Factors Affecting Selection Of Superstructures Construction Essay

The developers intend to develop a figure of new sites to supply low and medium rise luxury lodging adjustment for private sale in the current economic market. As portion of the planning addition it may be necessary to negociate other adjustment.

You have been successfully appointed as the ‘technical development director ‘ to organize the design and the building of the new and proposed developments, together with the after sale and care of this new constructing stock.

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Undertaking 2:

Evaluate with the aid of studies and remarks the assorted signifiers of infrastructures that could be used to safely reassign the superstructure loads to the land conditions identified in the dirt study.

Foundations are designed to administer all of the weight of a construction / constructing every bit over the land.

During the building of a edifice the weight is spread over certain points such as wharfs and columns and this requires the foundations to be spread equally under a edifice so that it reduces the weight of that edifice.

Foundations are either classified as shallow foundations or deep foundations.

Shallow foundations are used to reassign the burden of a edifice to the dirt at a degree closest to the floor of a edifice.

Deep foundations use hemorrhoids and different types of wharfs and reassign the burden to the dirt a batch deeper from the underside of the edifice compared to that of shallow foundations.

Foundations must besides follow with edifices ordinances delight see diagram overleaf.

Shallow foundations are tablets, strips or tonss.

Shallow foundations are close to the land surface and are less than the breadth of the picking usually less than 3m. This is where the surface burden or other surface conditions affect the bearing capacity ( the emphasis on the dirt ) of a foundation and is called shoal.

Shallow foundations are used when surface dirts are strong and able to back up the imposed tonss. These types of foundation are non suited in weak or extremely compressible dirts.

Deep foundations are Piers and coffers.

Deep foundations are those which are deep below the land surface so their bearing capacity wo n’t be affected by any surface conditions, usually at deepnesss of 3m below land degree.

Deep foundations are used to reassign the burden to a deeper deepness if unsuitable dirts are found nearer the surface.

Piers are foundations used for the carrying of heavy structural tonss and are built in situ in deep diggings.

Coffers are a deep foundation and are built above land degree and one time built is so sunk and used for unearthing or the dredging of stuffs from within the coffer.

Foundations are designed and built to build edifices which will stand up to the forces of nature and these forces are:

Frost heave this is a common job in sandy dirts and this is where the H2O in the land freezes and pushes upwards so expands and turns into ice.

The antonym of this job is Drought and this can do the shrinking of the land and is really common in clay dirts.

These jobs can impact the edifices foundations and in most instances will upset and check them. This can be easy avoided if you dig deep plenty and in most instances at least two tierces of a metre will do.

These forces can impact the construction of edifices so when building foundations attention must be taken to forestall colony or motion as this may do harm to the edifice one time constructed.

It is besides necessary to forestall against harm caused by the air current or atmospheric conditions.

Foundations are besides known as structural members and are merely like elephantine beams. They carry tonss like structural steel beams and their occupation is similar to that of foundations.

Foundations can be constructed from a figure of stuffs this is so the foundations are capable of transporting the heavy burden of a edifice.

The two types of burden imposed on edifices are:

Wind Loads:

Tonss imposed by air current.

Dead tonss:

These are lasting non traveling tonss such as the roof, walls and floors.

Imposed tonss:

They can dwell of anything that is n’t lasting such as furniture, people and snow tonss.

Foundations can be made from concrete, rock, concrete block, wood and steel but the best manner to build foundations is by utilizing strong, lasting, H2O immune stuffs.

The designing of foundations is a proficient occupation and is done by an Architect or a Structural Engineer they will decently size the foundations and stipulate the stuffs from which it should be constructed.

Foundations can merely be designed and constructed one time a dirt trial is carried out.

The result of the test/s will state us what we can and ca n’t construct on our site and the type of foundations we can put.

This will besides state us about how much the development will be and how long it should take to finish.

Once we have the consequences back from the dirt sample and cognize what we can construct. We would necessitate to fix our site before any edifice building work takes topographic point.

Then our site would hold to be prepared as this is an of import portion of this procedure. This would include the glade of trees and the placing of bets to tag the boundaries of our site.

The glade of trees is an of import portion of fixing our site as the roots from trees could damage the foundations as they grow, this is due to the big sum of H2O that trees takes out of the land and around it. As this can alter the balance of the undersoil and if any big trees need to be removed we would necessitate to let at least a twelvemonth for the land to settle before any work is started on the foundations.

Please see overleaf a diagram on the effects due to shrinkage and land crestless wave.

The remotion of about 300mm of the surface soil would necessitate to be done as this portion of the land would n’t be strong plenty to back up the construction of a edifice.

The surface soil may besides incorporate flora and works growing which could damage the foundations and the construction of the edifice one time built. This besides helps to flush out the work surface and flatten the land.

The digging and laying of foundations would include delving a hole for the foundations and puting and pouring a strong lasting stuff into the hole.

Then the trench would necessitate to be dug and one time it has been excavated attention must be taken as the walls of the trench may fall in and the wet in the dirt may run out or dry out.

Consideration must be taken when delving trenches from the clip it takes to delve to the conditions conditions. The edifice of the walls in the trench means that moisture conditions may halter the procedure and if the trench inundations, its walls may fall in and it ‘s recommended that the work is completed during dry conditions.

The excavation of trenches can be done by manus or machine depending on the size of the construction and this is done by utilizing the design drawings, leveling instruments and craming rods.

These tools are used to corroborate and place the deepness of the trenches for the needed foundations.

Below are the possible types of foundations we may utilize in the building of our edifice undertakings.

Strip foundations ( Deep Strip or Trench Fill, Traditional Shallow Strip and Wide Strip ) . Please see diagram of strip foundations overleaf.

Shallow Strip

Strip foundations are the most common type of foundations used this is because they are strong, inexpensive to build and can merely be used when the land conditions are good.

The breadth of the foundation will depend on the dirt type, but are normally 450mm broad for individual floor edifices and 600mm broad for two storey edifices and both will usually hold a thickness of more than 200mm.

These types of foundations are used to back up a line of tonss like burden bearing walls or if a row of columns require support and are ideal for 1 & A ; 2 floor houses.

Strip foundations are made by utilizing a concrete strip with a strengthened steel mesh as this will back up the walls of the trench. The trench deepness can change but should be at least 1000mm with a breadth of 600mm. The concrete should so hold a minimal deepness of 225mm. This is to avoid any harm to the foundations caused by any alterations in the surface soil.

The trench would hold to be excavated / dug until the clay has been found and the floor of the trench would hold to be covered with at least 150mm of concrete.

Wide Strip

This is used when the burden of the construction is high in relation to the weight bearing capacity of the undersoil.

Wide strip foundations are laid the same manner as standard strip foundations except that the trench is much wider and reinforced concrete is used.

Deep Strip or Trench Fill

Deep strip or known as Trench fill is an illustration of a shallow foundation and is constructed by delving a trench and so make fulling it with concrete or debris. It is besides used when house or shrinkable clays are present.

These foundations have smaller narrower trenches and are filled with concrete to within two brick classs of the finished land degree as it ‘s of import to be accurate if the walls are to be cardinal.

The costs of the stuffs used for this type of foundation are more expensive than the above but it takes less clip to construct and so labour costs below land degree are less expensive and the occupation is easier to make.

Deep strip foundations can besides be reinforced and can be an alternate to broad strip foundations in soft clay undersoil and should be at least 400mm broad and 900mm deep.

Pile foundations

Pile foundations can be used to back up different types of structural tonss and are used when the land is soft and for little constructions. These are frequently used because equal bearing capacities ca n’t be found at shallow plenty deepnesss to back up the structural tonss.

Piled foundations are made up of a group of columns built and inserted into the land and this type of foundation is designed to convey the burden of a edifice further into the undersoil.

Pile foundations are used when the surface dirts are really soft and when designed consideration should be taken so that the heap caps are tied together with beams or with a strengthened concrete slab. This is because they can work in tenseness and compaction and the foundations can move as a individual unit.

This type of foundation is used to back up edifices where conditions of the undersoil has shrinkable clays or with a high H2O tabular array.

They are besides used when other types of foundations ca n’t be used this is because the deepness would be excessively deep and it would n’t be economical to utilize.

Pile foundations are made up of a series of columns which sit on a burden bearing bed of the dirt up to 4m below the surface. Any deeper than this would be excessively expensive and ca n’t be used for little edifice undertakings.

Pile foundations would dwell of scaffold poles or lumber and the bottom terminal of the lumber would hold an Fe shoe with a point on.

This is done so that they can be easy driven into the land and the top of the lumber would besides hold an Fe set round them. This would forestall the lumber from dividing when their being driven into the land.

The excavation of foundations would usually be done by machine usually by a crab particularly if there are big bowlders in the land. This would be done by lifting a heavy weight called a monkey.

The monkey is hoisted up in the air and released and so will fall with force and drives the heap into the land.

The monkey can weigh anything from weights of 100kg to 1120kg and is usually dropped from highs of about 4.5m to 14m.

The hemorrhoids are so driven under all the walls or under the wharfs as this is where the weight of the edifice will be concentrated.

Please see diagram of pile foundations overleaf.

Pad or slab foundations

Pad foundations are suited for most sub dirts except loose littorals, crushed rocks and filled countries and are used for edifices over five narratives high.

This type of foundation is normally used for office blocks with a steel framed building and are normally constructed with strengthened concrete and where possible are usually square in program.

Pad Foundations are designed to cross in two waies with chief bars and the tablet is equal at all points under the dirt this is to avoid any unequal colony.

This is done by planing the Centre of gravitation of the foundations in line with that of the imposed tonss.


Raft foundations are the biggest type of foundations you can acquire and are designed and constructed to distribute the burden of a construction over the whole country. These are used on soft or loose dirts with a low bearing capacity so the tonss can be spread over a greater country.

Raft foundations can be used when the tonss are close together and are besides ideal for countries where there is tonss of H2O as the dirt bearing capacity is treated like H2O.

A raft foundation is made up of a concrete slab which will cover all of the laden country. It may all so be stiffened by ribs or beams which may be incorporated into the foundation. They are besides used to assist cut down any differential colony as the concrete slab will defy differential motions between lading places.

Raft foundations require reinforced steel at the top of the raft as this helps with clefts and more strengthened steel is required at the underside under the walls to defy any tensile emphasis.

In dirts with low compaction support will be needed at both the top and underside of the raft. The foundations would necessitate to be extended by at least 300mm past the external walls to assist protect the dirt from possible hoar and to assist distribute the burden.

When building raft foundations on sand we would necessitate to utilize a down base as this will assist to protect against dirt eroding. But when edifice on shrinkable clays the dirt under the foundations should be protected by widening the border of the raft between 125mm & A ; 150mm past the external wall. This is to protect it from any shrinking or enlargement of the clay.

Beginning of information

Roy Chudley & A ; Roger Greeno

Constructing building Handbook 2005

Jack Stroud Foster

Mitchell ‘s Structure & A ; Fabric Part 1 6th Edition 2000

Mitchell ‘s Structure & A ; Fabric Part 2 6th Edition 2000

Information besides provided by class lector Harish Patel


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