Unit 5 (Structures)

Unit 5 (Structures)

1. Definiton and types

   • Frame
     • They are formed by columns and beams that act as supporting element
   • A structure is a collection of elements arranged to support a body on an object
     • The structure of an object is the distrbution of its essential parts
   • Mass
     • They are solid, heavy and sturdy
   • Truss
     • They are composed of bars that form triangles
   • Suspended
     • They are held in place by cables and suspenders attached to sturdy supports

2. Forces, stresses and strength

   • A force is an influence that can deform a body or change its movement, or produce motion in a body at rest
   • Stresses are physical demands that an object withstands when one or more forces are applied to it
     • Compression
       • Caused by forces acting on a body that tend to fletten it or reduce its length or thickness
     • Tension
       • Forces acting on a body that tend to stretch it
     • Bending
       • Forces acting on an element that can make it curve or bend
     • Torsion
       • Forces acting on a body that make it twists
     • Shear
       • Two equal forces applied in opposite directions that act on lines of action to close each other
   • The strenght of a material is its ability to withstandexternal forces without breaking
     • So, it is essential to a structure to be strong, but it has some conditions:
       • Rigidity
         • The material doesn't change shape when force is applied to it
           • Elements that increase it:
             • Trussing
               • It is a method for making weak structures more rigid. This works because of the triangle, the only figure that cannot be deformed.
                 • It can also work if we do it with a quadrilateral structure, but only if we add a diagonal bar, since we divide it like this into two triangles
             • Brace
               • A part that is positioned diagonally between two bars to form a right angle
             • Stay cables
               • Cables that help support tensile stress
             • Sections
               • Bars with different cross-sections
                 • Close sections
                   • Round section
                   • Triangular section
                   • Square section
                 • Open sections
                   • L-shaped
                   • T-shaped
                   • U-shaped
                   • I-shaped
       • Equilibrium
         • When a body's structure remains stationary
           • Stable
           • Unstable
             • When a force is applied to the body, it makes it move
       • Stability
         • When a structure remains in equilibrium even when a force is applied to it
           • It depends on where the centre of gravity is placed, the point where the weight of an object is consdered to be concentrated
             • By widening the base of the structure
             • By locating the centre of gravity at a low point
             • By supporting the structure with stay cables
             • By making a good foundation for the structure
     • It depends on...
       • The structure's shape and the elements that form it
       • Types of forces applstructure and the points where they actied to the