Behavior of steel connections

Extended end-plate connections are widely used in steel structures as moment resistance connections and as an alternative to fully welded ones that have been considered for use in steel frames. These connections consist of end-plates welded to the end of beams and field bolted to the connecting columns. The understanding of the behaviour of joints is enhanced by developing analytical models. Various forms of analysis and mathematical modelling methods have been suggested to study the semi-rigid characteristics of beam-to-column joints and their influence on the response of the rest of the structural members. There is a simplified analytical model to represent the semi-rigid connection behaviour based on the moment-rotation characteristics of the joint. The component method does not apply to end-plate joints with pre-tensioned bolts and research into these types of end-plate connections are therefore much needed. Many types of research on end-plate steel connections have been carried out analytically and experimentally to determine an accurate method for predicting the connection rotational behaviour. Two experimental tests were conducted on beam-to-beam and beam-to-column joints. Both tests failed the column flange in the compression zone. There were also tests on three specimens to enable the prediction of the moment resistance and the rotation capacity about the minor axis of the beam-to-column semi-rigid joints. Thus it motivated the development of a mechanical model to assess the structural response of joints. Furthermore, connection types and details are numerous and innovative with many parameters, that must be accounted collectively to characterize the behaviour of the joint. Such parameters include whether the end plate is flush or extended, whether the end plate extends beyond one or both of the beam flanges, the diameter and the grade of the bolts, the number of bolt rows, the vertical and horizontal spacing of the bolts, the end-plate thickness, the stiffening of steel and the coefficient of friction at the contact surface. Because of this, it is almost impossible to study the behaviour of these joints comprehensively except by physical tests. However, due to a limited number of tests, the numerical simulations are widely used currently. The more accurate finite element model for parametric analysis is particularly important. The interaction between the different components of the joint should be taken into consideration in the modelling. The contact between these components, viz. end plate-column flange, bolt-column flange and bolt-end plate were represented using the surface-to-surface contact interaction technique.