Reinforcement of end-plate connections under low cyclic loading

The object of research is the bolted end-plate connections beam to column, which is used in steel structures to ensure the reliability of column-beam and beam-beam connections. However, there is no reinforcement recommendation in the current normative documents for end-plate connections under low cyclic loading. Method. The reinforcement of bolted end-plate connections under low-cycle cyclic loading is investigated at the design stage using the finite element method and the component method. Stiffening ribs are one of the most effective and convenient methods to reinforce connections. Firstly, the force transfer characteristics of three kinds of stiffening ribs are analysed by finite element method, and the best geometric parameter scheme of stiffening ribs is found. On this basis, a method for calculating the bending capacity of connections with stiffening ribs is proposed. After that the work of beam-column nodes using different reinforcement methods under monotonic and cyclic loads was numerically analyzed. Results. Based on the results of the numerical analysis, the damage mechanism of the beam to column joint, the relationship between the variation of bolt internal forces with the number of loading stages, and the size of the gap between the end plate and the column flange were derived. The analysis concluded that reinforcement of the end plate connection at the design stage improves the strength of the connection, and the use of large diameter bolts, end plate stiffening ribs and column stiffening ribs prevents plastic hinging of the structural load-bearing elements of the connection, which ensures the safety of the connection under cyclic loading.