Description:FIELD OF INVENTION

The invention relates to precast stairs.

PRIOR ART

More types of Stair elements due to variations in span, height & steps for different staircases which in turn Less repetitive elements, and inappropriate to proceed with many moulds for a limited scope.

Precast stair case is attractive as it does not require any finishing works and it can be used instantly at site. Usage of precast stair case allows swift and effect installation. But such precast stair cases of standard sizes cannot be customized at side for different size spaces and different heights. Such precast stair case can only be made at the factory or shop and shipped as a kit to the site where the modules are assembled and installed.

Hence flexibility of adjustment is very low with precast stair cases as known in prior art.

This process is costly, time consuming, often involving delays and additional cost.

OBJECT OF THE INVENTION

To optimize the moulds requirement and to accommodate all type of elements using limited moulds. At the same time, to provide cost-effective solution and simple one for site execution. Sensitivity: LNT Construction Internal Use.

This invention presents a new approach towards Optimization of Moulds for Precast Stair elements, developed & provided by EDRC-RBU (Precast team) which is an innovative solution and yet cost-effective. This innovative approach helps in optimization of moulds which in turn reduce the investment on moulds for the project. By adopting this, the execution process is simple & faster, and the same moulds can be utilized for future similar projects with slight modification if necessary.

This new approach has been developed for the 1st time ever & implemented successfully at project site and the same is elaborated as a case study.

The present invention overcomes the objections/suffering of prior art practice, and an object of the invention is to provide an improved method and improved and simplified stair case by which the installation of case may be done without undue equipment, easily, quickly and economically “adjust” the fabricated stair case at side of installation.

Another object of the invention is to provide an improved stair case assemblies which may be easily and quickly attached and adjustably positioned and used in various combination to make a desired stair case.

A still further object of the invention is to provide a improved stair case assemblies in accordance with the foregoing, which are simple in construction and economical to fabricate.

Still another object of the invention is to provide stair case assemblies as above set forth, which are strong and sturdy in construction and reliable in use.

SUMMARY OF INVENTION

Design & Construction of IT Park in SEZ Campus for L&T Infotech at Mahape, Navi Mumbai. Scope of project consists of two towers (office buildings), connected by corridor, common extended basement, and stilt levels. The Built-up area for the project is 1.37 MSft.

Project comprising of 2 basements, 3 stilts and 12 typical floors. The structural system configuration is of structural steel core, concrete filled tubes for columns, precast staircases, and partition walls.

Construction of staircases shall be with Precast technology instead of CIP concrete for faster construction due to timelines & to avoid on-site formwork, and as decided by the inventors after award of job.

Scope of work involved total of 7 staircases which are grouped into 3 types with respect to variation of span/ length. Another factor is variation of floor heights for basements, stilts & typical floors.

Element bifurcation resulted into large number of element types (48 nos.) for a total element count of 330 nos. which are very less repetitive and even some element types are of single digit repetition.

The demonstration of total precast scope in the project is illustrated in Fig. 1.

DESCRIPTION OF THE INVENTION

A stairway (set of steps) is between one floor or landing and the next and is referred as flight of stairs. The staircase typically gives access to various floors and roofs of the building. It so includes a flight of steps and one or more intermediate landing slabs between the floor levels.

Landings are incorporated between two staircases to attach it, creating it safer with a resting place partway up. Except for the landing between two flights of stairs, all the treads are rectangular and of similar dimensions.

After comprehensive study of the layouts of Staircase-1 to 7, few points are common in all staircases which helped in shaping this idea and resulted to the evolution of standard moulds i.e., Flexible moulds.

Part no. Part names
101 07 Staircases
102 ST-1,2,3,4
103 ST-5,6
104 ST-7
105 12 Typical floors
106 03 Stilt floors
107 02 Basements
108 330 Elements
109 48 Elements types

▪ Angle of inclination (26.6o) of flights which is similar for all staircases/ levels w.r.to riser-tread dimensions in addition to flight width, refer Fig.1a.
▪ The lone changes are at landing areas i.e., due to span variation, height variation, column cutouts and slab bearings etc., as depicted below the overlapped flights with variations, refer Fig.1b.
▪ Conception of standard moulds started by considering the periphery of the overlapped flights as mould surface. Thus, the Flexible moulds are generated for main direction flights (i.e., Mould-01 & Mould-02).
▪ Cross flights which have same angle of inclination can be produced using these standard moulds.

Fig.1a: Main flights (upward) at different stairs/ levels
Fig.1b: Variation at landing areas either side
Fig.1c: Conception of Moulds
Part no. Part names
110 MOULD -01

▪ Adjustable Stoppers which are part of moulds and will be operable for length variation of elements at landing areas which varies for different staircases.
▪ Packers/ fillers to be used in these standard moulds (i.e., deductions for columns, variation of steps, cross flight/ slab bearings etc.) to create required profile of elements for different staircase/ levels.
▪ Cross flight with significant repetitions is allotted with distinct mould (i.e., Mould-03).

Flexible Moulds (03 nos.) are proposed for this project to cater all type of elements i.e., main flights & cross flights/ mid-landings and casting of rectilinear mid-landings by using Site base plywood moulds.

3D illustration of Mould and packers/ fillers i.e., how to generate the required profile of elements by using the Flexible moulds, refer Fig.2a to 2e.

Fig.2a: Mould-01 Fig.2b: Element profile to be cast

Fig.2c: Packers/ fillers to be used in Mould-01 for required element
Part no. Part names
201 STOPPER

Fig.2d: Different Packers/ fillers used in Mould-01 for Main flight elements
Part no. Part names
202 Element profile

Fig.2e: Different Packers/ fillers used in Mould-01 for Cross flight elements
Part no. Part names
203 Element
204 Empty space in mould using stoppers

All the listed elements can be created by altering with suitable packers/ fillers for element types. Packers/ fillers can be formed by wooden boards, nylon pads and steel plates based on significant repetitions.

Fig.3: Conception of Mould
Part no. Part names
301 MOULD -02

Similar approach as depicted for Mould-01 shall be applicable for the elements to cast using Mould-02.

Fig.3a: Mould-02 Fig.4: Mould-03

Precast production drawings was also included as part of invention for efficient working of the invention (refer fig. 5).
Part no. Part names
501 M1-PR-02(Step-3)
502 M1-PR-13(Step-3)
503 M1-TH-03(Step-5)
504 M1-PC-03(Step-2)
505 STOPPER-1(Step-1)
506 BLANK SPACE
507 M1-PR-12(Step-3)

Another challenge is to convey this new approach in the form of production drawings to support the execution team i.e., how to cast the different elements by using the Standard/ Flexible 03 moulds.

It is essential to capture all the details in 3D BIM like mould profile, sequence of placing packers/ fillers & schedule in respective moulds to cast the specific elements.

1st time implemented this type of detailing in precast production drawings i.e., synchronizing packers/ fillers & standard mould details for respective elements in addition to reinforcement & connections using TEKLA Structures BIM.

The invention relates to a main stair flight modular assembly comprises of a main step standard module and an adjustable configurable end landing module extending therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers.

In another aspect, stair flight modular assembly has the landing module at the top end of the standard main module.

In another aspect, stair flight modular assembly has the landing module at the bottom end of the standard main module.

The invention also discloses a cross stair flight modular assembly comprising of a step, a top adjustable configurable end landing module extending from top end therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers, and a bottom adjustable configurable end landing module extending from bottom end therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers.

In another aspect, the invention discloses a stair case comprising of plurality of main stair flight modular assembly and cross stair flight assembly wherein each main stair flight modular assembly has atleast one main step standard module with an adjustable configurable end landing module extending either from top end or from bottom end therefrom and wherein each cross stair flight module assembly if any has a step sandwiched between a top adjustable configurable end landing module and a bottom adjustable configurable end landing module.

Thus it can be concluded that :-

▪ Flexible moulds application works well for the projects with limited scope & especially with less repetitive elements. This approach will reduce the cost of moulds significantly for the project.

▪ This is a benchmark for future similar jobs, as the same moulds (Mould-01&02) can be used for stair elements at future jobs with some minor modification (if needed) & with almost no cost of moulds.

Site pictures are illustrated in fig. 6A, 6B, 6C, 6D, 7A, 7B, 8A, 8B and 9.
Part no. Part names
601 Packers/fillers
602 Fillers
603 Stair Element

Fig. 6B - Depiction of Mould with fillers to cast required profile
Fig. 6C - Stair Mould - Main flight
Fig. 6D - Stair Mould - Cross flight
Fig. 7A - Main flights – Casted elements
Fig. 7B - Cross flights – Casted elements
Fig. 8A - Packers/ fillers placed inside mould-01
Fig. 8B - Packers/ fillers placed inside mould-02
Part no. Part names
801 3(a) Packers/fillers placed inside mould-01
802 3(b) Packers/fillers placed inside mould-02

Fig. 9 - Elements with different profile at landing

Variations and modifications may be made within the scope of the claims and portions of the improvement may be used without others.
, Claims:WE CLAIM :

1. A main stair flight modular assembly comprises :

- a main step standard module and an adjustable configurable end landing module extending therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers.

2. The main stair flight modular assembly as claimed in claim 1, wherein the landing module is the top end of the standard main module.

3. The main stair flight modular assembly as claimed in claim 1, wherein the landing module is the bottom end of the standard main module.

4. A cross stair flight modular assembly comprises :

- a step,
- a top adjustable configurable end landing module extending from top end therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers, and
- a bottom adjustable configurable end landing module extending from bottom end therefrom, wherein the landing module has a length-wise extending channel with slidable fasteners or stoppers.

5. A stair case comprising of plurality of main stair flight modular assembly and cross stair flight assembly wherein each main stair flight modular assembly has atleast one main step standard module with an adjustable configurable end landing module extending either from top end or from bottom end therefrom and wherein each cross stair flight module assembly if any has a step sandwiched between a top adjustable configurable end landing module and a bottom adjustable configurable end landing module.