Finite Element Study On A New Type Of Single-layer Timber Reticulated Shell Joints Considering Installation Error

With the advancement of factory manufacturing and modern connection technology,the role of wood structures in modern architecture is becoming more and more important.In order to meet the needs of the diversity of modern timber structure forms,new structural forms and new joint connections are still the current research hotspots.Representative of modern wood-framed buildings is a large-span wooden structure.Its design is diverse in shape,and it has received much attention in China in recent years due to its characteristics of environmental protection and wood fragrance.From the application examples at domestic and foreign,the single-layer timber reticulated shell joint connection mechanism contains heavier steel connector.On the one hand,the large amount of steel exposed causes the overall shape to be not beautiful enough.On the other hand,the excessive steel consumption leads to insufficient utilization of mechanical properties of materials.Our research group designed a new type of prefabricated single-layer wood mesh shell joint with pin connection,which has the characteristics of curtailing the use of metal materials,reducing the weight of the joint,decreasing the exposure of steel,and simplifying the appearance.Because the error during construction or installation is difficult to avoid.The new type of timber reticulated shell joint is proposed by the research group,in this thesis it is researched by numerical simulation method,and the influence of installation error on the mechanical performance is considered.This research is an important supplement to the experimental research,and it may provide a research foundation for determining the allowable installation error in the future.It has theoretical significance and practical value.The main work and conclusions are as follows:(1)The new reticulated shell joint(hereinafter referred to as "pre-improvement node")consists of "1 continuous timber member+ 4 non-continuous timber members + irregular steel connector".Two finite element models have been established that only consider the effects of weakening about the wood material near the hole.The finite element models consists of a joint model D1,the weak shape is a rectangle with a range four times the hole diameter,and joint model D2,the weak shape is a rectangle with a range twice the hole diameter.The finite element analysis results of the axial force applied to the member ends of the joints show that the simulation results of the two models are quite different from the experimental results.It is indicated that there are other factors affecting the mechanical performance of the joints,which is presumed to be installation error.(2)Consider the installation error effect analysis to improve the stress performance of the joint.During the modeling,a forced horizontal displacement perpendicular to the axial direction is applied to the end of the discontinuous wood components to reflect the rotation caused by the installation deviation.The results of finite element analysis of axial force performance show that the results of the unconstrained error are more consistent with the axial compression test results,and the D2 model is more consistent with the D1 model.On this basis,the finite element analysis of the bending performance of the D2 model is carried out.The results show that the stress of each part of the joint does not reach the allowable stress,and the joint will not be damaged under the design of the bending moment.(3)In combination with the improvement of the destruction phenomenon in the front joint axial compression test,an improved solution is proposed,that is,the continuous wood components in the front joint is cut in the middle to release the additional torque caused by the installation deviation during the loading process.The finite element analysis of the axial compression behavior is considered in the same way as the pre-reformed joint.The results show that the axial bearing capacity of the joint is improved before the improvement,which provides theoretical support for the subsequent axial compression test.(4)Combined with the installation deviation in the physical test,the forced horizontal displacement is applied to the end of the discontinuous timber member of the improved finite element model,but the value is different from the deviation considered for the improved joint.Comparing the finite element results with the experimental results,it is found that there are some differences.The main reason is that the gap between the 5 and 6 member has not been considered.In the future research,the installation error should be considered in many aspects.