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Chapter 4
- 1. BACHELOR OF QUANTITYSURVEYING (HONS) BLD 60104 CONSTRUCTION TECHNOLOGY 1 By Azrina Md Yaakob Azrina.MdYaakob@taylors.edu.my CHAPTER 4 CONCRETE FRAMED BUILDINGS
- 2. CONCRETE Mixture of cement,fine & coarse aggregate & water Basic construction: a) Concrete b) Formwork c) Reinforcement FRAMED Consists of: a) upright load bearing members such as posts in timber b) columns in concrete c) stanchions in steel which are arranged at the corners of the square or rectangular base Transfer loads of heavy structure plus any imposed loads via the f r a m e s t r u c t u r e members to a suitable lower ground BUILDING R e s i d e n t i a l , Commercial, Offices, Etc 1.0 BASIC DEFINITION
- 3. a) Concrete b) Formwork c)Reinforcement Frame Building
- 4. 1.1 CONCRETE • Increasesits strength during curing / hardening period • Portland cement is used –28days • Nominal max sizes of aggregates: 40, 20, 14 and 10mm; 5mm is for precast products • Grade 7 & 10 -plain unreinforced concrete • Grade 15 & 30 –RC with lightweight aggregates • Grade 25 –RC with dense aggregates • Grade 30 to 50 –pre-stressed concrete
- 5. 1.2 REINFORCEMENT Requirements: • Capableof achieving tensile strength without any undue strain • A material can be easily bend to any required shape • Surface must be capable of developing adequate bond between the concrete & reinforcement • Reasonable cost & acceptable to overall design concept • Steel in the form of bars • mild steel (R) & high yield (T) • nominal sizes: 6, 8, 10, 12, 16, 20, 25, 32mm
- 6. 1.3 FABRIC REINFORCEMENT • Structural members that require only small area of reinforcement • Can be reinforced by steel fabric, which can be supplied by sheets / rolls • Factory-made by welding • Sheets: 4800mm x 2400mm • Rolls: 48.00m & 72.00m with a common width of 2.40m
- 7. 1.4 FORMWORK • Amould / box into which wet concrete can be poured so that it will flow & finally set to the inner profile of the box • Requirements: • Strong enough to support the load of wet concrete • Must be accurately set out • Have grout-tight joints –grout leakage can cause honeycombing of the surface • Designed to be the max size that can be easily handled by hand & mechanical lifting device • Moisture content btw 15 –20% Bad Formwork Design : Leakage which cause honeycombing
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- 9. 1.4.1 FOUNDATION FORMWORK Thereare 2 types of foundation formwork: 1. Permanent formwork 2. Traditional timber formwork Benefits of using permanent formwork: Ø Less concrete waste Ø Requires less excavation than traditional wood planks Ø Easily transported because of the light weights Ø No skilled labours are needed Benefits of using traditional timber formwork: Ø It can be reused Ø Cheaper production cost Ø Higher availability than steel Ø Easy to work by using hammer and nails
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- 13. 1.4.3 BEAM FORMWORK • A beam form consists of a three-sided box which is supported by cross-members called headtrees. • Soffit board should be fixed inside the beam sides so that latter can be removed. This also can speed up the hardening process and also release the formwork for re-use.
- 14. 1.4.4 SLAB FORMWORK Thereis four type of slab formwork: 1. Timber beam slab formwork 2. Traditional slab formwork 3. Metal beam slab formwork 4. Modular slab formwork Metal beam slab fwk. Timber beam slab fwk. Modular slab fwk. Schema7c sketch of tradi7onal fwk.
- 15. 1.4.4.1 TRADITIONAL SLABFORMWORK • Consists of supports out of lumber or young tree trunks, that support tows of stringers • Assembled roughly to 2 meters apart, depending the thickness of slab • Between these stringers, joists are positioned roughly 30cm apart upon which boards or plywood are placed. • The stringers and joists are usually 4 by 4 inch or 4 by 6 inch lumber
- 16. 1.4.4.2 TIMBER BEAMSLAB FORMWORK • Similar to the traditional method • But stringers and joist are replaced with engineered wood beams • Supports are replaced with metal props • This method more systematic and reusable
- 17. 1.4.4.3 METAL BEAMSLAB FORMWORK • Similar to traditional method • But stringers and joist are replaced with aluminium forming systems or steel beams • Supports are replaced with metal props • More systematic and reusable
- 18. 1.4.4.4 MODULAR SLABFORMWORK • These systems consist of prefabricated timber, steel or aluminum beams and formwork modules • Modules are often no larger than 1 to 2 meter in size • Beams and formwork are typically set by hand and pinned, clipped, or screwed together
- 19. 1.5 CONCRETE FRAMEDBUILDING Concrete Framed Building Stump Ground Beam Ground Floor Slab Ground Floor Column 1st Floor Beam & Slab 1st Floor Column Roof Beam
- 20. 1.5.1 STUMP • Ashort column constructed on top of the pad foundation / pile cap to support ground beam & column above • To transfer the load of a building onto the pad foundation / pile cap • To raise ground beam & ground floor slab to the required height above GL
- 22. 1.5.2 BEAMS • Supportingwalls, joists, etc., at or near ground level, itself either resting directly upon the ground or supported at both ends by piers. • Vary in their complexity of design & reinforcement depends on loading • Erected over columns or piers taken into the soil • Transfer their loadings to columns • When erecting them, the piers must be already cast in the ground
- 23. 1.5.2.1 BEAM CONSTRUCTIONPROCESS Clearing the ground Blinding layer Reinforcements are then tied and bent separately; carried and laid over the columns and blinding Formwork erected to sides Concrete is prepared and poured
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- 25. 1.5.3 COLUMNS • Constructedfrom either plain concrete (1:3:6) / reinforced concrete (1:2:4) • Vertical structural element that transmits, through compression, the weight of the structure above to other structural elements below • To support beams or arches on which the upper parts of walls or ceilings rest • Columns must be properly located, and the choice of a steel beam or wood beams
- 26. 1.5.3.1 COLUMN CONSTRUCTIONPROCESS Link tied to main bars Adding spacer block Lapping Wood Bracing
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- 29. 1.5.4 FLOOR Functions ofGround Floor • Withstand load imposed upon them, dead & live load • Prevent the growth of greens inside the building by concrete over-site • Prevent damp penetrating the building –damp proof membrane • To be durable so to reduce the amount of maintenance / replacement work to a min • Provide acceptable finish which will meet the needs of users
- 30. Functions of UpperFloor • Support their own weight, ceilings & superimposed loads • Restrict the passage of fire; for high-rise building • Restrict transmission of sound from 1 floor to another • Durability • Bridge the specific span economically & be capable of fairly quick erection • Accommodate services • Provide acceptable finish which will meet the needs of users
- 31. Floor Slab • Theformwork for floor beam & floor slab is constructed together • Reinforcement for floor slab tied to beam reinforcement
- 32. 1.5.4.1 CONSTRUCTION OFGROUND FLOOR SLAB
- 34. a) Hardcore • Tofill hollows & to raise the finished level of an over-site concrete slab after removal of turf • Provide a firm working surface & prevent contamination of the lower part of wet concrete • Reduce the amount of rising ground moisture • hard, durable & chemically inert; will not attack concrete & mortar; readily be placed in in a compact & dense condition • 100-150mm thick b) Blinding • To even-off the surface of hardcore if a damp-proof membrane is to be placed under concrete bed • A layer of sand 25 –50mm thick
- 35. c) Damp ProofMembrane • To prevent dampness getting through a ground bearing concrete floor should be protected by an impervious layer, usually a 1200 gauge (0.3mm) heavy duty polythene damp-proof membrane. • The DPM can be positioned either on the sand blinding or on the concrete slab. • Joints in a Polythene DPM should be welted or taped and should overlap by at least 300mm. • The DPM must be linked with the DPC in the walls, to ensure that the entire interior of the building is protected from moisture by a continuous, impervious barrier.
- 36. d) Concrete FloorSlab • A typical concrete mix for a ground bearing slab is 1:2:4 mix. • The floor slab is usually placed over the DPM • The floor slab should not be less than 100mm thick. • Ensure all the services and ducts running under the floor are installed and tested before pouring the slab. • If required, the concrete slab may be reinforced with a layer of steel mesh • Once the concrete slab has been poured, it can be temped with a heavy beam to remove air and surplus water and ensure a level surface. • The concrete slab should be left to dry out for around two to three days
- 38. 1.5.4.2 CONSTRUCTION OFUPPER FLOOR SLAB 1) Construct coulmn 2) Slab formwork 3) Concreting
- 39. 1.5.4.3 FLOOR FINISHES Factorsto be considered during choosing a right floor finishes: • Durability –avoid premature replacement with extra cost & inconvenience • Function • Resistance to wear –resistance to indentation as floor has to withstand heavy furniture, fittings & equipment; resistance to abrasion in buildings subject to movable equipment • Economy –initial & maintenance cost • Non-slip qualities –bathroom & kitchen • Appearance –wood blocks & strip flooring
- 40. 1.6 ROOF BEAM • A load-bearing member in the roof structure. • Member that span across the openings & support structure or loading above them • Material : timber, steel & reinforced concrete • Purlin act as beam, reducing the span of the rafter enabling an economic section to be used
- 43. TUTORIAL 4 (A) • In a table form, explain the type of materials available for formwork. • Item to be included in the tables are: ü Suitability ü Advantages ü Disadvantages ü Cost Requirements: You should prepare the table form which need to be presented. Please state your name, student ID and title. (Group)
- 44. • In atable form, explain the type of materials available for floor finishes. • Item to be included in the tables are: ü Suitability ü Advantages ü Disadvantages ü Cost Requirements: You should prepare the table form which need to be presented. Please state your name, student ID and title. (Group) TUTORIAL 4 (B)