Foundations of Residential and Industrial Buildings

The foundations in residential and industrial buildings support considerably heavy loads. Floor loadings range from 450 to 1,500 kilograms per square metre, and the full range of foundation types is used for them. Spread footings are used, as are pile foundations, which are of two types, bearing and friction.

A bearing pile is a device to transmit the load of the building through a layer of soil too weak to take the load to a stronger layer

of soil some distance underground; the pile acts as a column to carry the load down to the bearing stratum. Solid bearing piles were originally made of timber, which is rare today; more commonly they are made of precast concrete, and sometimes steel H-piles are used. The pile length may be a maximum of about 60 metres but is usually much less. The piles are put in place by driving them into the ground with large mechanical hammers. Hollow steel pipes are also driven, and the interiors are excavated and filled with concrete to form bearing piles; sometimes the pipe is withdrawn as the concrete is poured.

An alternative to the bearing pile is the caisson. A round hole is dug to a bearing stratum with a drilling machine and temporarily supported by a steel cylindrical shell. The hole is then filled with concrete poured around a cage of reinforcing bars; and the steel shell may or may not be left in place, depending on the surrounding soil. The diameter of caissons varies from one to three metres. The friction pile of wood or concrete is driven into soft soil where there is no harder stratum for bearing beneath the site. The building load is supported by the surface friction between the pile and the lull.

When the soil is so soft that even friction piles will not support the building load, the final option is the use of a floating foundation, milking the building like a boat that obeys Archimedes' principle — it is buoyed up by the weight of the earth displaced in creating the foundation. Floating foundations consist of flat reinforced concrete slabs or mats or of reinforced concrete tubs with walls turned up around the edge of the mat to create a larger volume.

If these buildings do not have basements in cold climates, insulated concrete or masonry frost walls are placed under all exterior nonbearing walls to keep frost from under the floor slabs. Reinforced concrete foundation walls for basements must be carefully braced to resist lateral earth pressures. These walls may be built in excavations, poured into wooden forms. Sometimes a wall is created by driving interlocking steel sheet piling into the ground, excavating on the basement side, and pouring a concrete wall against it.

Deeper foundation walls can also be built by the slurry wall method, in which a linear series of closely spaced caisson-like holes are successively drilled, filled with concrete, and allowed to harden; the spaces between are excavated by special clamshell buckets and also filled with concrete. During the excavation and drilling operations the holes are filled with a high-density liquid slurry which braces the excavation against collapse but still permits extraction of excavated material. Finally, the basement is dug adjoining the wall, and the wall is braced against earth pressure.

Masonry

Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone such as marble, granite, travertine, limestone; concrete block, glass block, and tile. Masonry is a highly durable form of construction. However, the materials used, the quality of the mortar mid workmanship, and the pattern in which the units are assembled can affect the durabilityof the overall masonry construction.

Masonry is commonly used for the walls of buildings, retaining walls and monuments. Brick and concrete block are the most common types of masonry in use in industrialized nations and may be either weight-bearing or a veneer. Concrete blocks, especially those with hollow cores, offer various possibilities in masonry construction. They generally provide great compressive strength and are best suited to structures with light transverse loading when the cores remain unfilled. Filling some or all of the cores with concrete or concrete with steel reinforcement (typically rebar) offers much greater tensile and lateral strength to structures.

The use of materials such as brick and stone can increase the thermal mass of a building, giving increased comfort in the heat of summer and the cold of winter, and can be ideal for passive solar applications. Brick will not require painting and so can provide a structure with reduced life-cycle costs, although sealing appropriately will reduce potential spalling due to frost damage. Non-decorative concrete block generally is painted or stuccoed if exposed. The appearance, especially when well crafted, can impart an impression of solidity and permanence. Masonry is heat resistant and thus provides fire protection. Masonry walls are more resistant to projectiles, such as debris from hurricanes or tornadoes than walls of wood or other softer, less dense materials. Extreme weather causes degradation of masonry wall surfaces due to frost damage. This type of damage is common with certain types of brick, though rare with concrete block. If non-concrete (clay-based) brick is to be used, care should be taken to select bricks suitable for the climate in question. Masonry tends to be heavy and must be built upon a strong foundation (usually reinforced concrete) to avoid settling and cracking. If expansive soils (such as adobe clay) are present, this foundation needs to be quite elaborate and the services of a qualified structural engineer may be required, particularly in earthquake prone regions.

Masonry boasts an impressive compressive strength (vertical loads) but is much lower in tensile strength (twisting or stretching) unless reinforced. The tensile strength of masonry walls can be strengthened by thickening the wall, or by building masonry piers (vertical columns or ribs) at intervals. Where practical, steel reinforcements can be added.

The strength of a masonry wall is not entirely dependent on the bond between the building material and the mortar; the friction between the interlocking blocks of masonry is strong enough to provide a great deal of strength on its own. The blocks sometimes have grooves or other surface features added to enhance this interlocking, and some dry set masonry structures forego mortar altogether.

Solid masonry without steel reinforcement tends to have very limited applications in modern wall construction. While such walls can be quite economical and suitable in some applications, susceptibility to earthquakes and collapse is a major issue. Solid unreinforced masonry walls tend to be low and thick as a consequence.

Solid brickwork is made of two or more layers of bricks with the units running horizontally (called stretcher bricks) bound together with bricks running transverse to the wall (called header bricks). Each row of bricks is known as a course. The pattern of headers and stretchers employed gives rise to different bonds such as the common bond (with every sixth course composed of headers), the English bond, and the Flemish bond (with alternating stretcher and header bricks present on every course). There are no significant utilitarian differences between most bonds, but the appearance of the finished wall is affected. Vertically staggered bonds tend to be somewhat stronger and less prone to major cracking than a non-staggered bond.

Plasterwork

Plasterwork refers to construction or ornamentation done with plaster, such as a layer of plaster on an interior wall or plaster decorative moldings on ceilings or walls. This is also sometimes called pargeting. The process of creating plasterwork called plastering has been used in building construction for centuries.

Plasterwork is one of the most ancient of building techniques. Evidence shows that the dwellings of primitive man were erected in a simple fashion with sticks and plastered with mud. The pyramids in Egypt contain plasterwork executed at least four thousand years ago, probably much earlier, and yet hard and durable at the present time. From recent discoveries it has been ascertained that the tools of the plasterer of that time were practically identical in design, shape and purpose with those used today. For their finest work the Egyptians used a plaster made from calcined gypsum just like plaster of Paris of the present time, and their methods of plastering on reeds resemble in every way our lath, plaster, float and set work. Hair was introduced to strengthen the material.

Very early in the history of Greek architecture plaster of a fine white lime stucco was used, such has been found at Mycenae. The art had reached perfection in Greece morethan five centuries before Christ, and plaster was frequently used to cover temples externally and internally, in some cases even where the building was of marble. It formed a splendid ground for decorative painting.

Tools and materials include trowels, floats, hammers, screeds, scratching tools, utility knives, laths, lath nails, lime, sand, hair, plaster of Paris, a variety of cements, and various ingredients to form colour washes. While most tools have remained unchanged over the centuries, developments in modern materials have led to some changes. Trowels constructed from steel are available in a polycarbonate material that allows the application of certain new acrylic-based materials without staining the finish. Floats traditionally made of timber are often finished with a layer of sponge or expanded polystyrene.

There are two main methods used in construction of the interior walls of modern homes, drywall and plaster. In drywall a specialized form of sheet rock known as greenboard (yclept because on the outer paper coating is greenish) is screwed onto the wall-frames (studs) of the home to form the interior walls.

At the place where the two edges of wallboards meet there is a seam. These seams are covered with mesh tape and then the seams and the screw heads are concealed with the drywall compound to make the wall seem as one uniformpiece. Later this is painted or wallpapered over to hide the work. This process is called taping and those who use drywall are known as tapers.

Veneer plastering differs from the drywall method in a number of ways. The two most notable differences are that a thin plaster coat covers the entire wall and not just the seams, and secondly the drywall compound is a thick paste where plaster method uses a great deal of water and is applied very wet. Another difference is that walls intended to be plastered are hanged with blueboard (named as such for the industry standard of the outer paper being blue-grey in colour). This type of sheet rock is designed to absorb some of the moisture of the plaster and allows it to cling better before it sets. Plastering is also a one-shot one-coat application; taping usually requires sanding and then adding an additional coat since the compound shrinks as it dries. From a supply side the cost of plaster and drywall are approximately the same, but the labour cost of plastering is usually much greater.

Список литературы

1. A Dictionary of Architecture and Landscape Architecture / James Stevens Curl. - Oxford University Press. 2006. - 880p.

2. Агабекян, И.П. Английский для инженеров / И.П. Агабекян, П.И. Коваленко.- Изд. 7-е, стер. – Ростов н/Д: Феникс, 2009. – 317 с.

3. Brieger, Nick. Pohl, Alison. Technical English. Vocabulary and Grammar/ Nick Brieger. – Summertown Publishing. 2010.- 146p.

4. Луговая, А.Л. Английский язык для строительных специальностей средних профессиональных учебных заведений: Учеб. Пособие / А.Л. Луговая. – М.: Высшая школа, 2006. – 166 с.

5. Professional English in Use. Engineering: Technical English for Professionals / Mark Ibbotson.- Cambridge University Press. 2009.- 144p.

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