Construction Logbook - Thomas Shiels

CONSTRUCTION LOGBOOK Thomas Shiels Weeks 1 and 2

The main properties of a building include the strength, stiffness, material behaviour, shape and compression and tension. The main purpose of a building is to essentially do nothing, to not sway, shift, collapse or move in any way.

Forces A force is any influence that produces a change in the shape or movement of a body; a body can be anything from a bridge to a building

Tension forces stretch and elongate the material and the amount of elongation depends on the stiffness of the material, the cross sectional area and the magnitude of the load.

Compresson forces result in the shortening of the material.

There is not always tension when there is compression

Relationship: Generally, where there is tension, there is compression. However, in some circumstances, you can have compression without tension.

On the left, a diagram shows the compression and tension relationship of a bridge, and on the right, blocks are stacked on a table to show compression without any tension.

There are two types of loads, dead loads and live loads. Dead loads are permanent loads, in terms of a bridge, the dead load is the actual bridge structure and the pressure it puts on itself.

Whereas a live load is something that is applied to the structure, in terms of a bridge, this could be a car driving over it and it is important to understand how the force is sent to the ground through the structure.

The diagram to the left shows a dead load, which is the weight of the bridge itself, fixed and permanent

The diagram to the left shows a live load, being a car crossing the bridge, and how the force is distributed down to the ground through the structure to remain stable

The reaction to a live load has to be equal and opposite in order to be stable.

Structural Systems There are three types of structural systems: The enclosure system such as the facades of a building or roof sheeting, the structural system itself such as the skeleton of a building or the service systems such as the gas, electricity and water systems to a building.

There are different types of structural systems in terms of the structure of the building, as aforementioned a skeletal system is one like the Sydney Harbour Bridge, a shell structure like the Sydney Opera House, there is planar cladding, a membrane structure and a hybrid which is common and consists of a couple different systems together.

Joints The type of joint used in any structure is integral to its stability and operation. The three types of joints used are roller joints, pin joints and fixed joints.

Roller joints allow horizontal movement of an object when loads are applied to it, as seen in the diagram to the right

Pin joints allow two planar directions of movement, as seen in the diagram to the right

Fixed joints or rigid joints allow no movement and are ‘fixed’

There are multiple factors to consider when constructing a structure and they are all linking concepts which are applied to the structure before it’s built

Aesthetic Qualities Performance Requirements

Economic Ef?iciencies

Environmental Impacts

The aesthetic considerations refer to how a structure essentially looks. All structures are built to look differently and many have become famous essentially for their design and not their internal function or constructive prowess.

Economic efficiencies refer to the ability to complete the structure in the most economic fashion, meaning the least expense in the least amount of time. A lot of this will come down to the materials used, the efficiency of workers and minimising of delays.

Environmental impacts is quite important to consider in building a structure and it is the common aim to make all projects as environmentally friendly as possible by using different materials and methods of construction.

Structural Materials A strut is a slender element designed to carry a load parallel to its long axis. The load produces compression, as seen in the diagram to the right

A tie is very similar to a strut above, however it produces tension instead, as seen in the diagram below

A panel is a deep, vertical element designed to carry vertical or horizontal loads, as shown in the diagram to the right

A beam is a horizontal element designed to carry vertical loads by using its bending resistance, as shown in the diagram below

Week 3 There are two types of mass construction; modular and non-modular, then consisting of materials within these categories

Clay Brick

Modular

Mud Brick

Modular materials include clay bricks or honeycomb blocks and concrete blocks

Concrete Blocks

Concrete

Non-­‐Modular

Rammed Earth

Non-modular materials include concrete, rammed Earth used to build walls and monolithic stone which is very hard to use nowadays

Monolithic Stone

Bricks have been used for many hundreds of years in construction and have also changed a lot from the first hand made bricks to the now machine moulded and extruded type bricks of today.

The average brick weighs around 4kg.

To the right is a diagram with measurements of the average brick nowadays, which are red if they contain iron and become a more beige colour with the less iron a brick has in it

Bricks have the convenient ability to be arranged in a variety of ways, on all of their 4 sides

The above arrangement is called a ‘header course’

The above arrangement is called a ‘stretcher course’

The above arrangement is called a ‘soldier course’

The above arrangement is called a ‘brick on edge course’

Concrete blocks have also been used in construction for a long time and are created by mixing cement, sand, gravel and water, then shaping and curing it into blocks. Most concrete blocks are hollowed out to reduce weight and increase thermal mass, this also allows for reinforcement. The average concrete block weighs around 11kg.

To the left is a diagram of a typical concrete block, weighing around 11kg with holes through it for reinforcement. The typical measurements are also included

Activity – Building a Tower The objective was to transform a piece of balsa wood into the tallest tower possible that can sustain a weight placed on top of it. By slicing the balsa wood long ways and creating smaller pieces of wood that could be sticky taped together, this would give our group the height it needed, and the triangular base was the most efficient base to use.

The photos above and below show the construction process and the final product of the tower. Overall, we managed to build it quite tall and stable, but it was extremely flimsy and unable to support a load with stability. This may have been achieved better with shorter pieces of balsa wood and more connections between verticals with horizontals

Week 4 Concrete – can be divided into two categories

In Situ Advantages Fewer joints, more ?lexible in pouring concrete, mostly used in footings, can be sprayed using a pressure hose

Pre-­‐Cast Advantages Higher quality, better ?inishes, reduces construction time, more sandardised outcome, potentially more cost effective

Disadvantages

Disadvantages

Longer on-­‐site construction period, depends on weather when it can be carried out, higher quality is more dif?icult to achieve, requires framework and supports to be also constructed

Limited sizing due to transporting to site, much more planning to ensure timely arrival, requires a crane, higher maintenance costs

Concrete is made up of 4 different elements, which undergo a chemical change to harden over a short period of time. Concrete is 1 part cement (either Portland or lime), 2 parts fine aggregate (sand), 4 parts coarse aggregate (crushed rock) and 0.5 parts water.

If too much water is added, the concrete mix becomes fluid and shapeless, if too little water is added then it becomes not workable. It reaches 75% of its compressive strength in approximately 7 days, and full strength in approximately 28 days.

Concrete has many different properties which make it such a universally used product in construction. Its high hardness but low fragility, ductility and flexibility makes it perfect for foundations and columns which is it commonly used for and being very durable, it’s suited to these uses.

These properties can be strengthened through various methods. Porosity can be increased with more additives. Concrete has a high compressive strength but low in tensile strength, this is why steel reinforcement is common as this increase the tensile strength.

Reinforced concrete, as aforementioned, is to increase the low tensile strength of concrete. Steel rods as placed through the concrete and then more cement is poured to fill the gaps.

These drawings show where the steel rods come out of the beams and how concrete is poured around them to cure and add tensile strength to an already strong in compression member

In Situ Concrete is when concrete is poured and fabricated on site. This requires formwork to mould concrete into different shapes. It is mostly used for footings, and also common for retaining walls and structural elements. A float is used for a flat finish when curing the concrete and this is often a busy time on the work site as there is only a small timeframe when the concrete can be shaped before it sets and becomes non-workable.

Depending on the size of the slab that is being poured in situ, it may have to be done in sections, as it needs to be worked a considerable amount before it is cured. This results in construction joints, which become a weak point of the slab, and control joints are also used to absorb expansion and contraction of concrete due to thermal variations.

Pre-cast concrete is fabricated in a factory and therefore a controlled environment and transported to the site. This means it can be made independently of the weather and save on site construction time. Pre-cast connections in the concrete are included to connect to other walls and columns and the joints used are very dependant on the desired aesthetic look of the building. Due to the controlled environment in which it is cured in, the finishes can be of a higher quality than in situ.

Beams are mostly a horizontal structural element with a function to carry the loads along the length of the beam transferring them to the vertical supports. They can be supported at both ends of the beam, at numerous points or only one end (cantilever)

A cantilever is created when a structural element is only supported at one end; it carries the load along the length of the member and transfers it down the vertical supports. They can be horizontal, vertical or angled.

The diagram to the left shows both a beam and cantilever and their supports in the one picture very clearly

Spacing of elements generally depends on the spanning capabilities of the elements The ‘span’ is the distance measured between two structural supports; it is not necessarily the length of a member.

Spacing is the repeating distance between elements, which can be measured horizontally or vertically

Span and spacing are commonly used as interchangeable words, which is incorrect, as people assume they are the same thing. The left diagram shows spacing individually, then the right diagram clearly shows how the span of a member and the spacing of members are difficult concepts in the one picture.

Activity – Building a Structure In groups of 3, we were challenged to construct a structure that will span 1000mm and will take the greatest load at its centre. The maximum height of the structure was 400mm. Our group was given 2x plywood measuring 1200 x 3.2 x 90mm and 2x pinewood measuring 1200 x 35 x 35mm.

We proceeded to saw one of the pinewood pieces into 10cm (left photo) pieces evenly spaced and nailed onto one of the pieces of plywood (right photo). The other piece of pinewood was nailed across the top of the plywood (middle photo). The other piece of plywood was then nail over the pinewood members to enclose the structure. We believed that with the materials we were given, this was the best design to hold the highest loads.

Our design ultimately failed compared to others and past examples, only managing to hold 360kg. The structure failed in tension of the pinewood and compression of the plywood as visible in the photo above. If we were given this task again, I would propose using the plywood at the bottom as it has better tensile strength than the pinewood, this would allow it to carry a greater load.

Week 5 Walls can be constructed out of steel framing, concrete framing or timber framing, all having their advantages and disadvantages. These all act as load bearing walls.

Concrete Walls

• Can be pre-­‐cast or in situ • Typically use a grid of columns with concrete beams connecting the columns together

Steel Framing

• Typically use a grid of steel columns connected to steel girders and beams • Using light gauge steel for the framework

Timber Framing

• Uses a grid of timber posts or poles connected to timber beams and bracing for stability • Elements include top/bottom plate, vertical studs, noggings, cross bracing and ply bracing

The process of wood from a tree becoming usable timber for construction has many different stages and can be very time consuming depending on the method used to season the wood.

There are three methods to season (dry) wood, air seasoning which is slow but cheap, kiln seasoning which is fast and also solar kiln season which is less expensive and still quick.

Wood can be categorised into softwood and hardwood

• Douglas Pine, Hoop Pine

Softwood • Cypress Pine, Radiata Pine • Victorian Ash, Brown Box

Hardwood • Tasmanian Oak, Spotted Gum

Wood can be cut from a tree in three different ways, all having their advantages and disadvantages

Back Sawn advantages, opposite to quarter sawn, are that the wood is seasoned more rapidly and less prone to splitting from nailing. These are countered by the downsides that they can shrink over time and become more difficult to recondition. Â

Quarter Sawn advantages include that the grain is shown on the face of the wood, useful to know where to nail, and it is also a good weathering surface for flooring.

However, this method takes longer to season (dry) and nailing on the face of the wood makes it prone to splitting.

These diagrams show the shape of the piece of timber, which is achieved through each different method of cutting a tree

The Radial Sawn method of cutting a less results in less wastage during milling, as the whole tree can be utilised, but also means that the cut is a wedge shaped cross section and this can often be more difficult to detail in design and stack for storage

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Laminated Veneer Lumber -­‐ Made by laminating sheets of timber -­‐ Used for structural beams and frames Glue Laminated Timber -­‐ Made by gluing pieces of sawn timber -­‐ Mainly used for structural members Cross Laminated Timber -­‐ Made by gluing and pressing laminates -­‐ Used for structural members Plywood -­‐ Made by gluing and pressing laminates -­‐ Used in structural bracing

Properties of timber can be varying depending on the type of timber and the way it has been seasoned, but it is generally medium/low in hardness and fragility, high in flexibility, porosity and recyclability. As there is very little embodied energy in timber as it is a grown material, there is a great recyclability factor about it and low carbon footprint, also making it very cost effective to use in construction.

Medium Density Fibreboard -­‐ Made by breaking down soft and hardwood and binding the fibres with wax and resin - Used for structural systems

Columns are vertical structural members designed to transfer compressive loads.

Short columns are shorter in length and thicker in cross-section and are considered short if the length to cross-section is less than 12:1. Short columns generally fail by crushing.

These diagrams show a short column with a large cross sectional area and also how a short column will fail, through compression of forces pressing down on it

Long columns are taller in length and slimmer in cross-section and are considered long if the length to cross-section is greater than 12:1. Long columns generally fail by buckling.

This diagram shows the longer length of the column but smaller cross sectional area and also how a long column will fail; through buckling and bending in the middle

Week 6 Metals can be divided into three categories, ferrous, non-ferrous and alloys. They all have varying properties and are used for different elements of construction. Alloys are simply the combination of two metals to strength a property, most commonly to add more resistance to corrosion.

Non-­‐ Ferrous

Ferrous Iron

Aluminium, copper, zinc

Wrought iron, iron alloys

Titanium, bronze, brass

Iron is magnetic, reactive to chemicals and has good compressive strength. It is the 4th most common element on Earth, and therefore quite cheap. As iron is quite old, it has been developed and mostly replaced by steel, which is an alloy of iron.

Wrought Irom

Cast Iron

Steel

Steel has many forms and uses that have been aforementioned, however it’s production differs. It can be hot rolled where it is shaped whilst hot or cold rolled, where elements are folded from sheets that have been made and cooled. Steel sheeting, commonly known as corrugated iron, is mainly used for cladding and roofing, these elements must be galvanised, meaning a layer of zinc is added to increase the resistance to corrosion. Stainless steel is the most cathodic metal and is simply chromium added to steel, used for coils, sheets and wire.

Varied hardness, high ?lexibility, impermeable

High carbon footprint, high density, low fragility

Properties of Metals

High density, good conductors, very durable

High recyclability, generally cost effective

Roofs are the enclosing element to a building that can carry water away and be an aesthetic feature of any building. Types of roofs vary greatly depending on the building and its needs.

Flat roofs are defined to be less than 3 degrees pitch

A pitched roof is defined to have a greater than 3 degree pitch

Tiled roofs must have a slope of greater than 15 degrees to prevent water from being able to seep through the cracks if a gust of wind were to blow against the roof when water was draining

Concrete roofs are generally supported by beams and columns to transfer the load to the footings, all made of concrete. They are finished with a waterproof membrane as concrete has a low waterproofing property. Structural steel framed roofs can be flat or sloped and are constructed using beams, purlins and light sheet metal roofing.

A trussed roof is an efficient way to span a long distance, as they are very light and have a great strength to weight ratio. They can be made of timber or steel and be sloped or flat.

These diagrams are simple pictures of a flat truss and an angled truss, which are efficient methods to span long distances

Light framed roofs are the stereotypical roof where vertical struts span on an angle from a wall plate to a roof beam and are made triangular through horizontal struts connecting each wall plate at the bottom of the vertical struts.

Week 7 Rubber can be divided into two categories, natural and synthetic

Synthetic Rubber

Natural Rubber

First made in the beginning of the 20th Century

First used in the 13th Century

Produced in a lab generating variations like plastics

Sourced from a tree's sap

Natural rubber is used for seals, gaskets, floor lining, insulating (wiring), hosing and piping whereas synthetic rubber is used to make EPDM which is in gaskets and control joints, neoprene which is used for control joints also and silicone which acts as an all purpose seal. Rubber deteriorates when exposed to the elements for extended periods of time and therefore is mainly used inside to avoid this.

Low hardness, resists abrasions, waterproof

1.5x more dense than water

Properties of Rubber

High recylability, cost effective

High ?lexibility, waterproof

Plastics are made up of carbon, silicon, hydrogen, nitrogen, oxygen and chloride, all bound through chemical reactions. Divided into three categories, they are

Thermoplastics

Plastics

Thermosetting Elastomers

Thermoplastics are mouldable when heated and solid when cold, used for PVC piping, polyethylene (insulator) and Perspex. Thermosetting plastics can only be moulded once and include laminex (finishing surface) and polystyrene (insulator).

Elastomers can be seen separately from thermoplastics and thermosetting as it is synthetic rubber, and used to produce EPDM such as rubber sheeting, neoprene such as a waterproofing seal and silicone to also waterproof as well as separate materials in a gasket.

Medium hardness, mediu fragility, generally cost effective

High ductility, high ?lexibility, low density

Properties of Plastic Very durable, high recyclability except thermoplastics

Waterproof, poor conductor of heat and electricity

Paints are liquid until applied to a surface and become solid when exposed to the air, their main purpose is to protect a surface and colour an element. They are made up of a binder, the filmforming component, a diluent, which dissolves the paint and changes its viscosity and finally a pigment, which gives the paint its colour and opacity.

Oil Based

Water Based

Used prior to water based paints

Most common paints today, brushes cleaned with water

High gloss ?inish, not water soluable, cleaned with turpentine

Very durable and ?lexible

Paint needs its colour to be consistent and to reflect UV rays from the sun as it is always exposed to the elements, therefore also has to be extremely durable. The finishes on different paints can range from gloss through to matt.

Week 8 Glass is a universally used material in every building. It is made using three compounds, which when heated to around 600 degrees Celsius and cooled, produces glass. The compounds included are formers such as silica, flutes such as soda ash and stabilisers such as limestone. The formers are the basic ingredients to make glass, while flutes assist formers to melt at a lower level but this also makes the compound unstable, which is stabilised through adding limestone.

Very expensive to produce and transport, with a high embodied energy

High recylability and carbon footprint, low ductility

Properties of Glass

Waterproof, high density and hardness

High fragility and durability, corrosion resistnt

There are a vast amounts of different types of glass including clear float glass which is the simplest and cheapest, laminated glass which has a tough plastic interlayer and is quite safe and tempered glass which is cooled at a more rapid rate than normal glass which results in allowing it to have 4-5 times the bending strength compared to when it is cooled at a standard rate.

Double and triple glazed glassing is also available, where there are a number of sheeting of glass layered on top of each other, like a sandwich, which decreases heat loss and helps with insulation and retaining heat.

Float glass, which is the most common form of glass universally, produced in sheets is now made by machines in labs compared to blown glass many centuries ago. It has to be able to withstand winds, gravity, opening and closing, constantly environmental changes in weather and also the ability to cope with thermal expansion and contraction. Glass is essentially the buildings primary modulator of sunlight. One common problem with glass buildings is that, due to the inability to allow heat to transmit through it, they are often either too hot or too cold, which adds to the energy needed to modulate the temperature inside accordingly, on top of the already high embodied energy in glass.

Week 9 Construction detailing is essentially how materials are put together; the constructor, the builder or the fabricator can decide this As buildings move with thermal expansion and contraction, wind forces and even Earthquakes, movement joints are designed to allow for movement within the building.

The diagram to the left shows a joint under elongation and the effect that is has on that joint as forces pull away from the joint. The joint is stretched outwards compared to standard joints.

The diagram to the right, juxtaposing the one above, shows a joint under compression, as forces push towards the joint and it is clearly compressed compared to standard joints.

The diagram to the left shows a standard joint not experiencing any forces acting upon it and is useful to see the changes undergone in joints under compression and elongation

Monolithic

Composite

Can be a single material

When materials are combined, but the individual materials are can still be distinguished

Can be two or more materials combined making the individual materials indistinguishable

An eample of this is webbed glass, where the webbing is visible through the glass

Composite materials are used to act together to improve the property of a material. For webbed glass, this increases the safety of the glass because if it is smashed and broken, the webbing will hold the glass in place, instead of shards of glass falling and coming out which are very dangerous.

Fibreglass is a composite material made from glass fibres and epoxy resins to produce flat and profiled sheet products. Commonly used for translucent roofs, cladding, swimming pools and baths, this material is fire resistant, weatherproof, light and strong which gives it a range of extremely useful properties to be utilised.

Aluminium sheet composites improve aluminium properties by adding plastic, which in turn makes it a lighter weight, less expensive (because there is less aluminium used in production), shock and fire resistant and can be used for cladding. By using less aluminium this will also decrease the embodied energy of the product.

Timber composites are comprised of solid timber, engineered timber and galvanised pressed steel, they are used for beams and trusses and their most valued property is their maximum efficiency for use from minimum material, also making this composite very cost effective.

Activity – Group Site Visit This construction site was located just off the corner of Lonsdale and Swanston Street in the City, where a building company is part of the way through adding an extra 5 stories on top of an existing 25 story building. The estimated cost of the project is between $28-30 million and is dissimilar to many other sites as it is in the City and there is very little room for storage, safety of pedestrians and the local public must be taken into consideration in much more depth and also the fact that the site is not standalone, it is on top of an existing building, therefore the project has to be mindful of residents and workers in that existing building below.

As the existing building was not designed and constructed to hold an extra 5 stories on top, choice of materials was very important. Aerated concrete is being used for each floor instead of normal concrete, as it is much lighter and has a better fire resistance than concrete, which is important in such a tall building, if a fire were to occur. The photo on the left shows the ceiling of a story under construction, more importantly, the thick beige member running horizontally is a structural steel component that has been sprayed with vermiculite, which increases the fire resistance of the steel.

The entire building is fire and smoke proof through each floor, meaning if a fire were to be on the 27th floor, it would take hours before it could spread to other levels of the building.

The photo on the left shows a room that has had plasterboards put up on the walls and the structural elements of the ceiling. The photo on the right shows where the crane extends above the building to move and load heavy objects, and it extends through cut out rectangles in the roof of each story, which will be covered in, completing the building towards the end when the crane is no longer needed. The crane is mounted to the roof of the existing building.

Week 10 The Statue of Liberty which is one of the most iconic structures worldwide has undergone some constructional issues over its time which have been closely monitored and maintenance has been done to keep the structure safe functional. It is essentially an iron skeleton structure with straight members which is covered in a copper layering that is joined by iron ‘ribs’ connecting the skeleton to the copper.

The main issue in construction of this Statue was that galvanic corrosion would occur between the copper and iron frame, resulting in the need to separate them somehow. This was achieved through wrapping the junctions in a layer of shellac-impregnated cloth, however it did not functionally succeed long term.

The diagrams, from left to right, show how those responsible for the construction of the Statue of Liberty did not factor in that the shellac-impregnated cloth would hold moisture. Consequently, as the cloth expanded with moisture, more pressure was placed on the rivets holding the iron skeleton to the copper layering until they eventually broke off and had to be replaced with a Teflon-coated stainless steel.

The original iron armature was removed and replaced with a Teflon-coated stainless steel structure, which still requires monitoring over time.

Vertical and horizontal supports have been an focus point, however lateral supports are just as important for the countering of winds and more serious dangers such as Earthquakes. Lateral bracing is required to minimise damage from Earthquakes and prevent structures from collapsing when faces with strong gusts of wind. Wind forces depend on the surface area of the structure exposed and Earthquake forces depend on the mass above the foundation of the building.

They are opposing forces in the sense that winds are most dangerous at the top of a structure, whereas Earthquakes are most dangerous at the bottom of a structure. In areas prone to Earthquakes, buildings sit on seismic base isolators which disconnect the structure from the ground and allow the isolator to absorb forces from possible Earthquakes, making it much safer.

The diagram above shows a seismic base isolator, which connects the base of the buildings with the ground, through a lead core down the middle and interchanging rubber layers with metal plates, which aim to absorb Earthquake impacts and lessen the likelihood of the structure collapsing.

Factors when choosing materials for building include the health risks associated such as asthma causations, headaches, comfort of workers and minimising sick days which can all be modulated by choices of paints, glues and finishes. Also the impact on the environment is an important consideration, choosing renewable products such as timber where possible and recyclable options, as well as materials with a low embodied energy will help the environment and reduce effects of climate change and pollution.