Transcript Slide 1
Wall •Wall is a continuous, usually vertical structure, thin in proportion to its length and height, built to provide shelter as an external wall or divide buildings into rooms or compartments as an internal wall •Prime function of an external wall is to provide shelter against wind, rain and the daily and seasonal variations of outside temperature normal to its location, for reasonable indoor comfort. Functional Requirements •Strength and stability •Resistance to weather and ground moisture •Durability and freedom from maintenance •Fire safety •Resistance to passage of heat •Resistance to airborne and impact sound •Security Strength and stability •The strength of the materials used in wall construction is determined by the strength of a material in resisting compressive and tensile stress, and the way in which the materials are put together. •The stability of wall may be affected by foundation movement, eccentric loads, lateral forces(wind) and expansion due to temperature and moisture changes. Resistance to weather and ground moisture •Moisture which includes water vapour and liquid water may penetrate a wall by absorption of water from the ground that is in contact with foundation walls or through rain falling on the wall. •To prevent water, the impermeable layer (damp proof course) is built in about 150mm above ground level. Durability and freedom from maintenance Durability of a wall is indicated by the frequency and extent of the work necessary to maintain minimum functional requirements and an acceptable appearance. Fire safety The Building Regulations has set the standards for means of escape, limitation of spread of fire and containment of fire. The requirements of Part B of Schedule 1 to the Building Regulations are concerned to:Provide adequate means of escape Limit internal fire spread (linings) Limit internal fire spread (structure) Limit external fire spread Provide access and facilities for the fire services Resistance to passage of heat •The interior of buildings is heated by :•Conduction-the transfer of heat from heaters and radiators to air, •Convection-the circulation of heated air •Radiation-the radiation of energy from heaters and radiators to surrounding colder surfaces. •This internal heat is transferred through colder enclosing walls, roofs and floors by conduction, convection and radiation to colder outside air. •For insulation against loss of heat, lightweight materials with low conductivity are more effective than dense materials with high conductivity. •Dense materials have better thermal storage capacity than lightweight materials. Resistance to airborne and impact sound •Sound is transmitted as airborne sound and impact sound •Airborne sound is generated as cyclical disturbances of air from a radio (example), that radiate from the source of the sound with diminishing intensity. •The vibrations in the air caused by the sound source will set up vibrations in enclosing walls and floors which will cause vibrations of air on the opposite side of walls and floors. •Impact sound is caused by contact with a surface. Example, the slamming of a door or footsteps on a floor which set up vibrations in walls and floors that in turn cause vibrations of air around them that are heard as sound. •Effective insulation against airborne sound is a dense material barrier such as a solid wall, which absorbs the energy of the airborne sound waves. Walls may be classified as solid or framed. Solid wall (masonry wall) • constructed using brick or blocks of stone, or concrete laid in mortar with the block laid to overlap bonding (monolith) • Solid wall of bricks or blocks may be termed as block wall(masonry) • Continuous solid wall of concrete called as monolithic wall. Frame wall •constructed from a frame of small sections of timber, concrete or metal joined together to provide strength and rigidity over both faces or between the members of the frame. •Each of the two types of wall may serve as internal or external wall and as load bearing or non-load bearing wall. External Wall An outer wall of a building not being party wall (partition) and also means a wall next to an interior open space of any building Internal Wall Any wall that does not have a separation function between dwellings External wall Superstructural (above ground) Curtain wall & Cavity wall Substructural (under ground) Retaining wall -Gravity wall -Piling wall -Cantilever -Anchored wall Superstructure (above ground) Curtain wall •A curtain wall system is an outer covering of a building in which the outer walls are non-structural, but merely keep the weather out and the occupants in. •A curtain wall is designed to resist air and water infiltration, sway induced by wind and seismic forces acting on the building, and its own dead load weight forces. Wall and window system (cavity wall) •Cavity walls consist of two 'skins' separated by a hollow space (cavity). The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material, and therefore will slowly draw rainwater or even humidity into the wall. Substructural (under ground) Retaining wall •Retaining walls are structures designed to restrain soil to unnatural slopes. •The structure designed and constructed to resist the lateral pressure of soil when there is a desired change in ground elevation that exceeds the angle of repose of the soil Typical types of retaining wall:Gravity wall -standard wall type that holds the earth mainly through its own weight. Can pivot and topple easily, as the internal leverage of the earth pressure is high. Piling wall –Using long piles, this wall is fixed by soil on both sides of its lower length. If the piles themselves can resist the bending forces, thick wall can take high loads. Cantilever wall –uses the same earth pressure trying to topple it to stabilize itself with a second lever arm. Anchored wall –this wall keeps itself from toppling by having cables driven into soil or rock, fixed by expanding anchors(can be combined with other types of wall) Internal wall Structural Shear Wall & Core wall Non-structural Partition Wall Structural Internal Wall : Shear Wall Shear wall is a wall composed of braced panels (also known as shear panels) to counter the effects of lateral load acting on a structure. So, in order to prevent any deformation which may occur in wooden buildings, it is important to either (1) attach "diagonal bracings" between two columns, or (2) attach "structural wall boards" with screws to frames. Functions of shear wall:Strength •Shear walls must provide the necessary lateral strength to resist horizontal earthquake forces. Stiffness •Shear walls also provide lateral stiffness to prevent the roof or floor above from excessive side-sway. •Stiffness will prevent floor and roof framing members from moving off their supports. •Also, buildings that are sufficiently stiff will usually suffer less nonstructural damage. Structural internal wall : Core Wall •A "core wall" is a temporary reinforced-concrete structure located in the center of a building designed to absorb the potential horizontal forces generated by an earthquake. •The core acts as a cantilever beam coming from the basement and it stabilizes the building mainly with regard to horizontal forces like wind and earthquake. • A "load transferring frame," is set up in a column in four corners where the core wall is enclosed. •If an earthquake occurs, the core wall and the aboveground part of the steel frame combine to provide earthquake resistance. The system also includes safety systems such as a seismograph and an earthquake warning system. NON STRUCTURAL INTERNAL WALL PARTITION WALL •A partition wall is a wall for the purpose of separating rooms, or dividing a room. Partition walls are usually not load-bearing •Partition walls may be constructed with bricks or blocks from clay, terracotta or concrete, reinforced, or hollow. Glass blocks may also be used. •Wall partitions are constructed using beads and tracking which are either hung from the ceiling or fixed into the ground. The panels are inserted into the tracking and fixed. END