Question

For a 30-story office building, three options for pile foundations were investigated. The design option-1 has estimated 200 numbers 400 mm x 400 mm precast piles, and 50 m long made of 35 MPa concrete. The concrete CO2,eq emission is 800 kg/m3, and the steel content is estimated as 38 kg/m3 of the pile volume. The design option-2, based on 70 numbers of 700 mm diameter, 50 m long bored piles made of 50 MPa concrete, the emission is calculated as 820 kg/m3, and the steel content is 50 kg/m3. The design option-3, based on 140 numbers of 500 mm diameter, 50 m long post-tensioned piles made of 45 Mpa concrete, the emission is calculated as 790 kg/m3, post-tensioned steel content is 35 kg/m3. The emission for steel bars is calculated as 3 kg/kg of steel content and the emission for post-tensioned (PT) steel is provided as 5.5 kg/kg of PT steel content.

a. Estimate the concrete volume and steel content, PT steel content for all piles for in all three options.

b. Estimate the total CO2,eq emission in all three design options and suggest the best option.

Answer 1