Please is there anyone who can help me with my HNC civil engineering assignment

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JakeRobertson
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Stuck on one of the tasks for my Science and materials for construction and the built environment assignment. If anyone could provide me with any help for this task please do get in touch. TASK 2: A structural engineer is looking for a material to design a structural member in compression. The engineer needs to compare the behaviour of timber, steel and reinforced concrete structural members under compression. If steel has a maximum allowable compressive strength of 300 N/mm^2, concrete 40 N/mm^2, reinforced concrete 48 N/mm^2 and timber class C24 parallel to the grain 21.0 N/mm^2, what is the maximum load a test piece of each material of dimensions 50mm x 75mm made from each of these materials can carry and what would be an acceptable factor of safety.
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thefish_uk
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(Original post by JakeRobertson)
Stuck on one of the tasks for my Science and materials for construction and the built environment assignment. If anyone could provide me with any help for this task please do get in touch. TASK 2: A structural engineer is looking for a material to design a structural member in compression. The engineer needs to compare the behaviour of timber, steel and reinforced concrete structural members under compression. If steel has a maximum allowable compressive strength of 300 N/mm^2, concrete 40 N/mm^2, reinforced concrete 48 N/mm^2 and timber class C24 parallel to the grain 21.0 N/mm^2, what is the maximum load a test piece of each material of dimensions 50mm x 75mm made from each of these materials can carry and what would be an acceptable factor of safety.
The first bit is quite easy. You have 4 different strengths, one area (50 x 75 = 3750 square mm), multiply the strength by the area to get the capacity in Newtons for each of the four materials.

Factor of safety is a bit more difficult... Normally we combine two "partial" factors of safety, one being to reflect uncertainty in the loads (as we can't be totally sure the user will stick to the instructions we give them), the other being to reflect uncertainty in the material strength (as without testing each thing that's built to destruction we can't be totally sure of that either). We combine them by multiplying them together. There is a lot of statistics involved in working out exactly what the partial factors should be though in practice we just pick them out of the code.

Typically the highest "load factor" we'd use is 1.5 (there are others which can be chosen depending on what sort of load it is*). The material factors depend on the material and the quality they're generally manufactured to in the UK. Typically for steel it's 1.0**, concrete it's 1.5, reinforced concrete anywhere between 1.15 and 1.5 depending on how much steel is in it so use 1.5, timber it's around 1.3. Therefore your total safety factor is for steel 1.5, concrete and reinforced concrete 2.25, timber 1.95. If you want to provide only one, just say 2.

* This assumes Eurocode
** This just reflects the fact that the steel industry in the UK is advanced enough to be 100% sure that all the steel they produce is stronger than what they label it as.
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JakeRobertson
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(Original post by thefish_uk)
The first bit is quite easy. You have 4 different strengths, one area (50 x 75 = 3750 square mm), multiply the strength by the area to get the capacity in Newtons for each of the four materials.

Factor of safety is a bit more difficult... Normally we combine two "partial" factors of safety, one being to reflect uncertainty in the loads (as we can't be totally sure the user will stick to the instructions we give them), the other being to reflect uncertainty in the material strength (as without testing each thing that's built to destruction we can't be totally sure of that either). We combine them by multiplying them together. There is a lot of statistics involved in working out exactly what the partial factors should be though in practice we just pick them out of the code.

Typically the highest "load factor" we'd use is 1.5 (there are others which can be chosen depending on what sort of load it is*). The material factors depend on the material and the quality they're generally manufactured to in the UK. Typically for steel it's 1.0**, concrete it's 1.5, reinforced concrete anywhere between 1.15 and 1.5 depending on how much steel is in it so use 1.5, timber it's around 1.3. Therefore your total safety factor is for steel 1.5, concrete and reinforced concrete 2.25, timber 1.95. If you want to provide only one, just say 2.

* This assumes Eurocode
** This just reflects the fact that the steel industry in the UK is advanced enough to be 100% sure that all the steel they produce is stronger than what they label it as.
Thanks for the reply mate you have helped me a lot with this. I understand what I have to do now. thanks again
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India Sophie
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Help required for a HNC in construction assignment I need to write a letter as an architect to a client Discussing a planning phase for the project and ensuring reference is made to building regs,controls disabled access and current legislation. I also have my report make reference to legislation influence size shape proportion financial implications of design and then evaluation of the RIBA plan of work and its suitability as a tool in coordinating and managing the project. Many thanks if someone can help
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