Seismic Retrofit of a Multispan Prestressed Concrete Girder Bridge with Friction Pendulum Devices

Avossa, Alberto Maria; Giacinto, Danilo Di; Malangone, Pasquale; Rizzo, Fabio

doi:10.1155/2018/5679480

Cited by 18 publications

(13 citation statements)

References 43 publications

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“…frequency and damping). This is particularly dangerous for bridges equipped with seismic isolators [34,35], because they are designed on the basis of well-defined natural frequencies and damping. The specific codes on wind and structure interaction did not discuss this topic [36 -43].…”

Section: (B) ( )mentioning

confidence: 99%

Sensitivity Study of Dynamics Variability for Mild-carbon Steel Structures Affected by Corrosion

Lorenzo¹,

Landolfo²

2019

TOBCTJ

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Background:Corrosion propagation mainly occurs due to environmental conditions and to the absence of adequate maintenance. The corrosion propagation affects the structural performances of slender and thin structures, in particular in the case of structure very sensitive to the wind action and its dynamical phenomena, because commonly they are designed with a precise optimization of the stiffness/mass ratio. The static and dynamic wind action represent an immediate safety hazard in the case of structural stiffness and mass reduction due to the corrosion depth. Objective:This paper discusses the dynamics behavior variability due to the corrosion depth propagation for two significant examples of slender and thin structure (i.e. tower and truss roof). Methods:The structures assumed as case of study are made of mild carbon. The corrosion depth variability was estimated based on literature references. The structural natural frequencies and modal shapes are assumed as significant magnitudes to discuss the effect of the corrosion on the structural elements. Results:Results have shown that the corrosion depth gives a significant reduction of frequencies and modification of modal shapes. Conclusion:Results have shown that the corrosion depth affect the structural behavior long before a structural collapse. It suggests that a monitoring must be done to estimate the structure reliability for the Serviceability limit state under Characteristic design loads.

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Section: (B) ( )mentioning

confidence: 99%

Sensitivity Study of Dynamics Variability for Mild-carbon Steel Structures Affected by Corrosion

Lorenzo¹,

Landolfo²

2019

TOBCTJ

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“…Light structures, as for example tensile structures or suspended bridges, has a small ratio between structural weight and environmental or live loads. For this reason, differently from traditional reinforced concrete structures [1], they are sensitive to the snow action and in particular the wind action dynamics. The dynamic wind action can give local or global instability due to great displacements and/or rotations.…”

Section: Introductionmentioning

confidence: 99%

Geometrically Nonlinear Analyses of Tensile Structural Systems: Wind-Structure Interaction

Giovanni¹,

Taddeo²

2019

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Tensile structural systems as for example cables nets, suspended bridges or membranes usually have nonneglecting p-delta effects under wind action. Consequently, great displacements give a geometrically nonlinear structural behavior. In addition, the wind action is nonlinear spatially and time depending. This closely affect the dynamic interaction between loads and structure. For this reason, the calculation process needs to take into account the timedepending nonlinear response of the structure. Finally, the wind action can be critical for structural and it can induce global or local instability. Analyses has to be able to capture and to describe the instability response in term of displacements, in the case of cables net, or rotations, in the case of suspended bridges. The paper is focused on the wind-structure interaction analyses carried out by wind tunnel experiments. The wind action is generally given by wind tunnel experiments, and it is time depending. For roofs, it generally is given as pressure time histories measured by some pressure taps on the roof. The process from experiments to structural response is described using a case of study of cables net. The dynamic geometrically nonlinear analyses were performed using the TENSO non-commercial program, which can execute dynamic step-by-step integration of the nonlinear three-dimensional structure with geometric nonlinearities by the Newmark-Beta method with Rayleigh damping.

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“…Differently from traditional concrete bridges ( [1]), suspended bridges are cables structures with a geometrical non-linear behavior and they are sensitive to the wind action ( [2]). In addition, they have a small ratio between self-weight and length-span and this increases they vulnerability to dynamical action as for example the wind action.…”

Section: Introductionmentioning

confidence: 99%

Flutter Instability Calculation for Suspended Bridges Using Geometrically Nonlinear Analyses

Taddeo¹,

Giovanni²

2019

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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The paper investigates the modelling and calculation of the flutter instability condition due to the windstructure interaction in the case of suspended bridges. In particular, the paper is focused on FEM (Finite Element Model) analyses on three dimensional models that compute the flutter instability. Geometric non-linear flutter instability analyses were carried out using a research and design software program (TENSO), which enables nonlinear dynamic analysis of wind-structure interaction. All the bridge structure is modelled. In particular, the bridge deck model was simplified by a beam model located in the deck section's center of gravity and two massless rigid links to simulate the connection of the deck to the hangers and cables. The cables are represented by rectilinear cables element. The critical flutter speed was estimated using quasi-static approximation of the unsteady wind loads calculated by aerodynamic coefficients (i.e. lift, drag and moment coefficients) estimated by aerodynamic forces (i.e. lift, drag and moment) directly measured by wind tunnel tests. The executed analyses are by dynamic step-by-step integration of the nonlinear three-dimensional structure with geometric nonlinearities. The global stiffness matrix is updated at each load step by assembly of the stiffness sub-matrices of the elements, updated to account for the strain found at the previous time step, taking into account the geometric nonlinearity of the structure.Firstly, the calculation provides for the static equilibrium of the structure under dead, gravity and construction loads by nonlinear static analysis. It was computed simultaneously using two methods: step-by-step incremental method and a "subsequent interaction" method with variable stiffness matrix (secant method). The secant method is a finite-difference approximation of the Newton-Raphson's modified method for systems of nonlinear algebraic equations. The solution under gravity loads is subsequently used as the initial step of the dynamic wind load analysis. The Newmark-Beta method with Rayleigh damping is used for numerical integration of the dynamic equations. Wind loads on the bridge deck are time dependent and they are simulated by applying the aerodynamic coefficients as a function of the time-dependent angle of attack at a given mean wind speed U. Displacements and rotations of the bridge deck at progressively increasing values of U, are estimated. The velocity at incipient flutter is fixed when the reference deck vibration amplitude exceeds ±5°. Details of the analyses results and calculation are given for an example of suspended foot bridges. Vertical displacements (δ) and rotations of the deck about the longitudinal bridge axis (αx) in normalized format (i.e. upward deck displacements are positive and counterclockwise rotations are positive) are discussed.

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Seismic Retrofit of a Multispan Prestressed Concrete Girder Bridge with Friction Pendulum Devices

Cited by 18 publications

References 43 publications

Sensitivity Study of Dynamics Variability for Mild-carbon Steel Structures Affected by Corrosion

Sensitivity Study of Dynamics Variability for Mild-carbon Steel Structures Affected by Corrosion

Geometrically Nonlinear Analyses of Tensile Structural Systems: Wind-Structure Interaction

Flutter Instability Calculation for Suspended Bridges Using Geometrically Nonlinear Analyses

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