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.

Punching in two-way RC flat slabs with openings and L section columns

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Valdemir Colares Pinto ◽  
Vitor Branco ◽  
Denio Ramam Oliveira
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Failure Modes ◽  
Computational Simulation ◽  
Experimental Results ◽  
Design Codes ◽  
Nonlinear Simulation ◽  
Content Type ◽  
Flat Slabs ◽  
Failure Loads

Purpose This study aims to contribute to a better understanding of the influence of the position of openings around L cross-section columns in reinforced concrete flat slabs through a nonlinear computational analysis compared to experimental results. Design/methodology/approach Tests on four reinforced concrete flat slabs of 1800 x 1800 x 120 mm3 were carried out under symmetrical punching; one slab was referenced (without hole) and three had square holes of 100 x 100 mm2 close to columns and with centroid on the critical perimeter at 0.5 d and 2.0 d of the loaded area. A nonlinear analysis of the slabs was performed to aid the interpretation and preview of the experimental results, and to estimate the ultimate loads and failure modes. These estimates followed recommendations of ACI 318, Eurocode 2, NBR 6118, MC 2010 and critical shear crack theory. Findings The results showed that the presence of holes in the analyzed regions does not influence significantly the behavior of the slabs, leading to conservative structural design once the ultimate load estimates are low, while the computational results adequately estimated the slabs’ behavior. Research limitations/implications A few limitations were observed on how to implement the correct modeling system for computational nonlinear simulation. Practical implications All design codes underestimated failure loads and the theoretical method was not much better. The nonlinear computational simulations were satisfactory, presenting results close to experimental ones (97 per cent accuracy). Computational simulation also showed that the presence of holes does not significantly influence the load-vertical displacement behavior or failure loads. Social implications Structural and civil engineers and designers can observe with better details the punching phenomenon and make take secure decisions to building projects. They can preview accurate cases that are not cited in design codes and literature. Originality/value This is a very rare subject in literature that interests the entire scientific community and especially reinforced concrete designers. Presenting a new methodology to nonlinear flat slab with openings modeling to punching shear provoked by L cross section columns, case that is not cited in literature and design codes.

Seismic assessment of reinforced concrete columns with short lap splices

2021 ◽  
pp. 875529302199483
Author(s):  
Eyitayo A Opabola ◽  
Kenneth J Elwood
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Failure Modes ◽  
Concrete Columns ◽  
Seismic Assessment ◽  
Rc Columns ◽  
Lap Splices ◽  
Displacement Response ◽  
Force Displacement ◽  
Probable Failure

Existing reinforced concrete (RC) columns with short splices in older-type frame structures are prone to either a shear or bond mechanism. Experimental results have shown that the force–displacement response of columns exhibiting these failure modes are different from flexure-critical columns and typically have lower deformation capacity. This article presents a failure mode-based approach for seismic assessment of RC columns with short splices. In this approach, first, the probable failure mode of the component is evaluated. Subsequently, based on the failure mode, the force–displacement response of the component can be predicted. In this article, recommendations are proposed for evaluating the probable failure mode, elastic rotation, drift at lateral failure, and drift at axial failure for columns with short splices experiencing shear, flexure, or bond failures.

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 Design Method to Induce Ductile Failure of Flexural Strengthened One-Way Reinforced Concrete Slabs

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7647
Author(s):  
Huy Q. Nguyen ◽  
Tri N. M. Nguyen ◽  
Do Hyung Lee ◽  
Jung J. Kim
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
Design Method ◽  
Concrete Slab ◽  
Ductile Failure ◽  
Reinforced Concrete Slabs ◽  
Failure Loads ◽  
Ultimate Failure ◽  
Rc Slabs

Strengthening existing reinforced concrete (RC) slabs using externally bonded materials is increasingly popular due to its adaptability and versatility. Nevertheless, ductility reduction of the rehabilitated flexural members with these materials can lead to brittle shear failure. Therefore, a new approach for strengthening is necessary. This paper presents a methodology to induce ductile failure of flexural strengthened one-way RC slabs. Ultimate failure loads can be considered to develop the proposed design methodology. Different failure modes corresponding to ultimate failure loads for RC slabs are addressed. Flexural and shear failure regions of RC slabs can be established by considering the failure modes. The end span of the concrete slab is shown for a case study, and numerical examples are solved to prove the essentiality of this methodology.

Probabilistic Evaluation of Effects of Column Moment Magnification Factor on Seismic Performance of Reinforced Concrete Frames

2011 ◽  
Vol 243-249 ◽  
pp. 251-257 ◽  
Author(s):  
Ming Ji He ◽  
Chun Yang ◽  
Jian Cai ◽  
Yan Sheng Huang ◽  
Yi Wu
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Failure Modes ◽  
Fragility Curves ◽  
Frame Structures ◽  
Rc Frame ◽  
Magnification Factor ◽  
Rc Frame Structures

Enhancing column flexural capacity is the key measure in seismic capacity design to achieve strong column-weak beam failure mode and determinate the probabilistic relation between column moment magnification factor (CMMF). In the paper the effects of column moment magnification factor on seismic performance of reinforced concrete (RC) frames are evaluated to limit the occurrence probability of column-hinging failure modes within an acceptable tolerance. Monte Carlo simulation methodology is used to calculate the probability of drift demand exceeding drift capacity of two typical frame structures with consideration of major uncertainties. And fragility curves are constructed to obtain the relationship between CMMF and probability of structural damages and assess the seismic vulnerability of RC frame structures. Results show that the seismic performance of RC frame structures can be significantly enhanced by improving CMMF. The CMMF is required to be equal to or greater than 2.0 to achieve acceptable probability of exceedance of column-hinging failure mode.

scholarly journals Nonlinear numerical simulation of punching shear behaviour of reinforced concrete flat slabs with shear-heads

2019 ◽  
Author(s):  
D.V. Bompa ◽  
A.Y. Elghazouli
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Numerical Models ◽  
Three Dimensional ◽  
Structural Response ◽  
Analytical Models ◽  
Shear Behaviour ◽  
Flat Slabs ◽  
Modes Of Failure ◽  
Concrete Damage

This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

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 Simplified nonlinear analysis of reinforced concrete coupling beams subjected to cyclic loading

2020 ◽  
Vol 19 (3) ◽  
pp. 224-232
Author(s):  
Rafael Alves de Souza ◽  
◽  
Sergio F. Brena ◽  
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Nonlinear Analysis ◽  
Failure Modes ◽  
Tall Buildings ◽  
Shear Walls ◽  
Monotonic Loading ◽  
Good Precision ◽  
Coupling Beams ◽  
Failure Loads

Reinforced concrete shear walls connected by coupling beams form an efficient structural system to resist earthquake and wind loads in tall buildings. However, the analysis of the effects caused by cyclic loading in this kind of system are not so straightforward. In the present paper, simplified nonlinear analysis using monotonic loading are used in order to obtain the behavior of tested coupling beams subjected to cyclic loading. Numerical results have shown that numerical monotonic loading is able to predict with good precision the yielding and the failure loads of the tested coupling beams subjected to cyclic loading. Both the cracking patterns and the predicted failure modes also followed the experimental behavior, ensuring that monotonic loading may be applied to have a first insight concerning cyclic loading.

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