Life-cycle of fatigue sensitive structures under uncertainty

Fatigue is the one of the main contributors to problems related to structural safety of civil and marine structures. Life-cycle management (LCM) techniques considering various uncertainties can be used to predict the safe service life of fatigue sensitive structures, plan for their future inspections and support the decision making process regarding maintenance and repair actions. This paper provides a brief overview of the LCM of fatigue sensitive civil and marine structures under uncertainty. Probabilistic performance prediction, inspection scheduling and maintenance optimization for such structures are discussed

Efficient adaptive importance sampling for time-dependent reliability analysis of structures

Various methods have been used by researchers to evaluate the time-dependent reliability of structures. Among them, the stochastic-process-based method is theoretically the most rigorous but also computationally the most expensive. To enable the wide application of the stochastic-process-based method in the time-dependent reliability analysis of complex problems, an efficient importance sampling method is presented. This new method, extended from an existing method for time-independent reliability analysis, offers an efficient solution for time-dependent problems of structural systems with multiple important regions. Furthermore, to enhance the efficiency and robustness of the proposed method, a number of numerical measures are proposed. The capability and efficiency of the proposed method are demonstrated through two numerical examples

Optimum maintenance strategy for deteriorating bridge structures based on lifetime functions

The highway networks of most European and North American countries are completed or close to completion. However, many of their bridges are aging, and in the United States alone a very significant part of the about 600,000 existing bridges is considered to be deficient and must be replaced, repaired or upgraded in the short term. The funds available for the maintenance of existing highway bridges are extremely limited when compared with the huge investment necessary, and must, therefore, be spent wisely. In this paper, a model based on lifetime functions for predicting the evolution in time of the reliability of deteriorating bridges under maintenance is presented. This model uses the probability of satisfactory system performance during a specified time interval as a measure of reliability and treats each bridge structure as a system composed of several components. In this manner, it is possible to predict the structural performance of deteriorating structures in a probabilistic framework. In addition, the optimum maintenance strategy is identified using as objective the minimization of the present value of the life-cycle maintenance cost. An existing bridge is analyzed using lifetime functions and its optimum maintenance strategy is found.U.S. National Science Foundation - CMS-9912525; CMS-0217290.Colorado Department of TransportationDutch Ministry of Transportation, Public Works, and Water Management

Lifetime multi-objective optimization of maintenance of existing steel structures

In this paper, the lifetime performance of deteriorating structures, defined by their time dependent condition index and reliability index, is analyzed. The effect of preventive and essential maintenance actions on performance and cost in predicted, and the optimal times of application of preventive and essential maintenance actions are found. Due to significant uncertainty in the initial performance, effects of deterioration and of maintenance actions, as well as, times of application and cost of maintenance actions, the analysis is performed in a probabilistic framework. The reduction in performance due to deterioration is simulated using an extension of the model proposed by Frangopol (1998). The probabilistic condition index, reliability index, and cumulative cost profiles are computed using Latin Hypercube simulation. Optimization of times of application is performed using genetic algorithms. Results show the significant importance of preventive maintenance actions in reducing the lifetime cost of existing structures, but also their fundamental role of essential maintenance action in keeping structures safe and serviceable during the entire lifetime

Maintenance and safety of deteriorating systems: a life-cycle perspective

This paper reviews the key aspects associated with maintenance and safety of deteriorating infrastructure systems from a life-cycle perspective. The main conceptual aspects related to probabilistic optimization of maintenance and rehabilitation of structural systems are discussed. These aspects include life-cycle risk and sustainability assessment, risk-informed and utility-based decision making, and multi-objective optimization of interventions. In general, sustainability assessment is performed by quantifying economic, social, and environmental impacts associated with infrastructure management activities. This keynote paper also reviews various methods for determining optimum life-cycle maintenance, repair, and rehabilitation types and times, as well as the impact of such activities on the total life-cycle cost. The role of probabilistic performance indicators including reliability and risk, the sustainability assessment of deteriorating infrastructure systems, and risk- and utility-informed decision making are highlighted herein

Multi-objective probabilistic optimization of bridge lifetime maintenance : novel approach

Due to the increase in deterioration of the existing civil infrastructure, in particular bridge networks, governments and highway agencies are trying to find methods that allow a consistent and rational management of existing bridges. In this paper, a novel approach is presented. This approach uses multi-objective probabilistic optimization over time and defines performance of existing bridges in terms of lifetime condition, safety, and cost. The proposed approach aims at providing a tool for optimal maintenance management policy definition of a large group of similar structures. Consequently, emphasis is put on the use of limited information and low computational cost. Applications to real cases are presented showing the applicability of the method as well as its advantages in terms of reduction of costs and improvements in performance.(undefined

Lifetime Bridge Maintenance Strategies Based on System Reliability

This study proposes a methodology for a system reliability-based condition evaluation of existing highway bridges. The approach is illustrated for an existing steel bridge located in Colorado. USA. An optimum lifetime repair strategy based on minimum expected cost is developed. The initial optimum repair strategy is updated using both biennial visual inspections and specific non-destructive evaluation testing

Reliability-based approach to the robustness of corroded reinforced concrete structures

Currently, decisions on the maintenance and repair of infrastructural assets, structures in particular, are mostly based on the results of inspections and the resulting condition index, neglecting system robustness and therefore not making optimal use of the limited funds available. This paper presents a definition and a measure of structural robustness in the context of deteriorating structures which are compatible with asset management systems for optimal maintenance and repair planning. The proposed index is used to define the robustness of existing reinforced concrete (RC) structures to rebar corrosion. Structural performance and the corresponding reliability index are assessed using combined advanced reliability and structural analysis techniques. Structural analysis explicitly includes deterioration mechanisms resulting from corrosion, such as reinforcement area reduction, concrete cracking, and bond deterioration. The first-order reliability method, combined with a response surface algorithm, is used to compute the reliability index for a wide range of different corrosion levels, resulting in a fragility curve. Finally, structural robustness is computed and discussed based on the results obtained. A robustness comparison of different structures can then be used to determine structural types more tolerant to corrosion and these results used for planning maintenance and repairs

Probabilistic maintenance and optimization strategies for deteriorating civil infrastructures

In developed countries, civil infrastructures are one of the most significant investments of governments, corporations, and individuals. Among these, transportation infrastructures, including highways, bridges, airports, and ports, are of huge importance, both economical and social. Most developed countries have built a fairly complete network of highways to fit their needs. As a result, the required investment in building new highways has diminished during the last decade, and should be further reduced in the following years. On the other hand, significant structural deteriorations have been detected in transportation networks, and a huge investment is necessary to keep these infrastructures safe and serviceable. Due to the significant importance of bridges in the serviceability of highway networks, maintenance of these structures plays a major role. In this paper, recent progress in probabilistic maintenance and optimization strategies for deteriorating civil infrastructures with emphasis on bridges is summarized. A novel model including interaction between structural safety analysis,through the safety index, and visual inspections and non destructive tests, through the condition index, is presented. Single objective optimization techniques leading to maintenance strategies associated with minimum expected cumulative cost and acceptable levels of condition and safety are presented. Furthermore, multi-objective optimization is used to simultaneously consider several performance indicators such as safety, condition, and cumulative cost. Realistic examples of the application of some of these techniques and strategies are also presented.The authors gratefully acknowledge the partial financial support of the U.K. Highways Agency and of the U.S. National Science Foundation through grants CMS-9912525 and CMS-0217290. The second author also acknowledges the support of the Portuguese Science Foundation (FCT)

Multi-objective design of post-tensioned concrete road bridges using artificial neural networks

[EN] In order to minimize the total expected cost, bridges have to be designed for safety and durability. This paper considers the cost, the safety, and the corrosion initiation time to design post-tensioned concrete box-girder road bridges. The deck is modeled by finite elements based on problem variables such as the cross-section geometry, the concrete grade, and the reinforcing and post-tensioning steel. An integrated multi-objective harmony search with artificial neural networks (ANNs) is proposed to reduce the high computing time required for the finite-element analysis and the increment in conflicting objectives. ANNs are trained through the results of previous bridge performance evaluations. Then, ANNs are used to evaluate the constraints and provide a direction towards the Pareto front. Finally, exact methods actualize and improve the Pareto set. The results show that the harmony search parameters should be progressively changed in a diversification-intensification strategy. This methodology provides trade-off solutions that are the cheapest ones for the safety and durability levels considered. Therefore, it is possible to choose an alternative that can be easily adjusted to each need.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (BRIDLIFE Project: BIA2014-56574-R) and the Research and Development Support Program of Universitat Politecnica de Valencia (PAID-02-15).García-Segura, T.; Yepes, V.; Frangopol, D. (2017). Multi-objective design of post-tensioned concrete road bridges using artificial neural networks. Structural and Multidisciplinary Optimization. 56(1):139-150. doi:10.1007/s00158-017-1653-0S139150561Alberdi R, Khandelwal K (2015) Comparison of robustness of metaheuristic algorithms for steel frame optimization. Eng Struct 102:40–60. doi: 10.1016/j.engstruct.2015.08.012Beume N, Naujoks B, Emmerich M (2007) SMS-EMOA: Multiobjective selection based on dominated hypervolume. Eur J Oper Res 181:1653–1669. doi: 10.1016/j.ejor.2006.08.008Cai H, Aref AJ (2015) A genetic algorithm-based multi-objective optimization for hybrid fiber reinforced polymeric deck and cable system of cable-stayed bridges. Struct Multidiscip Optim 52:583–594. doi: 10.1007/s00158-015-1266-4Cao MS, Pan LX, Gao YF, Novák D, Ding ZC, Lehký D, Li XL (2015) Neural network ensemble-based parameter sensitivity analysis in civil engineering systems. Neural Comput Appl 1–8. doi: 10.1007/s00521-015-2132-4Chatterjee S, Sarkar S, Hore S, Dey N, Ashour AS, Balas VE (2016) Particle swarm optimization trained neural network for structural failure prediction of multistoried RC buildings. Neural Comput Appl. 1–12. doi: 10.1007/s00521-016-2190-2Coello CAC (2002) Theoretical and numerical constraint-handling techniques used with evolutionary algorithms: a survey of the state of the art. Comput Methods Appl Mech Eng 191:1245–1287. doi: 10.1016/S0045-7825(01)00323-1Coello CAC, Lamont GB, Veldhuizen DA Van (2006) Evolutionary algorithms for solving multi-objective problems. Springer-Verlag New York, IncComputers and Structures Inc. (2015) Introduction to CSiBridge. Integrated 3D bridge analysis, design and rating. Berkeley, California, USADeb K (2011) Multi-objective optimisation using evolutionary algorithms: an introduction. In: Wang L, Ng AHC, Deb K (eds) Multi-objective evolutionary optimisation for product design and manufacturing. Springer, London, pp 3–34Deb K, Nain PKS (2007) An evolutionary multi-objective adaptive meta-modeling procedure using artificial neural networks. In: Yang S, Ong Y-S, Jin Y (eds) Evolutionary computation in dynamic and uncertain environments. Springer, Berlin, pp 297–322Dong Y, Frangopol DM, Saydam D (2013) Time-variant sustainability assessment of seismically vulnerable bridges subjected to multiple hazards. Earthq Eng Struct Dyn 42:1451–1467. doi: 10.1002/eqe.2281Emmerich M, Naujoks B (2004) Metamodel assisted multiobjective optimisation strategies and their application in airfoil design. In: Parmee IC (ed) Adaptive computing in design and manufacture VI. Springer, London, pp 249–260European Committee for Standardisation (2003) EN 1991–2:2003. Eurocode 1: Actions on structures-Part 2: Traffic loads bridgesEuropean Committee for Standardisation (2005) EN1992-2:2005. Eurocode 2: Design of concrete structures- Part 2: Concrete Bridge-Design and detailing rules. BrusselsFomento M (2008) EHE-08: code on structural concrete. Ministerio de Fomento, MadridFomento M (2011) IAP-11: code on the actions for the design of road bridges. Ministerio de Fomento, MadridGarcía-Segura T, Yepes V (2016) Multiobjective optimization of post-tensioned concrete box-girder road bridges considering cost, CO2 emissions, and safety. Eng Struct 125:325–336. doi: 10.1016/j.engstruct.2016.07.012García-Segura T, Yepes V, Alcalá J (2014a) Life cycle greenhouse gas emissions of blended cement concrete including carbonation and durability. Int J Life Cycle Assess 19:3–12. doi: 10.1007/s11367-013-0614-0García-Segura T, Yepes V, Martí JV, Alcalá J (2014b) Optimization of concrete I-beams using a new hybrid glowworm swarm algorithm. Lat Am J Solids Struct 11:1190–1205. doi: 10.1590/S1679-78252014000700007García-Segura T, Yepes V, Alcalá J, Pérez-López E (2015) Hybrid harmony search for sustainable design of post-tensioned concrete box-girder pedestrian bridges. Eng Struct 92:112–122. doi: 10.1016/j.engstruct.2015.03.015Geem ZW, Kim JH, Loganathan GV (2001) A new heuristic optimization algorithm: harmony search. Simulation 76:60–68Giannakoglou KC (2002) Design of optimal aerodynamic shapes using stochastic optimization methods and computational intelligence. Prog Aerosp Sci 38:43–76. doi: 10.1016/S0376-0421(01)00019-7Hare W, Nutini J, Tesfamariam S (2013) A survey of non-gradient optimization methods in structural engineering. Adv Eng Softw 59:19–28. doi: 10.1016/j.advengsoft.2013.03.001Martí JV, Yepes V, González-Vidosa F (2015) Memetic algorithm approach to designing precast-prestressed concrete road bridges with steel fiber reinforcement. J Struct Eng 141:4014114. doi: 10.1061/(ASCE)ST.1943-541X.0001058Martí JV, García-Segura T, Yepes V (2016) Structural design of precast-prestressed concrete U-beam road bridges based on embodied energy. J Clean Prod 120:231–240. doi: 10.1016/j.jclepro.2016.02.024Martinez-Martin FJ, Gonzalez-Vidosa F, Hospitaler A, Yepes V (2012) Multi-objective optimization design of bridge piers with hybrid heuristic algorithms. J Zhejiang Univ Sci A 13:420–432. doi: 10.1631/jzus.A1100304Martini K (2011) Harmony search method for multimodal size, shape, and topology optimization of structural frameworks. J Struct Eng 137:1332–1339. doi: 10.1061/(ASCE)ST.1943-541X.0000378Marti-Vargas JR, Ferri FJ, Yepes V (2013) Prediction of the transfer length of prestressing strands with neural networks. Comput Concr 12:187–209. doi: 10.12989/cac.2013.12.2.187McGee R (1999) Modeling of durability performance of Tasmanian bridges. In: Melchers R, M.G S (eds) Applications of statistics and probability: civil engineering, reliability and risk analysis. A.A. Balkema, Rotterdam, pp 297–306Papadakis VG, Roumeliotis AP, Fardis MN, Vagenas CG (1996) Mathematical modelling of chloride effect on concrete du-rability and protection measures. In: Dhir RK, Jones MR (eds) Concrete repair, rehabilitation and protection. E&FN Spon, London, pp 165–174Paya I, Yepes V, González-Vidosa F, Hospitaler A (2008) Multiobjective optimization of reinforced concrete building frames by simulated annealing. Comput Civ Infrastruct Eng 23:596–610. doi: 10.1111/j.1467-8667.2008.00561.xProtopapadakis E, Schauer M, Pierri E et al (2016) A genetically optimized neural classifier applied to numerical pile integrity tests considering concrete piles. Comput Struct 162:68–79. doi: 10.1016/j.compstruc.2015.08.005Quaglia CP, Yu N, Thrall AP, Paolucci S (2014) Balancing energy efficiency and structural performance through multi-objective shape optimization: Case study of a rapidly deployable origami-inspired shelter. Energ Build 82:733–745. doi: 10.1016/j.enbuild.2014.07.063Ricart J, Hüttemann G, Lima J, Barán B (2011) Multiobjective harmony search algorithm proposals. Electron Notes Theor Comput Sci 281:51–67. doi: 10.1016/j.entcs.2011.11.025Sanad A, Saka MP (2001) Prediction of ultimate shear strength of reinforced-concrete deep beams using neural networks. J Struct Eng 127:818–828. doi: 10.1061/(ASCE)0733-9445(2001)127:7(818)Sarma KC, Adeli H (1998) Cost optimization of concrete structures. J Struct Eng 124:570–578. doi: 10.1061/(ASCE)0733-9445(1998)124:5(570)Shi X (2016) Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforced concrete structures. Front Struct Civ Eng 10:1–11. doi: 10.1007/s11709-016-0312-7Sreehari VM, Maiti DK (2016) Buckling load enhancement of damaged composite plates under hygrothermal environment using unified particle swarm optimization. Struct Multidiscip Optim 1–11. doi: 10.1007/s00158-016-1498-yTorres-Machi C, Chamorro A, Pellicer E et al (2015) Sustainable pavement management: Integrating economic, technical, and environmental aspects in decision making. Transp Res Rec J Transp Res Board 2523:56–63. doi: 10.3141/2523-07Vu KAT, Stewart MG (2000) Structural reliability of concrete bridges including improved chloride-induced corrosion models. Struct Saf 22:313–333. doi: 10.1016/S0167-4730(00)00018-7Xu H, Gao XZ, Wang T, Xue K (2010) Harmony search optimization algorithm: application to a reconfigurable mobile robot prototype. In: Geem ZW (ed) Recent advances in harmony search algorithm. Springer, Berlin, pp 11–22Yepes V, García-Segura T, Moreno-Jiménez JM (2015a) A cognitive approach for the multi-objective optimization of RC structural problems. Arch Civ Mech Eng 15:1024–1036. doi: 10.1016/j.acme.2015.05.001Yepes V, Martí JV, García-Segura T (2015b) Cost and CO2 emission optimization of precast–prestressed concrete U-beam road bridges by a hybrid glowworm swarm algorithm. Autom Constr 49:123–134. doi: 10.1016/j.autcon.2014.10.013Zavala GR, Nebro AJ, Luna F, Coello Coello CA (2013) A survey of multi-objective metaheuristics applied to structural optimization. Struct Multidiscip Optim 49:537–558. doi: 10.1007/s00158-013-0996-4Zavrtanik N, Prosen J, Tušar M, Turk G (2016) The use of artificial neural networks for modeling air void content in aggregate mixture. Autom Constr 63:155–161. doi: 10.1016/j.autcon.2015.12.009Zitzler E, Thiele L (1998) Multiobjective optimization using evolutionary algorithms - a comparative case study. In: Eiben AE, Bäck T, Schoenauer M, Schwefel H-P (eds) Conference on parallel problem solving from nature- PPSN V. Springer Berlin Heidelberg, Amsterdam, The Netherlands, pp 292–30