木结构螺栓连接试验研究及承载力设计值确定

Experiments of load-carrying capacity of bolted connections in timber structures and determination of design value

现行木结构设计规范只规定了相同强度等级木构件螺栓连接承载力的计算方法,不能满足工程实践中连接不同强度等级木构件的需要。采用东北落叶松和樟子松木材,分别进行了销槽承压试验和螺栓连接性能试验。试验验证了欧洲销连接屈服模式,并证明了在我国规范中螺栓连接设计考虑圆钢销塑性不充分发展的假定更符合实际情况。提出了销槽承压有效长度系数及螺栓连接承载力建议计算式,并引入了钢材的弹塑性强化系数,以体现钢材特性对承载力的影响。在保持与现行木结构设计规范可靠度一致的条件下,对螺栓连接的承载力设计值进行了校准,得到了对应于各种屈服模式的抗力分项系数。所提出的螺栓连接承载力建议计算式能用以计算不同强度等级木构件螺栓连接的承载力,且与现行规范的计算结果基本一致。

The calculations of the load-carrying capacity of bolted connections specified in the current code for design of timber structures apply only to connections of members made of wood of the same strength class. They do not apply to the connections of members made of wood of different strength in engineering practice. Tests of dowel-bearing strength of wood and tests of load-carrying performance of bolted connections were conducted using wood of northeast larch and pinus sylvestris var. mogonica,respectively. The European yield modes of dowel-type connections were verified,and the incomplete development of steel plasticity assumption,which has been used in the Chinese code,was proved the most suitable. The coefficient of effective compression length of dowel-bearing was developed and the equations to calculate the load-carrying capacity of bolted connections were proposed,in which an elasto-plastic coefficient was introduced to deal with different steel properties. In accordance with the reliability of the current design code,the design value of the load-carrying capacity of bolted connections was calibrated,and the partial safety factors with respect to different yield modes were obtained. The proposed equations can be used to predict the load-carrying capacity of bolted connections of members made of wood of different strength,and the results of the prediction are basically consistent with the current design code.