Improving the mechanical characteristics of semi-rigid saddle connections

Abstract

There are many steel structures in Iran with semi-rigid saddle connections. It has been observed that, during a strong earthquake, this type of connection can experience a premature fracture, which will endanger the stability of the structure. The present study endeavored to improve the mechanical characteristics including the initial stiffness, yield moment, maximum moment, crack rotation, and load transfer mechanisms of the conventional saddle connections using retrofitting methods. An experimental study was conducted on six full-scale specimens to study the effect of the retrofitting methods on the stiffness, yield moment, and maximum moment of the connection and for the prevention of premature fracture. A numerical study including 88 high-fidelity finite element models was conducted to further evaluate two selected retrofitting methods. Using the generated database, predictive expressions have been proposed for calculating the initial stiffness, yield moment, and crack rotation. The proposed retrofitting methods were shown to improve the mechanical characteristics of conventional saddle connections.