configured in accordance with the present invention has the advantage that it requires no synthetic or epoxy filling and thus does not harm stone surface, which can be easily reused subsequently. It prevents discoloration of stone panels/slabs due to dry-clad nature thereof. It is also suitable for easy and quick installation by the mechanical anchoring of stone panels/slabs thereto. It includes the following major components/sub-assemblies:

a) Subframe or Mullion,
b) Bracket for Mullion,
c) First Horizontal member or transome,
d) Second Horizontal member or back clip supported on transome, and
e) Fasteners for attachment to the walls and for fixing stone cladding of plurality of stone panels/slabs.
Aluminium is the preferred material for such undercut anchor system configured in accordance with the present invention, which has the following major advantages:

• Durability
• Flexibility
• Lightweight
• High corrosion resistance
• Insulation properties
• Recyclability
• Thermal efficiency
• Extrudability in different sections to achieve optimum strength in pre-engineered profiles.

A preferred material specification is Aluminium Alloy 6063 T6, which has ultimate tensile strength of at least 190 MPa (28,000 psi) and yield strength of at least 160 MPa (23,000 psi). It exhibits an elongation of 8% or more in thicknesses of 3.15 mm (0.124 inch) or less. It exhibits an elongation of 10% for thicker sections.

The material composition of Aluminium Alloy 6063 T6 is as given below:

• Silicon minimum 0.2%, maximum 0.6% by weight
• Iron no minimum, maximum 0.35%
• Copper, Chromium, Manganese, Titanium and Zinc 0 to 0.10%
• Magnesium minimum 0.45%, maximum 0.9%
• Other elements not more than 0.05% each
• Remainder Aluminium 0.15%.

KEY FEATURES OF UNDERCUT ANCHOR SYSTEM

1) Guarantees positive locking.
2) Free from expansion forces and stresses developed thereby.
3) Directly or indirectly mountable.
4) Reduces stone thickness.
5) Ease of assembly.
6) Uses extruded Aluminium profile, which is durable, flexible, lightweight.
7) Aluminium offers higher strength and resistance to corrosion.
8) Higher thermal efficiency and optimal strength.
9) Completely recyclable configuration offers an environmentally friendly system because every component/material can be re-used.
10) Allows the use of recycled Aluminum, instead of just virgin Aluminum.
11) Requires no synthetic/epoxy filling between the stone joints, thus makes it low-cost, unharmful to the natural properties of stones.
12) Easy, safe, and fast to install being a mechanical fixed system as compared to wet-fixing systems.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an undercut anchor system for mechanically mounting, supporting, and holding dry-clad stones on building structures, the undercut anchor system comprising:

• a profiled back clip fixed to a dry-clad stone panel/slab;

• the back clip having a cantilever portion projecting out from and connected to the base thereof by a bridge;

• an undercut fastener tightened in an undercut already made in the stone panel/slab to positively lock the back clip therein for mounting of the stone panel/slab free of expansion force and stresses therein;

• a profiled transome to be tightened on the building structure for mounting the dry-clad stone panel/slab thereon to keep;
• the transome having a lower hook support extending from the hook base connected to the base plate of the transome for supporting the cantilever portion of the back clip thereon, and the base plate of the transome having a projection extending parallel to the hook base thereof;

• a pair of fasteners tightened through the transome for fitting thereof in the building structure;

wherein the back clip and the transome are configured for aligning the projection of the transome with the bridge of the back clip and to support the stone panel/slab thereon; and the one end of the cantilever portion of the back clip is supported between the hook support and the projection of the transome.

Typically, the back clip is supported on the transome directly tightened on the building structure.

Typically, the back clip fitted with a stone panel/slab is supported on the transome indirectly tightened on the building structure by tightening the base plate of the transome by a fastener on a subframe having the bracket thereof fitted on the building structure by means of the fastener.

Typically, the back clip fitted with a stone panel/slab is supported on the transome is tightened on the wall of the building structure.

Typically, the fastener-side open end of each consecutive transome is facing upwards to fully support the weight of the respective stone panel/slab fitted with the back clips in turn supported on a respective transome for a secure mounting, supporting, and holding of the stone panels/slabs on the ceiling of the building structure.

Typically, the back clip fitted with a stone panel/slab is supported on the transome is tightened on the ceiling of the building structure.
Typically, the fastener side open end of each consecutive transome is facing away from each other to facilitate the sliding of the back clips fitted with a stone panel/slab on the respective transome for a secure mounting, supporting, and holding of the stone panels/slabs on the ceiling of the building structure.

Typically, the back clip and the transome are made from respective extruded aluminium sections configured to be safe against the stresses developed therein due to the weight of the stone panel/slab and causing the axial tension, bending, shear and a combination therein.

Typically, the back clip and the transome are made from the virgin or recycled aluminium material.

Typically, the aluminium material is aluminium alloy 6063 T6.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described in the following with reference to the accompanying drawings.

Figure 1 shows a back clip of the undercut anchor system configured in accordance with the present invention.

Figure 2 shows the transome of the undercut anchor system configured in accordance with the present invention. This transome is fixed on a wall directly or through a subframe via a bracket thereof.

Figure 3 shows an assembled view of the undercut anchor system configured in accordance with the present invention and having a back clip supported on a transome with the five critical cross-sections thereof.

Figure 4 shows a side view of the undercut anchor system directly fixed on the wall of a façade or interior of building structure and mounted with rows of stones.

Figure 5 shows a cross-sectional side view of the undercut anchor system of Figure 3 for fixing rows of stone panels/slabs indirectly mounted wall via a subframe.

Figure 6 shows a cross-sectional view of the undercut anchor system of Figure 3 for fixing rows of stone panels/slabs indirectly mounted via a subframe on the ceiling of a building structure.

Figure 7 shows a perspective view of the undercut anchor system of Fig. 3 depicted with the undercut anchor bolts for fixing in the stone panels/slabs on the wall and with a few stones are removed to depict its position therein.

Figure 8 shows a perspective view of the undercut anchor system of Fig. 7 after removing a pair of stones fitted with the back clip to depict the anchor fastener for fixing the transome on the subframe and its position therein.

Figure 9 shows a side view of two undercut anchor systems of Figure 7 fixed in two rows of stone panels/slabs indirectly mounted via a subframe through a bracket on the wall of the building structure.

Figure 10 shows a top view of the undercut anchor system of Figure 9 fixed with stone panels/slabs and indirectly mounted via a subframe or mullion on the wall of the building structure.

DETAILED DESCRIPTION OF THE INVENTION

In the following, an undercut anchor system for mechanically mounting and supporting dry-clad stone slabs/panels configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention.

Figure 1 shows a back clip 10 of the undercut anchor system 50 configured in accordance with the present invention. Back clip 10 includes a cantilever portion with eccentricity e1, thickness t1 projected from base of thickness t2, width W1. The projected cantilever portion has height d2 and is connected to its base by a bridge of thickness t. An undercut anchor bolt 12 available readily in the market is used to directly fix the back clip 10 in an undercut Uc made on stone in a known manner in a predetermined number of rows to form the wall W or ceiling R of the building structure for providing a dry stone-cladding by using stone panels/slabs of appropriate sizes to obtain the desired façade/interior layout. The wind-load (WL) on stones is distributed in the numerous undercut anchor systems 50 used and is a critical factor in deciding about the configuration of stone panels/slabs on the façade/interior layout. Three critical cross-sections 14, 16, 18 marked in red in back clip 10 are explained further. These three cross-sections 14, 16, 18 are critical for the checking and calculation of the local shear and bending stresses as well as axial tension developed in back clip 10 when stones S are mounted on the building structure by undercut anchor systems 50, to ensure the safety thereof.

Figure 2 shows a transome 20 of the undercut anchor system 50 configured in accordance with the present invention. This transome 20 is fixed on the wall W directly or through a subframe Fr via a bracket B thereof. Transome 20 includes a hook support HS and is connected to subframe Fr through a pair of anchor fasteners F for directly mounting on the wall W, or through a pair of fasteners 22 tightened on subframe Fr for indirect mounting on wall W via anchor fasteners F. The base plate of transome 20 has a width W2 and thickness t3 and lower hook support HS. This hook support HS has a hook base of thickness t5.having first critical cross-section 24 and a projected cantilever of thickness t4, height h2, and eccentricity e3, and having the second critical cross-section 24.

Figure 3 shows an assembled view of the undercut anchor system 50 configured in accordance with the present invention and having a back clip 10 supported on a transome 20. Three critical cross-sections 14, 16, 18 marked in red in back clip 10, as well as two cross-sections 24, 26 on the transome 20 are critical for calculation and checking for the local shear and bending stresses developed in the back clip 10 and transome 20 of the undercut anchor system 50 to ensure the safety thereof, as already discussed above. The lower cantilever of back clip 10 rests on the cantilever of transome 20, so that the dead load of stone as well as wind load exerted on the stone is transferred to the wall or ceiling of the building structure on which the undercut anchor system 50 with stone is directly mounted by anchor fasteners F, or indirectly mounted first by fasteners 22 on subframe Fr with bracket B, which is finally mounted on wall or ceiling by anchor fasteners F.

Figure 4 shows a side view of the undercut anchor system 50 directly fixed on the wall W of a building structure and mounted with rows of stone panels/slabs S1, S2. It is to be noted that the undercut anchor system 50 with the open ends (fixed with undercut fasteners 12 and fasteners F) thereof always face upwards to fix the adjoining rows of stones S1, S2 on wall W, so that the rows of stones S are securely supported on wall W by gravity by their own weight.

Figure 5 shows a typical detail of the subframe Fr of the undercut anchor system 50 of Figure 3 for fixing stone panels/slabs S on the wall W of the building structure. It shows stones S1, S2 forming a vertical covering on the wall W of by means of undercut anchor system 50. Each of undercut anchor system 50 to comprises a back clip 10 fixed by an undercut fastener 12 in the undercut Uc (Figure 1) already made in stones S1, S2 in a known manner. Subframes or subframes Fr having brackets B are fitted in the wall W by means of respective anchor fasteners F. Preferred spacing between the adjoining sub-frames Fr is 1.5 m at the most and generally depends on the thickness and size of the stones S. The transome 20 of each undercut anchor system 50 is first a back clip 10 of the undercut anchor system 50 is tightened in the respective undercut Uc already made in the respective stone S by means of an undercut anchor bolt 12. This process is repeated with all stones S to be fixed on the façade or interior wall W of the building structure. Subsequently, the subframes Fr are fitted with the corresponding number of brackets B and then these subframes Fr fitted with brackets B are fixed in the wall W by means of anchor fasteners F. The spacing between these subframes is predefined depending on the size and thickness of stone S to be mounted on the building structure, preferably this spacing is 1.5 m at most. Subsequently, the transome 20 of the undercut anchor system 50 are fitted on the corresponding subframe Fr by means of respective fastener 22 therefor and the subframes Fr are ready to support the stones S fitted with back clips 10 by means of the corresponding anchor bolts F thereon. Finally, the stones S1, S2 fitted with back clips 10 are placed on the respective transome 20 fitted on the corresponding subframe Fr support and complete the façade or interior of the building structure.

Figure 6 shows a cross-sectional view of the undercut anchor system 50 of Figure 3 for fixing stone panels/slabs S1, S2 on the ceiling of a building structure indirectly mounted via a subframe Fr discussed in Figure 5 above. However, in contrast to the fixing of undercut anchor system 50 with the open ends (fixed with undercut fasteners 12, and fasteners 22) thereof always face upwards to fix the stones S1, S2 on the wall W, as described in Figure 5 above, the undercut anchor system 50 are fixed in the subframes Fr fitted on the ceiling of the building structure by keeping adjoining undercut anchor systems 50 with the open ends (fixed with undercut fasteners 12, and fasteners 22) thereof always facing each other. Accordingly, the stones S1, S2 fitted with the back clip 10 thereof by the respective undercut anchor bolt 12 is facilitated to be easily slid on the transome 20 fitted under the subframe Fr by means of the corresponding fastener 22.

Figure 7 shows a perspective view of undercut anchor system 50 of Figure 3 with the undercut anchor bolts 12 for fixing, e.g. in two rows of stones S1, S2, which is partly removed to depict the position of fasteners 22.

Figure 8 shows a perspective view of undercut anchor system 50 of Figure 7 after removing one stone S of each row to clearly depict the anchor fastener F fixed on the transome 20 fitted on the subframe Fr and its position thereon. This transome 20 fitted on subframe Fr fixed in the wall W by the anchor fasteners F, is used for supporting the lower end of the cantilever portion of back clips 10 fixed on the stones S by means of undercut anchor bolts 12 (not visible here) to cover wall W, as per a predetermined layout.

Figure 9 shows a side view of two undercut anchor systems 50 of Figure 7 fixed in two rows of stone panels/slabs S1, S2 indirectly mounted via a subframe F through its bracket B on the wall W. Here again, it is clear that the open ends fixed with undercut fasteners 12 and fasteners 22 are facing upwards to fix the stone panels/slabs S1, S2 fitted with back clips 10 are supported on the bracket B fitted on the subframe Fr, so that these stones S are securely supported due to gravity on the wall W by their own weight.

Figure 10 shows a top view of the undercut anchor system 50 of Figure 8 fixed with two rows of stone panels/slabs S and indirectly mounted on the wall W. Here also, the stones S on the left-hand side rows are removed to depict the undercut anchor bolts 12 of the of the undercut anchor system 50.

The final configuration of a typical façade or interior wall or ceiling of a building structure is designed by considering the wind loads, dead loads and live loads exerted thereon during different seasons during the year. In particular, the aluminium extruded sections used for this undercut anchor system involves calculations of the optimum profiles therefor by considering the density, modulus of elasticity, minimum tensile strength, tensile yield strength, limiting bending stress, limiting axial compressive and tensile stresses, and limiting shear stress. The size of the stone, i. e. the length, width and thickness as well as weight thereof are also accounted for in these calculations. These include the wind loads on subframe or mullion, its bracket (both available in the market) as well as the undercut anchor system configured in accordance with the present invention mounted thereon.

These calculations also involve loading of the structure for supporting the dry-clad stone cladding made by using this undercut anchor system by obtaining the maximum designed wind pressure and the permissible deflections therein by considering the wind loads and stone size, e.g. height, width, and thickness thereof. This calculation process also involves calculating the maximum dead load of the dry-cladding of stones, which takes into account of the stone density and dead load at two locations therein.

Calculation for the undercut anchor system configured in accordance with the invention for a dry-clad stone mounting system in a building structure:

The following are the details of the calculation used for customizing the undercut anchor system configured in accordance with the present invention for mounting of stone panels/slabs on the walls, ceilings of a modern dry-clad building structure.

Material: Aluminium alloy 6063, T6 [as per IS:8118-1-1991] used for extruded undercut anchor system: [1 N/mm2 = 1 MPa]

Density : 27.1 kN/m3
Modulus of Elasticity : 70000 N/mm2
Minimum Tensile Strength : 185 N/mm2
Tensile Yield Strength : 160 N/mm2
Limiting Bending Stress : 160 N/mm2
Limiting Axial Compression Stress / : 175 N/mm2
Tensile Stress
Limiting Shear Stress : 95 N/mm2
Material factor ?m : 1.2

Stone Data:
Stone height : 900 mm Stone width : 1200 mm Stone thickness : 30 mm Wind load on Stone 1.2 m x 0.9 m : 1.728 kN
Dead load for 2 locations = 1.728 / 2 : 0.864 kN

Aluminium Back Clip (Figure 1)

Example:

Width (W1) : 50 mm
Projected cantilever width (h1) : 8 mm
Cantilever plate thickness (t1) : 3 mm
Base plate thickness (t2) : 4 mm
Bridge thickness (t) : 4 mm
Bridge-hole center distance or eccentricity : 19.2 mm
Hole to back clip-end distance : 10.8 mm
Eccentricity (e1) at section 14 : 2.2 mm
Eccentricity (e2) at section 18 : 19.2 mm

Local Bending & Stresses at section 14 in exemplary back clip:

Local forces due to dead load : 0.829 kN on 2 hook brackets
Therefore, local force : 0.415 kN per hook bracket
Factored local force (Ps) : 1.2 x 0.415 = 0.498 kN.

Checking for Shear at section 14 in the exemplary back clip:

Net shear area : W1 x t2 = 50 x 4 = 200 mm2
Limiting shear stress for Aluminium 6063-T6 = 95 Mpa
Shear capacity of back clip : 95 x 200 / 1.2 = 15.833 kN
Actual Induced Shear force (Ps) : 0.498 kN / 2 = 0.249 kN.

Checking for bending at section 14 in the exemplary back clip:

Section Modulus = (W1 x t2) / 6 = 50 x 42 / 6 = 133.333 mm3
Bending Moment = (Ps x e1) / 2 = 0.001 kN-m
Limiting Bending Stress = 160 Mpa or 160 N/mm2
Bending capacity of Back clip (Limiting bending stress x Section modulus)
= (160 x 133.333) / 1.2 = 0.018 kN-m
Actual Induced Bending Moment = 0.001 kN-m
Which is greater than (>) Bending moment of 0.001 kN-m.

Therefore, the exemplary back clip is safe in bending.

Combined Axial tension, Bending & Shear Stress at section 14 in the exemplary back clip:

[Actual Induced Local force (Ps) / Shear capacity] +
[Bending Moment / Bending capacity] = = 0.047. which is < 1.00

Therefore, the exemplary back clip is also safe under combined axial tension, bending and shear stress exerted at section 14 thereof.

Local Bending & Stresses at section 16 in the exemplary back clip:

Local forces due to wind load : Wind load x Stone size
= 1.6 kPa x 1.2 m x 0.9 m
= 1.728 kN on 2 hook brackets
Therefore, local force = 0.864 kN per hook bracket
Factored local force (Ps) : 1.2 x 0.864 = 1.037 kN.

Checking for Shear at section 16 in the exemplary back clip:

Local forces due to Wind Load : 1.728 kN on 2 hook brackets
Therefore, local force : 0.864 kN/hook bracket
Factored local force : 1.2 x 0.864 = 1.037 kN (?m = 1.2)

Net shear area : W1 x t1 = 50 x 3 = 150 mm2
Limiting shear stress for Aluminium 6063-T6 = 95 Mpa
Shear capacity of back clip : 95 x 150 / 1.2 = 11.875 kN
Which is greater than (>):
Actual Induced Shear force (Ps) : 1.037 kN / 2 = 0.518 kN.

Therefore, the exemplary back clip is safe in shear.

Checking for bending at section 16 in the exemplary back clip:

Section Modulus = W1 x (t1)2 /6 = 50 x(3)2 / 6 = 75 mm3
Bending Moment = (Ps x d2)/ 2 = 1.037 x 8 / 2 = 0.004 kN-m
Limiting Bending Stress = 160 Mpa or 160 N/mm2
Bending capacity of Back clip (Limiting bending stress x Section modulus)
= (160 x 75) / 1.2 = 0.01 kN-m,
which is greater than (>) Actual induced Bending Moment of 0.004 kN-m.

Therefore, the exemplary back clip is safe in bending.

Combined Axial tension, Bending & Shear Stress at section 16 in the exemplary back clip:

[Actual Induced Shear force (Ps) / Shear capacity] + [Bending Moment / Bending capacity] = 0.458, which is < 1.00.

Therefore, the exemplary back clip is safe under combined axial tension, bending and shear stress exerted also at section 16 thereof.

Local Bending & Stresses at section 18 in the exemplary back clip:

Local forces due to dead load : 0.829 kN on 2 hook brackets
Therefore, local force : 0.415 kN per hook bracket
Factored local force (Ps) : 1.2 x 0.415 = 0.498 kN.

Checking for Shear at section 18 in the exemplary back clip:

Net Tensile area : W1 x t2 = 50 x 4 = 200 mm2
Limiting Axial
Compressive/ Tensile stress for Aluminium 6063-T6 = 175 Mpa
Axial Tension capacity of back clip : 175 x 200 / 1.2 = 29.167 kN
Which is greater than (>):
Actual Induced Axial force (Pa) : 0.498 kN / 2 = 0.249 kN.

Therefore, the exemplary back clip is safe in shear.

Checking for Shear at section 18 in the exemplary back clip:

Net shear area : W1 x t2 = 50 x 4 = 200 mm2
Limiting shear stress for Aluminium 6063-T6 = 95 Mpa
Shear capacity of back clip : 95 x 200 / 1.2 = 15.833 kN
Which is greater than (>):
Actual Induced Shear force (Ps) : 1.037 kN / 2 = 0.518 kN.

Therefore, the exemplary back clip is safe in shear.
Checking for bending at section 16 in the exemplary back clip:

Section Modulus = W1 x (t2)2 / 6 = 50 x(4)2 / 6 = 133.333 mm3
Bending Moment = (Ps x e2)/ 2 = 1.037 x 19.2 / 2 = 0.01 kN-m
Limiting Bending Stress = 160 Mpa or 160 N/mm2
Bending capacity of Back clip (Limiting bending stress x Section modulus)
= 0.018 kN-m,
which is greater than (>) Actual induced Bending Moment of 0.01 kN-m.

Therefore, the exemplary back clip is safe in bending.

Combined Axial tension, Bending & Shear Stress at section 16 in the exemplary back clip:

[Actual Induced Axial force (Pa) / Axial Tension capacity] +
[Actual Induced Shear force (Ps) / Shear capacity] +
[Bending Moment / Bending capacity] = 0.601, which is < 1.00.

Therefore, the exemplary back clip is safe under combined axial tension, bending and shear stress exerted at section 18 thereof as well.

Aluminium Transome (Figure 2)
Example:

Width (W2) : 50 mm
Base plate thickness (t3) : 4 mm
Projected cantilever plate thickness (t4) : 3 mm
Projected cantilever thickness (t5) : 4.5 mm
Projected cantilever height (h2) at section 26 : 8 mm
Cantilever eccentricity (e3) at section 24 : 2.8 mm

Local forces due to dead load : 0.829 kN on 2 hook brackets
Therefore, Local force : 0.415 kN per hook bracket
Factored Local force (Ps) : 1.2 x 0.415 = 0.498 kN.
Local Bending & Stresses at section 24 in the exemplary transome:

Checking for Shear at section 24 in the exemplary transome:

Net Shear area : W1 x t2 = 50 x 4.5 = 225 mm2
Limiting Shear stress for Aluminium 6063-T6 = 95 Mpa
Shear capacity of transome : 95 x 225 / 1.2 = 17.813 kN,
which is greater than (>) Actual Induced Shear force (Pa) = 0.249 kN.

Therefore, the exemplary transome is safe in shear.

Checking for Bending at section 24 in the exemplary transome:

Section Modulus = W1 x (t5)2 / 6 = 50 x(4.5)2 / 6 = 168.75 mm3
Bending Moment = (Ps x e3)/ 2.8 = 0.498 x 2.8 / 2 = 0.001 kN-m
Limiting Bending Stress = 160 Mpa or 160 N/mm2
Bending capacity of transome (Limiting bending stress x Section modulus)
= 0.0225 kN-m,
which is greater than (>) Actual induced Bending Moment of 0.001 kN-m.

Therefore, the exemplary transome is also safe in bending.

Combined Axial tension, Bending & Shear Stress at section 24 in transome:

[Actual Induced Shear force (Ps) / Shear capacity] +
[Bending Moment / Bending capacity] = 0.045, which is < 1.00.

Therefore, the exemplary transome is safe under combined axial tension, bending and shear stress exerted at section 24 thereof as well.

Local Bending & Stresses at section 26 in the exemplary transome:

Local forces due to Wind Load : 1.728 kN on 2 hook brackets
Therefore, local force : 0.864 kN/hook bracket
Factored local force : 1.2 x 0.864 = 1.037 kN (?m = 1.2)
Checking for Shear at section 26 in the exemplary transome:

Net Shear area : W1 x t4 = 50 x 3 = 150 mm2
Limiting Shear stress for Aluminium 6063-T6 = 95 Mpa
Shear capacity of transome : 95 x 150 / 1.2 = 11.875 kN,
which is greater than (>) Actual Induced Shear force (Ps) = 0.518 kN.

Therefore, the exemplary transome is safe in shear.

Checking for Bending at section 26 in the exemplary transome:

Section Modulus = W1 x (t4)2 / 6 = 50 x(3)2 / 6 = 75 mm3
Bending Moment = (Ps x h2) / 2 = 0.004 kN-m
Limiting Bending Stress = 160 Mpa or 160 N/mm2
Bending capacity of transome (Limiting bending stress x Section modulus)
= 0.01 kN-m,
which is greater than (>) Actual induced Bending Moment of 0.004 kN-m.

Therefore, the exemplary transome is also safe in bending.

Combined Axial tension, Bending & Shear Stress at section 26 in transome:

[Actual Induced Shear force (Ps) / Shear capacity] +
[Bending Moment / Bending capacity] = 0.458, which is < 1.00.

Therefore, the exemplary transome is safe under combined axial tension, bending and shear stress exerted at section 26 thereof as well.

Apart from the above calculations, the anchor fasteners F fixed on the wall W or ceiling R as well as subframe or mullion Fr and the brackets B thereof are also checked for the maximum bending moment, shear force, axial forces in all 3-dimensions (X, Y, Z), and the maximum permissible deflection with a factor of safety (factored forces) of 1.2. The subframe and brackets are also checked for static strength moment resistance about XX and YY axes.
It is to be noted that any undercut bolt/fastener readily available in the market can be used by making the undercuts in the stone panel/slabs in the known manner.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The undercut anchor system configured according to the present invention for dry-clad mechanical mounting of panels/slabs in the façade, walls and ceiling of the building structures has following advantages:

• Undercut anchor system is easier to maintain and aesthetically great.

• Provides full safety from fall-down of stone panels/slabs from walls.

• Offers proportional and uniform load-distribution.

• Completely recyclable thus environmentally friendly.

• Enables use of both recycled and Aluminum.

• Requires no synthetic/epoxy filling between the stone joints, thus low-cost, does not harm stone slabs/panels.

• Easy, safe, and fast to install being a simple mechanical fixed system.

• Prevents stone discoloration over longer durations.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to imply including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description.
In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g. “horizontally”, “inwardly”, “outwardly”; “downwardly”, “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected”, refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.