(っ◔◡◔)っ ♥ STRUCTURES ♥ 
There are many different forces in nature:
gravity, which pulls us towards the earth and gives us weigh
The force of wind
Mechanical forces that moves machines
pressures of gases in closed containers
The force created by our own muscles
Forces caused by effects of heat, etc.
A force is anything that can deform a body (stattic effect) or change its state of moving or rest (dynamic effect).
All bodies must have a
structure that can
resist forces — birds' nests, shells, a tin, a skyscraper, electni.al towers, etc The first two are
𝐍𝐀𝐓𝐔𝐑𝐄 
𝐀𝐑𝐓𝐈𝐅𝐈𝐂𝐈𝐀𝐋 
Structures that are not made by humans
Structures that are made by humans
𝐋𝐎𝐀𝐃𝐒 
The forces that act on a structure are called LOADS
There are two main types of loads
𝐯𝐚𝐫𝐢𝐚𝐛𝐥𝐞 𝐥𝐨𝐚𝐝𝐬
𝗙𝗶𝘅𝗲𝗱 𝗼𝗿 𝗽𝗲𝗿𝗺𝗮𝗻𝗲𝗻𝘁 𝗹𝗼𝗮𝗱
Are occasional and changeable
They dont vary over time.They allways affect the structure in the same way.
Ways in wich loads affect the structure: direction, intensity, the point where the forces are applied, the shapy of the body.
𝐒𝐭𝐫𝐞𝐬𝐬𝐞𝐬 
When you make a physical effort you may notice that you can feel tension that increases as the effort increases. The type of tension is different in each case.
this internal tension is called stress. It happens to all bodies subjected to
the applying of one or more forces on them.
If the material or shape of the structure is not appropiate, stresses can cause it to break. If a structure is resistant, it can support or 'resist' the stresses.
There are 3 types of stresses
ᴛʀᴀᴄᴛɪᴏɴ
Forces try to strech the object they are acting upon. Opposing forces move outwards away from the body along the same trayectory but in opposite directions. The body tens to become longer.
𝐁𝐞𝐧𝐝𝐢𝐧𝐠 
Forces try to bend a body. This stress act on elements that are supported at their extremities and have weigh applied on them. Normally there are two forces that are separated by a certain distance and a third force acting in the opposite direction.
COMPRESSION
Forces try to flatten
or compress a body. Opposing forces to move inwards towards one another along the same trajectory and in opposite directions. The body tends to lose its shape and becomes compressed.
TORSION 
Forces try to twist a body. They try to turn the ends of the body in opposite directions.