BFRP布加固巴掌榫墩接木柱轴压性能研究

Study on axial compression performance of palm-tenon spliced timber columns reinforced with BFRP sheets

为研究BFRP布加固巴掌榫墩接木柱(简称“加固木柱”)的轴压受力性能,对10个木柱进行轴压试验,包括7根不同BFRP环箍层数和纵带层数的墩接柱、1根刻半榫墩接柱与2根完好木柱;分析加固木柱的破坏特征、荷载-变形曲线,对比加固前后木柱的失效模式、应变状态、承载力、刚度、延性等;提出适用于木构件的名义屈服点确定方法,以准确计算其位移延性系数。结果表明:BFRP环箍与纵带加固柱的墩接区整体性良好,承载力和刚度可恢复至完好木柱的80%~90%,延性提高9%~90%,加固后木柱具有良好的受力性能;按ESEP法确定的名义屈服位移合理可靠,可用于木柱屈服点的确定。建立数值仿真模型,在验证模型有效性的基础上,针对墩接高度、墩接长度对加固木柱的影响展开参数分析。结合参数分析结果,推导得到FRP加固巴掌榫墩接木柱轴压承载力计算公式。有限元分析表明,承载力随墩接高度的增加而减小,墩接长度对承载力影响较小;承载力公式计算值与试验值最大误差为12.1%,可为木结构建筑的修缮提供参考。

In order to study the axial compression performance of palm-tenon spliced timber columns reinforced with BFRP sheets(referred to as the reinforced timber column),the axial compression test was carried out on 10 specimens,including seven splicing columns with different number of BFRP transverse and longitudinal fiber layers,one ke-ban splicing column and two intact timber columns.The failure characteristics and load-displacement curves of the columns were analyzed,and a comparison was made between the before-and after-reinforcement columns for the failure mode,strain state,bearing capacity,stiffness and ductility.In order to accurately calculate the displacement ductility coefficient of timber components,the ESEP method was proposed to determine the nominal yield point of timber column.The results show that the integrity of the splicing area is good for the specimens with composite reinforcement of BFRP,and the ultimate bearing capacity and stiffness of reinforced timber columns can be restored to 80%-90%level of intact timber columns,as well as ductility can be increased by 9%-90%.This indicates that the reinforced timber columns have good mechanical performance.The nominal yield displacement determined by ESEP method is reasonable and reliable,which can be used to determine the yield point of timber components.Furthermore,a numerical simulation model was established,and the validity of the model was verified by the experimental results.Based on the model,the effect of splice height(hd)and splice length(ld)on the reinforced timber column were analyzed.A calculation formula was derived for the axial compression capacity of the reinforced timber column.The finite element analysis shows that the bearing capacity decreases with the increase of hd,and ld has little effect on the bearing capacity.The maximum error between the calculated value and the test value is 12.1%.The formula proposed in this paper can provide reference for the retrofitting of timber structures.