Investigating the Behavior and Reliability of Eccentrically Loaded Steel Connections Made with Bolts and Welds in Combination

Abstract

This paper investigates the behavior of eccentrically loaded connections made by combining fillet welds and high-strength pretensioned bolts. New models are introduced for characterizing the load-deformation behavior of slip-resistant bolted connections with different faying surface conditions. These models are utilized to improve the ability of the instantaneous center of rotation (ICR) method to predict the capacity of eccentrically loaded connections utilizing friction as a load-transfer mechanism including bolted-only and/or bolted-welded combination connections. Experimental results are used to quantify the accuracy of the ICR method in predicting the capacity of these combination connections considering different connecting elements to be participating in a single load resisting system. Finite-element (FE) analysis is used to investigate the load-transfer mechanisms within the combination connections. Reliability analysis is conducted using FE analysis assisted by machine learning to quantify the reliability level of the investigated connections and establish the resistance factors necessary to maintain the reliability level above prescribed thresholds. The reliability analysis shows that using the ICR method for designing these combination connections leads to a highly reliable connection for different types of faying surfaces.