Mechanical performance of early-age corbels in composite plate utility tunnels: Experimental and numerical study

Abstract

This study investigates the mechanical performance of early-age corbels in composite plate utility tunnels, designed to meet assembly and modularization requirements for nuclear power projects. To reduce construction time, precast slab are installed when the sidewalls' concrete (including corbels) have cured for seven days, and the top slab concrete must be poured later. This study used numerical simulation and static loading tests to examine the mechanical behavior of four early-age full-scale corbel specimens. with different longitudinal reinforcement anchorage forms and the presence or absence of stirrup configurations as primary parameters. The behavior of the tested specimens was discussed regarding the history of loading, damage patterns, load-deflection curve, toughness, and reinforcement strains. The results indicate that all specimens finally experienced flexural failure after going through the three stages of uncracked, working with cracks, and ultimate failure. The crack load, crack width, and crack development are mostly determined by the anchorage length and form of longitudinal reinforcements, which increased by 25.6 % after increasing the length. In contrast, the ductility and ultimate load of the specimens are significantly influenced by the stirrups. Compared to specimens without stirrups, those with stirrups exhibited an increase of up to 34.8 % and 15.3 % in ultimate load and a 152.4 % and 2.3 % improvement in toughness.