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Discrete modelling of hardening-induced cracking

Author(s): Dirk Schlicke, Gramos Muja
Paper category: Proceedings
Book title: Proceedings of the 2nd International RILEM/COST Conference on Early Age Cracking and Serviceability in Cement-based Materials and Structures Volume 2
Editor(s): Stéphanie Staquet and Dimitrios Aggelis
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 689-694
Total Pages: 6
Language : English

Abstract: Cracking is a basic principle of structural concrete, however, it is of great importance to avoid or at least mitigate hardening-induced cracking in order to fulfil special criteria of tightness, durability and/or optical appearance. Critical cases require a reliable assessment of hardening-induced cracking whereby the opportunity to distinguish between different types of cracking could enable very efficient constructions. In detail, it would be desirable to distinguish between smaller, locally restricted cracks, e.g. surface cracks or microcracking in the interior of the member, and wider macrocracks affecting the whole cross section, e.g. separating cracks or bending cracks.
As outlined in [1] and [2] the crack formation to be expected is strongly affected by the interplay between restraint stress resultants and Eigenstresses. In detail, smaller, locally restricted cracks are predominantly related to Eigenstresses, whereas wider macrocracks are usually caused by restraint stress resultants (restraint force and restraint moment). Nowadays, reliable assessments are enabled by analytical analysis of stress distributions in the critical cross section at decisive times, see e.g. [3] or [4]. But this procedure requires several conservative assumptions. Thus, coupled simulations of stress history and cracking would be very desirable. Several non-linear models already provide such solutions by applying specific failure criteria and constitutive laws, however, the adequate consideration of the reduction of restraint stresses due to softening and initial crack opening is not trivial and not always appropriately addressed. Recent investigations at the Institute of Structural Concrete at Graz University of Technology concentrated on the implementation of a discrete failure plane in thermomechanical 3D Finite Element models in order to enable profound studies of this effect [5]. This contribution presents the basic considerations, the implementation in the calculation model and the results of first validation studies.

Online publication : 2017
Publication type : full_text
Public price (Euros) : 0.00

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