Structural Principles: Forces, Materials, and Wood Production

Understanding Structural Elements and Forces

A structure is a set of elements capable of withstanding forces and transmitting them to the point where it rests, ensuring durability and stability. These forces are commonly known as loads.

Key Structural Forces

• Stress: The internal force that appears within elements when a structure is subjected to loads or other external forces.
• Tension: An internal force consisting of two forces that tend to increase an element's length (stretch it).
• Compression: An internal force that tends to decrease an element's length (compress it).
• Flexion (Bending): Forces that tend to bend an element.
• Shear (Cutting): Forces that act parallel to an element's cross-section, tending to cut it or displace one section relative to another.
• Torsion (Twisting): Forces that tend to twist sections of an element relative to each other.

Fundamental Structural Elements

Common structural elements include foundations, columns or pillars, beams, braces, and arches.

Resistance and Stability in Structures

A structure is resistant when it can withstand or retain its shape when loads are applied. The only geometric figure that cannot deform is the triangle, which is why it's often used in bracing. Arches, for example, provide excellent resistance to compression.

Stable structures maintain their position when a force is applied, preventing a loss of equilibrium.

Classification of Materials and Structures

Material Types

• Natural Materials
• Artificial Materials

Structural System Classifications

Structures can be classified based on various criteria:

• By Type of Construction: Massive, Vaulted, Timbered, Triangulated, Suspended.
• By Mobility: Rigid, Articulated.
• By Function: Permanent, Temporary.
• By Type of Elements: Frame structures, Laminar structures.

Alloys: Blending Materials

Alloys are mixtures of two or more materials, with at least one being a metal.

Wood Processing and Products

Steps in Obtaining Wood

1. Felling Trees

   Trees are cut down manually with axes and saws or with mechanical saws. The felled trees are then transported to a sawmill.

2. Sawing the Wood

   At the sawmill, the bark is removed, and the logs are cut longitudinally with vertical or circular saws into planks and boards.

3. Drying

   The cut boards are separated to allow air to circulate for natural drying, or they are dried in specialized kilns to reduce moisture content.

4. Distribution to Manufacturers

   The processed wood is distributed to joineries, carpentry shops, and factories where final wood products are prepared or natural wood panels are used. The bark removed earlier is often utilized as fuel.

Advantages of Artificial Boards

Artificial boards offer several benefits compared to natural wood:

• More economical
• Flat and smooth surfaces
• Available in larger sizes
• Less prone to deformation

Types of Artificial Boards

Plywood

Made from multiple layers of wood veneer glued together, with the grain of adjacent layers oriented perpendicularly. This construction significantly increases its strength and resistance to warping.

Particleboard (Agglomerate)

Produced from wood chips, sawdust, or shavings mixed with a resin binder, then pressed and glued under heat. The result is dense, uniform panels.

MDF (Medium-Density Fiberboard)

Manufactured from dry wood fibers, compressed at high pressure and temperature, and combined with synthetic resin. MDF is known for its smooth surface and consistent density, making it ideal for machining and finishing.