eBusiness Weekly
Engineering and Construction Matters
With Innocent Chatikobo
A steel structure is a metal structure which is made of structural steel components connected to each other to carry loads and provide full rigidity.
Mild steel is the most commonly used steel in the construction industry because its strong and long lasting. It is also preferred due to its relatively lower cost that other steel types such as stainless steel and high carbon steel
Properties /characteristics of steel
Steel has various characteristics that enables it to be used in construction and structural engineering projects such as roofs. Some of its properties utilised in construction are
Ductility: it responds to overloads in controlled fashion with managed load retention
Weldability and ease of joining: it is the easiest metal to weld without any problems. It is also compatible with more joining methods than other materials such as riveting, bolting, etc.
Workability(bending/forming): can be worked into different designs, shapes and forms easily than timber
Wear resistance: can withstand wear and tear
Corrosion resistance: if properly coated, it can withstand corrosion from chemicals more than timber
Strength: it is very strong and produces very strong structures which cover very large spans without any supports
Toughness: does not easily deform under load
Durability: it can tolerate harsh environmental conditions and can last for generations without any need for replacement
Examples where steel structures are used
Steel structures are used in almost every type of structure e.g.:
Heavy industrial buildings e.g., factories
High rise buildings
Equipment support systems e.g., elevator supports and pipe racks
Bridges
Towers and pylons
Airport terminals
Residential homes
Heavy industrial plants e.g., mining plant structures
Tank and solar panel support stands
Solar structures
Church structures
Agricultural structures such as Centre pivots, grading sheds, curers, animal housing, etc.
What determines the need for steel?
To consider using steel in a structure, the following are considered:
a) Span / building size – steel can be used for larger spans than the likes of timber
b) Weather and climatic conditions —steel can withstand harsh conditions e.g., high moisture conditions than wood
c) Customer preferences — some customers prefer using steel than other materials
d) Available skills — each material requires specific skills set e.g., timber needs a carpenter and steel needs a welder. If it’s a welder that is available, it will be good to consider steel
e) Intended application / use of the structure — some applications require a steel structure e.g., where there are high heat conditions or where there is too much exposure to water
f) Load requirements – steel can carry heavy loads and having lower dead loads than other materials such as stone and concrete
g) Availability of material – choice of material can also be made based on the material which is readily available
h)Natural factors — e.g., areas prone to termite attack will need the use of steel more than timber
Supporting structures
Steel structures are compatible with a wide range of supports e.g.
Concrete beams and columns
Steel columns
Load bearing bricks topped by a ring beam fitted with holding down bolts
The choice of support depends on several factors such as:
a. Ground conditions
b. Cost— steel column supports are more expensive
c. Time factor — steel columns are faster than brickwork and concrete columns
d. Size of building — multi-storey structures supports are better done using concrete
Advantages of using steel in structures
Using steel in structures has various advantages such as
Durability
Can cover large spans
Its more reliable
Takes a short time to work on e.g., in truss fabrication
Can easily be formed into any desired shape and design
Requires less raw materials than other structures such as concrete
Points to consider when working with steel
1)Proper / correct steel grades — ensure that the steel is of the correct grade to produce a strong and durable structure
2)Qualified workmen — a structure needs to be worked on by skilled and qualified workmen to produce a safe and habitable structure
3)Health and safety — working with steel have high risks and requires high level of safety
4)Proper hoisting equipment — because steel is heavy, it needs proper hoisting equipment to erect it e.g., motorized cranes
Challenges / disadvantages when working with steel
High cost — steel is more expensive than other materials
Skill requirement — steel needs highly skilled workmen to work on it for fabrication and rigging
Safety risks — steel has high safety risks
Equipment needs — working with steel needs more equipment than other materials from the fabrication process up to the erection e.g., welding machines, grinders, cranes, etc.
Steel grades — the market in Zimbabwe has been flooded by cheap steel grades that are not suitable for structural purposes
Supporting structures — steel needs strong supports e.g., in erecting a steel roof there is need for steel or concrete columns and ring beams
Innocent Chatikobo is an engineer by profession with AtroServe Engineering Zimbabwe. He has extensive knowledge and experience in structural engineering and construction. For your comments, views, questions and feedback he can be contacted on the following platforms; Cell: +263 777 950 224; +263 712 376 037; +263 782 502 732; Email: [email protected]; Facebook: AtroServe Engineering Zimbabwe
