Building Systems( Research)

8/2/2019 Building Systems( Research)

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Building systems and their types:

Buildings are those structures which are located above the ground level and they

are built according to the intended use for people as a residential, office and

other purposes which are of many types and built according to the environmentalgeological and other aspect of its surroundings.

Building Types:

Compared to the medieval ages, architecture nowadays has really changed a lot. Technical

revolutions, the advances in technology and industrialization and the demands for certain types

of buildings have exploded. This leads to magnificent works of art which over the years have

become true monuments and engineering breakthroughs which are stunning even in today's

standards.

Thus buildings and structures by type are different nowadays and they can be seen everywhere

in our home town. Steel buildings are structures made of metal and they use steel both for

exterior and interior support. The reason for steel buildings coming to life is that they provide a

good space for office spaces that can be rented and thus generate important revenue. But they

are also good as a living space, nonetheless. These types of buildings do have very good

reinforced structures and they are also cost effective. When it comes to heating, steel is a good

material that conducts heat so the cost for cooling the spaces within the building will be high.

Another drawback when it comes to steel buildings is that corrosion can really take its toll on

them in time and thus the cost of maintenance is also on the upper level.

When we are talking about storage sheds then we are talking about a single story structure that

has many other uses than of a residential space. These structures are generally used for storing

large crafts like airplanes, locomotives, ships and large vehicles and they are very tall given their

use. I am absolutely sure that you have seen these structures before, when traveling by plane

especially.

Another type of building is the industrial type. They are very large and are mostly built on many

square kilometers of land. They are mainly used for manufacturing of different products as well

as storage.

Architecture though has also functional factors that have to take care of. Architecture focuses on

practical use rather than looks. So each type of building be it a church, a prison, a castle or

something else has unique functional requirements that are linked directly with the


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architecture's meaning. This doesn't mean that any building is constructed with extreme care on

these factors. There are buildings that stand out there just to compliment a need, which of

course is subjective and thus won't render a high quality and a precise building construction

process. And yet, structural and functional factors weren't always vital. In the past, the

architects tried and also succeeded to define their buildings through unique carvings and models

that weren't actually linked with a functional mechanism, but rather they would look good and

render them different from other buildings.

Every building type has different design and efficiency depending on their

functions like e.g.

y Agricultural buildings

y Commercial buildings

y Residential buildings

y Educational buildingsy Government buildings

y Industrial buildings

y Military buildings

y Parking and storage

y Religious buildings

y Transit stations

y Other

Building components:

Component of buildings are as follow:

1. Foundation

2. Floors (Storys)

3. walls

4. Columns

5. Beams

6. Slabs

7. Doors & windows8. Stairs, Ramps, Elevators.

9. Roof of the building.


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Structural Types

The structural types are divided into the following categories.

Bridges and Viaducts

Buildings

Towers and Masts

Tunnels and Underground Structures

FLOORSOF A BUILDING:

Floors of a building is the level of the building which people lives and

consist of rooms ,kitchens ,halls and etc, and in any tall building it consist of

many floors also called storys.

WALLS:

Walls are the most important parts of any building which provides

partitions, provides privacy, can resist winds and possesses insulation and

also acts as a load bearing part of a building.

The buildings which are going to be is to be made should have satisfied the

required condition of its construction.

At first we should opt the geological investigation, which is very useful to the

bearing capacity of the soil and so the other aspects of soil which the building is

going to be made.


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The investigation of soil requires many tests which normally we have the tests for

compaction, percolation, Ph-test, squeeze test, worm test.

These tests are very useful and are a must to be done for having efficient

foundation with good bearing capacity to have strength and stability againstmoisture, differential settlements, collapse and other bad effects.

Soil compaction is another work which is to be done before the building and the

foundation is constructed.

Foundation:

A foundation is the lowest and supporting layer of a structure. Foundations are generally

divided into two categories: shallow foundations and deep foundations

Shallow foundations

Shallow foundations, often called footings, are usually embedded about a meter or so into soil. Onecommon type is the spread footing which consists of strips or pads of concrete (or other materials) which

extend below the frost line and transfer the weight from walls and columns to the soil or bedrock.

Another common type of shallow foundation is the slab-on-grade foundation where the weight of the

building is transferred to the soil through a concrete slab placed at the surface. Slab-on-grade foundationscan be reinforced mat slabs, which range from 25 cm to several meters thick, depending on the size of the

building, or post-tensioned slabs, which are typically at least 20 cm for houses, and thicker for heavier

structures.

Deep foundations

A deep foundation is used to transfer a load from a structure through an upper weak layer of soil to

a stronger deeper layer of soil. There are different types of deep footings including impact driven

piles, drilled shafts, caissons, helical piles, and earth stabilized columns. The naming conventions

for different types of footings vary between different engineers. Historically, piles were wood, later

steel, reinforced concrete, and pre-tensioned concrete.

Soil Compaction


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Soil Compaction

Soil compaction is defined as the method of mechanically increasing the density of soil. Inconstruction, this is a significant part of the

building process. If performed improperly,

settlement of the soil could occur and result inunnecessary maintenance costs or structurefailure. Almost all types of building sites and

construction projects utilize mechanicalcompaction techniques.

Why Compact?There are five principle reasons to compact soil: - Increases load-bearing capacity

- Prevents soil settlement and frost damage- Provides stability- Reduces water seepage, swelling and contraction

- Reduces settling of soil

Types of CompactionThere are four types of compaction effort on soil or asphalt:

y Vibrationy Impact

y Kneading

y Pressure

These different types of effort are found in the two principle types of compaction force: static

and vibratory.

Static force is simply the deadweight of the machine, applying downward force on the soil

surface, compressing the soil particles. The only way to change the effective compaction force

is by adding or subtracting the weight of the machine. Static compaction is confined to uppersoil layers and is limited to any appreciable depth. Kneading and pressure are two examples of

static compaction.

Vibratory force uses a mechanism, usually engine-driven, to create a downward force inaddition to the machine's static weight. The vibrating mechanism is usually a rotatingeccentric weight or piston/spring combination (in rammers). The compactors deliver a rapid

sequence of blows (impacts) to the surface, thereby affecting the top layers as well as deeperlayers. Vibration moves through the material, setting particles in motion and moving them

closer together for the highest density possible. Based on the materials being compacted, acertain amount of force must be used to overcome the cohesive nature of particular particles.


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Results of Poor Compaction

Both illustrations above show the result of improper compaction and how proper compaction

can ensure a longer structural life.

SOIL TYPES & CONDITION


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Every soil type behaves differently with respect to maximum density and optimum moisture.

Therefore, each soil type has its own unique requirements andcontrols both in the field and for testing purposes. Soil types are

commonly classified by grain size, determined by passing thesoil through a series of sieves to screen or separate the different

grain sizes. Soil classification is categorized into 15 groups, asystem set up by AASHTO (American Association of State

Highway and Transportation Officials). Soils found in nature arealmost always a combination of soil types. A well-gradedsoil

consists of a wide range of particle sizes with the smallerparticles filling voids between larger particles. The result is a

dense structure that lends itself well to compaction. A soil'smakeup determines the best compaction method to use. They are

three basic soil groups:

y Cohesive

y

Granulary Organic (this soil is not suitable for compaction and will

not be discussed here)

Cohesive soilsCohesive soils have the smallest particles. Clay has a particle

size range of .00004" to .002". Silt ranges from .0002" to .003".Clay is used in embankment fills and retaining pond beds.

CharacteristicsCohesive soils are dense and tightly bound together by molecular

attraction. They are plastic when wet and can be molded, butbecome very hard when dry. Proper water content, evenly distributed, is critical for proper

compaction. Cohesive soils usually require a force such as impact or pressure. Silt has anoticeably lower cohesion than clay. However, silt is still heavily reliant on water content.

Granular soilsGranular soils range in particle size from .003" to .08" (sand) and .08" to 1.0" (fine to medium

gravel). Granular soils are known for their water-draining properties.

Characteristics

Sand and gravel obtain maximum density in either a fully dry or saturated state. Testingcurves are relatively flat so density can be obtained regardless of water content. The tables that

follow give a basic indication of soils used in particular construction applications.

Guide to Soil Types

What to look for Appearance/Feel Water Movement When Moist When Dry


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Granular soils,fine sands andsilts

Coarse grainscan be seen.Feels gritty whenrubbed betweenfingers

When water andsoil are shaken inpalm of hand,they mix. Whenshaking isstopped they

separate

Very little or noplasticity

Little or nocohesive strengthwhen dry. Soilsample willcrumble easily.

Cohesive soils,mixes and clays

Grains cannot beseen by nakedeye. Feelssmooth andgreasy whenrubbed betweenfingers

When water andsoil are shaken inpalm of hand,they will not mix

Plastic and sticky.Can be rolled

Has high strengthwhen dry.Crumbles withdifficulty. Slowsaturation inwater.

MaterialsVibrating SheepsfootRammer

Static SheepsfootGrid RollerScraper

Vibrating Plate CompactorVibrating RollerVibrating Sheepsfoot

ScraperRubber-tired RollerLoaderGrid Roller

Lift Thickness ImpactPressure

(with kneading)Vibration

Kneading(with pressure)

Gravel12+ Poor No Good Very Good

Sand 10+/- Poor No Excellent Good

Silt 6+/- Good Good Poor Excellent

Clay 6+/- Excellent Very Good No Good

Fill Materials

Permeability Foundation SupportPavement Sub grade ExpansiveCompaction

Difficulty

Gravel Very High Excellent Excellent No Very Easy

Sand Medium Good Good No Easy

Silt Medium Low Poor Poor Some Some

Clay None+ Moderate Poor Difficult Very Difficult

Organic Low Very Poor Not Acceptable Some Very Difficult

Effect of MoistureThe response of soil to moisture is very important, as the soil must carry the load year-round.

Rain, for example, may transform soil into a plastic state or even into a liquid. In this state,soil has very little or no load-bearing ability.

Moisture vs. Soil DensityMoisture content of the soil is vital to proper compaction. Moisture acts as a lubricant within


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soil, sliding the particles together. Too little moisture means inadequate compaction - the

particles cannot move past each other to achieve density. Too much moisture leaves water-filled voids and subsequently weakens the load-bearing ability. The highest density for most

soils is at a certain water content for a given compaction effort. The drier the soil, the moreresistant it is to compaction. In a water-saturated state the voids between particles are partially

filled with water, creating an apparent cohesion that binds them together. This cohesionincreases as the particle size decreases (as in clay-type soils). l

Soil Density Tests

To determine if proper soil compaction is achieved for any specific construction application,

several methods were developed. The most prominent by far is soil density.

Why Test?

Soil testing accomplishes the following:

y Measures density of soil for comparing the degree of compaction vs. specsy Measures the effect of moisture on soil density vs. specs

y Provides a moisture density curve identifying optimum moisture

Types of Tests

Tests to determine optimum moisture content are done in the laboratory. The most common isthe Proctor Test, or Modified Proctor Test. A particular soil needs to have an ideal (or

optimum) amount of moisture to achieve maximum density. This is important not only fordurability, but will save money because less compaction effort is needed to achieve the desired

results.


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The Hand TestA quick method of determining moisture is known as the "Hand Test". Pick up a handful of

soil. Squeeze it in your hand. Openyour hand. If the soil is powdery and will not retain the shape made by

your hand, it is too dry. If it shatters when dropped,it is too

dry. If the soil is moldable and breaks into only acouple of

pieces when dropped, it has the right amount ofmoisture for proper compaction. If the soil is plastic

in your hand, leaves traces of moisture on yourfingers and stays in one piece when dropped, it has

too much moisture for compaction.

Proctor Test (ASTM D1557-91)

The Proctor, or Modified Proctor Test, determines the maximum density of a soil needed for aspecific job site. The test first determines the maximum density achievable for the materials

and uses this figure as a reference. Secondly, it tests the effects of moisture on soil density.The soil reference value is expressed as a percentage of density. These values are determined

before any compaction takes place to develop the compaction specifications. Modified Proctorvalues are higher because they take into account higher densities needed foe certain typed of

construction projects. Test methods are similar for both tests.

Proctor TestA small soil sample is taken from the jobsite. Astandard weight is dropped several times on thesoil. The material weighed and then oven dried for12

hours in order to evaluate water content

Modified Proctor TestThis is similar to the Proctor Test except ahammer is used to compact material for greaterimpact, The test is normally preferred in testing

materials for higher shearing strength.

Field TestsIt is important to know and control the soil density during compaction. Following are common

field tests to determine on the spot if compaction densities are being reached.


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Field Density Testing Method

Sand Cone Balloon Dens meter Shelby Tube NuclearGauge

Advantages * Large sample* Accurate

* Large sample* Direct readingobtained* Open graded material

* Fast* Deep sample* Under pipe haunches

* Fast* Easy to redo* More tests (statisticalreliability)

Disadvantages

* Many steps* Large area required* Slow* Halt Equipment* Tempting to accept flukes

* Slow* Balloon breakage* Awkward

* Small Sample* No gravel* Sample not alwaysretained

* No sample* Radiation* Moisture suspect* Encourages amateurs

Errors* Void under plate* Sand bulking* Sand compacted* Soil pumping

* Surface not level* Soil pumping* Void under plate

* Overdrive* Rocks in path* Plastic soil

* Miscalibrated* Rocks in path* Surface prep required* Backscatter

Cost * Low * Moderate * Low * High

Sand Cone Test (ASTM D1556-90)

A small hole (6" x 6" deep) is dug in the compacted material to betested. The soil is removed and weighed, then dried and weighed

again to determine its moisture content. A soil's moisture is

figured as a percentage. The specific volume of the hole isdetermined by filling it with calibrated dry sand from a jar andcone device. The dry weight of the soil removed is divided by the

volume of sand needed to fill the hole. This gives us the densityof the compacted soil in lbs per cubic foot. This density is

compared to the maximum Proctor density obtained earlier, whichgives us the relative density of the soil that was just compacted.

Nuclear Density (ASTM D2292-91)Nuclear Density meters are a quick and fairly accurate way ofdetermining density and moisture content. The meter uses a

radioactive isotope source (Cesium 137) at the soil surface(backscatter) or from a probe placed into the soil (direct

transmission). The isotope source gives off photons (usually

Gamma rays) which radiate back to the mater's detectors on the bottom of the unit. Dense soil

absorbs more radiation than loose soil and the readings reflect overall density. Water content(ASTM D3017) can also be read, all within a few minutes. A relative Proctor density with the

compaction results from the test.


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Soil Modulus (soil stiffness)This field-test method is a very recent development that replaces soil density testing. Soil

stiffness is the ratio of force-to-displacement. Testing is done by a machine that sendsvibrations into the soil and then measures the deflection of the soil from the vibrations. This is

a very fast, safe method of testing soil stiffness. Soil stiffness is the desired engineeringproperty, not just dry density and water content. This method is currently being researched and

tested by the Federal Highway Administration.

Compaction Equipment

ApplicationsThe desired level of compaction is best achieved by matching the soil type with its propercompaction method. Other factors must be considered as well, such as compaction specs and

job site conditions.

y Cohesive soils - clay is cohesive, its particles stick

together.* Therefore, a machine with a high impact force is required toram the soil and force the air out, arranging the particles. A rammeris

the best choice or apad-foot vibratory rollerif higher production isneeded.

*The particles must be sheared to compact.

y Granular soils - since granular soils are not cohesive and the

particles require a shaking or vibratory action to move them; vibratoryplates (forward travel) are the best choice.

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Building Systems( Research)