Establishment Of Constitutive Model At High Temperatures For Stainless Steel Bolt And Study On Mechanical Behavior Of Its T-stub

Nowadays,stainless steel has a great market potential in architectural and structural application,on account of its beautiful appearance,high corrosion resistance and ease of servicing and maintenance.Since the 1990 s,the European,America,Austria and New Zealand have promulgated some specifications for stainless steel structure design,and only the European promulgated a specification for stainless steel structure fire-resistance design which is far from complete.Domestic researchers started studying on stainless steel materials and components relatively late and the Chinese specification(CECS410-2015)for stainless steel structure design has many blanks that need to be filled,which seriously hindered the application and development of stainless steel structure in China.Hence,it is more and more important to strengthen the study on stainless steel members and structures.This paper focuses on the design parameters studying of stainless steel T-sub.Supported by the National Natural Science Foundation(NO.51578092),two experiments to investigate the mechanical behaviors of stainless steel T-stub at room temperature and the mechanical properties of A4-70 and A4-80 grade stainless steel bolt at elevated temperatures are carried out respectively.The main contents of the paper are summarized as follows:(1)An experiment including nine test specimens to investigate the mechanical behaviors of stainless steel T-stub was carried out firstly,plastic resistance,ultimate resistance and initial stiffness were obtained by analysising the load-displaement curves of specimens,then the test result were compared with the recommended values of EC3 and AISC.(2)Some effective finite element analysis(FEA)models were built using ABAQUS to investigate the influence of design parameters on the mechanical behaviors of stainless steel T-stub,the data obtained from the parameters studies were compared with the relative equations of EC3 to illustrate its applicability in designing stainless steel T-stub.(3)The other experiment studied on the mechanical properties of A4-70 and A4-80 grade stainless steel bolt at elevated temperatures was finished,and the reduction model of mechanical indexes for two types of stainless steel bolt with the temperature increasing was proposed.This paper summarized the advantages and disadvantages of constitutive model for stainless steel materials at elevated temperatures,and the constitutive model of A4-70 and A4-80 grade stainless steel bolt at high temperatures was proposed based on the Ramberg-Osgood equation.(4)Drawing lessons from the experiment about the stainless steel T-stub and bolt,steady and transient numerical simulations to discuss the fire-resistant performance of stainless steel T-stub were finished.Innovations in this paper as follows:(1)Investigating the mechanical behaviors of stainless steel T-sub by using experiment study and parameters studies firstly.(2)Proposing the reduction model of mechanical indexes for A4-70 and A4-80 grade stainless steel bolt with the temperature increasing by experiment investigation firstly.(3)Proposing the constitutive model of A4-70 and A4-80 grade stainless steel bolt at elevated temperatures firstly.(4)Discussing the fire-resistant performance of stainless steel T-stub using numerical simulations firstly.