Quasi-Static Calculation Analysis Of Seventh-Class Timber Structure With The Frame Of Dougong-Beam-Column

Since the formation of the Chinese civilization,timber structures have been the main form of Chinese architecture.These buildings are assembled by pre-machined tenon-and-mortise wood elements,which have not been too much damaged for thousands of years,which is enough to prove that they have excellent seismic performance.Studying the earthquake-resistant mechanism and mechanical properties of timber structures in ancient buildings plays an important role in the protection and restoration of existing ancient buildings,and also provides a certain reference for modern building structures.Based on the relevant provisions in the “Ying Zao Fa Shi”,this paper establishes a Song-style seventh-class Dou-gong layer model through Abaqus finite element analysis software,as well as two timber frame models with different Beam-to-column joints.Then adding quasi-static cyclic reciprocating displacement loads under three vertical loads.Calculations consider material elasticity,yield stress,and geometric nonlinearity.The deformation characteristics,hysteretic performance and energy response of the model are analyzed,and the following main results are obtained:(1)The column layer is swayed during loading,which changes the vertical displacement of the structure;The deformation mode of the Dou-gong layer model is related to the magnitude of the loading displacement.When the displacement is small,it is mainly elastic deformation,as the displacement increases,the Dou-gong rotates.Although the Dou-gong layer has good deformation performance,it is always in the elastic stage in the overall wooden frame because the stiffness is much greater than the column frame layer.Therefore,it is always in the elastic stage in the overall wooden frame,which presents a translation similar to rigid body.(2)The hysteresis curve of the Dou-gong layer is a full “bow” shape,and the lateral stiffness and energy consumption are relatively high,but it is difficult to exert the full bearing capacity in a timber frame;The hysteresis curve of the timber frame is "S".When the beam-column joint is dovetail,the deformation and energy consumption capacity is relatively higher;When the beam-column joint is a cross hoop joint,the stiffness of the structure is greater.(3)Under pseudo-static conditions,the total energy of the input structure can be converted into frictional energy,elastic strain energy,plastic strain energy and gravity potential energy.Among them,friction energy and plastic strain energy are both energy consumed by the structure,which can be expressed by hysteresis energy.The elastic strain energy is relatively high when the loading displacement is small,and the effect on the cross hoop joint is more obvious;Hysteretic energy is relatively small during the loading phase,but it is continuously consumed during the simulation experiment;Gravity potential energy accounts for more than 50% when the displacement is large,which is the most important energy conversion method of the structure.This kind of hybrid swing mechanism can greatly reduce the damage of timber elements in the earthquake,so that the structure has excellent continuous earthquake resistance.(4)The Abaqus numerical model can greatly reflect the deformation characteristics and mechanical properties of wooden structures under actual conditions.Moreover,it can obtain strain energy and friction energy that are difficult or impossible to obtain in actual experiments,which has great reference value.