Building Design Cosiderations

Building Design

• Environmental requirements
• Structural requirements
• Aesthetic requirements
• Cost constraints
• Dimensional constraints
• Statutory requirements
• Life of the building
• Manufacturing and erection considerations

WALLS

Walls are the vertical elements of a building which enclose the space within it and which may also divide that space

Functional Requirements

• strength and stability
• weather resistance
• fire resistance
• thermal insulation
• sound insulation

Form of Construction

• Masonry (e.g. brickwalls)
• Monolithic (e.g. concrete walls)
• Frame (e.g. timber stud)
• Membrane (e.g. sandwich)

Strength

Resistance to:

• stresses set up by its own weight
• superimposed loads
• lateral pressure (e.g. wind)

Stability

Resistance to:

• overturning by lateral force
• buckling caused by excessive slenderness

PERFORMANCE

Weather Resistance

Provide adequate resistance to rain and wind penetration:

• adequate thickness [for external walls, minimum 150mm - concrete; 225mm - brickwork]
• adequate damp proofing means at critical position

Fire Resistance

Walls can act as Fire Barriers to compartmentalise a building so that a fire is confined to a given area.
They can separate specific fire risks within a building to form safe escape routes.

Thermal Insulation

Act as barriers:

• to prevent heat loss to the environment (in "cool" areas)
• to prevent heat gain (in "hot" areas)

Sound Insulation

Requirements to prevent airborne sound and impact sound:

• external walls
• internal walls (prevention of passage of sound from one space to another)

MATERIALS

Types of Bricks & Blocks

• Clay bricks
• Calcium silicate bricks
• Concrete bricks
• Clay blocks
• Dense concrete blocks
• Aerated (lightweight) concrete blocks

Types of Mortars

• cement sand mortar
• cement lime sand
• cement sand with plasticiser
• lime and sand

Brickwall Strength

Slenderness Ratio

The slenderness ratio of a wall and the eccentricity of the load will indicate whether the wall will crush or buckle. The greater the slenderness and eccentricity, the sooner buckling will occur.
Slenderness Ratio = (Effective length or height) / Effective width
effective width - least lateral dimension

Effective Length

The effective length or height of a wall depends on how the wall is held at its ends or points of lateral support.

Major Elements in a Building

Relationship Between Foundation and Loading

A Framed Building