Finding out about forces in a simple beam - Revision history

DT Online at 15:29, 9 February 2021

2021-02-09T15:29:57Z

← Older revision		Revision as of 15:29, 9 February 2021
Line 23:		Line 23:
	Bridge designers deal with these internal forces by either providing enough material for there to be several routes through, so the forces are shared, or by adding additional support in some way - e.g. by a supporting '''[[Arch Bridges\|Arch]]'''. They also try to minimise the bridge self-weight by using open '''[[Truss Bridges\|framed structures]]''' instead of solid beams.		Bridge designers deal with these internal forces by either providing enough material for there to be several routes through, so the forces are shared, or by adding additional support in some way - e.g. by a supporting '''[[Arch Bridges\|Arch]]'''. They also try to minimise the bridge self-weight by using open '''[[Truss Bridges\|framed structures]]''' instead of solid beams.

	:::[[File:ForcesWithinStructure.png\|400px\|bottom]][[File:~~SupportedPaperBeamForces~~.png\|400px\|bottom]]		:::[[File:ForcesWithinStructure.png\|400px\|bottom]][[File:ArchSupportedPaperBeamForces.png\|400px\|bottom]]

DT Online at 14:39, 9 February 2021

2021-02-09T14:39:46Z

← Older revision		Revision as of 14:39, 9 February 2021
Line 1:		Line 1:
	Place a sheet of thin card between two blocks of wood to create a simple beam bridge. Note that the card can hardly support its own weight and soon bends or deflects if an extra load is added.		Place a sheet of thin card between two blocks of wood to create a simple beam bridge. The distance between the supports is known as the [https://en.wikipedia.org/wiki/Span_(engineering) '''Span''']. Note that the card can hardly support its own weight and soon bends or deflects if an extra load is added.

	:::[[File:PaperSheet2.png\|400px\|bottom]][[File:DeflectedPaperSheet.png\|400px\|bottom]]		:::[[File:PaperSheet2.png\|400px\|bottom]][[File:DeflectedPaperSheet.png\|400px\|bottom]]

			----
			<span style="color: blue">'''Activity:'''</span>
			*<span style="color: blue">What can you do to the paper to enable it to support itself better? Think about [https://en.wikipedia.org/wiki/Corrugated_fiberboard '''Corrugated Card'''].</span>
			*<span style="color: blue">Is it best to increase the length, width or depth of the card bridge? See '''[[Folded Paper Beam]]''' for ideas.
			</span>
			----

	Bridges have to support two loads: their own weight and any loads they are required to carry. Their own weight is a fixed amount and is known as the '''[[Dead Load]]'''. The additional amount a bridge has to carry can vary continuously ''(e.g. as traffic passes over or as the wind blows)'' and it is known as the '''[[Live Load]]'''. Bridges and other structures also have to cope with the effects of wind, weather and the constant heating and cooling as a result of day and night temperature differences.		Bridges have to support two loads: their own weight and any loads they are required to carry. Their own weight is a fixed amount and is known as the '''[[Dead Load]]'''. The additional amount a bridge has to carry can vary continuously ''(e.g. as traffic passes over or as the wind blows)'' and it is known as the '''[[Live Load]]'''. Bridges and other structures also have to cope with the effects of wind, weather and the constant heating and cooling as a result of day and night temperature differences.
Line 12:		Line 18:


	When the forces reach the bridge supports, or ~~abutments~~, they are met with equal and opposite forces known as the '''[[Reactions (structures)\|Reactions]]''' - check on [http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.		When the forces reach the bridge supports, or [https://en.wikipedia.org/wiki/Abutment '''Abutments'''], they are met with equal and opposite forces known as the '''[[Reactions (structures)\|Reactions]]''' - check on [http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.


	Bridge designers deal with these internal forces by either providing enough material for there to be several routes through, so the forces are shared, or by adding additional support in some way. They also try to minimise the bridge self-weight by using open framed structures instead of solid beams.		Bridge designers deal with these internal forces by either providing enough material for there to be several routes through, so the forces are shared, or by adding additional support in some way - e.g. by a supporting '''[[Arch Bridges\|Arch]]'''. They also try to minimise the bridge self-weight by using open '''[[Truss Bridges\|framed structures]]''' instead of solid beams.

	:::[[File:ForcesWithinStructure.png\|400px\|bottom]][[File:SupportedPaperBeamForces.png\|400px\|bottom]]		:::[[File:ForcesWithinStructure.png\|400px\|bottom]][[File:SupportedPaperBeamForces.png\|400px\|bottom]]
Line 25:		Line 31:

	----		----
	<span style="color: blue">'''Activity:'''		<span style="color: blue">'''Activity:'''</span>
	If the top compresses and the bottom stretches, what do you think happens along the centre of the sponge? Does it squash a little, stretch a little or stay the same? See '''[[Neutral Axis]]''' to find out.		*<span style="color: blue">If the top compresses and the bottom stretches, what do you think happens along the centre of the sponge? Does it squash a little, stretch a little or stay the same? See '''[[Neutral Axis]]''' to find out.</span>
			*<span style="color: blue">See '''[[Beam Bridge Models]]''' and try out different designs.</span>
			*<span style="color: blue">What would happen if a weight or load was dropped on to the beam instead of placing it carefully?</span>
	</span>		</span>
	----		----

DT Online at 10:24, 1 March 2017

2017-03-01T10:24:30Z

← Older revision		Revision as of 10:24, 1 March 2017
Line 12:		Line 12:


	When the forces reach the bridge supports, or abutments, they are met with equal and opposite forces known as the '''[[Reactions (structures)\|Reactions]]''' - check on [~~https~~://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.		When the forces reach the bridge supports, or abutments, they are met with equal and opposite forces known as the '''[[Reactions (structures)\|Reactions]]''' - check on [http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.

DT Online: Corrected Link

2015-12-23T20:41:07Z

Corrected Link

← Older revision		Revision as of 20:41, 23 December 2015
Line 12:		Line 12:


	When the forces reach the bridge supports, or abutments, they are met with equal and opposite forces known as the '''Reactions''' - check on [https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.		When the forces reach the bridge supports, or abutments, they are met with equal and opposite forces known as the '''[[Reactions (structures)\|Reactions]]''' - check on [https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.

DT Online: Added links

2015-12-22T14:03:30Z

Added links

← Older revision		Revision as of 14:03, 22 December 2015
Line 4:		Line 4:


	Bridges have to support two loads: their own weight and any loads they are required to carry. Their own weight is a fixed amount and is known as the '''Dead Load'''. The additional amount a bridge has to carry can vary continuously ''(e.g. as traffic passes over or as the wind blows)'' and it is known as the '''Live Load'''. Bridges and other structures also have to cope with the effects of wind, weather and the constant heating and cooling as a result of day and night temperature differences.		Bridges have to support two loads: their own weight and any loads they are required to carry. Their own weight is a fixed amount and is known as the '''[[Dead Load]]'''. The additional amount a bridge has to carry can vary continuously ''(e.g. as traffic passes over or as the wind blows)'' and it is known as the '''[[Live Load]]'''. Bridges and other structures also have to cope with the effects of wind, weather and the constant heating and cooling as a result of day and night temperature differences.

DT Online at 19:26, 17 December 2015

2015-12-17T19:26:04Z

← Older revision		Revision as of 19:26, 17 December 2015
Line 26:		Line 26:
	----		----
	<span style="color: blue">'''Activity:'''		<span style="color: blue">'''Activity:'''
	If the top compresses and the bottom stretches, what do you think happens along the centre of the sponge? Does it squash a little, stretch a little or stay the same? See '''[[~~Sponge Beam~~ Neutral Axis]]''' to find out.		If the top compresses and the bottom stretches, what do you think happens along the centre of the sponge? Does it squash a little, stretch a little or stay the same? See '''[[Neutral Axis]]''' to find out.
	</span>		</span>
	----		----

DT Online: DT Online moved page Finding out about forces in a simple beam bridge to Finding out about forces in a simple beam: Author request

2015-12-17T19:25:14Z

DT Online moved page Finding out about forces in a simple beam bridge to Finding out about forces in a simple beam: Author request

← Older revision	Revision as of 19:25, 17 December 2015
(No difference)

DT Online: Created article

2015-12-17T19:23:33Z

Created article

New page

Place a sheet of thin card between two blocks of wood to create a simple beam bridge. Note that the card can hardly support its own weight and soon bends or deflects if an extra load is added.

:::[[File:PaperSheet2.png|400px|bottom]][[File:DeflectedPaperSheet.png|400px|bottom]]

Bridges have to support two loads: their own weight and any loads they are required to carry. Their own weight is a fixed amount and is known as the '''Dead Load'''. The additional amount a bridge has to carry can vary continuously ''(e.g. as traffic passes over or as the wind blows)'' and it is known as the '''Live Load'''. Bridges and other structures also have to cope with the effects of wind, weather and the constant heating and cooling as a result of day and night temperature differences.

Bridges ''(and most other structures)'' deal with these loads by carrying them as forces through the structure until they come up against something firm enough to resist them - in the case of bridges, this is usually the solid earth.

::::::::::[[File:PaperBeamForces.png|400px]]

When the forces reach the bridge supports, or abutments, they are met with equal and opposite forces known as the '''Reactions''' - check on [https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law '''Newton's 3rd Law of Motion'''] to learn why this must be so ''(i.e. ‘to every action there is always an equal and opposite reaction’)''.

Bridge designers deal with these internal forces by either providing enough material for there to be several routes through, so the forces are shared, or by adding additional support in some way. They also try to minimise the bridge self-weight by using open framed structures instead of solid beams.

:::[[File:ForcesWithinStructure.png|400px|bottom]][[File:SupportedPaperBeamForces.png|400px|bottom]]

Designers must also make sure that each part of the structure is able to resist the forces generated within it. A simple beam will bend or deflect when loaded. Draw vertical lines on a simply supported sponge, or piece of rubber, to see that the top surface is squeezed together and the bottom surface is pulled apart when it is loaded.

:::[[File:SpongeBeam2.png|400px|bottom]][[File:SpongeStretch.png|400px|bottom]]

----
<span style="color: blue">'''Activity:'''
If the top compresses and the bottom stretches, what do you think happens along the centre of the sponge? Does it squash a little, stretch a little or stay the same? See '''[[Sponge Beam Neutral Axis]]''' to find out.
</span>
----

[[Category:Beams]]
[[Category:Structures Tasks]]