Keywords: three-dimensional joints, end plate connections, finite element modelling, material and geometric non-linearity, contact.

Nowadays it is recognized that connections and members of steel frameworks have a semi-rigid and non-linear behaviour. One of the main concerns is how to incorporate the connection characteristics into an analysis, since it is generally carried out under the assumption that joints are either fully rigid or ideally pinned. Modern design codes (Eurocode 3 [1]) introduce the concept that the actual joints behave in an intermediate way between these two extreme cases. At present, the research work is focussed on the development of methods for predicting the joint rotational response that can be described by means of the moment-rotation curve. The moment-rotation curve of the connection can be obtained by means of experimental tests and mechanical and numerical models.

Obviously, experimental tests are the most reliable and direct method in understanding the joint behaviour. However, it is impossible to test all of the connections that would be used in steel frames and this approach is usually reserved for research purposes.

Mechanical models are based on the simulation of the joint by using a set of rigid and flexible components. The non-linearity of the response is obtained by means of inelastic constitutive laws adopted for these spring elements. This approach has been used by Johnson and Law [2] and Yee and Melchers [3]. Their work already contains the basic principles of the component method, which has been recently proposed in Eurocode 3. This is an excellent and versatile analysis tool, which can be applied to a wide variety of joints. However, it lacks appropriate components to predict the behaviour of minor axis and three-dimensional joints.

Finally, numerical modelling provides a means of carrying out wide ranging parametric studies to complement existing experimental results. The finite element tecnique seems, in principle, to be the most suitable tool to investigate the response of a joint because modern finite element packages can model the material non-linearity, bolt pretensioning, variability of contact between plates, and so on. Many models have been proposed for the major axis. A large number of advanced finite element studies have been conducted on major axis joints. However, when the minor axis is considered, the knowledge is still very limited.

In the present study, three-dimensional semi-rigid steel joints are investigated for predicting their rotational behaviour. To do so, a three-dimensional finite element model has been developed using the ABAQUS code. The proposed three-dimensional joint configuration consists of extended end plate connections for both major and minor axes. The joint is subjected to a non-proportional load applied to both axes. The results obtained from the finite element analysis will be verified by comparing the moment-rotation curves with experimental results.

1

CEN, "Eurocode 3, Part 1.8: Design of Joints", European Committee for Standardization, Brussels, 2005.

2

R.P. Johnson, C.L.C. Law, "Semirigid joints for composite frames", in "Joints in structural steelwork", Pentech Press, London, 1981.

3

Y.L. Yee, R.E. Melchers, "Moment-Rotation curves for bolted connections", Journal of Structural Engineering, 112: 615-635, 1986. doi:10.1061/(ASCE)0733-9445(1986)112:3(615)

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)