Study On Wood Damage Model And Damage Identification Model Of Ancient Buildings

Wood structure is an outstanding representative of traditional architecture in China.However,due to long-term exposure to sunlight,bioerosion,alternating wet and dry,etc.,the appearance and microstructure of wood have changed,which causes the degradation of wood components and deformation.Structural safety factors.At present,the research on the wood damage model and damage identification model of ancient buildings is less involved.This article is based on the above issues,mainly includes:（1）The XRD（X-ray diffraction）diffraction patterns of wood with different damage degree were analyzed,and the wood damage rateγ_u was defined.According to the mechanical properties and stress-strain variation of wood with different damage degree,the mechanical property index attenuation was established with the damage rateγ_u as the parameter.Model and wood damage constitutive model.（2）The FT-IR（Fourier Transform infrared spectroscopy）spectra of wood with different damage degree were analyzed,the Fourier transform second-order derivative pre-processing infrared spectrum quantitative analysis model was established by partial least squares（PLS）.To determine the damage identification model parameters,Savitzky-Colay smoothing method was used.The second-order derivative pretreatment spectrum was calculated,and the double-wavenumber fitting result was selected.Based on the double-wavenumber corresponding absorption peak intensity,the wood FT-IR damage recognition model was established.（3）The relationship between the attenuation rate V of the stress wave propagation velocity and the decay area ratio A of different measuring points is analyzed,and a reliable V-A model is proposed.Firstly,the longitudinal and transverse non-destructive testing of the stress wave is carried out on the column members.Secondly,the physical properties and chemical properties of the stress wave propagation velocity are analyzed.Finally,the FT-IR and XRD analysis is performed on each grade of the sample,combined with the FT-IR damage identification model.Establish a damage identification model for wood nondestructive testing.（4）Analyze the variation law of dynamic parameter frequency and vibration mode of beam-column components under different damage degrees,combined with the relationship between the compressive elastic modulus E₁ of the grain and the radial compressive elastic modulus E₂ of the transverse grain and the damage rateγ_u.Further,a method for detecting damage of the member by using the dynamic parameter frequency of the member is obtained.（5）Exploring the correlation between mechanical property attenuation model,damage constitutive model,FT-IR damage recognition model,non-destructive detection damage identification model,mutual verification and application rules;and using old materials as a case,through FT-IR analysis,The mechanical properties test results of the samples were compared with the FT-IR damage identification derivation results,and the non-destructive testing identification and dynamic parameter identification results of the old materials were further derived.