Boundary element model for bond problems in reinforced concrete members (original) (raw)
Related papers
SN Applied Sciences, 2019
The bond mechanism plays a decisive role when anchorage failure in a reinforced concrete (RC) member occurs. A refined model of bond-slip is therefore needed to analyse RC members by analytical or finite element (FE) modelling where the anchorage of reinforcement is critical, such as at a lapped-splice or in any situation where the strength of a bar is required to be developed to achieve its ultimate strength. This paper presents results of FE modelling of some experimental RC specimens with anchorage of deformed steel reinforcing bars in tension, including the cases of end development and lapped splices of bars in specimens subjected to bending. The FE modelling of the anchorage length specimens with bond-slip laws calibrated from experimental results was better able to predict the load-deflection behavior observed during experimental tests. A comparison of the results obtained using the calibrated bond-slip laws with those using conventional Fédération Internationale du Béton bond-slip laws is made and discussion is provided on the effects of the anchorage lengths and bar diameters on the bond-slip relationships.
Finite element modelling of reinforcement with bond
Computers & Structures, 2006
This paper presents an efficient numerical model for simulating the bond between reinforcing bars and concrete. It is based on the onedimensional geometry of reinforcing bars, and it considers interface surface properties. In spite of its relative simplicity, it allows the application of the same physical models as in the case of a full surface interface. An arbitrary bond-slip relationship can be implemented within the model. Four sample analyses are presented: reinforcement bar pull-out experiment, an example of a beam collapsing due to shear failure, an analysis of the shear strength of pre-stressed hollow core slabs and an assessment of serviceability of a pre-stressed concrete slab in the newly built ice hockey arena in Prague.
Modelling reinforcement-to-concrete bond
The distribution of bond on the lateral surface of steel reinforcement embedded in concrete is explored through systematic solution of the governing field equations of the associated mechanical problem. By separating the variables, the state of stress in the concrete surrounding the bar is represented by coupling two independent solutions, each describing attenuation of bond stresses either in the longitudinal or in the radial directions of the cover respectively. Kinematic considerations are used to couple longitudinal slip with the radial translation of the cover, whereas the corresponding stress components developing along the lateral bar surface over the anchorage (radial pressure and bond stress) are related through a frictional relationship. Using the derived solution, various experimentally documented trends are reproduced analytically and interpreted. These include the processes of debonding and yield-penetration, and the sensitivity of development capacity to important desi...
NONLINEAR FE MODELLING OF ANCHORAGE BOND IN REINFORCED CONCRETE
The transfer of forces from the surrounding concrete to the reinforcing bars in reinforced concrete (RC) can be influenced by several parameters. In this paper an attempt has been made to study the influence of specimen geometry, bar diameter, strength of concrete, lateral confinement and embedment length on the bond properties of concrete. The embedment length of the bar was varied between 50mm and 400mm by varying the diameter of the bar, strength of concrete and lateral confinement. The different bar diameters of 16, 20 and 25mm were selected along with three different concrete strengths of 25, 40 and 65MPa. The specimens with the above parameters were modeled by using a nonlinear finite element analysis package. It has been found that for the same geometry, the specimens with small bond length exhibited high bond strength. With the range of bar diameters considered the bond strength of concrete decreases as the diameter of the bar increases. The splitting failure has been observed in unconfined concrete, while the pullout failure was predominant when the concrete laterally confined. In case of large embedment length, the post peak plateau is prolonged with small diameter bars when compared to the large diameter bars. The descending branch of the bond stress-slip response with large diameter bars has been found to be steep.
Local bond stress-slip model for reinforced concrete joints and anchorages with moderate confinement
Canadian Journal of Civil Engineering, 2017
This paper presents a summary of an experimental investigation and the derivation of a bond-slip model for reinforcing steel embedded in moderately confined concrete under monotonic and cyclic loadings. Moderately confined concrete encompasses the domain between unconfined and well-confined concrete, the limits of which are defined in the paper. The proposed constitutive law adapts and extends the well-known Eligehausen-Filippou model for well-confined concrete to moderately confined concrete. It is described by an envelope curve and degradation rules. The former is obtained through a confinement index, defined in this study as a function of the amount of confining steel and concrete, distance between confining steel and the rebar, and concrete segregation effect. It is proposed to adopt the same degradation rules used for well-confined concrete. These rules are validated through statistical tests for moderately confined concrete. They are found to predict correctly the main feature...
Experimental and finite element analysis of bond-slip in reinforced concrete
Revista IBRACON de Estruturas e Materiais, 2015
The modeling of reinforced concrete structures has taken advantage of the increasing progress on Computational Mechanics, in such way that complex phenomena, such as cracking and crushing, creep, reinforcement yielding, steel-concrete bond loss, can be modeled in a reasonable realistic way, using the proper set of numerical and computational resources. Among several options, the ones based on the Finite Element Method (FEM) allow complex analysis simulations of reinforced concrete structures, including the interaction of different nonlinear effects. This paper deals with the nonlinear finite element analysis of the bond-slip between reinforcing steel and concrete, taking into account an experimental study previously performed. The FEM analysis presented uses a combination of resources where the material behavior of concrete is described by the Microplane Constitutive Model, and an embedded reinforcement model is used to represent steel inside the concrete and take into account the e...
A new bond slip model for reinforced concrete structures
Engineering Computations, 2015
Purpose – The purpose of this paper is to present a new bond slip model for reinforced concrete structures. It consists in an interface element (3D) which represents the interface between concrete (modeled in 3D) and steel, modeled using 1D truss elements. Design/methodology/approach – The formulation of the interface element is presented and verified through a comparison with an analytical solution on an academic case. Finally, the model is compared with experimental results on a reinforced concrete tie. Findings – Contrary to the classical perfect or “no-slip” relation which supposes the same displacement between steel and concrete, the proposed model is able to reproduce both global (force-displacement curve) and local (crack openings) results. Originality/value – The proposed approach, applicable to large-scale computations, represents a valuable alternative to the no-slip relation hypothesis to correctly capture the crack properties of reinforced concrete structures.
Development of steel-concrete interface model for structural elements
2018
In numerical applications of reinforced concrete structures, the steel-concrete interface behavior has a vital importance when the cracking properties are investigated. A finite element approach for the steel-concrete interface to be used in large-scale simulations was proposed by (Torre-Casanova, 2013) and (Mang, 2016). It enables to calculate the slip between the steel and concrete in the tangential direction of the interface element representation. The aim is here to improve the initial bond-slip model to be more efficient and more representative. The document is divided into three parts: 1) The existing bond-slip model is evaluated. The bond-slip model is then improved by considering transversal and irreversible bond behaviors under alternative loads. The new bond-slip model is validated with several numerical applications. 2) Confinement effect is implemented in the bond-slip model to capture the effect of external lateral pressure. According to the performed numerical applicat...
Purpose – The purpose of this paper is to present a new bond slip model for reinforced concrete structures. It consists in an interface element (3D) which represents the interface between concrete (modeled in 3D) and steel, modeled using 1D truss elements. Design/methodology/approach – The formulation of the interface element is presented and verified through a comparison with an analytical solution on an academic case. Finally, the model is compared with experimental results on a reinforced concrete tie. Findings – Contrary to the classical perfect or “no-slip” relation which supposes the same displacement between steel and concrete, the proposed model is able to reproduce both global (force-displacement curve) and local (crack openings) results. Originality/value – The proposed approach, applicable to large-scale computations, represents a valuable alternative to the no-slip relation hypothesis to correctly capture the crack properties of reinforced concrete structures.