Construction Projects

In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of multitasking. Normally the job is managed by the project manager and supervised by the construction manager, design engineer, construction engineer or project architect.

For the successful execution of a project, effective planning is essential. Those involved with the design and execution of the infrastructure in question must consider the environmental impact of the job, the successful scheduling, budgeting, site safety, availability of materials, logistics, inconvenience to the public caused by construction delays, preparing tender documents, etc. In general, there are two types of construction: building construction and industrial construction. Each type of construction project requires a unique team to plan, design, construct, and maintain the project.

Building construction is the process of adding structure to real property. The vast majority of building construction projects are small renovations, such as addition of a room, or renovation of a bathroom. The owner of the property often acts as labourer, paymaster, and design team for the entire project. However, all building construction projects include some elements in common — design, financial, and legal considerations. Many projects of varying sizes reach undesirable end results, such as structural collapse, cost overruns, and/or litigation reason. Those with experience in the field make detailed plans and maintain careful oversight during the project to ensure a positive outcome.

Residential construction technologies and resources must conform to local building authority regulations and codes of practice. Materials readily available in the area generally dictate the construction materials used (e.g. brick versus stone or timber). The cost of construction on a per square metre basis for houses can vary dramatically based on site conditions, local regulations, economies of scale (custom designed homes are always more expensive to build) and the availability of skilled workers. Residential and all other types of construction can generate a lot of waste, careful planning is needed again here.

The popular method of residential construction in the United States is wood framed construction. As efficiency codes have come into effect in recent years, new construction technologies and methods have emerged.

University Construction Management departments are on the cutting edge of the newest methods of construction intended to improve efficiency, performance and reduce construction waste.

Industrial construction, though a relatively small part of the entire construction industry, is a very important component. Owners of these projects are usually large, for-profit, industrial corporations. These corporations can be found in such industries as medicine, petroleum, chemical, manufacturing, etc. Processes in these industries require highly specialized expertise in planning, design, and construction. As in building and heavy/highway construction, this type of construction requires a team of individuals to ensure a successful project.

Construction Managers

Construction managers plan, direct, coordinate, and budget a wide variety of construction projects, including the building of all types of residential, commercial, and industrial structures, roads, bridges, wastewater treatment plants, and schools and hospitals. Construction managers may supervise an entire project or just part of one. They schedule and coordinate all design and construction processes, including the selection, hiring, and oversight of specialty trade contractors, such as carpentry, plumbing, or electrical, but they do not usually do any actual construction of the structure.

Construction managers are managers who oversee construction supervisors and personnel. They are often called project managers, constructors, construction superintendents, project engineers, construction supervisors, or general contractors.

These managers coordinate and supervise the construction process from the conceptual development stage through final construction, making sure that the project gets completed on time and within the budget. They often work with engineers, architects, and others who are involved in the process. Given the designs for buildings, roads, bridges, or other projects, construction managers supervise the planning, scheduling, and implementation of those designs.

Large construction projects, such as an office building or an industrial complex, are often too complicated for one person to manage. Accordingly, these projects are divided into various segments: site preparation, including clearing and excavation of the land, installing sewage systems, and landscaping and road construction; building construction, including laying foundations and erecting the structural framework, floors, walls, and roofs; and building systems, including protecting against fire and installing electrical, plumbing, and air-conditioning systems. Construction managers may be in charge of one or several of these activities.

Construction managers determine the best way to get materials to the site and the most cost-effective plan for completing the project. They divide all required construction site activities into logical steps, estimating and budgeting the time required to meet established deadlines. Doing this may require sophisticated scheduling and cost-estimating techniques using computers with specialized software.

Construction managers also manage the selection of general contractors and trade contractors to complete specific phases of the project which could include everything from structural metalworking and plumbing to painting, installing electricity and carpeting.

Construction managers determine the labour requirements of the project and, in some cases, supervise the hiring and dismissal of workers. They oversee the performance of all trade contractorsand are responsible for ensuring that all work is completed on schedule.

Construction managers direct and monitor the progress of construction activities through construction supervisors or other construction managers. They are responsible for obtaining all necessary licenses and, depending upon the contractual arrangements, for directing or monitoring in compliance with building and safety codes, other regulations, and requirements set by the project insurers. They also oversee the delivery and use of materials, tools, and equipment, workers' safety and productivity, and the quality of the construction.

Working out of a main office or out of a field office at the construction site, construction managers monitor the overall construction project. Decisions regarding daily construction activities are generally made at the jobsite.

Managers might travel considerably when the construction site is not close to their main office or when they are responsible for activities at two or more sites. Management of overseas construction projects usually entails temporary residence in the country in which the project is being carried out.

Building Houses

In order to understand how a house is built we must start at the beginning. The first thing to do is to level the ground and make the foundations. These are usually made of concrete which is poured into trenches dug in the ground. They have to be strong enough to hold up the building, and so it is important to prevent them from cracking or shifting. While the foundations are being built, the main drains must be laid to connect up to the public sewers.

A timber-framed building has concrete foundation walls on top of a footing of concrete, and then timber sills which are anchored to the concrete while it is still wet. In brick-built houses the courses of bricks start on top of the concrete foundations. The first courses of bricks must be built carefully, for the whole house will rest on them.

Once the foundations and floor are complete, the main part of the house can be built up. In timber-framed houses the main supporting joists are sometimes made of steel or reinforced concrete. Heavy timbers must be used for supporting the roof and stairs and for door and window frames; for the rest of the structure lighter timber is used. In brick-built houses the walls are built up in double layers and the wooden framework for doors and windows as well as the wooden joists for the floors are incorporated as work goes on. As the house rises it is necessary to provide scaffolding and platforms for the workers to stand on. This is made of steel tubing with planks laid across, ladders to go up and down, and hoists to lift up the building materials.

The roof of the house may be flat or sloping. Rafters of wood are laid across, which are then covered with slates or tiles. In some places they are called shingles. They may be made of any material that is waterproof, including clay, concrete, metal, and asbestos. They are laid so that they overlap and let the water ran off.

A timber-framed house must be covered with either timber, bricks, or some other covering to finish the walls. There will also probably be an insulating layer of, for instance, glass fibre, to keep the house warm and dry. This will be put in between the living space and the roof to prevent heat escaping upwards. Brick-built houses have insulation put in the cavity between the walls and below the roof.

When the outer shell is complete, work can begin inside the house. The walls are usually lined with plaster. This may be applied straight on to brick walls or it may come in the form of plasterboard, which is attached to the walls on strips of wood called battens. Later it will be painted or papered for decoration; wet plaster must be given a few weeks to dry out before that can be done. Plastering must be carefully timed to fit in with the work of the plumbers and electricians.

Plumbers lay the pipes for the water supply, heating system, and drainage. They also have to fix the drainage pipes on the outside of the house, which will join up to the drains and sewers, and put in the bathroom and kitchen fittings to which the pipes are connected. Most of these pipes have to be hidden from view in the finished house and so some of them will be fixed so that they are behind the plaster after it has been applied, and some will be under the floorboards. Similarly, the electric wires and fittings will mostly be embedded in plaster or laid under the floors. Sometimes the wires are encased in plastic tubes which are laid around the edge of the floors and window frames. The plumber and electrician also work together in installing such things as central-heating boilers.

At the same time, carpenters will be working inside the house finishing the wooden floors, staircases, window frames and doors, as well as fitting cupboards. Last of all, the painters and decorators come in to paint the house inside and out.

Concrete

Concrete is a kind of artificial rock made from hydraulic cement, crushed stone or gravel, and sand. It has the great advantage that it can be made in whatever shape is needed. For this reason concrete is preferred to natural rock, which is difficult to extract from the ground and which has to be worked to the required shape.

By means of concrete it is possible to form such parts of buildings as walls, floors, beams or columns, bridge supports and girders, dams, roads and airfield runways, or blocks of stone of any desired shape. Concrete may be delivered ready-mixed, but it is one of the few building materials that can be made on the building site.

In the making of concrete, the proportions of the sand, gravel, and Portland or similar cement are carefully measured. The strength of the concrete is partly determined by the amount of cement in the mixture. More cement would give a stronger, more durable mix, but would be more expensive. It is important not to use too much water as this will make the concrete weak. On the other hand, the concrete must be packed densely in the moulds, which cannot be done if the mixture is too dry. Producing concrete of good quality is therefore a skilled business. Nowadays mechanical vibrators are used to make strong compact concrete from fairly dry mixes.

Concrete is strong in its resistance to loads trying to crush it (compression), but much weaker in resisting forces that tend to pull it apart (tension). It is not therefore suitable by itself for making beams or other parts liable to be bent or pulled. To overcome this weakness, steel rods may be embedded in the mixture, thus forming reinforced concrete. Reinforced concrete was first developed in France by Joseph L. Lambot in 1849. To make reinforced concrete the steel rods are held in position and the concrete poured round them.

The concrete bonds to the steel reinforcement. Any forces tending to pull the reinforced concrete apart will be resisted by the great strength of the steel rods, or bars. Nearly all concrete used for buildings and structures is reinforced.

The size of reinforced concrete beams can be reduced if the reinforcement is stretched before the concrete is poured into position and the pull maintained until the concrete is hard and strong. The stretching force is then removed and, as a result, the beam is compressed. This type of concrete usually has reinforcement in the form of wires and is known as prestressed concrete. Sometimes separate blocks of concrete are made with holes through them. Cables of wire are threaded through these holes so that the concrete blocks are like beads on a string. The cables are fetched, wedges are placed in the holes of the end block, and the cables are then released. The effect is to compress the row of blocks so that they form a beam or girder.

Lightweight concrete can be made by including processed clinker or air in the mix. Concrete can be made in different colours or painted with special paint. Different patterns can be made on the surface by using different types of shuttering. Sometimes the cement layer on the surface is removed after the concrete has set to expose the stones. This is called exposed aggregate. Concrete can be used for thin roofs called shells over large spaces such as gymnasiums or aircraft hangars. The thin slab is strengthened by curving.

Pre-cast concrete is concrete already made into building sections for later use in housing, bridges, and other structures. They are taken to the site, lifted by cranes, and fixed together with concrete.

Bricks

Good bricks are the most lasting of man-made building materials. They are not much affected by the weather and, if a building catches fire, brickwork resists the effects of fire longer than most other forms of construction. Bricks are fairly small and light and therefore easy to handle, but when they are bonded together with mortar they make extremely strong structures. Good brickwork needs very little maintenance, lasts for a long time, and looks attractive.

Brick is formed in three ways: the soft-mud, stiff-clay, and pressed brick processes. In the soft-mud process, clay is mixed with water to form a stiff paste which is then thrown by hand or forced by machine into wooden or metal box-like moulds of the size of a brick. Sand or water is sprinkled on the inside of the moulds to keep the clay from sticking. The sand or water also gives the brick a pleasant finish. Such bricks are called sand-struck or water-struck bricks. The soft, wet bricks are removed from the moulds for drying.

In the stiff-clay process, the ground clay is mixed with water in a long trough containing a revolving shaft with blades. The blades mix the clay with water as they revolve and at the same time push it forward into an extrusion machine. This forces it through a rectangular opening. It is extruded in a long bar of the length and width of a brick. A moving belt carries the clay bar to a cutter, which is a metal frame with a number of wires stretched across it. The wires are brought down on the bar to cut it into bricks, which are then dried. Bricks formed in this way are known as extruded wire-cut bricks.

In the pressed brick system, the clay is semi-dry, and is pressed by a heavy machine into metal moulds under such high pressure that the clay particles hold together. Because pressed brick has very little water, it needs little drying.

After being formed, bricks are loaded on rail trucks and pushed into driers, and then into kilns to be fired. Drying takes two to three days and then the bricks are ready for firing. Clay is the material most often
associated with bricks, but since the late 19th century other materials have been used. For example, calciumsilicate bricks, sometimes known as sand lime bricks, are made by pressing a mixture of moist sand and lime into brick shape by machine. The bricks are then steamed under high pressure in an autoclave. This process produces bricks of an attractive light sandy colour which can be textured and pigmented in a variety of ways.

Not all bricks are completely solid. Some have frogs in them. They make it easier to press and fire the bricks and reduce the weight. Lighter bricks are easier to handle and cheaper to transport. Nowadays many machine-made bricks have holes in them for similar reasons. These are called perforated bricks. Specials as the name suggests, are bricks made for a specific purpose. They are usually shaped to fit angles and curves or to produce a decorative effect. The colour of clay bricks depends on several factors. The type of clay used, chemicals in the clay, the supply of oxygen while the bricks are being fired, and the temperature the bricks reach during firing. The colours vary from dark purple to light yellow. Facing bricks to be used in the outer walls of buildings can be given a rough or textured surface, or they may be glazed to add to their attractiveness.

Sand-lime bricks are naturally white, off-white, or pink, depending on the sand used to make them. By adding pigments, any colours from pale pastels to dark tones can be produced.

Blocks are essentially oversize bricks — commonly about the size of six bricks. They may be made of clay or concrete. Clay blocks are hollow; concrete blocks may be solid or hollow. The advantage of blocks over bricks is that building can be carried out faster with them.

Beams

A beam is a structural element that is capable of withstanding load primarily by resisting bending. The bending force induced Into the material of the beam as a result of the external loads and external reactions to these loads is called a bending moment.

Beams generally carry vertical gravitational forces but can also be used to carry horizontal loads (i.e. loads due to an earthquake or wind). The loads carried by a beam are transferred to columns, walls, or girders, which then transfer the force to adjacent structural compression members.

Beams are characterized by their profile (the shape of their cross-section), their length, and their material. In contemporary construction, beams are typically made of steel, reinforced concrete or wood. One of the most common types of steel beam is the I-beam or wide-flange beam (also known as a universal beam or, for stouter sections, a universal column). This is used in steel-frame buildings and bridges. Other common beam profiles are the C- channel, the hollow structural section beam, the pipe, and the angle.

Internally, beams experience compressive, tensile and shear stresses as a result of the loads applied to them. Typically, under gravity loads, the original length of the beam is slightly reduced to enclose a smaller radius arc at the top of the beam, resulting in compression, while the same original beam length at the bottom of the beam is slightly stretched to enclose a larger radius arc, and so is under tension. Above the supports, the beam is exposed to shear stress.

There are some reinforced concrete beams that are entirely in compression. These beams are known as prestressed concrete beams, and are fabricated to produce a compression more than the expected tension under loading conditions. High strength steel tendons are stretched while the beam is cast over them. Then, when the concrete has begun to cure, the tendons are released and the beam is immediately under eccentric axial loads. This eccentric loading creates an internal moment, and, in turn, increases the moment carrying capacity of the beam. They are commonly used on highway bridges.

Mathematical methods for determining the beam forces (internal forces of the beam and the forces that are imposed on the beam support) include the moment distribution method, the force or flexibility method and the direct stiffness method.

Most beams in reinforced concrete buildings have rectangular cross sections, but the most efficient cross section is a universal beam. A universal beam is only the most efficient shape in one direction of bending: up and down looking at the profile as an I. If the beam is bent side to side, it functions as an H where it is less efficient. The most efficient shape for both directions in 2D is a box (a square shell), however the most efficient shape for bending in any direction is a cylindrical shell or tube. Efficiency means that for the same cross sectional area (volume of beam per length) subjected to the same loading conditions, the beam deflects less.

Framing Construction

Framing is a building technique based on structural members which provide a stable frame to which interior and exterior wall coverings are attached and covered by a roof comprising horizontal ceiling joists and sloping rafters (together forming a truss structure) or manufactured pre-fabricated roof trusses — all of which are Covered by various sheathing materials to give weather resistance.

Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions, both of bearing walls and non-bearing walls. Studs, wall plates and lintels serve as a nailing base for all covering material and support the upper floor platforms, which provide the

lateral strength along и wall. The platforms may be the boxed structure of a ceiling androof, or the ceiling and floor joists of the storey above. There three historically common methods of framing a house.

— Post and beam framing is now used in barn construction.

— Balloon framing using a technique suspending floors from the walls was common until the late 1940s, but since that time platform framing has become the predominant form of house construction.

–– Platform framing often forms wall sections horizontally on the sub-floor prior to erection, easing positioning of studs and increasing accuracy while cutting the necessary manpower. The top and bottom plates are end-nailed to each stud with two nails. Studs are at least doubled at openings, the jack stud being cut to receive the lintels (headers) that are placed and end-nailed through the outer studs.

Wall sheathing, usually a plywood or other laminate, is usually applied to the framing prior to erection, thus eliminating the need to scaffold. A multiple-stud post made up of at least three studs is generally used at exterior comers and intersections to secure a good tie between adjoining walls and to provide nailing support for the interior finish and exterior sheathing. Corners and intersections, however, must be framed with at least two studs. Nailing support for the edges of the ceiling is required at the junction of the wall and ceiling where partitions run parallel to the ceiling joists.

Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions. Studs, wall plates and lintels serve as a nailing base for all covering material and support the upper floors, ceiling and roof.

Exterior wall studs are the vertical members to which the wall sheathing and cladding are attached. They are supported on a bottom plate or foundation sill and in turn support the top plate. Interior partitions supporting floor, ceiling or roof loads are called loadbearing walls; others are called non-loadbearing or simply partitions. Interior loadbearing walls are framed in the same way as exterior walls.

Lintels (headers) are the horizontal members placed over window, door and other openings to carry loads to the adjoining studs. Lintels are usually constructed of two pieces of lumber separated with spacers to the width of the studs and nailed together to form a single unit. The preferable spacer material is rigid Insulation.

The complete wall sections are then raised and put in place, temporary braces added and the bottom plates nailed through the subfloor to the floor framing members. Once the assembled sections aгe plumbed, they are nailed together at the corners and Intersections. A strip of polyethylene is often placed between the Interior walls and the exterior wall, and above the first top plate of Interior walls before the second top plate is applied to attain continuity of the air barrier when polyethylene is serving this function. A second top plate usually laps the first plate at the comers and partition intersections and, when nailed in place, provides an additional tie to the framed walls.

Building Design

The design of a building begins with its future user or owner, who has in mind a perceived need for the structure, as well as a specific site and a general idea of its projected cost. The user or client brings these facts to a team of design professionals composed of architects and engineers, who can develop from them a set of construction documents that define the proposed building exactly and from which it can be constructed.

Building design professionals include those licensed by the state, such as architects and structural, mechanical, and electrical engineers, who must formally certify that the building they design will conform to all governmental codes and regulations. Architects are the primary design professionals; they orchestrate and direct the work of engineers as well as many other consultants in such specialized areas as lighting, acoustics, and vertical transportation.

The design professionals draw upon a number of sources in preparing their design. The most fundamental of these is building science, which has been gradually built up over the past 300 years. This includes the parts of physical theory that relate to building, such as the elastic theory of structures and theories of light, electricity, and fluid flow. There is also a large compendium of information on the specific properties of building materials that can be applied in mathematical models to reliably project building performance. There is also a large body of data on criteria for human comfort in such matters as thermal environment, lighting levels, and sound levels that influence a building design.

In addition to general knowledge of building science, the design team collects specific data related to the proposed building site. These include topographic and boundary surveys, investigations of subsoil conditions for foundation and water-exclusion design, and climate data and other local elements.

Concurrently with the collection of the site data, the design team works with the client to better define the often vague notions of building function into more precise and concrete terms. These definitions are summarized in a building space programme, which gives a detailed written description of each required space in terms of floor area, equipment, and functional performance criteria. This document forms an agreement between the client and the design team as to expected building size and performance.

The process by which building science, site data, and the building sрасе program are used by the design team is the art of building design. It is a complex process involving the selection of standard building systems, and their adaptation and integration to produce a building that meets the client's needs within the limitations of government regulations and market standards. These systems have become divided into a number of clear sectors by the building type for which they are intended. The design process involves the selection of systems for foundations, structure, atmosphere, enclosure, space division, electrical distribution, water supply and drainage, and other building functions. These systems are made from a limited range of manufactured components but permit a wide range of variation in the final product. Once the systems and components have been selected, the design team prepares a set of contract documents consisting of a written text and conventionalized drawings to describe completely the desired building configuration in terms of the specified building systems and their expected performance. When the contract documents have been completed, the final costs of the building can usually be accurately estimated and the construction process can begin.