UC San Diego

Architectural precast concrete (APC) cladding is a type of building façade composed by concrete panels separated from each other by joints and attached to the building structure with steel connections. Seismic damage to this component has been observed in past earthquakes, it is costly and time consuming to repair, and, importantly, it can be life threatening. APC cladding is unique among nonstructural components, since its heavy concrete panels span from floor to floor. As a result, this system is uniquely sensitive to both interstory drifts and floor accelerations. However, only few experimental or analytical programs have specifically focused on this type of façade. Since knowledge regarding the seismic behavior of APC façades is limited, design code prescriptions are relatively qualitative and do not accurately consider the many features of the system.

The first part of this dissertation aims to provide guidance to practitioners to improve the drift-compatible design of APC cladding. Results are based on three experiments: one system level experiment in which sixteen panels were installed on a full-scale building and two component tests on tieback connections. The combination of the results from these tests provided information on the how to improve the detailing of tieback connections to create the optimal compromise between good seismic performance and constructability. In addition, this part of the dissertation includes a one-of-a-kind study of a new type of corner system allowing for smaller corner joints thanks to a ductile fuse.

The second part of this dissertation presents an analysis of the accelerations developed in the APC cladding during seismic motions. This analysis is based on numerical models validated using data from the system level experiment. Initially, the dynamic characteristics of the APC cladding are analyzed using models of the panels and connections. Subsequently, the APC cladding is included in a building model, with the goal of determining the amplification of accelerations in the panels during service and design level motions. The study revealed issues in the way the panels are currently designed to resist seismic forces.