Analysis Of Joint Stiffness Based On Component Method And Improved Response Surface Method

At present,the steel structure joints have been generally considered to have a certain rotational stiffness.Component method is an important theoretical method to analyze the rotational stiffness of joints.Many problems are found in the application of component method for the joint stiffness analysis.The key lies in the bending component,including T-stub and stiffened T-stub(cruciform-stub),which extraction method are not clear and stiffness calculation are not accurate.To solve the above problems,this paper mainly carried out the following researches based on improved response surface method:(1)By changing the dimension parameters of T-stub in the joint domain,6 sets of fully extended end plate steel joint specimens were designed.The extraction method and behavior of the T-stub in the joints were analyzed,and the references to establish the accurate finite element model were proposed.(2)Combined with the finite element model,the factorial experiment was used to analyze the factors that affect the initial stiffness of the T-stub.The main factors affecting the initial stiffness of the T-stub and the interaction between the factors were analyzed.(3)Based on Monte Carlo sampling method,the response surface method is improved,and the improved response surface method can be used to obtain the tensile stiffness formula of complex components.Based on the experimental data,a large number of finite element models of T-stub were established.Response surface function of the T-stub obtained from the simplified mechanical model was used to improve and modify the initial stiffness calculation of T-stub.A more accurate formula for calculating the initial stiffness of T-stub is proposed.(4)To overcome the complexity of the force transfer between the stiffener and the T-stub,the concept of the component of the cruciform-stub is put forward.Combined with the finite element model,the factorial experiment was designed to analyze the influence factors of the cruciform-stub and the interaction between the main factors and the factors that affect the initial stiffness of the cruciform-stub was obtained.Large number finite element models of cruciform-stubs were established.Based on the response surface function obtained from the simplified cruciform-stub mechanical model,the improved response surface method is used to analyze the cruciform-stub and the accurate formula for calculating the initial stiffness of the cruciform-stub was obtained.(5)Based on the formula proposed in this article,the initial stiffness of the extended end plate connections is calculated by the component method,and the results are more accurate.At the same time,this paper proposed a moment-rotation curve model of the joints based on the initial stiffness.