Compressive failure mechanism of ultra-high performance concrete with coarse aggregates with orthogonal reinforcements for predicting the bearing capacity: Experimental and numerical investigation

The local compression behaviors of ultra -high performance concrete with coarse aggregate (UHPC-CA) with orthogonal secondary reinforcement is crucial for the engineering popularization of UHPC-CA. Moreover, no normative provisions apply specifically to UHPC-CA, thus the relevant blanks need to be filled in. This paper focused on the performance investigation and strength evaluation of UHPC-CA with orthogonal reinforcement. Variations of concrete strength, local area aspect ratio and volumetric reinforcement ratio were utilized to explore the performance under various locations and types of local loads. The results indicated that the average initial cracking ratio under two types of local loads was 46.5 % and 38.3 %, respectively. The ductility failure mode was manifested, which was characterized by multiple vertical splitting cracks. Compared with the specimens under center local load, the imbalance of failure mode, cracking development and orthogonal reinforcement confining effect was exacerbated for the specimens under eccentric or strip local loads. The orthogonal reinforcement began to yield when reaching 60 %-80 % ultimate load, while more than 40 %-60 % steel measuring points entered the yield state at ultimate load. Regardless of the designed parameters, superior performances during the service phase and reliable safety reserve in the ultimate state were exhibited by UHPCCA with the novel orthogonal reinforcement configuration method. Furthermore, based on the tested results and finite element analysis, the failure mechanism was discussed, while reasonable strength prediction model was suggested.