Valentino Bolis

Numerical Investigation of the In-Plane Performance of Masonry-Infilled RC Frames with Sliding Subpanels

AbstractA number of construction techniques have been proposed to improve the seismic performance of infilled RC frames by increasing the strength and stiffness of the infill and/or the frame. The increase of the seismic capacity of infilled frames with these techniques can improve substantially their seismic performance as long as the demand does not exceed the capacity, but it can eventually lead to brittle failures once the capacity is exceeded. This study assesses numerically a new construction technique that introduces flexibility to the system to ensure its ductile behavior and minimal damage by splitting the infill in subportions and allowing the sliding along the horizontal joints connecting these subportions. A numerical model, validated with data from tests on the components of the proposed structural system and able to capture the interaction between them, has been developed to provide insight into the load-transfer mechanism that develops, and to optimize the proposed detailing. A parametric s...

DISSIPATIVE ROOF DIAPHRAGM FOR THE SEISMIC RETROFIT OF LISTED MASONRY CHURCHES

ABSTRACT In the seismic retrofit of the existing masonry buildings, dissipative and deformable roof diaphragms could offer an efficient solution in cases where both the adoption of steel ties or stiff diaphragms would be ineffective. An innovative deformable, dissipative and lightweight roof diaphragm for the seismic retrofit of masonry churches is proposed. Such a diaphragm prevents the overturning of the side walls whilst allowing the onset of a controlled rocking mechanism. The specific diaphragm elasto-plastic response caps the seismic actions transferred by the roof diaphragm to the seismic resistant walls, in contrast to a rigid and a stiffened diaphragm. This effect is meant to mitigate the overload of the head walls, thus preventing their collapse or the need for their strengthening, which could require interventions invasive of the historical structure. The feasibility of the proposed retrofit strategy is assessed through the experimental characterization of a prototype diaphragm sub-assembly and non-linear dynamic analyses of the global response of two retrofitted reference buildings.

Seismic infill–frame interaction of masonry walls partitioned with horizontal sliding joints: analysis and simplified modeling

ABSTRACT This paper proposes a simplified approach to analyze the seismic performance of masonry infills with sliding joints in moment-resisting frame structures. The proposed methodology uses the equivalent strut approach, calibrated on the results of a novel analytical formulation, which considers the basic geometrical and mechanical properties of the infill. The method is validated through the comparison of the estimated infill resistance and shear demand on the column with those obtained from an extensive experimental and numerical study using refined finite element models. For the case studies considered, the simplified model offers a reliable estimate of the global and local response.

SIMPLIFIED MODELING OF MASONRY INFILL WALLS WITH HORIZONTAL SLIDING JOINTS

The vulnerability of masonry infilled frame structures has been demonstrated by many recent earthquakes and research studies and it is often triggered by the in-plane interaction between the flexible frame and the masonry infill (characterized by an inherent higher stiffness). Among the different solutions studied to mitigate such issue, a deformable infill typology with horizontal sliding joints has been proposed and tested by the authors in previous studies, capable of reducing the infill-frame interaction and of limiting the damage in the masonry, so that also the out of plane infill stability is maintained. This paper proposes a simplified approach to assess the seismic performance of this innovative masonry infill typology. Analytical formulations, based on geometrical and mechanical properties, are proposed to describe the in-plane response of the infill and its interaction with the bounding frame. Thanks to these formulations, a simplified numerical model for the infill, adopting an equivalent strut approach, is calibrated to be used in the non-linear analysis of infilled frame structures, accounting for their cyclic response. The reliability of the method is validated trough the comparison of the estimated infill resistance and shear demand on the column with those obtained from an extensive experimental campaign and numerical study based on refined finite element models. The results show the efficiency of the proposed simplified model in estimating the response of the infilled RC frame, in particular the shear action in the frame columns, which are the critical element of the structure. 3367 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 3367-3379