Journal Article

Seismic Behavior of External Socket Connections for Reinforced Concrete Columns

Samayoa, Julio A, Proestos, Giorgio T, Kowalsky, Mervyn J

2026

Overview

This study uses six large-scale experimental tests to investigate the seismic behavior of external socket connections for reinforced concrete columns. The tests evaluated the effects of key design parameters, including socket height and grout strength, on the performance of these connections under reverse cyclic lateral loads. The results indicate that socket height significantly affects whether the plastic hinge forms in the column above the connection or inside the socket and influences the required strength of the structural components. Shorter socket heights required higher grout strengths and increased shear capacity to avoid undesirable failure modes. Three primary failure modes were observed: grout crushing, shear failure, and flexural failure above the socket. Regardless of socket height, all tests showed that external socket connections effectively protect adjoining structural members by limiting plastic strain demands. These findings provide valuable insights into optimizing the design and performance of external socket connections in seismic regions. Keywords: accelerated bridge construction; external socket connection; large-scale tests; reinforced concrete column, seismic design; seismic performance.

• Publisher: American Concrete Institute
• Subject: Bridge construction / Bridges / Concrete / Concrete columns / Cyclic loads / Design optimization / Design parameters / Earthquake resistant design / Energy dissipation / Failure modes / Grout / Highway construction / Lateral loads / Plastic deformation / Plastic properties / Plasticity / Reinforced concrete / Seismic response / Sockets / Structural members