| The glued-in rods connection of timber structure can be applied to beam-column joints,column-foundation joints,and reticulated shell joints and so on.In order to improve the load capacity and energy dissipation capacity of the joints,domestic and foreign scholar have proposed to add energy-consuming connectors,or to use reinforcement/strengthening materials,among which FRP materials are more economical and operable.The glued-in rods connection is not limited to beam-column joints,but can also be considered for beam-beam splicing joints.However,there are relatively few studies on FRP-reinforced joints at this stage.In the experimental study of existing FRP to reinforced glued-in rods joint,it is found that the role of fiber cloth on each surface is different.It is necessary to systematically study whether only the local surface can be pasted under the condition of meeting the target bearing capacity,and how the fiber cloth pasted on different parts cooperates with the original glued-in rods joints or components.In view of the above problems,this paper chooses GFRP sheet,which has a comprehensive advantage over CFRP sheet in glued laminated timber specimens,as the reinforcing fiber material.By means of numerical simulation and experiment,after discussing the cooperative force between GFRP and glued-in rods in beam-beam glued-in rods splicing joints,analyzing the influence of local bonding mode on the mechanical performance of glued-in rods beam-column joints.The main contents are summarized as follows :(1)In order to research the bending performance and shear performance of the section,the beam-beam splicing flexural members are selected as the research object.The numerical simulation method is used to systematically analyze the stress state of each part of the splicing joints.The finite element analysis results are preliminarily checked by the theoretical calculation of the flexural bearing capacity of the simple glued-in rods splicing beam.It is found that although the three-sided reinforced type greatly improves the bearing capacity and reduces the stress of GFRP,the glued-in rods fails to give full play to the bearing capacity and the deformation capacity is also reduced.The bottom reinforced effect is the worst.(2)On the basis of finite element analysis,monotonic loading tests were carried out on simple glued-in rods splicing beams and three kinds of local GFRP reinforced glued-in rods splicing beams,and the failure mode,load-displacement curve and glued-in rods stress of the specimens were compared and analyzed.The experimental phenomena and results show that the bearing capacity of the bottom reinforced joints and the two sides reinforced joints is basically the same as that of the simple glued-in rods splicing joints,and the bearing capacity of the three sides reinforced joints is the largest.(3)In view of the deviation between the previous finite element analysis and the test results,considering the influence of adhesive layer cracking,the model change technology is used for further analysis.The improved bearing capacity is close to the test results,and then it is confirmed that the deviation of bearing capacity mainly comes from the bond slip between wood and glued-in rods.On this basis,the stress distribution of the beam section when the joint is destroyed is further analyzed.It is concluded that the bonding of GFRP will increase the height of the compression zone of the beam section,the normal stress of the glued-in rods is reduced,and the shear stress of the whole beam section is significantly lower than that of the simple glued-in rods joint.(4)Combined with the existing research using GFRP reinforced beam-column glued-in rods joints,three kinds of GFRP bonding styles are used to establish finite element models.The changes of joint bearing capacity,glued-in rods stress and GFRP sheet stress under monotonic loading are analyzed,and compared with the synergistic stress of spliced glued-in rods beams.The results show that the reasonable local bonding of GFRP can make it effectively cooperate with the glued-in rods,and the three GFRP bonding methods can slow down the stress growth of the glued-in rods.Considering the deformation capacity,economy and construction convenience,the reinforced type on both sides has more advantages,and has less influence on the deformation capacity of the joint when pasting two layers.Therefore,it is suggested that two layers of GFRP fiber sheets should be used to strengthen the beam-column joints of glued laminated timber by sticking on both sides. |
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