Focusing on the member end rotation due to strain penetration along reinforcing bars fully anchored in footings and bridge joints, this paper introduces a hysteretic model for the reinforcing bar stress versus slip response. This model can be integrated into fiber-based analysis of concrete structures using a zero-length section element. The authors demonstrate the ability of the proposed hysteretic model to capture the strain penetration effects by simulating the measured global and local responses of two concrete columns and a bridge T-joint system. Findings show that the analysis of concrete structures will appreciably underestimate the local response parameters that are used to quantify structural damage unless the strain penetration effects are satisfactorily modeled.

Modeling of Strain Penetration Effects in Fiber-Based Analysis of Reinforced Concrete Structures

This report covers integrated experimental and analytical investigations that permit predicting analytically the local bond stress-slip relationship of deformed reinforcing bars subjected to generalized excitations, such as may occur during the response of reinforced concrete (RIC) structures to severe earthquake ground motions.

http://elib.uni-stuttgart.de/opus/volltexte/2016/7455/pdf/eli26.pdf

Local bond stress-slip relationships of deformed bars under generalized excitations : experimental results and analytical model

An accurate and efficient analytical model describing the hysteretic behavior of R/C beam-column joints subjected to random cyclic excitations is presented. The model takes into account the cyclic bond deterioration along anchored bars as well as the hysteretic behavior of cracked R/C sections at beam-column interfaces, thus allowing consideration of the interaction between the two end sections of the joint.

Modeling of R/C joints under cyclic excitations

A better understanding of the bond behavior, which is one of the main behavioral aspects of reinforced concrete structures, is needed for fiber-reinforced plastic reinforcing bars, because tests have shown that the bond is different from that of steel reinforcing bars and varies with the type of reinforcing bar as well. In this paper results from bond tests performed on commercially available glass fiber-reinforced plastic (GFRP) reinforcing bars are presented and discussed. The experimental bond-slip curves have been obtained and some information about bond mechanisms have been derived. Furthermore, values of the elastic modulus and the tensile strength of the reinforcing bars have been measured. Finally, a numerical procedure for the identification of the constitutive bond stress-slip relationship, based on the experimental results, is presented.

Experimental and analytical evaluation of bond properties of gfrp bars

Reinforced concrete requires bond between plain concrete and the reinforcing steel. Accurate numerical modeling of structures that exhibit severe bond-stress demand requires exact representation of bond-zone response. A bond element is presented for use in high-resolution finite element modeling of reinforced concrete structures subjected to general loading. The model is defined by a normalized bond stress versus slip relationship and a relationship between maximum bond strength and the concrete and steel stress-strain state. A finite element implementation of the model is proposed that enables a 1- or 2-D representation of bond-zone action. Nonlocal modeling is used to incorporate the dependence of bond strength on the concrete and steel material state. Comparisons of simulated and observed response for systems with uniform and variable bond-zone conditions are presented.

Concrete-Steel Bond Model for Use in Finite Element Modeling of Reinforced Concrete Structures

This report presents an analytical model for predicting the behavior of single deformed reinforcing bars embedded in confirmed concrete and subjected to generalized excitations in the range of low cycle fatigue. The model is based on a general local bond stress-slip relationship, derived from the results of an extensive study performed at Berkeley, and on either a bilinear or a simple but sufficiently accurate nonlinear stress-strain relationship for the reinforcing steel bar. An efficient numerical scheme for the integration of the governing differential equation of bond along the embedment length of the bar is presented.

/pdf/analytical-model-for-concrete-anchorages-of-reinforcing-bars-1a3uh1e4yf.pdf

Analytical model for concrete anchorages of reinforcing bars under generalized excitations

Ein mathematisches Modell zur Berechnung des Verhaltens eines Rippenstabes, verankert in eng verbugeltem Beton und beansprucht durch beliebige zyklische Belastungen hoher Intensitat wird erlautert. Es umfasst die Formulierung eines vereinfachten Modells fur die Beziehung zwischen ortlicher Verbundspannung und ortlichem Schlupf, das aus umfangreichen, in Berkeley durchgefuhrten Versuchen abgeleitet wurde; die Benutzung eines einfachen, jedoch ausreichend genauen Modells fur das Spannungs-Dehnungs Gesetz des Bewehrungsstahles und die numerische Losung der Differentialgleichung des Verbundes. Ein Beispiel ist dargestellt und erlautert. 
A mathematical model is presented to predict the behavior of a deformed bar, embedded in well-confined concrete and subjected to generalized cyclic excitations in the range of the low cycle fatigue. It includes the formulation of a simplified model for the local bond stress-slip relationship, based on the elaboration of the result of an extensive experimental study carried out recently at Berkeley; use of a simple but sufficiently accurate model for the stress-strain relationship at reinforcing steel and the numerical solution of the differential equation of bond. An example is presented and commented.

http://elib.uni-stuttgart.de/opus/volltexte/2012/7430/pdf/eli17.pdf

Analytical model for deformed bar bond under generalized excitations

A mathematical model of a deformed bar an anchored in a concrete block, recently developed by the authors, has been generalized to cover the bond conditions found in exterior and interior joints of reinforced concrete frames subjected to severe earthquake loadings. The analytically predicted response compares well with the results of a series of tests conducted in Berkeley for monotonic and cyclic loadings. An extensive numerical investigation has been carried out to show the influence on the anchored bar behavior of different parameters such as: 1) Severity of hysteretic requirements, 2) Characteristics of steel (namely yield stress and strain hardening), 3) anchorage length. The results of this investigation are used to offer some practical recommendations and conclusions.

http://elib.uni-stuttgart.de/opus/volltexte/2012/7267/pdf/eli19.pdf

Vincenzo Ciampi

Papers

Analytical model for concrete anchorages of reinforcing bars under generalized excitations

Analytical model for deformed bar bond under generalized excitations

Hysteretic behavior of deformed reinforcing bars under seismic excitations