传统民居抬梁式木构架抗侧力性能试验研究

Experimental Study on Lateral Performance of Post-and-Lintel Timber Frame in Traditional Residences

为了解北方地区传统民居抬梁式木构架的抗震性能,制作了三榀足尺木构架模型,开展了低周往复的拟静力抗侧试验,研究木构架的受力特征、滞回曲线、骨架曲线、强度和刚度的退化、耗能规律等,揭示不同柱基础及荷载条件对木构架抗侧力性能的影响.研究结果表明:馒头榫连接的木构架是一种变刚度的摇摆体系,主要的表现形式为柱脚翘起,馒头榫节点的拔榫量;木构架竖向荷载下存在明显的P-Δ二阶效应,该影响不可忽略;在大变形下由于二阶效应不能自己复位,主要借助外部荷载进行复位;允许柱脚滑移使木构架在低周往复水平荷载下表现出更为明显的摇摆特性,相比柱脚限制的情况耗能能力减弱,捏拢效应更为严重,但在一定程度上保护馒头榫节点;竖向荷载增大有助于提升木构架的抗侧性能;作为山墙位置的木构架竖向荷载偏小,容易导致木构架的抗侧承载力与耗能能力不足.研究成果将为北方传统村落"四梁八柱"木结构民居抗震性能的评估、修缮与加固提供科学依据.

To understand the seismic performance of post-and-lintel timber frame of traditional residences in north China’s villages,three full-scale specimens based on the prototype were fabricated and tested subjected to pseudo-static cyclic lateral loading.The seismic performances of the timber frames(including the mechanical characteristics,the hysteretic and skeleton curves,the strength and stiffness degradation,and energy dissipation)were studied and the effects of various pedestal and loading conditions on lateral force resisting performance of timber frames were revealed.Results show that the wooden frame is a rocking self centering system with variable stiffness.The timber frames behave the uplift of column foot and obvious deformation of joints with pulled-out Mantou tenons.The P-Δeffect of the timber frame subjected to the vertical load is obvious and it cannot be ignored.The wooden frame in large deformation situation cannot self center and it can restore the original position relying on external loads to great extents.The timber frame in the condition of allowance of column foot to slip behaves obviously rocking characteristics subjected to cyclic loading with lower energy dissipation,more serious pinching effect,compared to those in the condition of column foot limitation.However,the timber frame in the condition of allowance of column foot to slip can preserve Mantou mortise-tenon joints to some extent than that of the condition of column foot limitation.The increase of the vertical load is beneficial to improve the lateral resistance of the timber frame.The timber frame at the place of the gable wall is easier to lead into the insufficiencies of the lateral resistance capacity and energy dissipation capacity,due to low compression loads from roof weights.The research results will provide a scientific basis for the seismic evaluation,repair and reinforcement of the"four beams and eight columns"wooden residences in north China’s villages.