88 / 2022-04-17 19:13:14

Fatigue Performance of Superimposed T-girders under Cyclic Overloading: an Experimental Study

superimposed T-girders, fatigue, new-old concrete interface, interface debonding, shear key

The wet connection method is widely used in construction of superimposed prefabricated concrete structures. Existing studies have proved that interfaces between the prefabricated layer and the cast-in-place layer significantly affect the static structural performance of superimposed reinforced concrete (RC) girders, while little has bene known about the fatigue performance. The objective of this study is to investigate the low cycle fatigue behavior of superimposed T-shape prefabricated RC girders under hogging moment induced by high-stress level cyclic load. In total 15 superimposed T-girders with three different interface connection configurations were tested. The failure mode, cracking and deflection behavior, steel strain development and the new-old concrete interfacial deformation were recorded and analyzed. It was found that the fatigue life of the superimposed T-girders is significantly reduced by the debonding of interface between the cast-in-layer and pre-cast layer concrete, although the eventual failure is still governed by the fracturing of tension reinforcement. As a result, the interfacial connection configuration plays a critical role in preventing such debonding failure. The corresponding debonding mechanisms were clarified through analyzing the histories of measured interfacial slips and steel strains.