4.3. Working conditions

Discuss with your peers the conditions that a structure must meet. A structure must meet several conditions to be able to function properly, the three basic are: 

Stability: 

It must remain equilibrium and not overturned, even when a force is applied to it. To do so, its centre of gravity must be centred on its base. The more centred and closer to the ground, the more stable the structure is. 

The centre of gravity of a body is the point of application of the weight of that body.

Resistance: 

it has to withstand the stresses to which it is subjected without breaking. The strength of a structure depends on its shape and the material with which it is built. 

Rigidity:

although all bodies are slightly deformed when applied a force, this deformation should not prevent them from fulfilling their function. A rigid object is stiff and does not bend, stretch, or twist easily. 

How can a structure be stable, resistant and low deformable? 

Stability 

An object is the more stable the closer its centre of gravity is to the ground and the greater its base. The centre of gravity is closely related to what we have called the moment of forces. The smaller the distance from the centre of gravity to the centre of the structure, the easier it will be to resist the force. Something you can apply even in your daily life 

The following solutions can be used to make a stable structure: 

1. Increase the size of your base.

2. Deepen the foundation or expand the foundation base.

3. Centre the weight of the fence at its base by lowering the centre of gravity.

4. Support the structure to prevent overturning

Resistance

A structure is resistant when it is able to withstand, to withstand, the efforts (loads) to which it is subjected. Logically, the forces and moments of those forces are responsible for those efforts. When forces act on structures they can do so in different ways producing forces: traction, compression, bending, torsion, shearing and buckling. We will study in more detail each of these ways of acting forces on structures. 

All materials have a break stress for each type of effort. This tension is the maximum force per unit of surface that can withstand without breaking. The order of the most common materials according to their highest to lowest resistance is: steel, stone, concrete, wood, plastic, yarn, cardboard and paper. 

For a structure to perform its function it must ) meet these conditions: be resistant (breaking strength), stable (resistance to overturning), and rigid (resistance to be deformed). 

In addition to the three basic conditions of any structure, we must take into account its economic viability and its aesthetic suitability.