Study On Static Characteristics Of Typical Chinese Dou-Gong Bracket

Ancient Chinese wooden frame building is a wooden building structure system with wood as the main building material,wood structure as the basic structural form,and beam-column frame system as the basic structural principle.A large number of wooden components are assembled into a whole ’ large wooden frame ’ to bear the load,and Dou-Gong is used as the key structural part and measurement unit to form an independent building structure system with unique external contour.Dou-Gong is a unique component of ancient Chinese wooden frame architecture,which plays an important role.It is a master of mortise and tenon connection,modulus system and assembly technology in ancient Chinese wooden frame architecture system.It has excellent mechanical properties.Its structural form and proportion are different from those of the past dynasties,and it has a clear development context and structural evolution law.In this thesis,seven types of Dou-Gong brackets are selected as the research object.Among them,the research of ’ Qing-style column head ’ is used as the basis of experiment and theory.The other six types of Dou-Gong brackets are selected according to the historical development order of Tang,Liao,Song,Yuan,Ming and Qing dynasties.Using the research method of combining structural form,simulation and structural test,the direction of coordinate axis of each Dou-Gong bracket type is clearly defined in this thesis.The vertical monotonic static loading is carried out on the Z axis,and the quasi-static loading under horizontal low cyclic loading is carried out on the Y axis and X axis.The overall static behavior of Dou-Gong bracket members,the internal force changes of key nodes and the internal force change of key components are systematically studied.The results of literature research show that the simulation technology based on finite element analysis can effectively analyze the static characteristics of Dou-Gong bracket after years of development and a large number of structural tests.Especially in the static behavior of full-scale model,it can not only avoid the high cost of specimen making,but also obtain the research results.For the structural test of the Dou-Gong scale model,the internal force variation characteristics of the key nodes and components when the Dou-Gong reaches the failure state can be obtained,which can effectively make up for the shortcomings of the simulation.The study obtained the following results:1.Construction form of Dougong : Combined with literature and field investigation,the experimental models of ’ Qing-style Dougong with three-liter Dou-Gong ’,the Dou-Gong of the main hall of Nanchan Temple in Tang Dynasty,the Dou-Gong of the mountain gate of Dule Temple in Liao Dynasty,the Dou-Gong of the main hall of Chuzu’an Temple in Song Dynasty,the Dou-Gong of Yanghe Building in Yuan Dynasty,the Dou-Gong of Konglinxiang Hall in Ming Dynasty,the Dou-Gong of No.7 tablet pavilion in Qing Dynasty were constructed.2.Dou-Gong bracket simulation:(1)The static structural behavior of the whole component: According to the simulation results,the variable stiffness linear elastic mechanics model on the Z axis and the hysteresis model on the Y axis and X axis of Dou-Gong brackets in Tang,Liao,Song,Yuan,Ming and Qing dynasties were established.According to the mechanical model,the key mechanical indexes of each bucket arch are calculated: at the strength level,the maximum horizontal thrust on the Y axis is Tang > Liao > Qing > Song > Yuan > Ming;the maximum horizontal thrust on the X axis is Qing > Ming > Tang > Song > Yuan >Liao.At the deformation level,the ultimate stiffness on the Z axis is Qing > Tang >Liao > Yuan > Song > Ming;the effective stiffness on the Y axis is Tang > Liao > Song >Qing > Yuan > Ming;the effective stiffness on the X axis is Song > Liao > Ming >Tang > Qing > Yuan.The ductility on the Y axis is Song > Yuan > Qing > Ming > Tang >Liao;the ductility on the X axis is Yuan > Song > Liao > Qing > Ming > Tang.At the energy level,the nonlinear coefficient on the Y axis is Ming > Song > Liao > Tang >Qing > Yuan;the nonlinear coefficient on the X axis is Song > Yuan > Liao > Qing >Ming > Tang.The equivalent viscous damping coefficient on the Y axis is Ming > Song >Qing > Liao > Tang > Yuan;the equivalent viscous damping coefficient on the X axis is Song > Yuan > Liao > Qing > Ming > Tang.In addition,the equivalent stress cloud map,equivalent elastic strain cloud map,strain energy cloud map,overall deformation cloud map and their maximum values of the static behavior of the six types of bucket arch models in the Z-axis,Y-axis and X-axis directions are obtained by simulation.(2)Internal force changes of key nodes: The equivalent stress nephogram and the maximum equivalent stress value of the first,second,third,fourth,fifth,first jumper and second jumper of the six types of Dou-Gong models in Tang,Liao,Song,Yuan,Ming and Qing Dynasties on the Z axis,Y axis and X axis were obtained.(3)Internal force changes of key components: The equivalent stress nephograms and the maximum equivalent stress values of seven key components of Dou-Gong bracket models of Tang,Liao,Song,Yuan,Ming and Qing dynasties on the Z axis,Y axis and X axis are obtained.3.Dou-Gong bracket structure test:(1)The static structural behavior of the whole component: When the test model is reduced to 60 mm,the ultimate bearing capacity on the Z axis is: Qing > Ming > Yuan >Song > Liao > Tang.According to the time sequence of Tang,Liao,Song,Yuan,Ming and Qing Dynasties,the damage of the components of the Dou-Gong has a tendency to increase gradually,and the damaged components gradually increase from the beginning to the upper part of the Dou-Gong,mainly concentrated in the middle of the Dou-Gong.(2)The internal force changes of the key nodes(the overall distribution of the stress/ strain curves of the six types of brackets): the first paving is linearly distributed on the Z axis,and the Y axis and the X axis are spindle-shaped.The second paving is spindle-shaped on the Z axis,Y axis and X axis.The third paving is linearly distributed on the Z axis,fusiformly distributed on the Y axis,and fusiformly distributed on the X axis.The fourth paving is linearly distributed on the Z axis,fusiform annular distribution on the Y axis,and annular distribution on the X axis.The fifth bedding is linearly distributed on the Z axis,fusiformly distributed on the Y axis,and irregularly distributed on the X axis.The first jump head is linearly distributed on the Z axis,Y axis and X axis.The second jumper is linearly distributed on the Z axis,and V-shaped on the Y axis and X axis.(3)Internal force changes of key components(the overall distribution of the stress /strain curves of the six types of bucket arches): the mudway arch is linearly distributed on the Z axis,V-shaped on the Y axis,and irregularly distributed on the X axis.The slow arch is linearly distributed on the Z-axis,fusiformly distributed on the Y-axis,and fusiformly distributed on the X-axis.Huagong is linearly distributed on the Z axis,and spindle-shaped on the Y axis and X axis.The two-layer Chinese arch is linearly distributed on the Z axis,V-shaped on the Y axis,and spindle-shaped on the X axis.Cotinus coggygria was linearly distributed on the Z axis,V-shaped annular distribution on the Y axis,and triangular annular distribution on the X axis.The bucket is linearly distributed on the Z axis and Y axis,and V-shaped on the X axis.The head is linearly distributed on the Z axis and the Y axis,and the X axis is dotted.4.The evolution law of static characteristics of Dou-Gong bracket(according to the time sequence of Tang,Liao,Song,Yuan,Ming and Qing):(1)From the strength level,the evolution law of the maximum horizontal thrust,the maximum stress value and the failure mechanism on the Z axis,Y axis and X axis are analyzed.Secondly,from the deformation level,the evolution law of stiffness,equivalent elastic strain,overall deformation and ductility on Z axis,Y axis and X axis is analyzed.Finally,from the energy level,the evolution law of nonlinear coefficient and equivalent viscous damping coefficient on Z axis,Y axis and X axis is analyzed.(2)In terms of the internal force change of key nodes,the evolution law of the maximum equivalent stress of the seven key nodes of the first paving,the second paving,the third paving,the fourth paving,the fifth paving,the first jump and the second jump is analyzed.(3)In terms of the internal force change of key components,the evolution law of the maximum equivalent stress of the seven key components of the mud arch,the slow arch,the Hua arch,the two-layer Hua arch,the Lu-Dou,the San-Dou and the Shua-Tou is analyzed.5.In terms of the application of Dou-Gong wood components,a standard house type that can apply six types of Dou-Gong symbols in Tang,Liao,Song,Yuan,Ming and Qing dynasties to ’ courtyard culture ’ is designed.This prefabricated wooden structure building product has both Dou-Gong and courtyard symbolic elements to help rural revitalization and reflect cultural self-confidence.