UC Berkeley

Failure of nonstructural components during an earthquake can cause widespread property damage, lead to lengthy downtime of the structure, and pose a life-safety threat to the occupants. Current code provisions aim to minimize the life safety threat by specifying lateral force demands and anchoring requirements. These code requirements are based on a simplified equation that does not fully consider the component attachment’s contribution to its overall dynamic response. Research suggests that the component attachment is an important parameter that determines its dynamic properties. Most analyses of the dynamic response of floor-anchored nonstructural components use an idealized single-degree-of-freedom system with a concentrated mass. Nonlinear behavior is included in the component force-displacement relations while the boundary conditions remain fixed based to the floor. Assuming a nonlinear behavior of the attachment changes the fixed-based boundary conditions and results in uplift at the base of the model. Models that include uplift at the base can be found for analysis of rocking structures and soil-structure interaction, but are rarely applied for analyzing nonstructural components. This dissertation focuses on acceleration-sensitive equipment and examines the attachment design of floor-anchored mechanical and electrical nonstructural components. The dissertation includes three parts. (i) An extensive experimental shaking-table test study of a nonstructural experimental model that is attached via several attachment designs to a concrete slab. The experimental results demonstrate that the selected attachment properties govern the boundary conditions of the nonstructural component and strongly influence its dynamic response. (ii) A mechanics-based numerical modeling approach for floor-anchored nonstructural components attached via steel channel connections. It defines a generalized analytical approach to estimate the force-displacement relations of the attachment and offers a simple approach for the engineer to estimate the contribution of the attachment design to the dynamic amplification of the component. (iii) A numerical study that examines the mechanics-based modeling approach with a wide range of input motions, component parameters, and attachment properties.