Study On Mechanical Properties Of Damaged Steel Beam And Column

The steel structure is widely used in modern engineering.During the service of steel structure,the steel members are inevitably received varying degree damage due to various factors.It is impossible for some large structures to immediately abandon the use or tear down.To achieve the maximum economic benefit while ensuring the safety,the mechanical properties of those partially damaged steel members should be analyzed with a proper calculation model to guarantee the safe operation and usage requirements.In this thesis,a major theme here is how the partial damaged influences components's behavior with the secondary loading.Referred to the damage assessment method in the classical damage mechanic book which considering elastic modulus decrease,the damaged steel beams and steel columns are analyzed by experiment,theory and finite element method from the three levels:material,cross section and element.The main work of this paper is as follows:Firstly,experimental study on material property variations about damaged steel with standard specimens' shows that different degrees of damage led to decline of elastic modulus in different way.This conclusion is obtained from.the tests of Q345 steel.The rule of elastic modulus decreases has been analyzed,and a new calculating method of elastic modulus of damaged steel is studied in this thesis.Secondly,the damage degree of cross section is analyzed,for example,H-section,based on the results of the material test,the damage degree is divided into three categories,and deriving the method for calculating the average elastic modulus of H-section which is damaged.The M-?-P relationship of damaged H-section is obtained,and the approximate expression of M-?-P relation of H-type narrow flange,mid-flange and wide flange cross section is obtained.Based on the parameter analysis,the influence of cross-section size on M-?-P relationship is obtained.Finally,completed the Q345 H-section damaged steel beam bending test and damaged steel column eccentric compression test.The load-displacement curves were obtained by experiment and Newmark method,and calculated results were agree well with the experimental results.The Newmark method and finite element analysis software ABAQUS were used to analyze parametric,the effects of flange width,flange thickness,web height,web thickness and damage degree on the mechanical properties of damaged steel beams and steel columns were analyzed.