CO2-Optimization of Post-Tensioned Concrete Slab-Bridge Decks Using Surrogate Modeling

Abstract

This paper deals with optimizing embedded carbon dioxide (CO2) emissions using surrogate modeling, whether it is the deck of a post-tensioned cast-in-place concrete slab bridge or any other design structure. The main contribution of this proposal is that it allows optimizing structures methodically and sequentially. The approach presents two sequential phases of optimization, the first one of diversification and the second one of intensification of the search for optimums. Finally, with the amount of CO2 emissions and the differentiating characteristics of each design, a heuristic optimization based on a Kriging metamodel is performed. An optimized solution with lower emissions than the analyzed sample is obtained. If CO2 emissions were to be reduced, design recommendations would be to use slendernesses as high as possible, in the range of 1/30, which implies a more significant amount of passive reinforcement. This increase in passive reinforcement is compensated by reducing the measurement of concrete and active reinforcement. Another important conclusion is that reducing emissions is related to cost savings. Furthermore, it has been corroborated that for a cost increase of less than 1%, decreases in emissions emitted into the atmosphere of more than 2% can be achieved.

Carbon Emission Optimization of Ultra-High-Performance Concrete Using Machine Learning Methods

“…where CO 2−eT is the CO 2 emissions at the transportation stage for the production of 1 m 3 UHPC (kg-CO 2 /m 3 ); CO 2 emission factor T is the CO 2 emission factor of the energy resource (kg-CO 2 /kg); M(i) is the amount of material used of concrete (kg/m 3 ); Lt is the transportation load (tons); d is the transportation distance (km); and e is the fuel efficiency (km/L). Considering that transportation emissions are highly dependent in all case studies [53,54], this study considers short-distance transportation. The distance of transport of UHPC ingredients to the manufacturing site is taken as 10 km [47,52], and the transport method is by truck.…”

Embodied Energy Optimization of Prestressed Concrete Road Flyovers by a Two-Phase Kriging Surrogate Model

“…The structures are verified according to the serviceability limit state (SLS) and the ultimate limit state (ULS) defined in Eurocode 2, considering the actions specified in Eurocode 1, which include dead loads of 44 kN/m and the environmental exposure class of concrete XC4. These demands are derived for each structural element and are detailed in [40].…”

“…Table 1. Dimensional ranges and their regulatory constraints [40]. The variables under consideration included the concrete's simple compressive strength and depth and width dimensions on the various decks' cross-sections (Figure 2).…”

Optimisation of Embodied Carbon and Compressive Strength in Low Carbon Concrete

“…However, there was an increase in carbon emission from 360 kgco 2e to 500 kgco 2e for 1 m 3 of concrete. Similarly [ 7 ] studied the optimisation of post-tension bridges with the aim of reducing carbon emission by reducing the bridge deck depth using different slenderness ratios. The results show that a cost increase of less than 1% corresponds to more than 2% increase in carbon emission.…”