Tension cracking in injection anchorages

The aim of this paper is to examine theoretically the behaviour of injection anchors having differing ultimate load shearing behaviour with regard to the crack-forming internal force. Two stages in the stress-strain state within an anchor are examined: firstly from the initial application of load when the anchor acts as a whole body until the first crack appears in the body of the fixed anchor length; secondly after cracks have formed normal to the longitudinal axis and their propogation along the fixed length. These cases are distinguished by levels of stiffness. At stages up to full load mobilisation part of the anchor will be cracked and part uncracked. Predictive equations are developed and an example is provided. Le but de ce texte est d’examiner theoriquement le comportement des tirants scelles ayant des differentes capacites a la force qui provoque les fissures. On examine deux etapes sous l’etat de contrainte-allongement: premierement a partir de l’application initiale de la charge quand le tirant agit comme un corps rigide jusqu’a Fapparition de la premiere fissure dans la partie scellee du tirant, deuxiemement apres l’apparition des fissures perpendiculairement a l’axe longitudinal et leur propagation le long de la partie scellee. Ces cas se distinguent par des valeurs differentes de raideur. Dans les etapes jusqu’a la rupture une partie du tirant va se Assurer e l’autre partie reste intacte. Des formules de prediction sont developpees et un exemple est donne.