A STUDY OF STRUCTURAL STABILITY IN TRADITIONAL WOODEN BUILDINGS

1.结构稳定性考虑1)本堂式：屋架内部构件间距较大，便于支撑屋檐的重量。2)双层塔式：显然，这种结构往往不稳定，因为屋檐与宝塔核心的跨度相比很长。而支撑屋檐的构件则构成了四根对角梁的内外一套，由横置在双方梁布置上的十字形支架支撑。这种对称的结构给建筑带来了巧妙的平衡。3)门（门）型：与柱子的跨度相比，屋檐很长，特别是在飞鸟和奈良时期建造的建筑物中。屋架内部没有空间支撑屋檐，上部结构容易打滑，导致屋檐下垂。传统木结构建筑受水平力（台风、地震）破坏的原因1)屋顶结构与基础结构的重量不平衡2)板条的存在3)基础的性质4)下垂的偷听。挠曲应力单位的变化挠曲应力单位的计算方法是将顶板结构自重引起的柱周围弯矩除以构件的总截面模量。这个值在以后的时期会减少。随着弯曲应力单元的减小，结构变得更加稳定。

1.Consideration of structural stability1)Hondo(Main hall of temple)type : Members inside the roof truss are widely spaced to easily support the weight of the eaves.2)To(Storied pagoda)type : Apparently this type of structure is often unstable because the eaves are long compared with the span of the core of the pagoda. But members which support the eaves form an internal and external set of the four diagonal corner beams are supported by cross shaped trestle wresting on double square arrangement of beams. This symmetrical structure gives the building a skillful balance.3)Mon(gate)type : The eaves are long compared with the span of the pillars especially in the buildings constructed in the Asuka and Nara periods. There is no space on the inside of the roof truss to support the eaves, so the upper structure tends to slip so that the eaves droop.2.Cause of destruction of traditional wooden buildings by a horizontal force(Typhoon, Earthquake)1)Lack of balance between the weight of the roof structure and the understructure2)Existence of battens 3)Nature of foundations 4)Drooping eaves3.Cange of bending stress unitThe bending stress unit is calculated by dividing the bending moment around the pillar incurred by the weight of the roof structure by the total section modulus of the members. This value is reduced in later periods. As the bending stress unit became less the structure became more stable.