Steel and Timber Structures in Seismic Areas

Research focus

The Peer review has evaluated this group as Average

A: Timber Structures (M. A. Parisi) The research on timber structures in seismic areas specificallt studies the connections between timber elements. Traditional carpentry joints and new types of connections realized with innovative technologies are both considered. These two branches of the research are not completely independent, because the new design criteria can be extended to the seismic upgrading of existing structures. Carpentry joints are typically found in existing buildings, often of historical importance. Mostly, these joints have been realized without reference to building codes and norms. It is thus necessary to characterize the mechanical behaviour of the most frequently adopted typologies as a function of the main design parameters, considering the connection both in the original condition and after its upgrade, performed according to current practice and to new proposals. Reference has to be made to service as well as to exceptional conditions, specifically to seismic action. The objective is to select reinforcement criteria that may satisfy current safety standards, respecting as much as possible the original conceptual design. The innovative connections considered are recent proposals in the field of modern design of new timber structures, where various materials are associated to timber in order to improve its mechanical characteristics. The research is coordinated with a research group at the university of Trento, where the experimental work was carried out. B: Modeling of Steel Moment-Resisting Frames (MRFs) (M. G. Mulas) In MRFs subjected to horizontal loading, the transfer of moments between beams and columns connecting to the same joint produces high values of shear stresses inside the panel zone of the joint itself and of normal stresses inside the flanges of the columns. Due to a strong earthquake yielding can be reached at the joint and any of the surrounding elements. Two aspects must be considered: (i) the description of the panel zone stiffness; (ii) the correct representation of the panel zone strength and of its post-linear behaviour. To provide a tool for the comprehensive seismic analysis of MRFs, a structural model has been developed to describe the deformation modes of the panel zone in beam-to-columns joints, without resorting to a computationally heavy FE discretization. The model takes into account the finite dimensions of the joint, and can incorporate the most recently proposed constitutive models for monotonic and cyclic loading. The capability of global models (the panel zone model and a steel beam model previously developed) in reproducing the seismic behaviour of MRFs has been subsequently assessed by comparison with some experimental tests performed on a two-story one-bay frame. In parallel, the joint zone has been analysed with a 3D finite element modelling, extending the studies to two types of improved steel moment-resisting connections, either reinforced with cover plates or weakened with reduced beam section (RBS) detail: the aim is to protect the potentially vulnerable beam-to-column groove welded joint by relocating the plastic hinge away from the face of the column. C: Seismic Resistance of Steel Structures (C. A. Castiglioni The research in this period focused on the following topics: - Static and seismic behaviour of storage racking systems - Innovative seismic resistant design of structures - Behaviour of composite steel-concrete frames The research on Seismic Behaviour of Pallet Racking Systems has been performed at DIS, in cooperation with other International research Institutions, with national and international Industrial Associations dealing with the racking industry. Extensive experimental research was carried out, encompassing both cyclic tests on components (beam-to-column connections and base-plate connections), pseudo-dynamic and pushover tests as well as dynamic shaking table tests on a number of 132 full scale three storeys, two bay racks, fully loaded with approximately 100kN masses. Static and dynamic tests were carried out to study the sliding of the pallet on the steel beams. These tests allowed an assessment of both static and dynamic friction factor. Numerical parametric studies were carried out, adopting non-linear finite element models, calibrated on the experimental data and encompassing the sliding phenomenon. A number of cyclic quasi-static tests were carried out on full scale beam-to-column connections made of a steel beam connected to a steel column (eventually partially encased in R.C.) and by a R.C. slab connected to the beam by studs. Different types of beam-to-column connections (rigid, semi-rigid, welded, bolted, etc.) were considered. The application of dissipative devices within the connection has also been studied. The results allowed for the identification of a dissipative system presently under patent procedure. Numerical simulations, parametric studies and two series of dynamic shaking table tests were also performed.

Dipartimento di afferenza

Dipartimento di Ingegneria Strutturale (DIS)

Docenti afferenti

Full Professors
Carlo Castiglioni
Carlo Urbano
Claudio Chesi
Associate Professors
Claudio Bernuzzi
Maria Adelaide Parisi
Maria Gabriella Mulas
Assistant Professors
Marco Valente