Experimental Characterization of Bond Fatigue Using Beam-End Tests with Push-In Loading

Abstract

Realistic characterization of fatigue loading resistance is a paramount for an economical and reliable structural design of reinforced concrete (RC) and prestressed concrete (PC) structures. The need for innovative experimental methods for the characterization of fatigue behavior is driven by the current aims to construct wind turbine towers that must resist up to N = 10 7 loading cycles corresponding to 25 years of service life. Considering the number of possible configurations with regard to structural geometries, cross-sectional layout of reinforcement and loading scenarios, experimental data are required that capture the key mechanisms driving the fatigue damage between the reinforcement and concrete matrix. Experimental investigations of bond behavior under fatigue loading have been reported in the literature in the 90′s of last century. Since then, no systematic investigation of bond fatigue behavior has been published. As a consequence, no assessment rules are available for the bond fatigue, only separate assessment rules for concrete and steel. The present paper will report on the ongoing research of bond fatigue behavior using the beam-end test setup. The test campaign includes the push-in loading with the goal to provide data characterizing the compressive behavior of reinforced cross sections in wind turbine towers.

Experimental and theoretical evidence for the load sequence effect in the compressive fatigue behavior of concrete

“…3d-f, the dominating dissipative mechanism is related to plastic deformations within the material structure, a spatial uniformity of energy dissipation and of the inelastic state variables can be assumed. The fact, that the damage developing in the pre-peak regime is relatively small while the plastic strain grows rapidly suggests, that the pulsating plastic sliding along the aggregate interfaces can be regarded as the dominating source of energy dissipation [72][73][74]. Such a distributed dissipative mechanism does not exhibit localization, at least until the final stage of fatigue life.…”

Stress configuration‐based classification of current research on fatigue of reinforced and prestressed concrete

“…Experimental methods that isolate the development of fatigue-induced splitting cracks (4) have been recently developed by the authors in form of a modified beam-end test with a push-in loading. 51,59,60 An example of the test results is provided in Figure 2 illustrating that the bond fatigue behavior exhibits two phases of damage accumulation. 61 In the first phase, the bond can be considered confined with fatigue debonding up to the development of the longitudinal splitting crack.…”