Design Principles
- 2. PREFABRICATION Definition : Prefabrication is the practice of assembling components of a structure ina factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is used to distinguish this process from the more conventional construction practice of transporting the basic materials to the construction site where all assembly is carried out.
- 3. NEED FOR PREFABRICATION • Cost of construction • shorter construction time • easy of expansion • utilization of material • attractive finishes • highly efficient for weather resistance • single source assurance • insurance advantage
- 4. ADVANTAGES OF PREFABRICATION • Self supporting • Time consumption reduced • Quality control • Prefabrication can be located where skilled labour is more readily available • Escape from bad weather and hazardous environment • Less waste may be generated • On-site construction and congestion is minimized.
- 5. DISADVANTAGES OF PREFABRICATION • Careful handling • Attention has to be paid to the strength and corrosion-resistance • Leaks • Transportation costs • Heavy duty cranes • Precision measurement and handling
- 6. Requirements for planning and layout of prefabricated plant PLANNING REQUIREMNTS 1. Selection of the type of plant 2. Locationof the plant site 3. Type of production process used 4. Finalizing the area required
- 7. Plant layout requiremnts 1. Manufacturing cost 2. Process requirement 3. Nature of operation 4. Nature of maintainance 5. Future expansion 6. Adequate spce b/w machinaries 7. Adequate space for storage materials 8. Easy access of labour and equipment to all working areas. 9. Nearest location for strong fractional relationship activities. 10. Providing shortest and most convenient flow of materials within the plant. 11. Providing maximum safety to workers. 12. Good visual control of work progress. 13. Providing simple space for inspection and maintenance work.
- 8. MODULAR COORDINATION Definition : Modular coordination is a concept of coordination of dimension and space, in which buildings and components are dimensioned and positioned in a term of a basic unit or module. • It is internationally accepted by the International Organization for Standardization (ISO) and many other countries.
- 9. AIMS OF MODULAR COORDINATION 1.The principle object is to assist rationalization and industrialization within the building industry, by standardization in such a way that components may be manufactured on an industrial scale and erected efficiently on site, thereby improving economics of building. 2. Facilitates cooperation between building designers, manufacturers, distributors, contractors and authorities. 3. To permit the use of building components of standard sizes to construct any building 4. In design work, to simplify the preparation of building drawings 5. Optimizes the number of standard sizes of building components.
- 10. • 5. Encourages as far as possible the interchangeability of components, in whatever materials, forms or methods of manufacture. • 6. Simplifies site operations by rationalizing setting out, positioning and assembly of building components. • 7. Ensures dimensional coordination between installation (equipment, storage units, other fitted furniture, etc.) as well as with the rest of the building.
- 11. BENEFITS • Better coordination and cooperation between various parties in construction. • Reduction in design time, especially with the use of standard details and dimensional coordination. • Reduction in manufacturing and installation cost. • Reduction in wastage of materials, time and manpower in cutting and trimming on site. • Facilitating prefabrication .
- 12. BASIS • Modular coordination is essentially based on: • a. The use of modules ( basic modules and multi-modules) • b. A reference system to define coordinating spaces and zones for building elements and for components which form them. • c. Rules for locating building elements within the reference system • d. Rules for sizing building components in order to determine their work sizes • e. Rules for defining preferred sizes for building components and coordinating dimensions for buildings.
- 13. Module Standard unit size used to coordinate the dimensions of buildings and components Basic module The basic module is the fundamental unit of size in modular co-ordination. The co- ordinating sizes of building components, of the parts of buildings they form and of buildings themselves shall be multiples of the basic module. Multi-Module Multimodules are selected multiples of the basic module; different multimodules will suit particular applications. Sub module Fraction of a basic module
- 14. Modular reference system • Definition : three dimensional system of orthogonal space coordinates within the positions and sizes of components, elements and installations can be related by references topoints, lines and planes. • Used mainly during planning and design stage.
- 15. TYPES OF GRID PATTERNS FOR REFERENCE 1. Continuous grid 2. Superimposed grid 3. Displacement of grid or tartan grid 4. Interrupted grid or neutral zone 5. Axial reference 6. Boundary reference 7. Flush reference 8. Interaxial reference
- 16. TYPES 1. Continuous grid : All dimesions in either direction are based on one increment only. 2. Superimposed grid : increament is superimposed on a multi modular grid.
- 17. TYPES 3. Displacemnt of grid or tartan grid : Homogeneousand repetitive realtion between atleast2 basic increments. 4.Interrupted grid or neutral zone : non modular interruption.
- 18. TYPES 5. Axial reference : coordinate the position of a particular component by placing the component so that the middle axis coincides with modular coordinating grid.
- 19. TYPES 6. Boundary reference : coordinate the position of the building components and determines the nominal size of the component by placing b/w parallel modular coordinating grids.
- 20. TYPES 7. Flush reference : coordinate the position of building components and its relationship to the other components by placing one surface of the component to a modular cordination grid.
- 21. TYPES 8. Interaxial reference : based on combination of both axial and boundary reference.
- 22. STANDARDIZATION • Repeated production of standard sizesor layout ofcomponents or entire structures. • Definition : It isdefined as the creation and use of guidelines for the productionof uniform interchangeable components especially for useinmass production. • It is done by providing a national scale mandatory for whole country by the competent authorities and publish their catalogues of standard prefabricates, standard housing units oreven for a whole building.
- 23. Objectives Of STANDARDIZATION • To start designing with recommended dimensions by the designers. • Facilitate and provide necessary guidelines and considerations when adopting standard PF elements. • Reduce the errorsand rectification process which occur during insitu construction. • Encourage the industry to move from labour intensive to labour saving construction methods. • Promote wider use of standard PF building components.
- 24. Advantages of standardization • Manufacturing process is made easy. • During erection and completion of PF components,standardization helps to make use of repeated equipment which leads to economy in all aspects. • Designing process is made easydue to elimination of unwanted choices.
- 25. DISUNITING OF PREFABRICATED STRUCTURE 1. System consisting of linear member disunited at joints 2. System for prefabricates of entire rigid frame 3. System consisting of I,T,U of straight members disunited at points of minimum moment. 4. Two hinged and three hinged arches.
- 26. System consisting of linear member disunited at joints • Manufacturing and hosting process is very simple. • Auxillary scaffoldings are not necessary. • Joints are at the corners where the maximum moment exist therefore forming of joints is difficult. • Joints are overdimensioned and necesity of additional materials. • Moment resistant joints are replaced by Hinged joints.
- 27. System for prefabricates of entire rigid frame • Lessen the no.of joints and caste larger memeber in one lead. • Adoptable only for site prefabrication. • Hoisting is a problem • Stress distribution of straight members during hosting is statically determined generally. • But statically redudant condition may occur due to tilting. • If the 2 points of the member is not hosted uniformly,torsion will take place. • Connecting the 2 points by a single suspension point by a balance or a cable rocker enables the frame to be hoistedat one singlepoint.(statically determinate)
- 28. Continued.. • Hoisting of asymmetric frames are more difficult. • Precast in location close to the final location. They can aso be produced in a vertical position standing side by side. Advantages • Small no. Of joints • Rapid hoisting work • Easy for construction of long balls having numerous no. Of uniform frames.
- 29. System consisting of I,T,U of straight members disunited at points of minimum moment • Division into members wherethe moments are smaller. • Called as Lambda method in some countries. • Junctions are resited in places where the moments are smaller. • Generally near zero points of moments corresponding tothedead load. • Hinge like joints can also be formed. • Drawback maily during hoisting and temporary bracing of L shaped asymmetric frame. • Resting of frame member on each other necessitates the use of cantilevers having half depth and proper forming of this cause difficulty. • Roof can be a pitched roof too.
- 30. Two hinged and three hinged arches • These are normally used for bridging span more than 20-25m. • Their production and placing is more difficult than straight members. • Arch can be two hinged and three hinged but they can also be fixed at footings and can be constructed with or without tie. • These members are generally precast and assembled in statistically determinant three hinged variance. • The reinforcing bars protruding both sides are welded together and the joint between the members is filled in with insitu concrete. • The prefabrication of larger arches in the horizontal position is found to be more economical.
- 31. IS CODE SPECIFICATIONS IS 395-1966 : Code of practice for composite construction IS 3201-1965 : criteria for design and construction of precast concrete trusses IS 6322-1971: code of practice for the construction of floors and roofs using precastdouble curved shell units IS 10297-1982: code of practice for the design and construction of floors and roofs using precast reinforced, prestress concrete ribbedor cored units. IS 10505-1983: code of practice for the construction of floor and roofs using precasr reinforced concrete waffle units. IS 6061 (Part I) 1971 code of practice for the construction of floor and roofs with joist for hollow filler blocks, part I with hollow concrete fillerblocks
- 32. Continued.. IS 6061 (Part II) 1971 code of practice for the construction of floor and roofs with joist for hollow filler blocks, part I with hollow clay filler blocks IS 6073-1971: speecification for the autoclayed reinforced cellular concrete of floor and roof units. IS 6072-1971: speecification for the autoclayed reinforced cellular concrete of wall slabs. IS 6441 (Part IV) 1973: methods of test for autoclay cellular concrete blocks, part IV with strength deformation and cracking of flexural members subjected to bending by short duration loading test. IS 6441 (Part VII) 1973: methods of test for autoclay cellular concrete blocks, part IV with strength, deformation and cracking of flexural members subjected to bending only.