THE DEPARTMENT OF ARCHITECTURE UNIVERSITI TEKNOLOGI MARA PERAK AAR451 CONSTRUCTION TECHNOLOGY 1
Detail Study On Masonry Construction [Loadbearing]
Building Vs. Soil What are the Issues?
Building Vs. Soil Continuous structural system – loadbearing construction case study
Subsoil must safely support the combined building loads + ensure that unreasonable movements of the building do not occur.
Building load vs. soil resistance
Continuous structural system – loadbearing construction case study
Continuous Structures [Loadbearing Construction] •
The Structural Concept
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These are continuous supporting walls which transfer the combined loads and forces through their construction, mainly by direct compression. Materials commonly used for this purpose are stone, brick, block and concrete.
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Continuous supporting wall may be the oldest form of structural organisation. See Baba and Nyonya’s House in Melaka, Kelly’s Castle, etc.
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Walls are constructed from fairly small units such as bricks, blocks or stones rely on their strength by being laid in horizontal courses so that their vertical joints are staggered or bonded across the face of the wall.
In this way the compression loads which initially affect individual, or a series of, bricks, blocks or stones can be successfully distributed through a greater volume of the wall. The units are held together by an adhesive mixture known as mortar, thereby completing the structural enclosure.
Building construction Continuous structural system – load bearing construction.
Trial holes or trial pits.
Physical exploration – using trial holes method. Trial holes dug into the ground. This techniques can provide a reliable source of information which costs as little as 1-2 per cent of the total building expenditure.
The trial holes need to be formed to sufficient depth to expose likely soil which support the foundation.
Initial site works
Site survey. – identifying site data and new levels formation. [Land surveyor]
Excavation
Excavation will consist of removing the top soil from the area of proposed building. [@ min. 300mm deep] – top soil : not suitable to receive any structural loading. Forming the trenches for foundations.
Building : Setting Out
Setting out the building foot-print and setting out the areas of the site which are required to be excavated.
Foundation construction Function of a foundation.
Functional requirement of a foundation Function– the resolved dead, imposed and wind loads may be transferred through the building by continuous walls or through isolated piers, by columns or piers or combinations of these techniques. Because each of these structural systems results in foundation types which transfer the loads to the supporting soil in different manners. The selection of a foundation type should reflect the optimum relationship between building structure and the characteristics of soil used as support. Case study – Sedec housing development [Raft foundation]; Taman Iskandar Bistari [raft foundation for single storey building and pad foundation on RC piles].
What is FOUNDATION of a small scale building? A foundation is the base on which a building rests, and its purpose is to safely transfer the load of a building to a suitable subsoil. The basic function of a foundation. Function of a foundation: to transfer the imposed load of a building or structure onto a suitable substratum. It provides strong base for building to rest on. What are the TWO (2) factors that influence the choice and the design of a foundation for a small scale building? a. the total loads of the building. Why ……… b. the nature and bearing capacity of the subsoil. Why ………
Choice of foundation For a single or two storey house using continuous load-bearing masonry walls [brick, block or stone], a form of strip foundation will be probably be most appropriate, and can consist of horizontal strip or vertical strip of mass concrete located beneath ground level. The depth of the foundation will depend upon the depth of adequate bearing soil, and he avoidance of certain phenomena which detrimentally affect the upper layers of the bearing soil.
Three [3] common type of foundations used in load bearing cavity wall construction and why these foundations are being used.
1.0 Deep Strip Foundation Greater ground stability since earth is not left exposed. It reduced need for planking and strutting to form earthwork support therefore considerable cost savings for the contractor. No need for operatives to work at base of trench and therefore is much safer especially in poor ground conditions. Introduced as building land became more scarce and access to deeper load bearing strata was required. The trenches must be wide enough for the ground worker and the bricklayer to gain access.
Why We Used Deep Strip Foundation [1.0]. Vertical strip foundation (Deep Strip) [1.1]. greater ground stability since earth is not left exposed. [1.2]. It reduced need for planking and strutting to form earthwork support therefore considerable cost savings for the contractor. [1.3]. No need for operatives to work at base of trench and therefore is much safer especially in poor ground conditions. [1.4]. introduced as building land became more scarce and access to deeper load bearing strata was required. The trenches must be wide enough for the ground worker and the bricklayer to gain access.
Vertical strip foundation; is generally used in firm soil where costs can be reduced because they are self-supporting and do not require the trench support.
2.0 Horizontal Strip Foundation (Wide Strip) Similar to ordinary strip foundations except that they are wider. They are made wider in order to spread the load over more area of soil. The wide strip foundation is usually used in poorer bearing soil conditions. Can be used to spread the load over a larger surface area so that the loading per m2 is reduced.
Why We Used Wide Strip Foundation [2.0]. Horizontal Strip Foundation (Wide Strip) [2.1]. Similar to ordinary strip foundations except that they are wider. They are made wider in order to spread the load over more area of soil. [2.2]. The wide strip foundation is usually used in poorer bearing soil conditions. [2.3]. can be used to spread the load over a larger surface area so that the loading per m2 is reduced.
Horizontal strip foundation; to be located at bearing soil level at – min. 600mm deep or depending on soil condition and geography locations.
Strip foundation
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What is the type of foundation constructed for this building?
Case Study: Foundation design in relation to wall construction.
Case Study: Foundation design in relation to wall construction.
Case Study: Foundation design in relation to wall construction.
Blockwork
Strip foundation
Case Study: Foundation design in relation to wall construction.
Case Study: Foundation design in relation to wall construction.
3.0 Raft Foundation Usually used where strip foundations would cover more than 50% of the ground A Typical RAFT FOUNDATION details in area below the building and Load Bearing [Cavity Wall] Construction hence becomes more economic to produce. Used where the soil has low load bearing capacity including loose sand, soft clays, filled material. This is achieved by casting a slab of concrete over the whole ground area and thickening the slab where walls are to be placed .
Why We Used Raft Foundation [3.0]. Raft Foundation [1]. Usually used where strip foundations would cover more than 50% of the ground area below the building and hence becomes more economic to produce. [2]. Used where the soil has low load bearing capacity including loose sand, soft clays, filled material. [3]. This is achieved by casting a slab of concrete over the whole ground area and thickening the slab where walls are to be placed .
A Typical RAFT FOUNDATION details in Load Bearing [Single Wall] Construction
Foundation type :
F4.11 Surface raft foundation
Materials for foundation construction The materials employed to make foundations must be strong and durable. [ foundation are constructed below ground – it is not possible or practical to carry out maintenance on the once they have been installed in the ground.
Due to this situation, the foundation are constructed from a good quality dense concrete; consisting of cement, fine aggregate or well graded coarse sand, and coarse aggregate of natural gravel [or crushed stone]. All graded concrete for foundation; according to the designer’s specification for strength required.
Other Case Study – Foundation Type : for Reinforced Concrete Frame [RC] Construction [FOR NONE LOAD BEARING WALL CONSTRUCTION]
Other Case Study – Foundation Type : for Reinforced Concrete Frame [RC] Construction
Type of foundation used for a single storey post and beam construction and the rationale of its usage.
Pad foundation [a]. Used to support an individual point load due to a structural column. [b]. The load would be concentrated in relatively small areas of the pad with large expanses being either non-load bearing or having lightweight loadings, meaning that small slabs to spread the load from the skeletal structure can be cast. [c]. They may be circular, square or rectangular.
[FOR NONE LOAD BEARING WALL CONSTRUCTION]
Ground floor construction
Performance requirements + The ground floor must provide a LEVEL SURFACE capable of supporting people, furniture, equipment, wheeled traffic, partitions, finishes, etc. + It must also provide environmental control against the passage of water (liquid and vapour) heat.
FOUR (4) [commons] primary functions of floor for domestic building. i. provide a level surface with sufficient strength to support the imposed loads of people and furniture. ii. exclude the passage of water and water vapour to the interior of the building. iii. Provide resistance to unacceptable heat loss through the floor. iv. provide the correct type of surface to receive the chosen finish.
Common floor construction a. Solid ground floor construction b. Suspended floor construction.
Solid Floor Construction
Solid floor construction [In cavity wall construction suitable for tropical climate]
Solid ground floor construction
Suspended Floor Construction
Common floor construction a.Suspended floor construction. Advantages + disadvantages a. Advantages i.
Timber panels as final finish to the floor.
ii. No direct contact with earth/soil – [no direct contact with moisture]. iii. Acting as thermal buffer space. [Good insulation]. b. Disadvantages iv. Timber prone to attack by dry rot. [If no adequate air ventilation underside of the floor]. v. Ventilation inlet for under floor ventilation are easily blocked due to poor maintenance. vi. Suspended timber floor unable to accept greater loading; thus it is only suitable for domestic building.
[TYPICAL CONSTRUCTION] TIMBER SUSPENDED FLOOR FOR GROUND FLOOR [FOR SINGLE WALL LOAD BEARING CONSTRUCTION]
[Typical Construction ] for Tropical Climate
Suspended floor construction
Suspended timber ground floor construction
Suspended timber ground floor construction
Suspended timber ground floor construction Suspended timber, concrete slab level, timber boarding, cavity wall.
Wall construction
External Wall Construction
External wall construction The Function The main function of an external wall involves providing the environmental control between the external and internal climates of a building. An external wall is usually required to support the combined dead, imposed and wind loads of the roof and floor construction, as well as its own combined loads, and transfer them safely to a foundation. Apart from the technical requirements, considerations of appearance must be a critical part of the design since to a very large extent an external wall determines the architectural character and quality of a building.
Summary: Functions of the external wall The external wall of a house has two [2] basic functions: 1. To support the loads of suspended floors and roof 2. Environmental protection
The commons five [5] requirements of the external wall needed to fulfill the functions of the external wall i. Strength and stability ii. Weather protection iii. Good thermal insulation iv. Fire protection v. Durability
i. Strength and stability ii. Weather protection iii. Good thermal insulation iv. Fire protection v. Durability
Construction Type of ‘load bearing WALL’.
Two commons wall construction type in load bearing [continuous structure system] using bricks and blocks [1]. Solid wall construction [2]. Cavity wall construction [Option 3]. Outer bricklayer with internal timber framing
Function of bricks in load bearing wall: i.to transfer load or to support the combined, imposed and wind loads of the roof and floor construction; as well as its own combined loads, and transfer them safely to a foundation. ii. to provide a environmental control between the external and the internal climates of a building. The reasons bricks are used: i. Bricks are easy to be constructed to form a wall and structural support. ii. Economical to construct walls using bricks. iii. Widely available in the local market. iv. utilized traditional building trades skill.
Solid Wall Construction
Cavity Wall Construction
Type of Wall Construction Vs. Thermal Properties
Solid Wall Construction
ONE BRICK WALL [Solid Wall Construction] Non cavity loadbearing wall construction. [Flemish bonding type]
Cavity Wall Construction
Cavity Wall
Typical Cavity Wall External Blockwork and Internal Blockwork layers [optional only for external plastering] + Rigid Insulation
Typical Cavity Wall External Brickwork and Internal Blockwork construction + Insulation
A Typical load bearing construction
Cavity Wall Ties
Cavity wall Ties Provision of wall ties The two leaves are connected by wall ties. These must be strong enough to develop mutual stiffness in the leaves and they must be so designed that water cannot pass from outer to inner leaf. The mortar droppings cannot easily lodge on wall ties during building of the wall and bridge the cavity.
Brief definition of a cavity wall. ďƒźCavity walls; these consist of outer bricks or block leaf or skin separated from an inner layer brick or block leaf or skin by air space called as cavity. ďƒźTHE TWO EAVES OF CAVITY wall are tied together with wall ties. The width of the cavity should be between 50mm to 75mm. Cavities are not normally ventilated and should be sealed at eaves level.
The Basic Functions of a wall tie. Â The primary function of a wall ties system; [1]. Is to enable the outer masonry to withstand wind loads while allowing differential movement between adjacent continuous vertical sections of masonry leaf. [2]. Preventing wall from buclking. [Masonry wall should not be considered a continuous panel but rather as a series of loads sharing units].
Cavity wall Ties Why is cavity wall Ties used in the cavity wall construction + The wall ties ensured structural integrity and mutual support for the leaves. + Tied together the two wall and preventing the wall from buckling under applied load.
Construction drawings
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Typical Cavity Wall Tie Spacings
Cavity Wall Tie
Typical Cavity Wall Ties - Double triangle type [stainless steel]