Concrete Framed Structures

CONCRETE FRAMED STRUCTURES


concrete frame is a common form of structure, comprising a network of columns and connecting beams that form the structural ‘skeleton’ of a building. This grid of beams and columns is typically constructed on a concrete foundation and is used to support the building’s floors, roof, walls, cladding and so on.

Beams are the horizontal load-bearing members of the frame. They are classified as either:

Main beams: Transmitting floor and secondary beam loads to the columns; or
Secondary beams: Transmitting floor loads to the main beams.

Columns are the vertical members of the frame and are the building’s primary load-bearing element. They transmit the beam loads down to the foundations. 

LOADS


Structural analysis is a very important part of a design of buildings and other built assets such as bridges and tunnels, as structural loads can cause stress, deformation and displacement that may result in structural problems or even failure.

The building regulations require that structures must be designed and built to be able to withstand all load types that they are likely to face during their life-cycle.

These loads include:

DEAD LOADS 

The downwards forces on the building coming from the weight of the building itself, including the structural elements, walls, facades, and the like.

They are also known as permanent or static loads, they are  predominantly associated with the weight of the structure itself

LIVE LOADS

The downward force on the building coming from the expected weight of the occupants and their possessions, including furniture

DYNAMIC LOADS

these occur commonly in bridges and similar infrastructure and are the loads created by traffic, including braking and accelerating loads.

ENVIRONMENTAL LOADS

Environmental loads may act on a structure as a result of topographic and weather conditions.

  • Wind loads– This is a very important design factor, especially for tall buildings, or buildings with a large surface area

    Burj Khalifa the tallest building on the planet is designed in such a way that it withstands wind loads 
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The roof pitch is designed to withstand snow loads

Snow loads – The shape of a roof is a particularly important factor in the magnitude of the snow load. Snow falling on a flat roof is likely to accumulate, whereas snow is more likely to fall of a steeper the roof pitch

  •  Thermal loads – All materials expand or contract with temperature change and this can exert significant loadson a structure. Expansion joints can be provided at points on long sections of structures such as walls and floors so that elements of the structure are physically separated and can expand without causing structural damage.

 

CLADDING 


Cladding – components that are attached to the concrete frame of a building to form non-structural, external surface. This is as opposed to buildings in which the external surfaces are formed by structural elements, such as masonry walls, or applied surfaces such as render. 

Glass cladding

 

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Whilst cladding is generally attached to the structure of the building, it typically does not contribute to its stability. However, cladding does play a structural role, transferring wind loads, impact loads, snow loads and its own self-weight back to the structural framework.

Since concrete has little tensile strength, it generally needs to be reinforced. Rebar, also known as reinforcement steel (or reinforcing steel), is a steel bar or mesh of steel wires used to strengthen and hold the concrete in tension. To improve the quality of the bond with the concrete, the surface of the rebar is often patterned.

Concrete frames can be precast (manufactured off-site) or cast on site.

PRECAST CONCRETE 


Precast concrete is a form of concrete that is prepared, cast and cured off-site, usually in a controlled factory environment, using reusable moulds. Precast concrete elements can be joined to other elements to form a complete structure. It is typically used for structural components such as; wall panels, beams, columns, floors, staircases, pipes, tunnels, and so on.

Precast concrete frames are typically used for single-storey and low-rise structures. The concrete members transported to the site where a crane then lifts and places them into position to construct the frameImage result for precast concrete

FORMWORK


Concrete members can be formed on site with the use of formwork. This is a temporary mould into which concrete is poured. Traditional formwork is fabricated using timber, but it can also be constructed from steel, glass fibre reinforced plastics and other materials. Shuttering is perhaps the most popular type of formwork and is normally constructed on site using timber and plywood.

SLIP FORMWORK 

Slip form is a method of construction in which concrete is poured into the top of a continuously moving formwork. As the concrete is poured, the formwork is raised vertically at a speed which allows the concrete to harden before it is free from the formwork at the bottom.. 

Slip form is most economical for structures over 7 storeys high such as bridges and towers, as it is the fastest method of construction for vertical reinforced concrete structures, but it can also be used for horizontal structures such as roadways.

 

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Details on Steel framed structures

This period of July we zero in structures, from wooden framed structures to concrete framed structures pre-engineered buildings and load bearing structures so makes sure to come back for more 
Most steel assembly is done with a type of steel called mild steel. Mild steel is a material that is immensely secure.  Take a circular bar of steel 1 inch / 25mm in diameter. If you were to attach this bar securely to your ceiling you could hang from it 20,000 Kg (which is 20 tons), or any one of the following:

  • 2 and a half African Elephants
  • 1 and a half London City Routemaster Double-Decker Buses 
  • 18 Toyota Vitz  

We urge you to try this at home unless you are coupled.

This immense strength is of great benefit to buildings.  The other important feature of steel framing is its flexibility.  It can bend without cracking, which is another great advantage, as a steel building can flex when it is pushed to one side by say, wind, or an earthquake.  The third component of steel is its plasticity or ductility.  This means that when subjected to great force, it will not suddenly crack like glass, but slowly bend out of shape.  This property allows steel buildings to bend out of shape, or deform, thus giving warning to inhabitants to escape.  Failure in steel frames is not sudden – a steel structure rarely collapses.  Steel in most cases performs far better in an earthquake than most other materials because of these properties.

However, one important property of steel is that it quickly loses its strength in a fire. At 500 degrees Celsius (930 degrees F), mild steel can lose almost half its strength. This is what happened at the collapse of the World Trade Towers in 2001. Therefore, steel in buildings must be protected from fire or high temperature; this is usually done by wrapping it with boards or a spray-on material called fire protection.

 

 PRIME EXAMPLES STEEL FRAME STRUCTURES 

Steel construction is most often used in 

  • High rise buildings because of its strength, low weight, and speed of construction
  • Industrial buildings because of its ability to create large span spaces at low-cost
  • Warehouse buildings for the same reason
  • Residential buildings in a technique called light gauge steel construction
  • Temporary Structures as these are quick to set up and remove

TYPES OF STEEL BUILDING CONSTRUCTION

There are several types of steel building construction. Steel construction is also called steel  fabrication.

Conventional Steel Fabrication is when teams of steel fabricators cut members of steel to the correct lengths and then weld them together to make the final structure. This can be done entirely at the construction site, which is labour-intensive, or partially in a workshop, to provide better working conditions and reduce time.

Bolted Steel Construction occurs when steel fabricators produce finished and painted steel components, which are then shipped to the site and simply bolted in place. This is the preferred method of steel construction, as the bulk of the fabrication can be done in workshops, with the right machinery, lighting, and work conditions. The size of the components is governed by the size of the truck or trailer they are shipped in, usually with a max length of 6m (20ft) for normal trucks or 12m (40ft) for long trailers. Since the only work to be done at the site is lifting the steel members into place (with cranes) and bolting, the work at the site is tremendously fast. Pre-engineered buildings are an example of bolted steel construction that is designed, fabricated, shipped and erected by one company to the owner.

Light Gauge Steel Construction is a type of construction that is common for residential and small buildings in North America and parts of Europe. This is similar to wood framed construction, except that light gauge steel members are used in place of wood two-by-fours. Light gauge steel is steel that is in the form of thin (1-3mm) sheets of steel that have been bent into shape to form C-sections or Z-sections.

WEIGHT OF STEEL FRAME STRUCTURES

Consider a single storey building measuring 5 x 8m (16 x 26ft). Let us first construct this in concrete, with four columns at the corners, beams spanning between the columns, and a 150mm (6″) thick concrete slab at the top. Such a structure would weigh about 800 kg/m2, or 32 Tons (32,000 kg) in total. If we build this of steel instead, with a sloping roof covered with corrugated metal sheeting with insulation, this would weigh only about 65 kg/m2. The steel framed building will weigh only 2.6 Tons (2,600 kg). So the concrete building is over 12 times heavier! This is for single storey structures – in multi-storey structures, the difference will be less, as the floors in multi-storey steel buildings are built of concrete slabs for the economy – but the difference is still significant. 

This low weight of steel frame buildings means that they have to be firmly bolted to the foundations to resist wind forces, else they could be blown away like deck umbrellas!

ADVANTAGES OF STEEL STRUCTURES

Steel structures have the following advantages:

  • They are super-quick to build at the site, as a lot of work can be prefaced at the factory.
  • They are flexible, which makes them very good at resisting dynamic (changing) forces such as wind or earthquake forces.
  • A wide range of ready-made structural sections are available, such as I, C, and angle sections
  • They can be made to take any kind of shape and clad with any type of material
  • A wide range of joining methods is available, such as bolting, welding, and riveting

DISADVANTAGES OF STEEL STRUCTURES

Steel structures have the following disadvantages:

  • They lose strength at high temperatures and are susceptible to fire.
  • They are prone to corrosion in humid or marine environments.
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TILE INSTALLATION GUIDE

A ceramic tile will outperform and outlast nearly any other floor covering product created for the same application.

Here at constructionweb, I lead you to the choice of tiles to layout and grouting. 

When it comes the selection of tiles, A lot comes into play this includes; 

SELECTION OF TILES 

  • Material –  Tile materials are porcelain, ceramic, brick, marble, laminate, slate, mosaic and vinyl. All these materials are available in many colours and price ranges.
  • Installation – Rooms such as the living room and kitchen require tough tiles that will last for long. Kids bedroom require tiles that will stand up to abrasion and heavy use as well. 
  •  Durability – While some tiles are resistant to wear and tear, some other options such as granite and marble may be prone to cracks and staining. Before tile selection, carefully consider the foot traffic in the intended area of installation
  • Resistance to water– In areas of installation such as the kitchen and bathroom floors, some of the better options for tiles are materials such as marble, granite, mosaic or ceramic. However, you must also remember that the smooth finish on marble and granite can increase the chances slipping. Slip resistant tiles are the best option. 

Hardwood and laminate are not good choices for the kitchen or bathroom 

Picture: Bathroom designs the USA
  • Resistance to chemicals –  Slates are hardy  tiles and the best choice for areas with chemical handling 
  • Maintenance– The ease of cleaning or maintenance should be put into consideration, Ceramic tile is long-lasting and relatively easy to maintain. Glazed ceramic tile is generally resistant to stains, water, fire and dirt, and can be cleaned up with a damp mop or sponge and common household cleaners.  Unglazed porcelain tile is popular for its natural look and chameleon properties, it is slightly more difficult to maintain and requires extra sweeping and damp mopping to prevent staining.
  • Pricing – Well, the price should be in your budget 
  • Availability – In case of tile breakage long after installation,  A similar tile should be readily available at the local depots 

GROUT 

Grout simply is a sealant used to lock the tiles tight, keeping water out and bonding the tiles together preventing the edges from chipping and cracking. Grout helps in controlling the functionality and durability of tiles and plays a major role in the day-to-day maintenance and the overall longevity of your tiles.

There are three methods when it comes to choosing the most suitable grout :

  • Matching grout
    Matching the grout colour to the tile colour makes the grout lines less noticeable and therefore the tile itself is accented. This is the best option if you have over-the-top beautiful tiles with a basic layout. 
  • Contrasting grout
    Picture: Homesteady

    A conflicting grout colour and tile colour will emphasize both the design and layout of the tiles, rather than the tile itself. Grout is a whole other design decision, therefore, gives it the consideration it deserves.

  • Neutral grout
    A neutral grout produces an appearance somewhere in between matching and contrast. Guess who lacked a clear explanation of this 

    EXTRA TILE TIPS

  • When dealing with mismatched tiling, don't vary the size, shape or colour palette and vice versa — always have a single consistent feature.
  • Though tile is durable and long-lasting, you may need to replace broken floor tiles occasionally. If you didn't save spares from the initial installation, there are a few options.

Thank you for reading, Do have a great day ahead

 

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Basic requirements of a building

Hi Construction savvy,  The year 2017 is and will never come back to your life, You had a rough one? hang on in there 2018 will be interesting to you.  Never give up on your dreams.

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Basic requirements of a building 

1. Strength and Stability: Building should be capable of transferring the expected loads in its life period safely to the ground. Design of various structural components like slabs, beams, walls, columns footings should ensure safety. None of the structural components should buckle, overturn and collapse.

2. Dimensional Stability: Excessive deformation of structural components give a sense of instability and result into a crack in walls, flooring etc. All structural components should be so designed that deflections do not exceed the permissible values specified in the codes.

3. Resistance to Dampness: Dampness in a building is a great nuisance and it may reduce the life of the building. Great care should be taken in planning and in the construction of the building to avoid dampness.

4. Resistance to Fire: Regarding achieving resistance to fire, the basic requirements laid down in the codes are:
(a) the structure should not ignite easily.
(b) building orientation should be such that spread of fire is slow.
(c) In case of fire, there should be means of easy access to vacate building quickly.

5. Heat Insulation: A building should be so oriented and designed that it insulates interior from heat.

6. Sound Insulation: Buildings should be planned against outdoor and indoor noises.

7. Protection from Termite: Buildings should be protected from termites.

8. Durability: Each and every component of the building should be durable.

9. Security against Burglary: This is the basic need the owner of the building expects.

10. Lighting and Ventilation: For healthy and happy living natural light and ventilation are required. Diffused light and good cross ventilation should be available inside the building.

11. Comforts and Conveniences: Various units in the building should be properly grouped and integrated keeping in mind the comfort and convenience of the user.

12. Economy: Economy without sacrificing comfort, convenience & durability is another basic requirement of the building.

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Roofing Systems and solutions

I have been arguing with other builders and roof experts which roofing system is the most beautiful, They all have different opinions or rather tastes and preferences. This article is inspired by them!

Here is all you need to know about roofing systems and factors to consider when choosing the type of roofing, but before that

The roof is the covering on the uppermost part of a building or shelter which provides protection from animals and weather, notably rain or snow, but also heat, wind and sunlight. Roofing also denotes the framework that supports that covering.

Roof systems and materials generally are divided into

  1.  Low pitched roofs.
  2. High pitched roofs.

-Low pitched roofing includes water impermeable, or weatherproof, types of roof membranes installed on slopes less than or equal to  15°

-High pitched roofing includes water shedding types of roof coverings installed on slopes exceeding  15°

TYPES OF PITCHED ROOFS

Gabled roofing 

The roof slopes around a triangular extension of the end wall. This piece of wall is the gable. 
 
Hipped  Roofing
A  hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus a hipped roof house has no gables or other vertical sides to the roof. 
A square hip roof is shaped like a pyramid.
Shed -ROOFING 
This simple roof has only one slope. It is commonly used on lean-to structures, such as additions. 
Mansard
A modified version of the pitched roof that creates a spacious living area in the roof space. a four-sided gambrel-style hip roof characterized by two slopes on each of its sides with the lower slope, punctured by dormer windows, at a steeper angle than the upper 

 

Low-pitched  roofing 
There are five types of low slope roof membranes or systems. 

  • Built-up roof (BUR) membranes
  • Metal panel roof systems for low-slope applications
  • Polymer-modified bitumen sheet membranes
  • Single-ply membranes
    • Thermoplastic membranes (e.g., PVC, TPO)
    • Thermoset membranes (e.g., EPDM)
  • Spray polyurethane foam-based (SPF) roof systems

Most low-pitched roof membranes have three principal components:

  • Weatherproofing layer or layers — the weatherproofing component is the most important element because it keeps water from entering a roof assembly.
  • Reinforcement — reinforcement adds strength, puncture resistance and dimensional stability to a membrane.
  • Surfacing — surfacing is the component that protects the weatherproofing and reinforcement from sunlight and weather. Some surfacings provide other benefits such as increased fire resistance, improved traffic and hail resistance, and increased solar reflectivity.

With some roof membranes, a component may perform more than one function.

High pitched 

There are divisions of high pitched roof coverings.

  • Asphalt shingles
  • Clay tile and concrete tile
  • Metal roof systems for steep-slope applications
  • Slate
  • Wood shakes and wood shingles
  • Synthetic

Steep-slope roof systems typically are composed of individual pieces or components installed in shingle fashion. Steep-slope roof assemblies typically consist of three primary parts:

  • Roof deck — a roof deck is the structural substrate and usually is a wood-based material such as plywood or oriented strand board (OSB).
  • Underlayment — underlayment provides temporary protection until a roof covering is installed and provides a secondary weatherproofing barrier. Sometimes underlayment is referred to as “felt” or “paper.”
  • Roof covering — the roof covering is the external water shedding material.
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TESTS ON QUALITY CEMENT

Quality tests on cements at construction site (also called field tests on cement) are carried to know the quality of cement supplied at site. It gives some idea about cement quality based on colour, touch and feel and other tests.

Tests on Cement at Construction site

The following are the quality tests on cement at construction site:

Color test
Presence of lumps
Adulteration test
Temperature test
Float tests
Strength test
Setting test
Date of packing

 

Color Test of Cement

The color of the cement should be uniform. It should be grey colour with a light greenish shade.

Presence of Lumps

The cement should be free from any hard lumps. Such lumps are formed by the absorption of moisture from the atmosphere. Any bag of cement containing such lumps should be rejected.

Cement Adulteration Test

The cement should feel smooth when touched or rubbed in between fingers. If it is felt rough, it indicates adulteration with sand.

Temperature Test of Cement

If hand is inserted in a bag of cement or heap of cement, it should feel cool and not warm.

Float Test

If a small quantity of cement is thrown in a bucket of water, the particles should float for some time before it sinks.

Setting Test

A thick paste of cement with water is made on a piece of glass plate and it is kept under water for 24 hours. It should set and not crack.

Strength of Cement Test

A block of cement 25 mm ×25 mm and 200 mm long is prepared and it is immersed for 7 days in water. It is then placed on supports 15cm apart and it is loaded with a weight of about 34 kg. The block should not show signs of failure.

The briquettes of a lean mortar (1:6) are made. The size of briquette may be about 75 mm ×25 mm ×12 mm. They are immersed in water for a period of 3 days after drying. If cement is of sound quality such briquettes will not be broken easily.

Date of Packing:

Strength of cement reduces with time, so it is important to check the manufacturing date of the cement. Generally, the cement should be used before 90 days from the date of manufacturing.

 

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