Effects of Wall‐to‐Floor Interactions on Seismic Response of Platform‐Type CLT Buildings

ABSTRACT Platform‐type cross‐laminated timber (CLT) buildings feature discontinuous wall segments supported by CLT floors. In practice, CLT floors are often treated as rigid diaphragm, yet the wall‐to‐floor interactions (WFIs) associated with flexibility of floors remain insufficiently investigated during seismic performance assessment. This study addresses this gap through a rigorous and validated modelling framework. A beam‐spring shear wall model is first developed, benchmarked against experimental data of shake table test on a three‐story CLT building to demonstrate the measurable influence of WFIs on global drift and local connector responses. The modelling framework is subsequently extended to a six‐story CLT building where nonlinear dynamic analyses were conducted at two intensity levels. The responses from a shell‐based floor model were compared to those from a counterpart model employing an idealized rigid floor (RF) representation. Specifically, the shell‐based model exhibited 90%–120% larger median drift with consistently greater dispersion at mid‐height stories; its hold‐down (HD) deformation showed pronounced height‐dependent amplification, with interior connectors at upper stories experiencing more than twice that of the RF model. Likewise, the cumulative connector energy per story reached roughly two to three times the value of the RF model, which by contrast remained strongly base‐dominated. Additionally, correlation analysis further demonstrated a stronger and more consistent global‐local relationship between drift and HD uplift when WFIs are considered. These findings confirm that WFIs represent a significant system‐level mechanism in platform‐type CLT buildings and should be explicitly incorporated into seismic analysis and design practice.