Research On The Effect Of Damage On The Seismic Behavior Of Timber Beam

The existing ancient wooden buildings in China have been undergone many vicissitudes and encountered various natural and human factors.As a result,the functionalities of wooden structures has been seriously degraded.As the key bearing component of the traditional wooden building,the wooden beam is subjected the same impact.Moreover,most of them have been deformation and damage,which result in a significant reduction in safety performance of the ancient wood structures.However,there are few studies and researches on the effects of various types of damages on working performance in service of timber beams.In view of this,the present study to take the Douglas fir wood beams for research objects,conduct the research on the effect of the damage on the seismic performance of timber beams.The main contents are as following:(1)The state-of-the-art of the damage of the existing wooden beam members is extensively surveyed.The stressing features,forms of damages and the cause of damages are analyzed.On the other hand,combining the research goal and contents,the damage process and characteristics are simulated by changing the damage form of the beam and controlling the different sizes of the damage.In addition,based on the same size timber beam testing,the damage of wooden beams in different severity and reflect the stressing features are simulated.Finally,the experimental data of different damage forms of wood are collected.(2)According to the code of Standard for Test Method for Wood Structure,the working characteristics of the typical three points loading test device are analyzed.The loading beam is employed to load on the the experimental sample,the low cycle reciprocating loading is applied by the servo loading hydraulic press,and the error between the three points loading two loading points is balanced,the additional stress generated by the loading test device is reduced,which lays a good foundation for achieving the ideal experimental data.(3)The wood properties of the wood are tested according to the standard test method,and the physical and mechanical parameters such as the compressive strength of the wood,the compressive strength of the cross grain,the modulus of elasticity and the coefficient of friction were obtained.The loading test of the 14 groups of wooden beams was carried out,the F-A hysteretic curves of wood beams under different degrees of damage and the failure modes of damaged timber beams are obtained.Further analysis of F-? hysteresis curve,the F-?skeleton curve,stiffness degradation curve and equivalent viscous damping curve of wood beams are obtained.The seismic performance of damaged timber beams is further analyzed by comparing the results of experimental study with numerical simulation.This study present a positive and useful reference for the study on the deformation and damage of wood beams.Due to the limitations of experimental conditions and theory,the artificial simulation of the damage relationship between damaged wood beams and actual natural damage still needs to be carried out further research in the future.