Macro-Modelling of Combined in-Plane and Out-of-Plane Seismic Response of Thin Strengthened Masonry Infills

Abstract

Some strengthening techniques, aimed to increase the infill Out-Of-Plane (OOP) resistance and its safety against OOP collapse, have been recently tested at the University of Padova. Based on this experimental work, a new infill macro-model consisting of two nonlinear fibre struts for each diagonal direction, able to predict the combined In-Plane/Out-Of-Plane (IP-OOP) seismic response of the panels, is proposed in this paper and calibrated on the abovementioned experimental results for thin clay masonry panels strengthened by two external plaster layers, directly applied on the masonry surface, containing a biaxial basalt fibre grid. These macro-models were then used to carry-out parametric nonlinear static analyses on typical reinforced concrete infilled frames, designed both traditionally and seismically, with the aim of evaluating their lateral response both in the case of IP forces only (by assuming two force distributions applied to the frame) and in the case of IP-OOP combined forces (by applying OOP equivalent static forces to the panels). The main effects of the OOP forces are presented through pushover curves and drift profiles associated to the achievement of the various infill and frame limit states. Numerical results show the effectiveness of the infill strengthening in terms of improvement of the infills OOP performance and thus of the overall structural response.

Experimental Testing and Numerical Modeling of Robust Unreinforced and Reinforced Clay Masonry Infill Walls, With and Without Openings

“…In particular, thin clay masonry infill walls proved to be the most vulnerable due to their strong interaction between in-plane (IP) and out-of-plane (OOP) behavior. Specifically, the lateral deformation of the RC frame causes IP damage to the infill panel which, in turn, significantly reduces its OOP strength, thus increasing its vulnerability and probability of OOP collapse (Komaraneni et al, 2011;Donà et al, 2017Donà et al, , 2019. This was observed by various authors in the aftermath of significant earthquakes, among which the most recent are L'Aquila 2009-Italy (Bazzurro et al, 2009;Braga et al, 2011;Ricci et al, 2011), Lorca 2011-Spain (De Luca et al, 2014;Hermanns et al, 2014), Simav 2011-Turkey (Dogangün et al, 2013), Emilia 2012-Italy (Penna et al, 2014;Verderame et al, 2014), Kefalonia 2014-Greece (Manos et al, 2015), and Central Italy 2016 (Fragomeli et al, 2017;Masi et al, 2017).…”

Experimental Calibration of the Ip Behavior of Strengthened Infill Walls and Seismic Analysis Including Ip/Oop Effects

“…Indeed, they are generally classified as non-structural elements, and there are still no clear standard indications on their modeling/verification procedures; therefore, they are often overlooked in the design phase. In particular, thin masonry infills are characterized by very brittle behavior and high IP/OOP response interaction [1,2,3,4,5]. Hence, they are easily damaged even at medium-low seismic intensities and are consequently responsible for high losses in building functionality and high repair costs [6].…”

Strengthening of In-Plane and Out-of-Plane Capacity of Thin Clay Masonry Infills Using Textile- and Fiber-Reinforced Mortar

“…The brittle behavior of clay masonry infill walls leads to an uncontrolled collapse that may occur without any warning, representing a serious hazard for human lives. Furthermore, the in-plane (IP) damage of the infill, induced by the RC frame deformation, yields to a reduction of the OOP strength, thus increasing the probability of infill out-of-plane ejection (Donà et al 2017(Donà et al , 2019. As a consequence, the seismic vulnerability of infill walls increases considering their combined IP/OOP response.…”