Experimental Study On Eccentric Compression Of Xinjiang Poplar Columns Reinforced With BFRP

Xinjiang poplar resources are relatively rich,is one of the main local tree species in Xinjiang,widely distributed in Xinjiang.Xinjiang poplar has the characteristics of drought tolerance,light-loving and fast-growing wood,which can meet the requirements of timber construction.However,Xinjiang poplar has the disadvantages of easy cracking and low strength,which may have certain safety risks in the use of timber structures.Therefore,it must be strengthened and repaired before it is used.At present,scholars at home and abroad mainly focus on the mechanical properties of wood columns of a few species such as pine and Chinese fir under axial compression.However,there are relatively few studies on the mechanical properties of Xinjiang poplar reinforced by BFRP under eccentric compression.Therefore,this paper firstly collects and sorts out the basic mechanical properties of three domestic tree species.Secondly,it carries out testing in shearing strength parallel to grain of Xinjiang poplar and the eccentric compression test of Xinjiang poplar wood column strengthened with BFRP,and obtains the eccentric compression bearing capacity formula related to the eccentricity.The main research work and results are as follows:Taking eccentricity as variable,the eccentric compression test of unreinforced Xinjiang poplar columns was carried out,and the failure mode,load-displacement curve,load-longitudinal strain curve and ultimate bearing capacity were analyzed.The results show that the typical failure modes of axial compression and bias compression timber columns are mainly bending failure,but the failure processes are different.Under the action of different bias loads,the variation law of the cross-section strain in the middle of Xinjiang poplar column along the height of the cross-section basically satisfies plane section assumption.With the increase of eccentricity,the decreasing amplitude of ultimate bearing capacity shows a decreasing trend,and the relative eccentricity reduction coefficient in the calculation formula of bias bearing capacity is fitted,and the calculated results are in good agreement with the experimental results.Taking BFRP reinforcement mode as variable,the influence of BFRP reinforcement mode on mechanical properties of Xinjiang poplar columns under eccentric compression was studied.The failure mode,load-displacement curve,load-longitudinal strain curve and ultimate bearing capacity and ductility of Xinjiang poplar columns strengthened by BFRP were mainly analyzed.The influence of three different BFRP reinforcement methods on the eccentric compression performance of Xinjiang poplar columns was analyzed from the ultimate bearing capacity and ductility indexes,and the results showed that the optimal reinforcement effect of Xinjiang poplar columns was obtained by sticking longitudinal strips on the tension side and sticking one layer of BFRP on the whole side.Based on the effect of the optimal reinforcement method,the eccentric compression tests of Xinjiang poplar columns strengthened by BFRP under different eccentricities were carried out,and the failure modes,load-displacement curves,load-longitudinal strain curves,ultimate bearing capacity and ductility of Xinjiang poplar columns strengthened by BFRP were analyzed.The results show that the variation law of the cross section strain in the middle section of Xinjiang poplar column strengthened by BFRP meets plane section assumption basically.Compared with unreinforced Xinjiang poplar columns,the ultimate bearing capacity and ductility of BFRP reinforced Xinjiang poplar columns increased by 7.69%-14.71% and4.46%-39.71%,respectively.