FraMCoS 7 2010 Jeju, South Korea

Integration of contact elements in RGIB module of the Finite Element software “CESAR LCPC”: Application to concrete structures affected by internal swelling reactions

A significant number of existing concrete dams are at present deteriorated by chemo-mecha- nical processes known as internal swelling reactions (ISR). These pathologies, which include delayed ettring- ite formation as well as alkali-aggregate reactions, are responsible for cracking and expansion…

First page of: Integration of contact elements in RGIB module of the Finite Element software “CESAR LCPC”: Application to concrete structures affected by internal swelling reactions
Year 2010
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Abstract

A significant number of existing concrete dams are at present deteriorated by chemo-mecha- nical processes known as internal swelling reactions (ISR). These pathologies, which include delayed ettring- ite formation as well as alkali-aggregate reactions, are responsible for cracking and expansion of the material which lead to degradation of structures behaviour. The chemo-mechanical modelling of these phenomena is already elaborated by considering the influence of temperature and humidity in the development of expan- sion. This modelling is valid only for continuous media. In order to widen the domain of modelling applica- bility, this paper describes a novel procedure for modelling displacement discontinuities in ISR-affected con- crete structures, mainly to take into account two phenomena: firstly the modelling of the isolated cracks opening that result from interactions between pathology and mechanical behaviour of the structure, and sec- ondly, the evaluation of the potential efficiency of stress release (e.g. sawing of dams), the procedure of which consists in the creation of cutting lines in the structure for release of excessive compressive stresses, reclosing of the cut being a result of subsequent swelling. The elaborated model, aimed to possibly combine contact elements and non-linear coupled models of durability mechanics related to ISR modelling, was ap- plied to the 3D simulation of ISR in an example of simple gravity dam. Displacements and stresses at the con- tact elements zone were computed and compared with results of the dam computations without contact ele- ments. The results show that the creation of cutting lines in the dam studied leads to decrease of the stresses in the structure, which confirms a favourable effect of this stress release technique in order to deal with ISR affected structures.