Pretension Value Researsh Of Anchor Bolt For Exposed Steel Column Base

In steel buildings, performance of frame structure is mainly controlled by the connection performance of structure. One of the most important connection is the column base connection and beam-to-column connection. In our country, exposed steel column bases are widely used in the low rise steel buildings because of its good seismic performance and its workability. But column stiffness maybe change due to warping of bottom plate and pull-out of anchor bolt under the earthquake load, it should be rigid or semi-rigid, but became flexible column base. Then the bearing capacity and stiffness are affected.Exposed steel column base is connected mainly through the anchor bolt and the foundation, and its pretension will be used on the anchor bolt in practice. If the pretension value of anchor bolt is calculated with the method of considering high-strength bolt, that is, the tension design value is defined to 80% of the pretension value on the basis of the existing "Code for design of steel structures". But in fact, the pretension values are not considered when the general anchor bolts are designed, the design strength are decreased. In practical work, the author found that there is not strict limit standard to control the actual anchor bolt pretension, the influence of super tension or owe twist on the mechanical performance of column base is in an unknown state, so it is necessary to study deeply.In order to define the impaction of the anchor bolt pretension, in this thesis, we designed the exposed steel column base accroding to practical engineering and set up the model with ABAQUS. The pretension of anchor bolt is calculated relativing to percentage of the material design value of strength, therefore, models of 40%、 45%、50%、55%、60%、65%、70%、75%、80% are set up to study, and defined the effect of pretension to the mechanical of steel column base. According to this we can control the pretension reasonably and provide reference for steel engineering design and construction. It will has practical application value and theoretical significance.