Abstract
The seismic response of existing masonry structures is strongly influenced by floor and roof in-plane properties. A strengthening intervention is often needed for traditional timber floors to overcome their low in-plane stiffness and to preserve historical buildings. In this study, the effects of unreinforced and reinforced timber floors on the seismic behaviour of an existing listed masonry building are investigated with dynamic non-linear analyses by means of the Discrete Element Method (DEM). With this approach, the failure processes and collapse sequences of masonry structures can be captured in detail. A previously developed model of the floor cyclic behaviour, based on experimental data, is applied herein to DEM models of the masonry building. Different seismic ground accelerations, different floor types and different floor-to-wall connections are considered. The results highlight the effectiveness of the analysed floor strengthening solution in reducing the out-of-plane displacements of masonry walls. With adequate connections, the reinforced floor is able to transfer the seismic forces to the shear-resistant walls up to the shear-sliding collapse of the structural sidewalls. A comparison with the ideal rigid diaphragm case confirms the good performance of the strengthened floors. The small observed out-of-plane displacements are compatible with the masonry wall capacity, and the reinforced floor hysteretic cycles contribute to dissipate part of the input energy. Moreover, different designs of the connections can also cap the transferred seismic forces to an acceptable level for shear-resistant walls.
Highlights
The seismic assessment and retrofitting of existing masonry buildings remains a challenging topic in structural engineering due to both the complexity and variability of unreinforced masonry structures and the several factors affecting their dynamic behaviour.1 3 Vol.:(0123456789)Bulletin of Earthquake Engineering (2021) 19:6003–6026Among these factors, the in-plane flexibility of traditional timber floors and the lack of effective connections to load bearing walls are usually responsible for the development of local collapse mechanisms
This study investigates the influences of the floor in-plane hysteretic properties and the floor-to-wall connection properties on the seismic response of a typical heritage masonry building
Numerical simulations by means of the Discrete Element Method (DEM) were carried out to investigate the effectiveness of strengthening solutions for timber floors to enhance the seismic performance of a masonry building
Summary
The seismic assessment and retrofitting of existing masonry buildings remains a challenging topic in structural engineering due to both the complexity and variability of unreinforced masonry structures and the several factors affecting their dynamic behaviour Among these factors, the in-plane flexibility of traditional timber floors and the lack of effective connections to load bearing walls are usually responsible for the development of local collapse mechanisms. Several in-plane strengthening techniques for timber floors have been experimentally studied in recent years, with a particular focus on the reversibility of the intervention and its compatibility with the existing parts of the buildings These solutions may use steel elements, fibre-reinforced polymer strips, timber boards or timber-based panels (Gubana, 2015).
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