Investigation On Beam-Column Pinned Connections In Steel Structures

Compared with concrete structure,steel structures have many advantages such as shorter construction period and lighter weight since it plays an important role in the super high-rise structure or large span structure.Steel joints are usually designed to be rigid,semirigid or ideally pinned connections.The bolted connection is the most popular one among pinned connections.But there are some problems with it especially when the stress in structures is too big to use the bolted connection.That’s why pinned joints come into engineering practice.The pinned joint includes two main components,namely the primary and secondary ear plates and the pin.The internal force transimits through the ear plate to the pin which leads to a clear force path and relatively simple structure.There are many systematic researches about the performance of the pinned connection and also corresponding design specifications in foreign countries.On the contrary,China’s specifications involved very little.Code for Design of Steel Structures GB50017-2003 involves no design formula for pinned joints while the updated Code for Design of Steel Structures GB 50017-201X(Revision for Approval)only contains the design formula for ear paltes.Therefore,based on an Aerospace Group’s Laboratory’s structural pinned joints which were adopted to connect the steel column and steel trusses of the second floor in a long-span steel structure under heavy loads,the corresponding pinned connection test was carried out,and then the finite element simulation was used to verify each other with the test.Further more,the finite element method was used to analyze the influence of each parameter on the pinned joint performance and get the design formula for pinned joints.The main contents of this paper are as follows:(1)Based on the engineering example,four test specimens were designed,including two full scale pinned connection specimens and two 1:2 scale sub-structure specimens,to examine the bearing performance of the pinned joints.The test results showed that the pinned joints have enough safety factors to meet the design requirements;(2)The finite element simulation of the tests was carried out by ABAQUS,and the finite element results matched the test results well which means it can help to assess the pinned joint performance.It can be found that the stress concentration phenomenon mainly appears in the contact part between the ear plate and the pin while the stress of the rest part is small.In the substructure,the I-shaped steel member yielded before the pin which is beneficial to its structural seismic behavior;(3)After verifying the finite element model based on the existing experimental data,the parametric analysis was carried out by the software.The relevant parameters include the ear plate length a,the ear plate edge c,the pin diameter d,the clearance between the ear plate and the pin e,the yield strength of the pin f_y and the ear plate thickness t.Six or seven models were established for each parameter and the tested specimen was set as the standard model.(4)Based on the analysis of the parameters given in Chapter 4,the influence factor was defined and the design formula of the pinned connection was obtained.