Experimental Investigation of Out-of-Plane Seismic Behavior of Precast Composite Sidewalls of Utility Tunnels with Grouted Sleeve Joints

The precast composite utility tunnel is a semi-precast structural system that combines the advantages of both cast-in-place and prefabricated construction, provides superior impermeability and a shorter construction period, and therefore holds broad potential for engineering applications. To investigate the seismic performance of precast composite sidewalls of utility tunnels with grouted sleeve joints under out-of-plane loading, a series of out-of-plane cyclic loading tests were conducted on the full-scale precast composite and monolithic cast-in-place sidewall specimens. The influences of axial compression ratio of the sidewall and joint height from the bottom slab on the out-of-plane performance of the precast composite sidewalls were also considered in this experimental study. The test results indicate that the seismic performance of precast composite sidewall specimens with grouted sleeve joints is essentially equivalent to that of cast-in-place sidewall specimens, satisfying the seismic design requirement for prefabricated structures. Both specimen types exhibited fundamentally similar crack development patterns, characterized by horizontal flexural cracks in the out-of-plane direction and diagonal shear cracks in the in-plane direction. With increasing axial compression ratios, all specimens showed reductions in cumulative hysteretic energy dissipation, equivalent viscous damping, and ductility coefficients. Compared to the precast composite specimens with 150-mm joint height, the precast composite specimens with 300-mm joint height demonstrated a 4.41% enhancement in energy dissipation capacity and a 6.85% reduction in ductility coefficient. Residual deformation assessment based on residual crack width and displacement angle revealed that both cast-in-place and precast composite sidewall specimens with 150-mm joint height met the repairability criteria at an interstory drift ratio of 2.0%. In contrast, precast composite sidewall specimens with 300-mm joint height exceeded both limits at the same drift level. An increase in the joint height leads to greater residual deformation in the precast composite specimen and aggravates the extent of structural damage.