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Optimum shape and length of laterally loaded piles
Fenu, Luigi,Briseghella, Bruno,Marano, Giuseppe Carlo Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.1
This study deals with optimum geometry design of laterally loaded piles in a Winkler's medium through the Fully Stressed Design (FSD) method. A numerical algorithm distributing the mass by means of the FSD method and updating the moment by finite elements is implemented. The FSD method is implemented here using a simple procedure to optimise the beam length using an approach based on the calculus of variations. For this aim two conditions are imposed, one transversality condition at the bottom end, and a one sided constraint for moment and mass distribution in the lower part of the beam. With this approach we derive a simple condition to optimise the beam length. Some examples referred to different fields are reported. In particular, the case of laterally loaded piles in Geotechnics is faced.
Optimum shape and length of laterally loaded piles
Luigi Fenu,Bruno Briseghella,Giuseppe Carlo Marano 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.1
This study deals with optimum geometry design of laterally loaded piles in a Winkler’s medium through the Fully Stressed Design (FSD) method. A numerical algorithm distributing the mass by means of the FSD method and updating the moment by finite elements is implemented. The FSD method is implemented here using a simple procedure to optimise the beam length using an approach based on the calculus of variations. For this aim two conditions are imposed, one transversality condition at the bottom end, and a one sided constraint for moment and mass distribution in the lower part of the beam. With this approach we derive a simple condition to optimise the beam length. Some examples referred to different fields are reported. In particular, the case of laterally loaded piles in Geotechnics is faced.
Simplified method to design laterally loaded piles with optimum shape and length
Luigi Fenu,Bruno Briseghella,Giuseppe Carlo Marano 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.2
Optimum shape and length of laterally loaded piles can be obtained with different optimization techniques. Inparticular, the Fully Stress Design method (FSD) is an optimality condition that allows to obtain the optimum shape of the pile,while the optimum length can be obtained through a transversality condition at the pile lower end. Using this technique, the structureis analysed by finite elements and shaped through the FSD method by contemporarily checking that the transversality condition issatisfied. In this paper it is noted that laterally loaded piles with optimum shape and length have some peculiar characteristics,depending on the type of cross-section, that allow to design them with simple calculations without using finite element analysis. Some examples illustrating the proposed simplified design method of laterally loaded piles with optimum shape and length areintroduced.
Time-Dependent Analysis of Precast Segmental Bridges
Gian Felice Giaccu,Davide Solinas,Bruno Briseghella,Luigi Fenu 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.2
Prestressed segmentally constructed balanced cantilever bridges are often subjected to larger deflections than those predicted by calculations, especially for long-term effects. In this paper, the case of modular balanced cantilever bridges, which are prestressed segmental bridges obtained through a repetition of the same double cantilever, is investigated. The considered bridges are two typical cases of modular balanced cantilever both subjected to large deformations during their lifetime. In this case, due to the unusual employed static scheme, creep deflections indefinitely evolve over time particularly at the end of the cantilevers and in correspondence with the central joint. These remarkable deflections cause discomfort for vehicular traffic and in certain cases can lead to the bridge collapse. Important extraordinary maintenance interventions were necessary to restore the viability of the bridges and to replace the viaduct design configuration. To this aim, the static schemes of the structures were varied, introducing new constraints, new tendons, and carbon fiber reinforcements. In the present work, time analysis was performed to compare the time-dependent behavior of the bridge according to two different creep models, the CEB-FIP Model Code 2010 and the RILEM Model B3, with the real-time-dependent behavior of the bridge observed during its lifetime. The two different employed models exhibit different behaviors in terms of displacements and bending moments acting on the bridge. Interesting considerations are made on their reliability in simulating the long-term creep effects that evolve indefinitely over time. Moreover, retrofitting techniques have been proposed and modeled to predict their effectiveness in reducing time-dependent deflections.