off site fabrication

Evaluate Applications of Off-Site Fabrication

Sunny MahajanCE 501

Individual Tool Assignment

Definition

• CII defines" Prefabrication is a manufacturing process, generally taking at a specialized facility, in which various materials are joined to form a component part of the installation"

• In other words simplest form of prefabrication is building brick used throughout the world.

Classification

• Non-Volumetric Off-site fabrication - Small parts of building components to construct the main parts of building components. Such as wall partitions, pipe work, structural steel parts, etc.

• Volumetric Off-site fabrication - Units comprising usable space. Such as toilet units, plant rooms, lifts etc.

• Modular Buildings - Most units are substantially complete in themselves. Such as retail unit, houses, temporary units, medium rise office etc.

Present Usage & Potential

Residential Commercial Heavy Civil

Modular

Volumetric

Non- Volumetric

Industrial

(Types of Construction)

(Typ

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site

fabr

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Present

Potential

Process

Prefabrication and preassembly

Building Construction and installation

Site PreparationEngineeringDesign

Standardization

Cartoon by Mr. Buckminster Fuller.

History

Hong Kong Banking Corporation Headquarter

Renkioi Hospital

The Dymaxion House

Re-emergence

• With the technological advances in fields such as BIM, IT, CAD and computing, Off-site fabrication is more effective and feasible.

Recent Trends

• Prefabrication using BIM has been very successful as it has removed all past fallacies in prefabrication construction.

• Advances in computing has enabled to facilitate decision making for prefabrication. Using graph theory and IFC Database different feasible configuration can be computed.

• New market are evolving for exporting volumetric modularization units. Which can cater increased return on investments for existing manufacturing industries.

Parameters

• Time• Productivity• Cost• Waste • Quality• Safety

Few aspects of Cost

Additional Cost Savings Cost

Crane (Capacity) Productivity (Cutting learning Curve)

Fabrication facility On-site cost saving shorter construction period

Transportation Less on site work

Fewer construction workers

Less Transportation (Materials)

Efficient use of Crane

Unplanned on-site remedial works

Changes to project cash flow

Mc Graw Hill Construction - Smart Market Report on ' Prefabrication & Modularization' which conducted a internet survey of hundreds of AEC professionals. This study indicates that :- a. 66% report that project schedules are decreased. 36% by four week or more. b. 65% report that project budgets are decreased. 41% by 6% or more. c. 77% report that construction waste is decreased. 44% by 5% or more.

Limitations

• Labor Union• Transportation

Evaluate Applications of Off-site fabrication (Highways)• Considering Highway Industry and 5DPM, off-site

fabrication can help Quality control, minimal public disruption and environmental impact.

• Off-site fabrication can help manage cost, schedule and quality complexity which may be a solution for context/shareholders constraints.

Cost Schedule FinancingTechnical Context

Reference - Shane, J., Strong, K., and Gransberg, K. (2012). “Guidebook: Project Management Strategies for Complex Projects”, SHRP2 and Transportation Research Board.

Example - T 30 Hotel TowerNo. Items B2B Traditional buildings

(including 5-star hotel)

1 Construction waste 25t About 3000t

2 Construction dust No Yes

3 Construction ignition work (welding & gas cutting) No Yes

4 Construction water consumption No About 5000t

5 Wall & Ceiling decoration No plaster Plaster

6 Steel consumption 68 kg/m2 Reinforced concrete: about 75kg/m2 Steel structure: about 140kg/m2

7 Concrete consumption 100 kg/m2 About 1000 kg/m2

8 Construction site material delivery 150 vehicles About 1000 vehicles

9 Construction scaffold No Yes

10 Top sealing & Elevation 15 days About 1 year

11 Interior decoration 1 month About 1 year

Note: The foundation is not included. Designed by construction design institute per BSB parameters & local geological features, BSB foundation is similar to that of conventional buildings, only that it can be reduced due to lighter building weight.

References• Shane, J., Strong, K., and Gransberg, K. (2012). “Guidebook: Project Management Strategies

for Complex Projects”, SHRP2 and Transportation Research Board.• Broad Sustainable Building Co. Ltd. “T 30 Tower Hotel : Technical Briefing”.• Eastman C., and Sacks R. "Relative Productivity in the AEC Industries in the United States for

on-site and off-site activities". Journal of Construction Engineering and Management, ASCE, July 2008.

• Tam V.W.Y., Tam C.M., Zeng S.X., and Ng. W.C.Y. "Towards adoption of Prefabrication in Construction". Journal of Building and Environment, Science Direct, October 2006.

• Haas C.T., O'Connor J.T., Tucker R.L., Eickman J.A., and Fagerlund W.R. Report on "Prefabrication & Preassembly Trends & Effects on the Construction Workforce" for Center for Construction Industry Studies. The University of Texas at Austin, May 2000.

• Gibb Alistair G.F. " Off-site Fabrication: Prefabrication, Pre-assembly and Modularisation" John Wiley & Sons, 1999.

• Mc Graw Hill Construction - Smart Market. "Report on Prefabrication & Modularization: Increasing Productivity in the Construction Industry “. 2011.