In‐plane/out‐of‐plane interaction of strong masonry infills: From cyclic tests to out‐of‐plane verifications

Abstract

The construction of RC frame structures with masonry infills is part of the traditional building practice in many European countries and worldwide. Several studies have been recently conducted to improve further the understanding of the seismic response of masonry infills, which are mainly focused on weak/slender clay masonry panels representing a common typology of the past, whereas very limited research has been devoted to stronger/thicker masonry infills, which nowadays are being adopted with increasing frequency in newly designed RC structures for their excellent thermal and acoustic performance. In order to fill this gap, within a systematic experimental and numerical research program, the in‐plane and out‐of‐plane experimental response of ‘strong’ masonry infills has been investigated at the Eucentre and the University of Pavia. In particular, this paper presents the framework and discusses the results of out‐of‐plane static cyclic tests on full‐scale, single‐storey, single‐bay RC frame specimens infilled with 35 cm thick tongue and groove clay unit walls, the related damage propagation and the failure mechanisms. The in‐plane/out‐of‐plane experimental interaction evaluated in terms of stiffness and strength reduction and period increase in function of previous in‐plane damage is also introduced, with the aim of providing a simplified out‐of‐plane strength verification within the European codified design procedures.

Detection of infill wall damage due to earthquakes from vibration data

“…Firstly, for the purpose of the results generalization, it should be remarked that the onset and the development of the infill damage strongly depends on both the material and geometrical properties of infills and the surrounding frame, as well as on the construction techniques and the type of stress state mobilized in the panel. The damage evolution observed on the tested infills is consistent with that observed in other real experimentations available in the literature, [51,52] where masonry infills built in contact with the surrounding frame are tested under IP cycle loads. A collection and classification of the main failure mechanisms for masonry infilled frames can be found in [53,54] ; in these works, five main causes of damage and failure are proposed: the failure of the surrounding frame, the shear sliding, the corner crushing, the diagonal compression, and the diagonal tension (cracking) of infills.…”

“…In framed RC and steel buildings, infills are the most important non-structural elements that may affect the structural dynamic response [3,18] and the seismic performance, [19][20][21][22][23] sometimes leading to the development of undesirable effects, such as the activation of soft storey mechanisms or the shear failure of short unconfined columns. [24,25] Thus, not only damage to structural elements but also to non-structural components often reflects in changes on the dynamic behaviour of infilled structures, as proved by some authors that investigated the dynamic response of infilled buildings after damage produced by earthquakes all around the world.…”

Experimental and analytical studies of infill wall with sliding joints considering a door opening

“…[59][60][61] Also, a significant challenge for the sliding configurations is guaranteeing sufficient out-of-plane capability of the infill walls with door openings. 62 While these solutions indeed offer wall panels with commendable ductility and mitigate damage compared to conventional infill walls with door openings, they still exhibit undesirable corner crushing and crack development in the infill walls surrounding the door openings once the inter-story drift ratio higher than 3.0%. [63][64][65] Consequently, supplementary fixtures are often deemed necessary to safeguard both the infill wall and door opening.…”

“…A crucial consideration in avoiding possible damage to the fragile wall panels with door openings lies in ensuring that the subpanels possess a higher resistance than the friction force of the sliding joints 59–61 . Also, a significant challenge for the sliding configurations is guaranteeing sufficient out‐of‐plane capability of the infill walls with door openings 62 …”

Experimental and numerical investigations on interaction between reinforced‐concrete grid frame and ceramsite foam concrete infill

“…The CGF had stronger constraints on infilled walls than traditional RC frames, and the integrity and mechanical properties of cast-in-situ infilled wall were better than masonry infilled wall. 24 Hence, the calculation model of references 19,21,25 might not be suitable for the study of the interaction between cast-in-situ CFC infill and RC grid frame. In addition, the mechanical properties of CGF with filled wall had also been reported in references.…”