Timber trusses

Roof trusses in Europe appeared al list in the Roman era and are in use until now adays. Various styles of trusses are discussed in this work. The investigation here concentrated on the differences between ‘open truss’ to ‘close truss’. Backed with computerized simulation, it was found that ‘close truss’ has a significant advantage of about 30% over the ‘open truss’ truss. An offer for the evaluation of the truss was presented and as well as explanation for changing back from ‘close truss’ to ‘close truss’ started in the mid-18th century.欧洲的屋顶桁架（roof trusses）最早可追溯至罗马时代，且至今仍在工程中应用。本研究探讨了多种桁架形式，重点聚焦于空腹桁架（open truss）与实腹桁架（close truss）之间的性能差异。借助计算机模拟手段，研究发现实腹桁架相较空腹桁架具备约30%的显著优势。本研究不仅提出了桁架性能评估方案，还解释了18世纪中期开始出现的从空腹桁架回归实腹桁架的现象。