In examining the different types of foundations the first that we review is the raft foundations. A raft foundation is basically a large concrete slab designed to cover the whole area or part of the site. It is used on soft or weak natural soil or made-up ground (fill) or ground liable to subsidence as in mining areas, or where column are closely spaced that their bases may be to close, touch or overlap, for example, where seventy-five per cent of the site may be covered. Though a raft foundation is used for weak soil it cannot be used for Jamaica beach homes that require a much more sturdy foundation.
Types of Raft Solid raft consists of a solid two-way reinforced concrete slab. Light rafts are used for small load bearing type buildings or light framed structures with low bearing pressures. For heavier and larger building thicker and deeper raft are used.
Beam and slab raft consist of slab bearing directly on the ground with bean ribs project above it. It is useful where loads or rigidity needs require a slab thicker than three hundred millimeters. This was experimented on for some beachfront property for sale in Jamaica, but the concept was quickly abandoned.
Cellular Raft consists of top and bottom slabs (rafts) with edge and intermediate beams in both directions forming hollow cells. This is useful where raft stresses are high and deep beams (nine hundred millimeters) are necessary to provide the greater rigidity required. Sometimes the depth may be full basement storey or storeys using reinforced concrete cross-walls, monolithic, with floors and rafts.
Pile Foundations Pile foundations are those which transmit loads to deeper levels by means of long column bedded in the soil They are suitable on soils of low bearing capacity, where the water table level is high, where there is the presence of shrinkable clays or other materials near the surface which is liable to movement. This is what is used for most beachfront properties for sale in Jamaica.
Types of piles Friction piles transmit their load to the surrounding soil by means of friction between the pile surfaces and the soil, that is, the piles are supported by friction between soil and pile. End bearing piles carry their loads through weak strata down to a bearing in firm strata below.
Short-Bored piles are relatively short length piles used in firm shrinkable clay as a means of pitching the foundation below the zone of moisture movement. They are usually large in diameter (three hundred millimeters) relative to their short lengths so no steel reinforcement is normally necessary and they are stiff.
Factors which determine Width and Depth of Foundations The width and depth of foundation varies with the: o Character of the subsoil o Weight of the wall and the load which it carries o Nature and strength of the คอนโดมือสอง กรุงเทพ materials to be used in the design of the foundations; and o Likely behavior under load of the soils on which the foundation rest
Concrete in Foundations The strength of concrete is influenced by a number of factors: 1. Proportion and type of cement 2. Type, proportions, grading and quality of aggregates 3. Water content 4. Method of accuracy of batching, mixing, transporting, placing, compacting and curing concrete.
The majority of concrete foundations contain ordinary cement, although this may be varied special circumstances. The customary standard mix is 1:2:4.
Foundation Selection Factors o Soil conditions o Type of structure o Structural load economics of foundation types o Time available for construction o Life of building o Future use of building
Settlement Settlement is the vertical downward movement of a foundation on a compressible soil.
Causes of settlement 1. Consolidation of soil particles 2. A reduction in the moisture content of certain soils which shrinks on drying out 3. The general movement of the earth due to various causes 4. Overloading the soil
The foundation is the most fundamental aspect of Jamaica beach homes as no matter how good a design is, it will not hold up if the foundation is weak.
ไม่มีความคิดเห็น:
แสดงความคิดเห็น