Investigation on fatigue performance and life prediction of PBL connectors in steel-UHPC composite structure

Abstract

This paper presents an investigation into the fatigue performance and life prediction of perfobond strip connectors (PBLs) in steel-ultra-high performance concrete (UHPC) composite structure, based on three static push-out tests and nine fatigue tests. From the three static push-out tests results, the fatigue load and load amplitude for fatigue tests are determined. A comparative analysis is then conducted on the fatigue life, failure modes, slip curves, shear stiffness degradation laws and failure mechanisms of PBL connectors under static and fatigue loading conditions. Two-stage fatigue cumulative damage mode applicable to PBL connectors in UHPC is then proposed. Finally, based on above analysis, the fatigue life prediction model of the PBL connectors in UHPC is proposed and validated by experimental results. The results indicate that the load amplitude remains the primary factor affecting the fatigue life of PBL connectors. The fatigue cumulative damage of PBL connectors in UHPC is more unstable compared to that of PBL connectors in normal concrete, showing three-stage fatigue cumulative damage under small load amplitude and five-stage fatigue cumulative damage under large load amplitude. The final failure mode of PBL connectors in UHPC under static and fatigue test is characterized by the fracture of the transverse rebar, whereas in normal concrete, the failure mode primarily involves the crushing and splitting of the concrete slab at the PBL connectors. The fatigue damage of PBL connectors in UHPC more accurately is divided into two stages: the UHPC-dominated damage stage and the transverse rebar-dominated damage stage. The fatigue life prediction model of PBL connectors is proposed and validated by experimental results.