731 Use of t he Te nsil e Strength in Anchorage to Concrete E mp loi de la r es istance a la traction lo rs d' an crages dans Ie beton Re chnerische Erfa ss ung der Bauteilbeanspruchungen durch Befestigungen Ro lf EliGEHAUSEN "rof Dr. Univ Stuttgart Stuttgart, Germany SUMMARY Rolf Ehgehausen. born 1942. receIved his Dlpl Ing in 1968 at the TechnIcal Untver- sity Braunschweig and Dr Ing In 1979 at the UniversIty of Stutt- gart From 1979 1981 he was research engineer at the Uni- versity of California al Ber keley Smce 1984 he IS Professor for fas- tening technology at the Institute fur Werk- steff e 1m Bauwesen, S l u11gart Jas ko OZBOLT Dr Ing. Unlv. Stuttgart Stuttgart, Germany Jasko Dzbolt. born 1955, rece l' ved his Dlpl Ing In 1978 and Dr Ing In 1982 at the Univers ity of Zagreb . In 1980 he performed a post-graduate study a: the TNO Institute In Delft, and from 1987 _ 1988 a postdoctoral study at Northwestern University Since 1989 Research Engtneer at Inslltut fUr Werkstoffe 1m Bauwesen, Stut!- gar! Anchonng elements, such as headed studs, are used 10 transfer co ncentra t ed loa ds Into reinforced concre te members From ex penmen ta l eVidence It IS known that, prOVided the steel St rength of the stud IS high enough, fa ilure occurs by pulling out a concrete cone formed by clrc umferentral crack growth In the so-called mixed mode, w ith significant size effect. Numencal analyses md ,ca te that the dommant mfluence fa cto r on the fa il ure load IS the concrete fracture energy, It IS shown that In such appli ca tions, the load transfer from the anchor Into the concrete may safely be done by uSing the concrete tenS il e strength . RESUME Des ele ments d'ancrage tels que les boulons sont utilises pour transmettre localement des Cha rges dans une structure en be ton arme. Selon rev ldence expenmentale, II est clair Que s; la r eSiS tance de r acier du boulon est suff,sante, la rUlne est alteinte pa r arrachement d'un cone en beton. une f'ssure clfculalfe se devefoppe, accompagnee d'un effet de ta , lIe slgnlflcat" dans ce QU'on appelle un ((mode rnlxtell. Les analyses numenques ,nd'quent que l'lnfluence domlnante Sur la charge ultlrne a l'energle de fracture du beton. II es t I res Interessant que dan s ce type de Ie beton pUlsse tra nsmenre des ch arges de l'ancrage a la masse enserrante sans J aide de I'armature, et ceci grace a la mobilisation de sa res is tan ce a la tra ction lUSAMMENFASSUNG BefeStigungselemente w le Kopfbolzen werden hauflg emgesetzt: um Lasten m Stahlbe:.ontrag- werke elnzulelten . Ve rsuche zergen, dass das Ve rsagen bei ausrelchend hoher du rch die Ausb lldung eines Betonausbru ch kegels hervorgerufen w lfd Ole Bruchlast hangt nach den Ergebnlssen der numerlschen Untersuchungen hauptsachllch von der Betonbruchenergre ab o Es Wlfd drsku tlert. dass In dlesen Anwendungsfaflen die Be tonzugfestlgkell 10 Anspru ch ge- nommen werden kann. ohne dass e ln S,cherher tsr;Sllco besteht