唐代斗栱与清官式斗栱的挑檐性能对比——兼论斗栱演变的力学因素

Comparisons of Overhanging Performance of Dougong in Official Buildings in Tang and Qing Dynasties——On the Mechanic Elements of the Evolution of Dougong

本文设计了唐代斗栱与清官式斗栱简化模型,应用力学领域的有限元模拟方法,并开创性地应用数字图像相关实验方法,以模拟和实验两种方式获得了斗栱模型在竖向载荷产生的弯矩下关键构件的角刚度,进而定量对比了唐代斗栱与清官式斗栱的挑檐性能。模拟结果显示,唐代斗栱角刚度比清官式斗栱高约一倍;清官式斗栱模型的实验结果与有限元模拟基本吻合,其承力模式较为简明;而唐代斗栱模型的实验结果表现出了特殊的粘连-锁死区效应,其角刚度也远小于模拟结果。以上结果说明,从唐代到清代,斗栱的演变出现了两种趋势:其一是挑檐性能难以强化,其二是承力模式趋于简化。基于这些定量结果,本文总结出斗栱形制演变中的两个重要线索,对进一步探寻斗栱演变的推动力具有一定的启发意义。

This paper designs and applies simplified models of the Dougong in the Tang and Qing dynasties,using the Finite Element Method and a pioneering experimental method that measures displacement field with DIC,as well as simulation and experiment,to obtain the angular stiffness of the key components of the Dougong model under the bending moment caused by vertical load,and quantitatively compares the mechanical properties of Dougong in Tang and Qing dynasties from the perspective of supporting eaves.The simulation results show that the angular stiffness of Dougong in Tang dynasty is about twice as high as that of Dougong in Qing dynasty.The experimental results of the model of Dougong in the Qing dynasty are basically in agreement with the results of finite element simulation,and the bearing mode of Dougong in Qing dynasty is concise.The experimental results of the model of Dougong in the Tang dynasty show a special adhesion-locking zone effect,and the angular stiffness of Dougong in the Tang dynasty is also much smaller than the simulation results.The above results show that from Tang to Qing dynasties,there are two trends in the evolution of Dougong:one is that it is difficult to strengthen the performance of cornice,the other is the simplification of the bearing mode.Based on these quantitative results,this paper summarizes two important clues in the evolution of Dougong,which has certain enlightening significance for further exploring the driving force of the evolution of Dougong.