STRUCTURES
A force is anything that can deform a body
(static effect) or change its state of
movement or rest
(dynamic effect).
there are many different forces in nature :
-Gravity, which pulls us towards the earth and gives us weight.
-The force of the wind
- Me chanical forces that move machme.
-Ressures of gases m closed container
-The force created by the effects of heat ,etc.
-Forces caused by the effects of heat, etc
Loads:
The forces that act on a structure are called loads.
Fixed or permanent loads dont 't vari over time they always affect the structure in the same way. For example, the obiect's own ii myht, the weight of bodies always on top nf another obiect, etc.
Variable loads are occasional and changeable for example , the weight of snow on a root, the pressure of water on a dam (the water level can very), etc.
Stresses:
When you make a physical effort you may notice that you can feel
bear. hold, resist or support a tension that increases as the effort increases. The t>pe of tension is different in each case.
Livings things feel this effect - it can be slight or if it strong it can even hurt us Obiects do not have feehngs, but forces act on them in a similar way and produce deormations. In both cases this internal tensión is called -stress-, it happens to all bodies subjected to the applying of one or more forces on them.
The characteristic of the loads (intensity, direction, traiectory and point of application).
The shape of the obiect bearing the loads.
types of stresses
BENDING: Forces try to bend. This stress acts to on elements that are supported at their extremities and have a weight applied to them. Normally, there are two forces tht are separated by certain distanc and a third force acting in the opposit direction.
TRACTION: Forces to try to strech the object they are acting upon.Opposing forces move outwards away from the body along the same trajectory but in opposit directions.
COMPRESSION: Forces try to flatten or compress a bodt. Opposing forces move inwards towards one another along the same trajectory and in opposite directions. The body tend to lose its shape and becomes compressed.