SLABS
The floor construction of a dwelling must fulfill several criteria and the following design functions must be taken into consideration.
n The provision of a uniform, level surface
n Sufficient strength and stability
n Exclusion of dampness from inside of building
n Thermal insulation (max.0.45 W/square metre K)
n Resistance to fire
DEFINITION OF SLABS
n Is a structure which is formed vertically to support it’s load and other similar type of load.
n The slab must be consolidate and stable to bear the “dead” and “life loads”.
n To ensure stability, the floor need sufficient vertical support to address the possible of limbering when it is loaded by a big loads.
THE FUNCTIONS OF SLABS
n To prepare a plane surface.
n To support loads.
n Operate as a sound, fire and heat insulator or resistance.
n As a ceiling to the beneath floor.
n The space between the floor and ceiling can be used to placed building equipment and materials.
CHARACTERISTICS OF SLABS
n Must have long lasting endurance without any improvement or repairing
n Capable to withstand and resist on great fire for certain period
n Resistance to heat transmitting.
n Sound proof
THE FAILURES OF SLABS
n Caused by the soil moisture below the floor:
n the moisture penetration from the underground to the floor surface depends on the soil features.
n the earth water level.
n The buildings basement condition whether it is plane or steep
EXAMPLES OF SLAB
Typical one-way beam grid and slab system. This parking structure has columns on a rectangular grid pattern. The essentially one-way design of the system can be seen by the relative lengths and sections of the main beam, and the primary and secondary beams under the slab. The rectangular shape of the unsupported slab also indicates one-way slab action
Typical waffle-slab for parking structure. With columns on a 33-ft x 27-ft pattern, the design uses 3-ft square waffles. Note the infilling of the squares at the head of the column to resist both shear and negative moments.
Waffle-slab roof, San Diego Airport. Not heavily loaded as a roof structure, the waffle slab system could be extended into the overhang where the moments are negative. Note also the supporting columns with a built-in point of zero moment at two-thirds height. (San Diego, California)
Typical flat slab construction for a parking structure. Note the square column capitals that increase the area of the slab resisting punching shear at the columns.
Typical flat plate construction. This office building under construction uses flat plates for the floors and constant section columns without capitals. The shear stiffness of the building is provided by elevator shafts and stair wells. Due to the relatively small floor loading and the close column spacing, flat plate construction was possible. For heavier loading and larger column spacing, column capitals are required (GoddenF73), and for even larger spans to reduce the self-weight, waffle slabs are used (GoddenF77)
TYPES OF THE SLAB
SOLID GROUND
n Benefits
n The cost is cheaper for plane area.
n Could reduce the construction of brick wall.
n Don’t need any air ventilation under the brick wall.
n Reduce the heat loss through the floor.
n Can avoid the risk of decay caused by dryness.
n Have varieties of floor finishing.
HANGING SLAB
n Build as a wood platform which is elevate from the concrete surface layers.
n There’s a beneath under the floor that allow the air ventilation.
n The plank is install horizontally to the girder which is support by wall slab of half brick thickness.
n “void slab” is placed at the outside wall.
UPPER FLOW
n construct by using wood or “konkrit bertulang”.
n the construction of basic floor from wood
n size gildger depends on the load that it support
SUSPENDED FLOOR
n All type of floors which are on the ground.
n Suspended slabs rest on the foundation wall.
n These are supported on the edges.
MONOLITHIC SLABS
n With Monolithic slabs, the footing and the slab are all one piece of concrete.
FLOATING SLABS
n With Floating slabs the foundation wall rests on a poured concrete footing.
n The slab is poured after the foundation has been completed.
