A NOVEL METHOD FOR NONLINEAR DYNAMIC ANALYSIS OF BEAM-COLUMN STEEL MEMBERS

Evaluation and subsequent strengthening of new and existing structures for extreme loading cases, such as explosion, blast, earthquake or fire, require a realistic and pragmatic design approach to be formulated and for which there is a significant dearth of scientific data in the literature. This paper addresses, in generic form, an innovative nondiscretisation semi-analytical mechanical-based formulation for the nonlinear dynamic response of an isolated beamcolumn steel element, which importantly incorporates the second order effects in the strain-displacement field. The modelling of the cross-section as comprising of elastic and inelastic domains allows for the spread of yielding to be modelled accurately, whilst the effects of large displacements, material nonlinearity and the rate-dependent effect of steel material due to dynamic loading are taken into account. The advantage of the technique is that it overcomes the large discretisation schemes needed using plastic zone methods, which have been established elsewhere to be problematic both in terms of computational efficiency and accuracy. It is also advantageous in providing an accurate alternative to plastic hinge methods, whose accuracy is compromised because of the lumping of inelasticity at the ends of the member. The generic technique that is developed is shown to agree with solutions obtained from the finite element method while it has the potential to be used as a platform for structural analysis and design in which scenarios of progressive collapse are important.

Keywords:

non-linear , dynamic , non-discretisation , beam-column steel element