Key Messages
Learn How Science Helps Us Build Structures That Last For Millennia
When it comes to building structures that will last for generations, there are few things more impressive than mastering the science of building foundations that can withstand the test of time.
Fortunately, humans have access to centuries old research and scientific discoveries that teach us how to manage the inherent forces of nature that affect a structure and its materials.
Using this information, we’re able to create strong structures that use appropriate materials that can resist stress and changes in force.
Knowing what types of beams are necessary for certain roof structures, how to address a fatigued structure, and being able to anticipate potential issues can all help ensure that your building is structurally sound and capable of withstanding anything nature throws its way.
With a proper understanding of physics principles, you can build something resilient enough to pass even the greatest tests.
The Study Of Structures Unlocks The Secrets Of Strength And Performance
The study of biological and artificial structures began as far back as the seventeenth century, pioneered mainly by Galileo and Robert Hooke.
After Galileo was persecuted by the Catholic Church for his work in the field of astronomy in 1633, he switched disciplines to focus on the strength and character of different physical materials.
This set off a series of developments in understanding how structure and material responded to force and stress.
In the mid-1650s, scholars began researching how different materials and structures reacted under heavy loads while Robert Hooke also discovered more about matter at an atomic level at this time.
He wrote that a structure could only resist a load by pushing back with an equal force – for example, if a cathedral places its weight on a foundation, the foundation will either break or push up with an equal force.
This basic concept is still used today when building structural works.
Understanding Stress And Strain: How Physics Helps Explain The Elasticity Of Materials
Solid structures are not just affected by psychological problems like stress – they are also affected by forces within the material itself.
That’s where the concepts of stress and strain come in.
Stress measures the degree to which atoms and molecules inside the material are being pushed apart by external forces, while strain measures how much they’re being pulled apart.
It’s measured by comparing an object’s increase in length to its original length.
Stress and strain tell us a lot about stiffness in a given material.
A material with high Young’s Modulus of Elasticity (YME) is more elastic than one with a low YME, for instance rubber would be far more elastic than diamond.
Together, these measures give us a better idea of how solid structures will respond to forces over time, which is key for engineers who build them.
How Tensile Forces Allowing Solids To Change Shape Under Pressure
Tensile forces are an important factor when it comes to structures and materials.
These forces, which act upon atoms in a solid material, pull the atoms in different directions rather than pushing them together.
This is how rubber changes shape when pulled: the tensile force actually moves the atoms apart in order to make room for extension.
Tensile forces play an integral part in pressurized vessels like bladders, arteries, diving cylinders and balloons.
When you blow up a balloon, for example, the molecules inside stretch out because of these tensile forces.
The same thing happens with sails; they stretch out when hit by a gust of wind.
Interestingly enough, tensile forces can also cause creep – a process where a solid material gets deformed over time due to mechanical stress that is being applied regularly.
It’s similar to how new shoes become more comfortable after wearing them repeatedly: due to the redistribution of stresses from areas of heavy use to less-used areas over time.
Finally, it’s important to note that when tension is applied, it causes a simultaneous contraction “lateral” action – at angles perpendicular to the direction toward which it was stretched Initially – meaning that if tensile were all that was happening in blood vessels then they would just keep growing instead of staying the same size over time.
Ancient Structures Have Stood The Test Of Time Thanks To Compressive Forces
Structural stability largely depends on compressive forces acting upon it.
When a structure is built with compression, its elements are held together by many little pieces pushing against each other rather than pulling apart.
This creates a strong bond that can last for centuries or even millennia, like ancient castles and churches which have stood the test of time.
Our ancestors knew intuitively that their structures must be able to withstand compressive force in order to stay standing, and they practiced this understanding long before we had scientific knowledge about it.
Even children know instinctively how important compression is: when they build towers with blocks, they know that if it isn’t balanced properly and too tall, it will eventually collapse due to tension.
And usually, when a compressed structure does fall, it’s because of a lack of stability rather than strength.
Unlike tension structures which may fail under extreme stress, compression ones rarely collapse for the same reason – making them much more reliable.
That’s why you can trust Structures built on compression to retain their integrity over long periods of time!
How Beams Help Engineers Tackle The Challenges Of Roof Design
The invention of the beam was incredibly important for making compressive structures safer.
Before the beam, roofs posed a major challenge for engineers since the weight of the roof pushed out on the walls rather than downward.
This resulted in tensile forces that potentially caused buildings to collapse in on themselves.
Having windows worsened matters even more as it weakened the walls and lessened their ability to support the roof’s weight.
To combat this, engineers created beams which supported heavy loads at right angles to their length while not putting any horizontal force on them; this shifted much of the roof’s force away from the walls and made it much safer than before.
What’s more, beams also occur in nature – just think about how horses are able to carry their riders despite having weak legs!
This is likely because of their curved spine acting as a beam supporting most of its load away from its feet.
Therefore, when building compressive structures such as houses or stable bridges, making sure you install strong beams is absolutely essential to keeping it safe and stable over time.
The Danger Of Cracks: How Localized Stress Can Cause Bridge Collapses
Any structure – even newly built bridges – can become unstable and possibly collapse due to cracks or other problems with the material.
This was highlighted by C.E.
Inglis in 1913, when he wrote about irregularities in materials, like holes, cracks, or sharp corners – all of which can increase localized stress in material that appears stable.
Moreover, adding new material to a structure without proper considerations can also add to the stress of the structure instead of taking it away.
Furthermore, not all cracks are created equal; only those reaching a specific length known as the “critical Griffith crack length” can present an actual danger to a structure.
The Griffith crack length is dependent on the level of stress within the structure’s material.
The higher the level of stress, the shorter its critical Griffith crack length becomes; hence why short cracks usually do not pose any risk while longer ones might be a sign that something is wrong with the material itself and should not be ignored.
In essence, if left unchecked, certain flawed materials and unsustainable cracks can cause structures to completely collapse if proactive steps aren’t taken.
How Scientists Address Force And Crack Problems To Ensure Structural Safety
Tensile and compressive forces can both cause a structural collapse, but not necessarily because of cracks.
When tensile forces are applied to a material, the interatomic bonds in it stretch out until they eventually break, which then results in cracks or holes.
On the other hand, when a structure fails from compression, it’s usually caused by shearing: when one part of a material is forced to slide past another part at around a 45-degree angle.
As with tensile forces, if the crack reaches what’s called the critical Griffith length, splinters may even shoot out due to the sudden release of energy.
Thankfully, scientists are researching ways to design and build structures that will be highly resistant to these kinds of structural failure.
How Metal Fatigue Impacts Our Safety: The Importance Of Experimentation And Calculations
Man-made structures are often prone to fatigue, which can cause them to lose strength or even collapse due to the heavy load they bear.
To prevent this from happening, metallurgists have done a lot of testing and calculations to determine how to calculate metal fatigue in these structures.
This is necessary for ensuring our safety.
The calculations for structural strength are based on probability and statistics, meaning that there’s still some risk that a structure could collapse despite sound building calculations.
To eliminate this risk and make structures more efficient, experts use experimental testing when new structures are in development or existing structures need reevaluating.
Many examples of this include airplanes; between 1935 and 1955 around 100 airplanes were built and tested until destruction to evaluate their stability.
Through such testing and calculations, we can significantly reduce the chances of a structure collapsing by making the weak points stronger as well as reducing material and weight in areas that are less prone to breaking down.
All these measures together increase the safety and efficiency of man-made structures which ultimately keeps us safe!
Wrap Up
Structures is an important book that details the fundamental principles of both natural and man-made structures.
With a focus on stress, strain, force and strength, the book delves into the science behind structure design and maintenance.
Researchers play an important part in understanding these concepts to keep us safe from potential collapses.
In conclusion, Structures is a great resource for anyone interested in the science behind the buildings and towers we depend on every day.
