Optimising Building Design Optimising Building Design for Sustainability Using for Sustainability Using High Performance Concrete High Performance Concrete Doug Jenkins - Interactive Design Services Daksh Baweja – The University of Technology, Sydney. Joanne Portella– DMC Advisory, Melbourne.
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Optimising Building Design for Sustainability Using High Performance Concrete Doug Jenkins - Interactive Design Services Daksh Baweja – The University.
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Optimising Building Design for Optimising Building Design for Sustainability Using High Sustainability Using High Performance ConcretePerformance Concrete
Doug Jenkins - Interactive Design ServicesDaksh Baweja – The University of Technology, Sydney.Joanne Portella– DMC Advisory, Melbourne.
Introduction Introduction Focus of emissions reduction strategies in Australia has been on
cement reduction.– Can significant emissions reductions be made with the use of
high strength concrete? Outline of study:
– Effect of high strength concrete and high supplementary cementitious material (SCM) content on total CO2 emissions.
– Typical flat slab building structure– 5 grades of concrete– Reinforced or post-tensioned slab
Alternative Concrete MixesAlternative Concrete MixesTable 2: Mix Design Details
• Design to AS 3600 simplified method.• Checked to equivalent frame method (Warner et al)• Prestress force balanced approx. 85% of dead load• Deflections checked with non-linear finite element
analysis
Slab SectionsSlab Sections
• Reinforced slab depth controlled by deflections:• 25 MPa – 300 mm• 40 and 65 MPa – 250 mm
• Prestressed slab depth controlled by punching shear• 40 MPa – 180 mm• 65 MPa – 170 mm
Deflection AnalysisDeflection Analysis
• Non-linear finite element analysis; 4 node plate-shell elements
• Stress-strain curve formulated to give correct moment-curvature behaviour, allowing for:• Cracking of the concrete• Tension stiffening and loss of tension stiffening• Long term creep and shrinkage effects
ConclusionsConclusions The mixes with minimum emissions allowed a small
reduction in CO2 emissions for the reinforced slabs, compared with the standard “reference case” concrete.
All of the prestressed slabs showed a much more significant reduction in total emissions, in spite of the higher cement content of the concrete used.
The high SCM 40 MPa mix gave the lowest overall emissions with a prestressed slab, but the emissions from the 65 MPa mix were only marginally higher.
ConclusionsConclusions Higher strengths allowed the use of a reduced depth
of slab, with associated savings in other works. These savings were not included in this analysis.
The high SCM mixes had a reduced early-age strength which is likely to impact on the construction program.
ConclusionsConclusionsThe overall reduction of CO2 emissions
was not a simple function of the reduction of Portland cement in the concrete, but was also based on how the material properties of the concretes used influenced the structural efficiency of the design.