scholarly journals Assessing fragility of a reinforced concrete element to snow avalanches using a non-linear dynamic mass-spring model

2018 ◽  
Vol 18 (9) ◽  
pp. 2507-2524
Author(s):  
Philomène Favier ◽  
David Bertrand ◽  
Nicolas Eckert ◽  
Isabelle Ousset ◽  
Mohamed Naaim
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Response ◽  
Fragility Curves ◽  
Dynamic Pressure ◽  
Concrete Element ◽  
Element Analysis ◽  
Yield Line Theory ◽  
Pressure Fields ◽  
Line Theory ◽  
Mass Spring

Abstract. This paper presents an assessment of the fragility of a reinforced concrete (RC) element subjected to avalanche loads, and more generally to dynamic pressure fields applied orthogonally to a wall, within a reliability framework. In order to obtain accurate numerical results with supportable computation times, a light and efficient Single-Degree-of-Freedom (SDOF) model describing the mechanical response of the RC element is proposed. The model represents its dynamic mechanical response up to failure. Material non-linearity is taken into account by a moment–curvature approach, which describes the overall bending response. The SDOF model is validated under quasi-static and dynamic loading conditions by comparing its results to alternative approaches based on finite element analysis and the yield line theory. Following this, the deterministic SDOF model is embedded within a reliability framework to evaluate the failure probability as a function of the maximal avalanche pressure reached during the loading. Several reliability methods are implemented and compared, suggesting that non-parametric methods provide significant results at a moderate level of computational burden. The sensitivity to material properties, such as tensile and compressive strengths, steel reinforcement ratio, and wall geometry is investigated. The effect of the avalanche loading rate is also underlined and discussed. Finally, the obtained fragility curves are compared with respect to the few proposals available in the snow avalanche engineering field. This approach is systematic and will prove useful in refining formal and practical risk assessments. It could be applied to other similar natural hazards, which induce dynamic pressure fields onto the element at risk (e.g., mudflows, floods) and where potential inertial effects are expected and for which fragility curves are also lacking.

scholarly journals Assessing fragility of a reinforced concrete element to snow avalanches using a non-linear mass-spring model

2017 ◽  
Author(s):  
Philomène Favier ◽  
David Bertrand ◽  
Nicolas Eckert ◽  
Isabelle Ousset ◽  
Mohamed Naaim
Keyword(s):  
Reinforced Concrete ◽  
Fragility Curves ◽  
Concrete Element ◽  
Yield Line Theory ◽  
Mass Spring Model ◽  
Line Theory ◽  
Reliability Methods ◽  
Mass Spring ◽  
Overall Bending ◽  
Wall Geometry

Abstract. This paper presents an assessment of the fragility of a Reinforced Concrete (RC) element subjected to avalanche loads within a reliability framework. In order to obtain accurate numerical results with supportable computation times, we propose a light and efficient Single-Degree-Of-Freedom (SDOF) numerical model for an RC element. The model represents the behavior of an RC wall, summing up the main physics involved. Non-linearity was taken into account by a moment-curvature approach, which describes the overall bending response until collapse. The SDOF model was validated by a finite element as well as yield line theory analyses. It was then embedded within a reliability framework to evaluate the failure probability as a function of avalanche pressure. Several reliability methods were implemented and compared, suggesting that non-parametric methods provide significant results at a moderate level of computational burden. The sensitivity to material properties, such as tensile and compressive strengths, steel reinforcement ratio, and wall geometry was also investigated. Finally, the obtained fragility curves were discussed with respect to the few proposals available in the snow avalanche engineering field. This systematic approach will prove useful in refining formal and practical risk assessments and could be applied to other phenomena that also lack fragility curves.

scholarly journals A reliability assessment of physical vulnerability of reinforced concrete walls loaded by snow avalanches

2013 ◽  
Vol 1 (3) ◽  
pp. 2589-2632
Author(s):  
P. Favier ◽  
D. Bertrand ◽  
N. Eckert ◽  
M. Naaim
Keyword(s):  
Reinforced Concrete ◽  
Fragility Curves ◽  
Human Beings ◽  
Snow Avalanches ◽  
Limit States ◽  
Engineering Structures ◽  
Rc Structures ◽  
Yield Line Theory ◽  
Non Gaussian ◽  
Structure Collapse

Abstract. Snow avalanches are a threat to many kinds of elements (human beings, communication axes, structures, etc.) in mountain regions. For risk evaluation, the vulnerability assessment of civil engineering structures such as buildings and dwellings exposed to avalanches still needs to be improved. This paper presents an approach to determine the fragility curves associated with Reinforced Concrete (RC) structures loaded by typical avalanche pressures and provides quantitative results for different geometrical configurations. First, several mechanical limit states of the RC wall are defined using classical engineering approaches (Eurocodes – EC2), and the pressure of structure collapse is calculated from the usual yield line theory. Next, the failure probability is evaluated as a function of avalanche loading using a Monte Carlo approach, and sensitivity studies (Sobol indexes) are conducted to estimate the respective weight of the RC wall model inputs. Finally, fragility curves and relevant indicators such a their mean and fragility range are proposed for the different structure boundary conditions tested. The influence of the input distributions on the fragility curves is investigated. This shows the wider fragility range and/or the slight shift in the median that has to be considered when the possible correlation/non-Gaussian nature of the input distributions is accounted for.

scholarly journals Finite Element Analysis of Bearing Capacity of Reinforced Concrete Pipe Strengthened by TRC

2021 ◽  
Vol 261 ◽  
pp. 02044
Author(s):  
Xinming Zhao ◽  
Cheng Kan ◽  
Yuxiao Ye ◽  
Shaowei Hu ◽  
Baibing Zhou
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Mesh Size ◽  
Element Model ◽  
Displacement Curve ◽  
Concrete Element ◽  
Element Analysis ◽  
Element Mesh ◽  
Concrete Pipe ◽  
Load Simulation

A non-linear 3D finite element model was established to simulate the three edge-bearing test of TRC reinforced concrete pipe. The pipe load-displacement curve, cracking load, and ultimate load simulation values are in good agreement with the test values. Subsequently, a parametric study was conducted. The effects of reinforcement layer bonding mode, mesh size of concrete element, mesh distribution rate and concrete compressive strength on the performance of reinforced concrete pipeline strengthened by TRC were considered. It provides a basis for the design of TRC reinforced concrete pipes.

Analytical Plastic Capacity Formulation for Plates Subject to Ice Loads and Similar Types of Patch Loadings

2006 ◽  
Author(s):  
Ha˚vard Nyseth ◽  
Gabriel Holtsmark
Keyword(s):  
Load Capacity ◽  
Plate Bending ◽  
Element Analysis ◽  
Yield Line Theory ◽  
Geometry Configuration ◽  
Line Theory ◽  
Patch Load ◽  
Ice Loads ◽  
Patch Loading ◽  
Capacity Formulation

The response of plates subjected to patch loads with length/ height less than the dimensions of the plate field is of importance for the design of hulls strengthened for operation in ice covered waters and other comparable types of loading. An analytical plastic capacity formulation for plates subjected to patch loading of any rectangular geometry configuration has been derived, which from comparison with nonlinear finite element analysis is seen implicitly to limit the permanent deflection to be up to 0,40% of the frame spacing. The analytically derived formulations for the plastic bending based load capacity are based on yield line theory. Expressions for single and multiple patch loads are included, where the derivation is based on the assumption that the response for a single patch load is equal to the response from a sequence of identical patch loads located within the same plate field, and spaced a certain minimum distance apart. The expressions may serve as basis for rule requirements for plates subject to ice loads and other types of patch loads. For the considered longitudinally and transversely stiffened plate cases, nonlinear FE calculations show that the proposed plate bending based load capacity formulations generally give rise to permanent deformations in the plate up to 0.40% of the frame spacing, when the plate model analyzed is extended to include adjacent plate fields. Comparisons of nonlinear FE calculations show the pressure-deformation relationship of the single and repeated load patch to be the same within the range of permanent deformations considered. Comparison of the analytically derived plate formula with DNV Arctic Rules and Finnish-Swedish Ice Class Rules (FSICR) indicates that the plate formula of the DNV/FSICR gives similar results for the same load levels. The analytically derived formula, however, provides a more consistent utilization of the plate bending based capacity that is valid for a wider range of patch load geometries. Comparison of the IACS Polar Class (PC) Rules formulation indicates that the IACS plate formulation is increasingly non-conservative for small patch lengths, and that the application should be restricted to cover larger patch lengths only, e.g. l/s > 1,0.

scholarly journals Failure Mode Prediction for One-Way Reinforced Concrete Flat Slabs with Rectangular Columns

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Dênio Ramam Oliveira ◽  
Lins Sandro Damsceno
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Cross Sections ◽  
Failure Modes ◽  
Flat Slabs ◽  
Yield Line Theory ◽  
Line Theory ◽  
Failure Loads ◽  
The One ◽  
Rectangular Columns

Flat slabs are reinforced concrete plates directly supported on columns, without intermediary beams. This structural system has been sufficiently used in the last decade, mainly for successful reach large spans and allowing "layouts" flexible. On the other hand, these slabs can be characterized as two-ways or one-ways, depending on the loading conditions, it is still stand out that NBR 6118 does not distinguish the types of flat slabs and make no reference to how much the punching resistance in the case of the one-ways flat slabs and it is known that normally these flat slabs presents low failure loads compared to the two-ways one. In this work presents a proposal, completely detailed in Damasceno’s master thesis (2007), for forecast the failure mode of one-way flat slabs with rectangular columns and without shear reinforcement, based on the prescriptions of CEB-FIP MC90 and on the Yield Line Theory. Equations that describe the behavior of the slabs in the limit between punching shear and flexure failures, considering the material’s properties, dimensions of the flat slab and the column’s cross sections, rate of flexure reinforcement in two directions, etc. are presented, parameters that influence on the slabs’ behavior. The estimates had been satisfactory and able to forecast one-way flat slabs’ failure modes.

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