  Historic structures are important for our society but could be prone to
structural deterioration due to long service durations and natural impacts.
Monitoring the deterioration of historic structures becomes essential for
stakeholders to take appropriate interventions. Existing work in the literature
primarily focuses on assessing the structural damage at a given moment instead
of evaluating the development of deterioration over time. To address this gap,
we proposed a novel five-component digital twin framework to monitor
time-varying changes in historic structures. A testbed of a casemate in Fort
Soledad on the island of Guam was selected to validate our framework. Using
this testbed, key implementation steps in our digital twin framework were
performed. The findings from this study confirm that our digital twin framework
can effectively monitor deterioration over time, which is an urgent need in the
cultural heritage preservation community.
