Structural Principles and Landscapes Over Structure

GSD 6242 Ecologies, Techniques, Technologies IV Spring 2015 Niall Kirkwood FASLA Alistair McIntosh FASLA

The Diagnostic Section has Material, Constructional and Structural Implications

Vocabularies of Construction have Structural Properties

Boundary: Walls are Vertical Panel Structures

Surface: Paving Systems are Horizontal Slab Structures

Surface Transition: Stairs, Retaining Walls & Perrons are Beams

Object: Tents are Membranes, Bridges & Pergolas are Frames, Rennie & Canvas Shade Structures are

Hybrids

1.0 Materials and Landscape Structures Carry Loads

Types of Loading:

1.1 Dead Load is the self weight of the materials of a structure

1.2 Live Load is the temporary applied load created by the use of the structure such as people dancing on a deck or snow load on a pavilion roof

1.3 Thermal Load is the internal load created in a material or structure by temperature changes and the consequent expansion and contraction of a material or structure

1.4 Dynamic Load is the temporary applied load created by wind or similar temporary effects

All Structures are designed to accommodate the worst combination of theses four loading categories

2.0 Materials and Structures Move to React to Loads

2.1 It is by deflecting that materials and structural configurations develop resistance to applied loads

This resistance to applied loads limits further deflection and when the applied loads are removed the material or structure returns to its original dimensions and configuration

The applied loads flow along load paths through the elements and joints of a structure to the foundations where the sum of loading action and foundation reaction equals zero and achieves equilibrium

3.0 Loading Induces Tensile & Compressive Stresses in Materials and Structures.

3.1 Tensile Stress lengthens a material or structural element

3.2 Compressive Stress shortens a material or structural element

3.3 The change in length of a material or structural element under load induced stress is called Strain

Tension Compression

4.0 There are Landscape Structures that are Composed of Simple Tension and

Compression Elements.

Steel Cable Pergola in Tension Standing Stones in Compression

5.0 Most Landscape Structures are Composed of Elements Subject to Combinations of Tension and Compression in Four Loading Conditions.

Bending

Shear

Torsion

Buckling

Bending

Cantilever Bending

Shear

Torsion

Column Buckling

Beam Buckling

5.1 Loading Conditions

Simply Supported Beam Double Cantilever Beams

5.2 Loading Influences Efficient Structural Shape: Bending Moments

Shear Web

Torsion Resistance

5.2 Loading Influences Efficient Structural Shape: Shear & Torsion

Column to Roof Beam Moment Connections Reduce Buckling and Allow Thin Columns.

5.2 Loading Influences Efficient Structural Shape: Buckling

Diagonal Struts Prevent Deck Beam Buckling

6.0 Structural Properties of Materials

6.1 The structural properties of materials determine their efficient structural shape and use in landscape details and landscape structures

Strength is a measure of the load per unit area a material can resist - stress

Stiffness measures the deformation of a material per unit of length – strain

Ductility is a measure of the ability to substantially deform under stress before failure

Brittleness is a property where a material fails without significant deformation

Elasticity is the ability of a material to return to its original shape after a normal load is removed

Creep is the permanent deformation of a material under long term loading

6.2 Steel Beam in CompressionSteel Cable in Tension

Compression Cord

Tension Cord

7.0 Pergola: Structural Understanding

7.0 Pergola: Structural Understanding

7.0 Pergola: Structural Understanding

7.0 Pergola: Structural Understanding

8.0 Landscape Over Structure: A River Pier

8.0 Landscape Over Structure: A River Pier

Top Soil

Structural Soil

Filter FabricDrainage FillRigid InsulationProtection BoardWaterproof Membrane

8.0 Landscape Over Structure: A River Pier

8.1 Landscape Over Structure: Extensive Green Roof

8.1 Landscape Over Structure: Extensive Green Roof

8.2 Landscape Over Structure: Hybrid Green Roof

8.2 Landscape Over Structure: Hybrid Green Roof

9.0 Stair