WO2018116324A1

WO2018116324A1 - Mechanism for connecting one precast element to other

Info

Publication number: WO2018116324A1
Application number: PCT/IN2017/050614
Authority: WO
Inventors: Ajit BHATE
Original assignee: Precast India Infrastructures Pvt. Ltd.
Priority date: 2016-12-23
Filing date: 2017-12-23
Publication date: 2018-06-28

Abstract

Disclosed is mechanism (100) for connecting a precast element (22) to a structural member (12). The mechanism comprises at least one first insert (10)configured in 5 the structural member (12), a sleeve (14) arranged within entire width of the structural member (12), at least one second insert (20) configured in a precast element (22). Specifically, the second insert (20) includes a slit (24) adapted on a face thereof. The mechanism moreover comprises a T-bolt (30) connecting the precast element (22) with the structural member (12). The T-bolt (30) includes a 10 collar (32) adapted at first end, threading at second end, and an indicator groove (36) configured parallel to the collar (32) at the second end. The mechanism (100) also comprises a flexible rubber seal/washer (50) and at least one washer plate (40). 15

Description

MECHANISM FOR CONNECTING ONE PRECAST ELEMENT TO

OTHER

Field of the invention

The present invention relates precast connections, and more particularly, to a mechanism to connect one precast element a structural member by mechanical means. Background of the invention

The prior art of connecting one such precast element to the other in a fixed manner, mostly is restricted by the following major options a) Bolting, whereby a bolt can be either throughout both elements (1), or embedded in one, and passing through the other element (through an embedded sleeve) (2) and getting locked with a nut on both/ one side depending on the nature of extent (1 or 2); and

b) Welding, whereby steel inserts are placed in both the elements, which then come back to back, where they are welded together

Apart from above, other methodologies to mount one precast element on the surface of the other include screwing, anchor fastener, hanging on hook, hanging on ledges, and the like which are all traditional arts.

However, the prior art methods of connecting one precast element with other have following disadvantages.

A) Bolting:

(i) Difficult to match perfectly due to low tolerances

(ii) Through and through holes allow water from outer surface to seep to the inside (iii) Grouting the holes is very difficult since they are mostly in perfect horizontal axis

(iv) The nut-pockets need to be filled/ patched with mortar and these patches are visible on surface even after painting sometimes, thereby reducing the aesthetic appeal

(v) No confirmation whether the nut has been tightened enough as per design, as also, sometimes, the bolt itself rotates while tightening the nut, which is not correct procedure

(vi) Wear and tear of threading may be possible in transport, installation phase

(vii) No assurance of whether the grout has covered the bolt completely

(viii) On site drilling of holes/ keeping sleeves in pre-planned locations

(ix) If water comes in contact with the bolts, inside the elements, then it may lead to rusting, thereby weakening the structural system

(x) Bolting usually also entails use of other ancillary structural steel elements for connection, like channels, angles, plates, etc, which all require coordination and instrumentations

B) Welding:

(i) Welding at heights is a skillful job and ideally requires certified welders, thereby increasing cost

(ii) Difficult to take heavy machinery at higher levels, requiring scaffolding, platform, etc

(iii) Lack of supervision and quality may cause safety hazard in later stages

(iv) Quality assurance is a challenge at every connection

(vi) Rusting may occur, so anti-corrosive paint required

(viii) On-site work, resources (machinery) required increases. Accordingly, there exists a need to provide a mechanism for connecting one precast element with other which overcomes above-mentioned drawbacks. Objects of the invention

An object of the present invention is to mount one heavy precast panel on another precast panel.

Yet another object of the present invention is to provide absolutely clean surfaces on the outer facia of the precast element with no visibility of the connection at all, thus making the whole arrangement very intriguing. The connection is also not visible from the inner surface of the structural element

Summary of the invention

Accordingly, the present invention provides a mechanism (100) for connecting a precast element (22) to a structural member (12). The mechanism comprises at least one first insert (lO)configured in the structural member (12). The first insert includes an opening (10a) at the centre and grout tubes (12a, 12b) for grouting. The mechanism (100) further comprises a sleeve (14) arranged within entire width of the structural member (12), wherein the opening (10a) of the first insert (10) aligns with the sleeve (14). The mechanism (100) furthermore comprises at least one second insert (20) configured ina precast element (22). Specifically, the second insert (20) includes a slit (24) adapted on a face thereof. The mechanism moreover comprises a T-bolt (30) connecting the precast element (22) with the structural member (12). The T-bolt (30) includes a collar (32) adapted at first end, threading at second end, and an indicator groove (36) configured parallel to the collar (32) at the second end. The mechanism (100) also comprises a flexible rubber seal/washer (50) placed between structural member (12) and the precast element (22), and at least one washer plate (40), wherein the flexible rubber seal/washer (50) having an opening at the centre thereof. Typically, upon aligning the structural member (12) and the precast element (22), the T-bolt (30) is inserted from the first insert (10) through the sleeve (14) to the slit(24) of the second insert (20) and the T-bolt (30) is rotated such that the collar (32) doesn't come out of the slit (24) and keeps the T-bolt (30) in locking position thereby joining the structural member (12) and the precast element (22).

Brief description of the drawings

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein Figure 1 shows front view and side view of a first insert of the mechanism of connecting a precast element to the structural member , in accordance with the present invention;

Figure 2shows front view and side view of a second insert of the mechanism of connecting a precast element to the structural member , in accordance with the present invention;

Figure 3 shows a side view and a front view of a T-bolt of the mechanism of connecting a precast element to the structural member, in accordance with the present invention; and

Figure 4 shows a cross sectional view of the mechanism of connecting a precast element to the structural member, in accordance with the present invention. Detailed description of the embodiments

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments. Referring now to figures 1-4, there is shown a mechanism (100) for connecting one precast element with other. In an embodiment, other precast element may be a structural member. The mechanism (100) comprises at least one first insert (10) configured in receiving precast element (12). In an embodiment, the first insert (10) is hollow rectangular housing having a shear key one side and holdfast on other sides except the connecting face.

The first insert (10) is a donor insert. The first insert (10) is embedded in the structural member (12) before casting. Specifically, the first insert (10) is an assembly of welded plates, having an opening (10a) at the centre and flex grout tubes(12a, 12b) for grouting. In an embodiment, the first insert (10) is designed as per the loads and capacity of structural element. The first insert (10) is connected appropriately to the steel inside the structural element and sufficient holdfasts are provided.The first inset (10) is connected to a sleeve (14). Specifically, the sleeve (14) is arranged within entire width of the structural member (12). Figure 1 shows the first insert (10).

The first insert (10) is a working portion from inside the building, where the external precast element/facade, for example the precast element (22) and the structural element (12)are connected together to form a rigid connection.

The mechanism (100) further comprises at least one second insert (20) configured in mounting precast element (22).In an embodiment, the second insert (20) is hollow rectangular housing having a shear key one side and holdfast on other sides except the connecting face. The second insert (20) comprises a slit (24) adapted thereon.

The second insert (20) also known as receptor inserts. The second insert (20) is embedded in the precast element like facade, normal/ decorative cladding/ any shaped precast element before casting. The second insert (20) is an assembly of welded hollow sections with end holds fast plates. In an embodiment, the second insert (20) is designed as per the loads and capacity of precast element. The second insert (20) is connected to the steel mesh of the precast facade as per design. Figure 2 shows the second insert (20).

The mechanism (100) further comprises a T-bolt (30) as shown in figure 3. The T- bolt (30) is a fabricated T-bolt, with diameter designed as per the loads. The T- bolt (30) comprises a collar (32) at one end and threading for a nut (34) at other end. The T-bolt also includes an indicator (36) which is configured parallel to the collar (32) and indicated position of the collar (32) when inside the second insert (20).

In an embodiment, the first insert (10) and the second insert (20) and T Bolt (30) are made of stainless steel. However, it may be evident to those skilled in the art to make the inserts from any other material having strength. The sleeve (14) is made of corrugated steel, stainless steel, PVC or any other suitable material satisfying design requirement.

The mechanism (100) furthermore comprises a washer plate (40). The washer plate (40) is a stainless steel plate with slotted holes. The mechanism (100) also comprises a flexible rubber seal/washer (50). The flexible rubber seal/washer (50) is placed between structural member (12) and the precast element (22). In an embodiment, the flexible rubber seal/washer (50) is backed with polyurethane waterproof liquid for it to stick to the structural element (12) from outside. The flexible rubber seal/washer (50) gets pressed against structural member (12) when the precast element/facade (22) is brought near the structural element (12) and the nut (34) is tightened. This rubber seal (50) acts like a shutter to stop the grout from flowing from inside to outside as well as to stop any water to flow from outside to inside of the structural member (12). The flexible rubber seal/washer (50) includes an opening at the centre to allow passing the T-bolt (30) therethrough. Specifically, figure 4 shows washer plate (40), a flexible rubber seal/washer (50) and a shuttering plate (60) for grouting. The shuttering plate (60) is placed temporarily over the first insert (10) before grouting to stop the grout come out of the first insert (10).

In an embodiment, a rubber seal is applied with adhesive on its backside of the T- bolt (30).

The second insert (20) is a junction where the T-bolt (30) is connected to hold the precast element (22) with the structural member (12). In another aspect, the present invention provides a method for connecting a precast element (22) to the other i.e. the structural member (12). The method is described in conjunction with the mechanism of figure 1 o 4.

The method comprises placing and aligning the first insert (10) at the required junction in the structural member (12). This is done before casting the structural member. While casting the structural member, the first insert (10) is stiffed and aligned. The first insert (10) is connected to the steel bars which form a main or shear reinforcement of the structural member (12). In an embodiment, the mouth of the first insert (10) is temporarily closed as to avoid the concrete penetration while casting.

The method further comprises placing and aligning the second insert (20) at the required junction in the precast element (22) prior to casting thereof. While casting the precast element (22), the second insert (10) is stiffed and aligned. The first insert (10) is connected to the steel bars which form a main or shear reinforcement of the precast element (22). In an embodiment, the mouth of the second insert (20) is closed to avoid the concrete penetration while casting.

Specifically, the alignment is checked for structural member (12) and the first insert (10) accordingly after casting. The method furthermore compriseserecting and aligning the precast element (22). The first insert (10) and the second insert (20) are matched with each other and the flexible rubber seal/washer (50) is installed in between the structural member and the precast element.

The method moreover comprises inserting the T-bolt (30) from the first insert (10) to the second insert (20) through the slit (24). The T-bolt The collar (32) of the T- bolt (30) passes through the slit (24). Thereafter, the T-bolt (30) is rotated such that the collar (32) doesn't come out of the slit (24) and keeps the T-bolt (30) in locking position. Thereafter,slotted washer plate (40) is placed on the T-bolt (30) from the end at which the nut (34) is to be configured i.e. within the first insert (10). Specifically, a nut is rotated to tighten the T-bolt (30) fully. In an embodiment, the T-bolt (30) is oiled or covered with thin polymeric paper to have smooth rotation without friction, in case of de-connection of the precast element (22) with the structural member (12).

Finally, the method comprises the grouting. The grouting is carried from bottom grout pipe i.e at grout pipe (12b) of the first insert (10). Specifically, gaps within the structural member (12) where the first insert (10), T Bolt (30) and sleeve (14) is configured are filled and the gaps within the precast element (22) where the second insert (20) and T Bolt (30) is configured are kept open or filled with PU foam or any other suitable filler material accepted as per design. The tube through which this filler material is injected in the gap is not shown. After filling the whole connection within the structural member (12), the excess grout comes out from top grout pipe (12b). It ensures that the whole assembly is fully grouted. More specifically, a grout gun (not shown) is used for grouting which pumps grout from bottom grout pipe (12a).

In an embodiment, the multiple precast elements (22) can be connected to a single structural element (12). The gap between the multiple precast elements (22) erection gaps are filled with a backing rod and sealed with joint sealant (for example PU or silicon) like standard glazing/ ACP panel methodology. In another embodiment, the mechanism (100) uses locking of the T-bolt (30) either manual, or hydraulically driven, pneumatically driven, with retractable spring coil-uncoil mechanism, rotary mechanism, magnet driven or any other suitable methodology known in the art.

In retractable spring coil-uncoil mechanism, the T-bolt's collar (32) is designed in a manner to retract at the time of going into the slit and then expand back into the second insert (2)) after passing through the slit (14).

Advantages of the invention

1. The mechanism for connecting one precast element to other of the present invention is fast and less labor dependent.

2. The mechanism for connecting one precast element requires no or less supporting structure for installation.

3. The mechanism for connecting one precast element to other gives full proof guarantee to ensure intended design.

4. The mechanism for connecting one precast element to other is consistent to measure performances.

5. The mechanism for connecting one precast element to other requires minimum on-site activities.

6. There are no water leakages through holes.

7. The mechanism for connecting one precast element to other is simple to explain and train the manpower. 8. The mechanism for connecting one precast element to other of the present invention has more strength, since the accessories are having embedment length in concrete of parent elements, unlike bolting and welding. 9.Shear Strength of steel is used in form of plates, which is much more than circular formed sections. lO.Shear Key provided in design, which provides more strength. 11.No on-site concreting/ wet connection, so less quality lapse chances.

12.The connection is hidden to non-visible sides of both the elements, thereby providing a clean look and aesthetic appeal. 13. Provision of a 'fixed' connection, as per design consideration.

14. The facade panels can be removed very easily if required or can be changed in future if required by the owner 15. Carpet area inside the building can be increased, since the facade panel is placed outside the structural member, which in case of brick wall, is placed on the structural member

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

Claims

We claim

1. A mechanism (100) for connecting a precast element (22) to a structural member (12), the mechanism comprising:

at least one first insert (lO)configured in the structural member (12), the first insert having a opening (10a) at the centre and grout tubes (12a, 12b) for grouting;

a sleeve (14) arranged within entire width of the structural member (12), wherein the opening (10a) of the first inset (10) aligns with the sleeve (14);

at least one second insert (20) configured in a precast element (22), the second insert (20) having a slit (24) adapted on a face thereof;

a T-bolt (30) connecting the precast element (22) with the structural member (12), the T-bolt (30) having a collar (32) adapted at first end, threading at second end, and an indicator groove (36) configured parallel to the collar (32) at the second end;

a flexible rubber seal/washer (50) placed between structural member (12) and the precast element (22), the flexible rubber seal/washer (50) having an opening at the centre thereof; and

at least one washer plate (40),

wherein upon aligning the structural member (12) and the precast element (22), the T-bolt (30) is inserted from the first insert (10) through the sleeve (14) to the slit(24) of the second insert (20) and the T-bolt (30) is rotated such that the collar (32) doesn't come out of the slit (24) and keeps the T-bolt (30) in locking position thereby joining the structural member (12) and the precast element (22).

2. The mechanism (100) as claimed in claim 1 , wherein the first insert (10) and the second insert (20) are made of stainless steel.

3. The mechanism (100) as claimed in claim 1 , wherein the flexible rubber seal/washer (50) is backed with polyurethane waterproof liquid for it to stick to the structural element (12) from outside.

4. The mechanism (100) as claimed in claim 1 , wherein a shuttering plate (60) is placed temporarily over the first insert (10) before grouting to stop the grout come out of the first insert (10). 5. The mechanism (100) as claimed in claim 1 , wherein a nut (34) is provided at the second end of the T-bolt 30 to tighten the T-bolt (30).

6. A method for a connecting a precast element (22) to a structural member (12), the method comprising

placing and aligning a first insert (10) in the structural member (12) before casting the structural member (12);

placing and aligning a second insert (20) in a precast element (22) before casting the precast element (22).

matching the first insert (10), a sleeve (40) and the second insert (20); installing a flexible rubber seal/washer (50) between the structural member

(12) and the precast element (22);

inserting a T-bolt (30) from the first insert (10) to the second insert (20) through a slit (24) of the second insert, wherein a collar (32) of the T-bolt (30) passes through the slit (24);

rotating the T-bolt (30) such that the collar (32) doesn't come out of the slit (24) and keeps the T-bolt (30) in locking position;

placing the slotted washer plate (40) on the T-bolt (30) from the second end at which the nut (34) is to be configured i.e. within the first insert (10);

rotating the nut tighten the T-bolt (30); and

grouting from bottom grout pipe (12b) of the first insert (10).

7. The method for a connecting a precast element (22) to a structural member (12), wherein mouth of the first insert (10) is temporarily closed as to avoid the concrete penetration while casting.

8. The method for a connecting a precast element (22) to a structural member (12), wherein the mouth of the second insert (20) is closed to avoid the concrete penetration while casting.

9. The method for a connecting a precast element (22) to a structural member, wherein the T-bolt (30) is oiled or covered with thin polymeric paper to have smooth rotation without friction.