Reliability Analysis of Lateral Bracing Forces in Metal-Plated Wood Trusses

This paper presents a reliability study of metal-plated (MP) wood truss webs laterally braced by single or double braces, and the results provide a reference for amending relevant prescriptions in truss design codes. The objectives of the study were to: (1) characterize specific random variables that are involved in the single-braced or double-braced MP truss web systems; and (2) conduct reliability-based analyses to quantify the bracing forces of such systems based on the characterized random variables. Experimental studies were performed to evaluate one of the random variables, namely the out-of-plane rotational stiffness of the MP connection. Moreover, three-dimensional numerical models were constructed to simulate the structural responses of the single-braced and double-braced truss web systems subjected to eccentric loads applied. Reliability analyses were then performed using response surface method. Results of the reliability analyses show that the conventional 2% rule is conservative and a rational lateral-to-axial-load ratio of 1.25% may provide MP truss bracing designers a supplement solution when MP truss joints are fabricated in compliance with the relevant manufacturing and handling provisions and other system stability implementations (e.g., roof sheathing and diagonal bracing) are present.