Numerical vs. experimental behaviour of bolted dual-steel T-stub connections ANA-MARIA POP, DANIEL GRECEA, ADRIAN CIUTINA Department of Steel Structures and Structural Mechanics Politehnica University of Timisoara 1, Ioan Curea, 300224 Timisoara ROMANIA anamaria.pop@ct.upt.ro, daniel.grecea@ct.upt.ro, adrian.ciutina@ct.upt.ro Abstract: - The present research represents the numerical investigation used to characterize the behaviour of bolted dual-steel T-stub connections. The study is based on existing experimental investigation on T-stub components performed at the Politehnica University of Timisoara, using mild and high strength steel. First a calibration of numerical results is performed based on the monotonic experimental response. The challenge of the numerical investigation is represented by the calibration of cyclic curves, using adequate FEM techniques. The third step of the analysis would be the parametric investigation on monotonic response, by changing different characteristics of the T-stub components. Key-Words: - Numerical behaviour, experimental behaviour, bolted dual-steel, T-stub, monotonic and cyclic loading 1 Introduction The seismic resistant buildings located in seismic zones are designed on the principle of their dissipative behaviour in case of earthquake. This means that the dissipative elements chosen to absorb the seismic input will develop plastic deformations thereby reducing the demand on non-dissipative members. To avoid increasing the size of sections in dissipative and non-dissipative members because it also changes their stiffness, the best way to accomplish this demand is to realize them of MCS (Mild Carbon Steel) and HSS (High Strength Steel) respectively. The structures made from two different steel grades are called Dual – Steel (DS) structure. In this type of structure, Mild Carbon Steel (MCS) – S235 is use in dissipative elements (beams) and High Strength Steel (HSS) – S460, S690, in non-dissipative elements (columns, end-plate). In this way, MCS members have to work like fuses, dissipating the seismic energy through plastic deformation, while the HSS ones, had to remain predominantly elastic, or with limited damage, being responsible for robustness of the structure. Dual Steel (DS) concept is extended to connections, too, on the same philosophy related to ductile and brittle components, in order to achieve both ductility and robustness criteria. In fact, when connect MCS beams to HSS columns will result a DS beam-to- column joint. Base on Eurocode 8 rules, the dissipative zones could be located either in elements or in beam-to- column joints. In extended end-plate bolted connection, besides the column web, the end-plate in bending becomes very important for ductility. So, end-plate connections could prove adequate rotation capacity if special measures are taken, e.g. use of relatively thin end-plates, avoiding brittle failure of welds and bolts etc. From this point of view, T-stubs are basic components of the component method used in EN 1993-1.8 (Fig.1) for evaluation of strength and stiffness of bolted end-plate beam to column joints. According to Eurocode 3, T-stub macro-component failed down by 3 types of failure mode, named 1, 2 and 3 (Fig.2 and Table 1). Fig.1. End-plate connection: T-stub element Recent Advances in Civil and Mining Engineering ISBN: 978-960-474-337-7 192