PSI - Issue 60

Anupoju Rajeev et al. / Procedia Structural Integrity 60 (2024) 222–232 Author name / Structural Integrity Procedia 00 (2019) 000–000

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data. Compression and tension damage parameters can be obtained from experimental investigation but for simplicity many empirical formulae have been proposed. Birtel and Mark [24] has used two empirical equations in his analysis of RC beam shear failure. The same equations have been adopted in this study and are given below. � =1−� � � �� � �� � � � � −1�+ � � �� � (1) � =1−� � � �� � �� � � � � −1�+ � � �� � (2) b c and b t are constants whose values can be determined from experiments. Here a value of 0.7 is assumed for both. CDP model requires several other information related to the concrete and in practice these values almost remain constant for different grades of concrete. The typical values of these parameters are listed below in Table 1.

Table 1 Material parameters for Concrete damage plasticity model

Parameter

Value

Dilation Angle

31 o

�� �� K

Eccentricity

1

1.16

0.667

Viscosity parameter 0 � �� � �� is defined as the ratio of peak compressive strength in biaxial loading to peak strength in uniaxial loading. The parameter K is a function of yield surface coefficient and generally assumes a value of 0.667 [25]. Dilation angle and Eccentricity are assumed to be 31 o and 1 respectively. Hence, the above parameters along with stress-strain data and degradation data completes the input for CDP model in Abaqus [25]. Tension and compression stiffness recovery are used for cyclic loadings where the element experiences a rapid change in strain direction. The stress strain curve has been calibrated and the peak parameters after considering the strain rate and confinement effects are given in Table 2.

Table 2 Modified strength parameters of concrete

Parameter � (Nominal static compressive strength) � � � (Modified peak compressive strength) � � � (Modified yield strain) �� (Dynamic elastic modulus)

Value

17 MPa

29.26 MPa

0.0054

28.30 GPa

2.2. Geometrical and model parameters

The diagram illustrating the structural arrangement and reinforcement specifics for the beam-column joint used in this analysis can be found in Fig. 1. The lower beam has been deliberately designed to be rigid, essentially functioning as a fixed, immovable base. This design choice aids in representing the column as a simple cantilever