This study adopts a combined approach of full-scale local test and numerical simulations to clarify our understanding of the axial damage modes of grouted connections. A modified finite element model is used to examine the influence of shear key height and spacing on the overall mechanical performance and failure patterns of grouted connections

aimed to provide a basis for optimized designs. The results indicate that the axial ultimate bearing capacity manifests limited variation with the shear key spacing

but vertical displacement is more sensitive to it. A small spacing tends to induce localized inclined cracks

while a large one may lead to brittle damage. Shear key height significantly influences the load-bearing mechanism and stiffness of the connection structure; at its minimum

the bearing capacity is relatively low. Its variation imposes a considerable effect on damage distribution and damage modes

but little on primary damage angles

reducing the performance of the connection structure if it is excessively small or excessively large. With a comprehensive consideration of the strength

ductility

failure mode

stress distribution

and construction cost

we recommend the shear key spacings suggested by API and HSE

and the shear key height ranges by NORSOK and ISO.