Volume 9, Issue 4, 2000

Analysis and Experimental Study for Steel Fibre Pullout from Cementitious Matrices

C. G. Karayannis

Reinforced Concrete Laboratory, Civil Engineering Dept., Democritus University of Thrace, Xanthi 671 00, Greece

(Received 3/00 ; accepted 6/00)

ABSTRACT

A model for the response of steel fibres embedded in a cementitious matrix and subjected to a pullout load, is presented. The pullout behaviour is dictated by the force transmission between fibre and matrix through an interfacial layer surrounding the fibre. Three distinct pullout load - bearing mechanisms are considered. The first one assumes perfect bond between matrix and fibre and is used for the description of the elastic stage when no real ‘‘slip’’ occurs. The second one is a transitional mechanism, which describes the behaviour at the onset of debonding, and the last one is a frictional dynamic pullout mechanism based on the matrix hydration shrinkage and a fibre - matrix misfit consideration. Pullout and pullthrough tests of steel fibres from cementitious matrices are also reported herein in order to investigate experimentally the pullout mechanisms, generate related data and use them complementary to the developed model. An attempt for the validation of the proposed model through comparisons between experimental data and analytical behaviour curves is also included.