Robust Design Optimization for Low-Cost Concrete Box-Girder Bridge

[EN] The design of a structure is generally carried out according to a deterministic approach. However, all structural problems have associated initial uncertain parameters that can differ from the design value. This becomes important when the goal is to reach optimized structures, as a small variation of these initial uncertain parameters can have a big influence on the structural behavior. The objective of robust design optimization is to obtain an optimum design with the lowest possible variation of the objective functions. For this purpose, a probabilistic optimization is necessary to obtain the statistical parameters that represent the mean value and variation of the objective function considered. However, one of the disadvantages of the optimal robust design is its high computational cost. In this paper, robust design optimization is applied to design a continuous prestressed concrete box-girder pedestrian bridge that is optimum in terms of its cost and robust in terms of structural stability. Furthermore, Latin hypercube sampling and the kriging metamodel are used to deal with the high computational cost. Results show that the main variables that control the structural behavior are the depth of the cross-section and compressive strength of the concrete and that a compromise solution between the optimal cost and the robustness of the design can be reached.This research was funded by the Ministerio de Economia, Ciencia y Competitividad and FEDER funding grant number [BIA2017-85098-R].Penadés-Plà, V.; García-Segura, T.; Yepes, V. (2020). Robust Design Optimization for Low-Cost Concrete Box-Girder Bridge. Mathematics. 8(3):1-14. https://doi.org/10.3390/math8030398S11483Lee, K.-H., & Kang, D.-H. (2006). A robust optimization using the statistics based on kriging metamodel. 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Multiobjective optimization of post-tensioned concrete box-girder road bridges considering cost, CO2 emissions, and safety. Engineering Structures, 125, 325-336. doi:10.1016/j.engstruct.2016.07.012Martí, J. V., García-Segura, T., & Yepes, V. (2016). Structural design of precast-prestressed concrete U-beam road bridges based on embodied energy. Journal of Cleaner Production, 120, 231-240. doi:10.1016/j.jclepro.2016.02.024Yepes, V., Martí, J. V., García-Segura, T., & González-Vidosa, F. (2017). Heuristics in optimal detailed design of precast road bridges. Archives of Civil and Mechanical Engineering, 17(4), 738-749. doi:10.1016/j.acme.2017.02.006Sun, X., Fu, H., & Zeng, J. (2018). Robust Approximate Optimality Conditions for Uncertain Nonsmooth Optimization with Infinite Number of Constraints. Mathematics, 7(1), 12. doi:10.3390/math7010012Rodriguez-Gonzalez, P. T., Rico-Ramirez, V., Rico-Martinez, R., & Diwekar, U. M. (2019). A New Approach to Solving Stochastic Optimal Control Problems. Mathematics, 7(12), 1207. doi:10.3390/math7121207Moayyeri, N., Gharehbaghi, S., & Plevris, V. (2019). Cost-Based Optimum Design of Reinforced Concrete Retaining Walls Considering Different Methods of Bearing Capacity Computation. Mathematics, 7(12), 1232. doi:10.3390/math7121232Sierra, L. A., Yepes, V., García-Segura, T., & Pellicer, E. (2018). Bayesian network method for decision-making about the social sustainability of infrastructure projects. Journal of Cleaner Production, 176, 521-534. doi:10.1016/j.jclepro.2017.12.140Valdebenito, M. A., & Schuëller, G. I. (2010). A survey on approaches for reliability-based optimization. Structural and Multidisciplinary Optimization, 42(5), 645-663. doi:10.1007/s00158-010-0518-6Doltsinis, I., & Kang, Z. (2004). Robust design of structures using optimization methods. Computer Methods in Applied Mechanics and Engineering, 193(23-26), 2221-2237. doi:10.1016/j.cma.2003.12.055Simpson, T. 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Sustainable bridge design by metamodel-assisted multi-objective optimization and decision-making under uncertainty

[EN] Today, bridge design seeks not only to minimize cost, but also to minimize adverse environmental and social impacts. This multi-criteria decision-making problem is subject to variability of the opinions of stakeholders regarding the importance of criteria for sustainability. As a result, this paper proposes a method for designing and selecting optimally sustainable bridges under the uncertainty of criteria comparison. A Pareto set of solutions is obtained using a metamodel-assisted multi-objective optimization. A new decision-making technique introduces the uncertainty of the decision-maker's preference through triangular distributions and thereby ranks the sustainable bridge designs. The method is illustrated by a case study of a three-span post-tensioned concrete box-girder bridge designed according to the embodied energy, overall safety and corrosion initiation time. In this particular case, 211 efficient solutions are reduced to two preferred solutions which have a probability of being selected of 81.6% and 18.4%. In addition, a sensitivity analysis validates the influence of the uncertainty regarding the decision making. The approach proposed allows actors involved in the bridge design and decision-making to determine the best sustainable design by finding the probability of a given design being chosen.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (Project: BIA2017-85098-R).García-Segura, T.; Penadés-Plà, V.; Yepes, V. (2018). Sustainable bridge design by metamodel-assisted multi-objective optimization and decision-making under uncertainty. Journal of Cleaner Production. 202:904-915. doi:10.1016/j.jclepro.2018.08.177S90491520

Recycled versus non-recycled insulation alternatives: LCA analysis for different climatic conditions in Spain

[EN] The construction sector represents more than 40% of energy consumption in the European Union, as well as one of the biggest causes of environmental impact. Therefore, this sector needs a great deal of intervention through policies that promote the energetic efficiency of the buildings. One of the most important structural components to reach this energetic efficiency is the facades. In this work, the facade ventilated is chosen due to its better thermal insulation behaviour. The environmental impact of the facade ventilated depends on the thermal insulation material. The goal of this paper is to evaluate the environmental impact of different ventilated facades according to their thermal insulation behavior. For this purpose, the life-cycle assessment is applied in ventilated facades with different materials in different locations. The materials studied are the rock wool, the natural cork and the recycled cork, and the locations considered are the different climatic areas of Spain. To reach a complete environmental assessment all the ventilated facades life-cycle is considered, from cradle to grave. To do this we use the Open LCA software with the Ecoinvent database with the ReCiPe method. The results show that the recycled cork is the thermal insulation with the lowest environmental impact regardless the location.The authors acknowledge the financial support of the Spanish Ministry of Economy and Business (Project: BIA2017-85098-R) and the Spanish Ministry of Science and Innovation (Project: PID2020-117056RB-I00), along with FEDER funding. In addition would also acknowledge the Spanish Ministry of Science, Innovation and Universities for David Martinez-Munoz University Teacher Training Grant (FPU-18/01592).Ata-Ali, N.; Penadés-Plà, V.; Martínez-Muñoz, D.; Yepes, V. (2021). Recycled versus non-recycled insulation alternatives: LCA analysis for different climatic conditions in Spain. Resources Conservation and Recycling. 175:1-8. https://doi.org/10.1016/j.resconrec.2021.105838S1817

Life cycle assessment of earth-retaining walls: An environmental comparison

[EN] Earth-retaining walls are one of the most common structures in civil engineering, a discipline of the construction sector, which is known to produce one of the highest environmental impacts. Therefore, developing cleaner design and construction practices could contribute to a more sustainable future for our planet. To make a step towards this goal, this study comprises the life cycle assessment (LCA) of the four most common earth-retaining walls built between 1 to 6 m of height: cantilever walls, gravity walls, masonry walls and gabion walls to obtain the best solutions for the environment. To assess the environmental impacts caused throughout their whole life-cycle including the production, construction, use and end of life phases, we used the OpenLCA software, the ecoinvent 3.3 database and the ReCiPe (H) method. The associated uncertainties have been considered and the results are provided in both midpoint and endpoint approaches. Our findings show that gabion and masonry walls produce the lowest global impact. On the one hand, gabion walls cause less damage to human health but on the other hand, masonry walls cause less damage to the ecosystems. Furthermore, gravity walls produce similar impacts to gabion and masonry walls between 1 and 3 m of height as well as fewer impacts than cantilever walls for a height of 4 m. In conclusion, gabion and masonry walls are preferable to concrete walls for heights between 1 and 6 m and cantilever walls should be used over gravity walls for greater heights than 4.5 m.This research was funded by the Spanish Ministry of Economy and Competitiveness along with FEDER funding (Project BIA2017-85098-R).Pons, J.; Penadés-Plà, V.; Yepes, V.; Martí Albiñana, JV. (2018). Life cycle assessment of earth-retaining walls: An environmental comparison. Journal of Cleaner Production. 192:411-420. doi:10.1016/j.jclepro.2018.04.268S41142019

Optimization of prestressed concrete road bridges by the response surface methodology

[ES] Los puentes son infraestructuras esenciales para mejorar la comunicación dentro de un territorio. La optimización constituye un proceso que permite obtener puentes de menor coste bajo ciertas restricciones. Debido a la complejidad de los problemas estructurales, la optimización matemática no es útil y se recurre a la optimización heurística debido a su mayor eficacia. En este trabajo se presenta una alternativa a la optimización heurística basada en los metamodelos. El procedimiento consiste en una reducción de los factores iniciales mediante el diseño de experimentos, reduciendo significativamente la complejidad del problema sin perder información. Posteriormente, se aplica la metodología de la superficie de respuesta para obtener el óptimo del problema. Este procedimiento se aplica a un tablero de un puente de losa maciza que cumpla todas las restricciones de las normativas.[EN] Bridges are essential infrastructures to improve communication in a region. Optimization is a process that can be used to obtain cheaper bridges under certain restrictions. Due to the complexity of the structural problems, mathematical optimization is not useful and heuristic optimization is used due its greater efficiency. This work presents an alternative to heuristic optimization based on metamodels. The process consists of reducing the initial factors by design of experiments, which significantly reduces the complexity of the problem without losing information. Then, response surface methodology is applied to obtain the optimum of the problem. This process is applied to a solid slab bridge deck that accomplish with all regulatory restrictions.Los autores agradecen la financiación del Ministerio de Economía y Competitividad, junto con los fondos FEDER (Proyecto: BIA2017-85098-R) y del Consejo Nacional de Desarrollo Científico y Tecnológico CNPq/Brasil (Proc. 302736/2017-4).Penadés-Plà, V.; Yepes, V.; Kripka, M. (2019). Optimización de puentes pretensados mediante la metodología de la superficie de respuesta. Revista CIATEC-UPF. 11(2):22-35. https://doi.org/10.5335/ciatec.v11i2.9159S223511

Life-Cycle Assessment: A Comparison between Two Optimal Post-Tensioned Concrete Box-Girder Road Bridges

[EN] The goal of sustainability involves a consensus among economic, environmental and social factors. Due to climate change, environmental concerns have increased in society. The construction sector is among the most active high environmental impact sectors. This paper proposes new features to consider a more detailed life-cycle assessment (LCA) of reinforced or prestressed concrete structures. Besides, this study carries out a comparison between two optimal posttensioned concrete box-girder road bridges with different maintenance scenarios. ReCiPe method is used to carry out the life-cycle assessment. The midpoint approach shows a complete environmental profile with 18 impact categories. In practice, all the impact categories make their highest contribution in the manufacturing and use and maintenance stages. Afterwards, these two stages are analyzed to identify the process which makes the greatest contribution. In addition, the contribution of CO2 fixation is taken into account, reducing the environmental impact in the use and maintenance and end of life stages. The endpoint approach shows more interpretable results, enabling an easier comparison between different stages and solutions. The results show the importance of considering the whole life-cycle, since a better design reduces the global environmental impact despite a higher environmental impact in the manufacturing stage.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (BRIDLIFE Project: BIA2014-56574-R).Penadés-Plà, V.; Martí Albiñana, JV.; García-Segura, T.; Yepes, V. (2017). Life-Cycle Assessment: A Comparison between Two Optimal Post-Tensioned Concrete Box-Girder Road Bridges. Sustainability. 9(10):1864-1-1864-21. doi:10.3390/su9101864S1864-11864-2191

Study of criteria used to obtain a sustainable bridge

[Otros] The sustainable development of bridges is mainly based on meeting the three pillars of sustainability (economic, social and environmental factors) which have different goals. Each main criterion groups a large number of subcritera. Therefore, achieve a sustainable bridge is a complicate problem that involves a high number of factors in each stage of bridge life-cycle. For this reason, decision-making is a helpful process to solve the sustainability problem. The objective of this work is to review the bridge life-cycle decision-making problems that involve criteria that represent the pillars of the sustainability. While some works only consider criteria related to one or two of these pillars, the most current works consider criteria that involve all the pillars of sustainability. Furthermore, most of the works reviewed only study one stage of bridge life-cycle. This study shows the criteria used in some revised journal articles in each bridge life-cycle phase and, the multi-attribute decision-making used to achieve the sustainability. In addition, a small explanation of the obtained information will be carried out.The authors acknowledge the support from the Ministry of Competitiveness and FEDER funding (Project BIA2014-56574-R)Penadés-Plà, V.; Yepes, V.; García-Segura, T.; Martí Albiñana, JV. (2017). Study of criteria used to obtain a sustainable bridge. ISEC. 1-6. https://doi.org/10.14455/ISEC.res.2017.177S1

Robust decision-making design for sustainable pedestrian concrete bridges

[EN] In recent years, there is a trend toward the construction of sustainable structures. The goal of sustainability in structures involves several criteria that are normally opposed, leading to a decision-making process. In this process, there is a subjective portion that cannot be eliminated, such as qualitative criteria assessment of and assigning criteria importance. In these cases, decision-makers become part of the decision-making process, assessing it according to their preferences. In this work, a methodology to reduce the participation of decision-makers in achieving the goal of sustainability in structures is proposed. For this purpose, principal component analysis, kriging-based optimization, and the analytical hierarchy process are used. Principal component analysis is used to reduce the complexity of the problem according to the highly correlated criteria. Kriging-based optimization obtains sustainable solutions depending on all the perspectives of sustainability. Finally, the analytical hierarchy process is applied to reduce the optimized sustainable solutions according to the decision-maker's views. This methodology is applied a continuous concrete box-girder pedestrian bridge deck to reach sustainable designs. This methodology allows a reduction of the complexity of the decision-making problem and also obtains sustainable robust solutions.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (Project: BIA2017-85098-R).Penadés-Plà, V.; Yepes, V.; García-Segura, T. (2020). Robust decision-making design for sustainable pedestrian concrete bridges. Engineering Structures. 209:1-10. https://doi.org/10.1016/j.engstruct.2019.109968S110209García-Segura, T., & Yepes, V. (2016). Multiobjective optimization of post-tensioned concrete box-girder road bridges considering cost, CO2 emissions, and safety. 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Expert Systems with Applications, 39(8), 7121-7131. doi:10.1016/j.eswa.2012.01.032Pan, N.-F. (2008). Fuzzy AHP approach for selecting the suitable bridge construction method. Automation in Construction, 17(8), 958-965. doi:10.1016/j.autcon.2008.03.005Aghdaie, M. H., Zolfani, S. H., & Zavadskas, E. K. (2012). Prioritizing constructing projects of municipalities based on ahp and copras-g: a case study about footbridges in Iran. The Baltic Journal of Road and Bridge Engineering, 7(2), 145-153. doi:10.3846/bjrbe.2012.20Zavadskas, E. K., Liias, R., & Turskis, Z. (2008). Multi-attribute decision-making methods for assessment of quality in bridges and road construction: State-of-the-art surveys. The Baltic Journal of Road and Bridge Engineering, 3(3), 152-160. doi:10.3846/1822-427x.2008.3.152-160Penadés-Plà, V., García-Segura, T., Martí, J., & Yepes, V. (2016). A Review of Multi-Criteria Decision-Making Methods Applied to the Sustainable Bridge Design. 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Metodología para valorar la sostenibilidad con baja influencia de los decisores

The goal of achieving sustainable structures involves a set of criteria that are usually opposed. This leads to the need to create a decision-making process. In every decision-making process there are subjective assessments that depend on the decision-maker. This is why decision-makers become an important part of the process because of their subjective assessment. This paper proposes a methodology in which the subjective assessment of the decision-maker in the assessment of sustainability in structures is reduced. Different processes are applied to reduce uncertainty in decision-making processes. In the first place the analysis of main components is applied, in the second place the optimization based on kriging, and finally the AHP method. All this is applied to a continuous concrete deck of beams for pedestrian walkways to achieve sustainable designs, reducing the complexity in making decisions on the most sustainable solution.Los autores agradecen el apoyo financiero del Ministerio de Economía y Competitividad español, así como la financiación del FEDER (Proyecto: BIA2017-85098-R)

Aplicación de optimización kriging para la búsqueda de estructuras óptimas robustas

All the structural problems have an associated variability or uncertainty. In the design of structures there are parameters such as the dimensions of the structure, the mechanical characteristics of the materials or the loads that can have variations with respect to the design value. The goal of the robust design optimization is to obtain the design that is optimum and is less sensitive to variations of these uncertain initial parameters. The main limitation of the robust design optimization is the high computational cost required due to the high number of optimizations that must be made to assess the sensitivity of the objective response of the problem. For this reason, kriging model is applied to carry out the optimization process more efficiently. In this work, it is going to apply the robust design optimization on a continuous pedestrian bridge of prestressed concrete and box section.Los autores agradecen el apoyo financiero del Ministerio de Economía y Competitividad español, así como la financiación del FEDER (Proyecto: BIA2017-85098-R)