timber underframe

例句：

1. 1.The construction of the bridge was supported by a timber underframe.
   这座桥的建设得到了一个木结构的下框架的支持。
2. 2. The new building is designed with a timber underframe that can withstand heavy loads.
   这座新建筑采用了一种可以承受重负载的木结构下框架设计。
3. 3. The engineers used a timber underframe to reinforce the foundation of the building.
   工程师们使用了一个木结构下框架来加固建筑物的基础。