4.461: Building Technology 1 CONSTRUCTION AND MATERIALS FALL TERM 2004 SCHOOL OF ARCHITECTURE AND PLANNING: MIT

Transcription

1 4.461: Building Technology 1 CONSTRUCTION AND MATERIALS Professor John E. Fernandez FALL TERM 2004 SCHOOL OF ARCHITECTURE AND PLANNING: MIT Concrete and Composites Stadelhofen Station Zurich Santiago Calatrava Valls Image courtesy of Per Waahlen, photographer, and Structurae

2 1. Introduction practice research 2. Concrete Issues ductility CO 2 generation durability 3. Improved Structural Materials substitution dematerialization technology transfer 4. Material Selection and Evaluation (CES) multi-objective optimization material indices/ CES software 5. New and Emerging Materials new concretes composites 6. Architectural Form and Research Priorities research development: NFRC design

3 1. Introduction practice research 2. Concrete Issues ductility CO 2 generation durability 3. Improved Structural Materials substitution dematerialization technology transfer 4. Material Selection and Evaluation multi-objective optimization material indices/ CES software 5. New and Emerging Materials new concretes composites 6. Architectural Form research development: NFRC design

4 ductility Stress - Strain Curves Not To Scale brittle ceramics full plasticity metals Stress, σ elastic zone σ δ partial plasticity reinforced concrete Stress, σ, P/A Strain, δ E = σ/ δ extensive cold drawing plastic brittle plastic flow viscous flow elastomer Stress, σ ductile Strain, δ, L/L Strain, δ Image by MIT OCW.

5 ductility Failure strain, Є f Є f - measure of the deformation of the material at final fracture stress Material Figure X ε f concrete, unreinforced (compression) 0 Ceramics Fracture and failure is unpredictable concrete, reinforced soda glass low-alloy steel mild steel carbon steel stainless steel, austenitic Probability function stainless steel, ferritic cast irons iron aluminum copper brasses and bronzes natural rubber 5.0 Fracture stress (ceramic) Tensile Ductility, ε f (except for certain materials such as concrete, unreinforced) Images by MIT OCW.

6 ductility Toughness, G f, and Fracture toughness, K c measures of energy absorption potential through resistance to crack propagation. G f ( toughness), K c (fracture toughness) - both material properties. G f = energy per unit of crack area Various ways of measuring depending on the material. Therefore, search for materials that have high resistance to cracks that are formed through loading or other lifecycle stresses. Sometimes toughness is also referred to as the area under the stress-strain curve.

7 Silicon Nitride (Glass ceramic) Aluminium Nitrides (Glass ceramic) 10 Alumina Fibre Granite Carbon Fibre Fracture Toughness (ksi.in^1/2) 1 Limestone Normal Density Concrete Ice (H2O) Machineable Glass Ceramic 0.1 Aerated Concrete Low Density Refractory Brick Lightweight Concrete Ceramic foam (carbon) e6 Price per density

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9 CO 2 generation Ecological Issues Concrete production contributes 8% of world s total CO 2 emissions. Research in building materials for the developing world is a moral obligation. Issues Poverty allevation Safety Health (IAQ, toxicity) Resource Management Cultural Issues Form (resonance with place) Process (acknowledges local skill set) Material (regional resources)

10 100 Concrete (High Performance) Carbon Steel Cement (Super Sulphate) Alumina Tungsten - High Alloy (<89%W) Diamond 10 Sandstone(2.35) Granite(2.63) Common Hard Brick Carbon Matrix Composite Marble(2.7) Plaster of Paris 1 Epoxy SMC (Carbon Fibre) Young's Modulus (10^6 psi) Low Density Refractory Brick Concrete (Insulating Lightweight) Insulation Board, perpendicular to board Medium Density Aluminium Foam ( ) 1e-3 Ultra Low Density Wood (Transverse) ( ) 1e-4 Natural Rubber (NR), unfilled 1e Production Energy (kcal/lb)

11 durability Concrete Need for durable reinforcing and water impermeable concrete matrix Especially for freeze/thaw climates

12 1. Introduction practice research 2. Concrete Issues ductility CO2 generation durability 3. Improved Structural Materials substitution dematerialization technology transfer 4. Material Selection and Evaluation multi-objective optimization material indices/ CES software 5. New and Emerging Materials new concretes composites 6. Architectural Form research development design

13 dematerialization, substitution, technology transfer P C S(n) A B S(r) W(r) G R 10 6 W(n) Quantity (tons) W(n) B P S(r) Projection 10 3 W(r) G S(n) A 10 2 C R Year Image by MIT OCW.

14 dematerialization, substitution, technology transfer Concrete Dematerialization: a decrease in the material input per unit service Is occurring in certain industrial sectors but ecological rucksack needs to be accounted for Substitution: substituting concrete best in situations in which safety is at high risk of compromise Technology transfer: best employed in situations in which to lengthen lives of existing building stock (such as infrastructure refurbishment using carbon/epoxy reinforcing) 100 Percentage of Total (weight) Projection Image by MIT OCW. Year Measurement of Percentage of Renewable Versus Nonrenewable Materials Consumption in the US

15 1. Introduction practice research 2. Concrete Issues ductility CO2 generation durability 3. Improved Structural Materials substitution dematerialization technology transfer 4. Material Selection and Evaluation (CES) multi-objective optimization material indices/ CES software 5. New and Emerging Materials new concretes composites 6. Architectural Form research development design

16 multi-objective optimization

17 multi-objective optimization

18 100 Carbon Steel 10 1 Young's Modulus (10^6 psi) Normal Density Concrete 1e-3 1e-4 1e Thermal Expansion (µstrain/ F)

19 ceramics Glass ceramics Machineable, good fracture toughness Very HPC (Ductal) Ductile concrete Ceramic foams Lightweight, structural material New laminated glasses Laminated glass (Dupont SGP interlayer)

20 new concrete Ductile concrete Steel whisker reinforcement Increased toughess Increased water impermeability (few micropores) ductile concrete Bending strength, MPa normal concrete Displacement, microns Image by MIT OCW.