Luca Marchi

Light Steel-Timber Frame with Composite and Plaster Bracing Panels

The proposed light-frame structure comprises steel columns for vertical loads and an innovative bracing system to efficiently resist seismic actions. This seismic force resisting system consists of a light timber frame braced with an Oriented Strand Board (OSB) sheet and an external technoprene plaster-infilled slab. Steel brackets are used as foundation and floor connections. Experimental cyclic-loading tests were conduced to study the seismic response of two shear-wall specimens. A numerical model was calibrated on experimental results and the dynamic non-linear behavior of a case-study building was assessed. Numerical results were then used to estimate the proper behavior factor value, according to European seismic codes. Obtained results demonstrate that this innovative system is suitable for the use in seismic-prone areas thanks to the high ductility and dissipative capacity achieved by the bracing system. This favorable behavior is mainly due to the fasteners and materials used and to the correct application of the capacity design approach.

A Dissipative Connector for CLT Buildings: Concept, Design and Testing

This paper deals with the conception and characterization of an innovative connection for cross-laminated timber (CLT) panels. The connection is designed to provide an adequate level of dissipative capacity to CLT structures also when realized with large horizontal panels and therefore prone to fragile shear sliding failure. The connector, named X-bracket, has been theorized and designed by means of numerical parametric analyses. Furthermore, its cyclic behavior has been verified with experimental tests and compared to that of traditional connectors. Numerical simulations of cyclic tests of different CLT walls anchored to the foundation with X-brackets were also performed to assess their improved seismic performances. Finally, the analysis of the response of a 6 m × 3 m squat wall demonstrates that the developed connection provides good ductility and dissipation capacities also to shear walls realized with a single CLT panel.

NUMERICAL SIMULATION OF THE COUPLED TENSION-SHEAR RESPONSE OF AN INNOVATIVE DISSIPATIVE CONNECTION FOR CLT BUILDINGS

This work presents a numerical macro-element model able to simulate the dynamic response of an innovative ductile and highly dissipative bracket for assembling of crosslaminated timber structures. This bracket resists to both tensile and shear forces and has been conceived to realize all the seismic-resistant joints of the building with a unique type of connection able to maximize the seismic capacity of the entire structure. The main issue of these kinds of connection is the reliability of numerical models in reproducing the coupled tensionshear behaviour and dissipative capacity with reduced computational effort, so as to simulate the non-linear response of complex buildings. With this aim, a numerical macro-element model was developed within the finite-element framework OpenSees using an assembly of linear beams and plastic hinges capable of simulating the complete tension-shear strength domain of the connection. The macro-element model was calibrated referring to the results from quasi-static cyclic-loading tests of the connector performed in pure shear and pure tension. The coupled tension-shear behaviour of the macro-element model was then validated on the results from independent numerical simulations performed using detailed 3D models with solid finite elements, including material and geometric non-linearity. Obtained results demonstrate that the developed macro-element model is able to describe accurately the hysteretic behaviour of the bracket with a very low computational effort. Therefore, it can be conveniently adopted to simulate the seismic response of complex structures. 247 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 247-254

Dynamic simulation of an irregular masonry building with different rehabilitation methods applied to timber floors

Abstract. The in-plane stiffening of timber floors is normally supposed to be an improvement of the seismic performance of un-reinforced masonry buildings. A modelling strategy to simulate the non-linear behaviour of masonry buildings with simple or strengthened timber floors is presented: it allows to implement the in-plane hysteretic response of the floors and different types of failure of the masonry walls. This model was used to predict the modification of the seismic response of a two-storey masonry building subjected to different rehabilitation techniques applied to the timber floors. The case-study building is irregular in plan to study also torsional effects and out-of-plane deformation of the walls. The mechanical parameters of the non-linear elements representing masonry piers and floors were calibrated replicating experimental tests available in literature. The outcomes of this work were obtained with non-linear dynamic analyses, in order to allow the model to consider not only the actual elastic and post-elastic stiffness of the floors but also their energy dissipation capacity. Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 2269-2282