In Japan, fire-resistant wooden construction using “sacrificial layer design,” which is generally accepted in Europe, is not permitted. Instead, fake fire-resistant timber construction has been developed by covering timber with plasterboard and finishing it with a thin wood layer. A more rational approach is to finish steel or reinforced concrete (RC) structures with wood. Therefore, a hybrid structure combining RC and timber (CLT) was developed.
The columns consist of CLT panels forming a box-shaped section used as formwork for concrete casting. Under normal conditions, the RC core supports the building, while during earthquakes, the combined CLT–RC columns resist lateral forces. Floors are also made by casting concrete over CLT panels, allowing each panel to serve as structure, formwork, and finish. Using CLT for slabs reduces temporary supports and enables earlier work on lower floors.
