Modelling the Tensile Softening Behaviour of Concrete in LS-Dyna Software

This paper aims to study the fracture behaviors of high-volume fly ash-self-compacting concrete (HVFA-SCC) mixed with seawater and sea-sand (SWSS) or freshwater and river sand (FWRS). Three-point bending test were performed on 24 notched beams fabricated with varying in replacement ratio of fly ash (0%, 30%, 50%, and 70%) and the type of water and sand (SWSS and FWRS). The initial and unstable fracture toughness of these test specimens are determined by the double- K fracture model. The effect of fly ash replacement ratio and type of water and sand on the fracture parameters is analyzed and discussed. In addition, the cohesive fracture toughness of all the test specimens is calculated by using Gauss–Chebyshev integral method and the weight function method based on the bilinear tensile softening curve given in CEP-FIP Model Code. A comparison of fracture toughness parameters of determined from the experimental approach and analytical approaches is presented in these SCC specimens. Results show that SCC mixed with SWSS replacing FWRS can improve the unstable fracture toughness and fracture energy, and decrease its brittleness behavior. The cohesive fracture toughness of SWSS-SCC specimens is underestimated by these analytical methods based on the tensile softening curve given in CEP-FIP Model Code.

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Softening behaviour of continuous thin-walled steel beams. Two numerical methods

Journal of Constructional Steel Research ◽

10.1016/0143-974x(95)00006-h ◽

1996 ◽

Vol 36 (1) ◽

pp. 1-13 ◽

Cited By ~ 5

Author(s):

K.T. Thomopoulos ◽

E.S. Mistakidis ◽

E.K. Koltsakis ◽

P.D. Panagiotopoulos

Keyword(s):

Numerical Methods ◽

Steel Beams ◽

Softening Behaviour ◽

Thin Walled

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Quantitative Assessment of the Influence of Tensile Softening of Concrete in Beams under Bending by Numerical Simulations with XFEM and Cohesive Cracks

Materials ◽

10.3390/ma15020626 ◽

2022 ◽

Vol 15 (2) ◽

pp. 626

Author(s):

Ireneusz Marzec ◽

Jerzy Bobiński

Keyword(s):

Experimental Data ◽

Numerical Simulations ◽

Extended Finite Element ◽

Three Point Bending ◽

Material Parameters ◽

Error Measures ◽

Rational Bézier Curve ◽

Initial Fracture ◽

Experimental Values ◽

Tensile Softening

Results of the numerical simulations of the size effect phenomenon for concrete in comparison with experimental data are presented. In-plane geometrically similar notched and unnotched beams under three-point bending are analyzed. EXtended Finite Element Method (XFEM) with a cohesive softening law is used. Comprehensive parametric study with the respect to the tensile strength and the initial fracture energy is performed. Sensitivity of the results with respect to the material parameters and the specimen geometry is investigated. Three different softening laws are examined. First, a bilinear softening definition is utilized. Then, an exponential curve is taken. Finally, a rational Bezier curve is tested. An ambiguity in choosing material parameters and softening curve definitions is discussed. Numerical results are compared with experimental outcomes recently reported in the literature. Two error measures are defined and used to quantitatively assess calculated maximum forces (nominal strengths) in comparison with experimental values as a primary criterion. In addition, the force—displacement curves are also analyzed. It is shown that all softening curves produce results consistent with the experimental data. Moreover, with different softening laws assumed, different initial fracture energies should be taken to obtain proper results.

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