| 1. |
- Sarmiento Nova, Silvia J., et al.
(författare)
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Metamodel-Based Reliability Assessment of Reinforced Concrete Beams Under Fatigue Loads
- 2021
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Ingår i: Proceedings of the 1st Conference of the European Association on Quality Control of Bridges and Structures. - Cham : Springer. ; , s. 84-92
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Konferensbidrag (refereegranskat)abstract
- It is well-known that highway bridges are frequently under cyclic load; therefore, deterioration due to fatigue is one of the most important phenomena to be analyzed when determining a bridge safety margin. This paper studies how uncertainties related to fatigue models for concrete structures affect reinforced concrete element’s reliability, and the critical parameters in fatigue damage are investigated. To this end, a metamodel-based method is described and used to calculate the probability of failure and reliability index values of an application example. Metamodel-based methods have become an essential and efficient tool to determine structural safety as the possibility to decrease the computational cost and couple the reliability approach with nonlinear finite element analysis (NLFEA) allows a better estimation of structural reliability. Results show how the proposed method can reduce the computational cost of traditional reliability simulation methods, maintaining a good accuracy.
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| 2. |
- Sarmiento Nova, Silvia J., et al.
(författare)
-
Pressure Distribution Patterns Between the Ballast and the Concrete Slab in Railway Trough Bridges
- 2021
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Ingår i: Proceedings of the 31st European Safety and Reliability Conference and (ESREL 2021). - Singapore : Research Publishing (S) Pte Ltd.. ; , s. 1093-1100
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Konferensbidrag (refereegranskat)abstract
- In Sweden, a substantial amount of railway bridges is approaching their intended lifespans and are planned to be replaced. However, it is not sustainable neither from a financial nor an environmental perspective to replace these bridges if they are still sound and safe. Thus, an evaluation of their actual capacity is required with the aim of extending their lifespans. A way to obtain a more accurate capacity is to determine the loads that are acting on them. Available literature points out the lack of experimental investigations on sleeper-ballast contact pressure, as well as on the stress distribution along and across the ballast. Consequently, railway bridge design has been based on traditional rather than rational assumptions, which can be quite conservative. In this paper, a review of models is carried out for evaluating stress patterns on the surface of the slab on ballasted concrete bridges. Then, a simplified finite element model of a concrete trough bridge, a common type of structure in Sweden, is used in a parametric analysis aimed to understand how the identified pressure distribution patterns affect the performance of this type of structure. Finally, with the purpose of studying how some parameters influence the bridge safety, a probabilistic reliability analysis is used. The reliability index beta (b) is obtained using the polynomial response surface method and its value is compared for different boundary condition scenarios. Also, the sensitivity factors for the considered random variables are compared and analyzed. Results show that the assumption of support condition and pressure pattern has a significant impact on the capacity, failure mode and probability of failure of this type of structure.
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| 3. |
- Sarmiento Nova, Silvia J., et al.
(författare)
-
Response Surface Method strategies coupled with NLFEA for structural reliability analysis of prestressed bridges
- 2021
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Ingår i: IABSE Congress Ghent 2021. - Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE). ; , s. 1813-1822
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Konferensbidrag (refereegranskat)abstract
- The Response Surface Method (RSM) has become an essential tool to solve structural reliability problems due to its accuracy, efficacy, and facility for coupling with Nonlinear Finite Element Analysis (NLFEA). In this paper, some strategies to improve the RSM efficacy without compromising its accuracy are tested. Initially, each strategy is implemented to assess the safety level of a highly nonlinear explicit limit state function. The strategy with the best results is then identified and used to carry out a reliability analysis of a prestressed concrete bridge, considering the nonlinear material behavior through NLFEA simulation. The calculated value of ? is compared with the target value established in Eurocode for ULS. The results showed how RSM can be a practical methodology and how the improvements presented can reduce the computational cost of a traditional RSM giving a good alternative to simulation methods such as Monte Carlo.
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