STRUCTURAL CONDITIONS

• STABLITY: the capacity of a structure to remain uprighy and not  fall over. A structure's centre of Gravity must  be centred over its base and close to the groud for it to  be nmore stable.

Have a look next  video  in Spanish, in which you  can learn  how to  find it  in simple objects or the difference between  the gravity Centre in men and women.

• RESISTANCE
• RIGIDITY

Strong Structures with Triangles

Why the triangles are very important for make a structure stable:

FORCES AND LOADS

When a force acts on a structure, that force becomes a load to the structure. 

A typical load that acts on a structure is it's own self-weight or gravitational force. Your own body weight is a load on your skeleton.

There are basically two types of generic loading on a structure:

•  Permanent load: it doesn't vary over the time (e.g. own weight).

•  Variable load: it varies over the time (e.g. weight of snow).

Stress (internal force) is a force that appears when a structure receives an external force. 

There are typically 5 different types of stress:

    a) Tension
    b) Compression
    c) Shear
    d) Bending
    e) Torsion

TYPES OF STRUCTURES

A structure is a set of elements arranged in an optimum way to support a body or an object.

The structure of an object is the ordely distribution of its essential part. This is what gives the object its shape.

Most large structures are one of the following types: mass, frame, truss, vaulted, shell, geodesic or pneumatic.

In the next  video  you  can see examples of the different  types  of structures.

Tacoma Narrows Bridge collapses

The Tacoma Narrows Bridge collapses due to high winds on this day in 1940.  

     

The Tacoma Narrows Bridge was built in Washington during the 1930s and opened to traffic on July 1, 1940. On November 7, high winds buffeted the area and the bridge swayed considerably. The first failure came at about 11 a.m., when concrete dropped from the road surface. Just minutes later, a 600-foot section of the bridge broke free.

Have a look to the next video:

Structures, Loads and stresses

 

If you want to test how shapes and materials affect structures' resistence, visit this website:  Test Lab