Out-of-Plane Seismic Response of Masonry Façades Using Discrete Macro-Element and Rigid Block Models

Abstract

This paper investigates the out-of-plane response of masonry façades under earthquakes by means of two different approaches. A discrete macro-element approach, based on modelling the structure by means of spatial deformable macro-elements interacting through nonlinear zero-thickness interfaces, and the classical approach in which the masonry façade is assumed as a rigid block subjected to earthquake loading. The latter method neglects the elasticity of the masonry element and contemplates the energy dissipation only at each impact by means of a coefficient of restitution. The results of dynamic non-linear analyses, performed with the two methods on a real case of a church façade, provide a first comparison between the two approaches highlighting some limits of application of the simplified rigid block model.

Influence of the Elasto-Plastic Behavior of Tie-Rods in the Response of Rocking Masonry Walls Through Seismic Demand Hazard Curves

“…Its size and slenderness are respectively given by and . The equation of motion, found in previous works of the Authors [14], [15], [17], is the following: (1) The right hand side contains the seismic input term as acceleration time history of the earthquake. The terms on the left hand side are related to the inertia forces, the self-weight stabilizing the response up to a rotation threshold equal to , the tie-rod of stiffness ( ) and the transverse walls simulated by a spring bed of unitary stiffness ( ).…”

Economic vs environmental isocost and isoperformance curves for the seismic and energy improvement of buildings considering Life Cycle Assessment

“…Indeed, from a structural point of view it is difficultand sometimes not significant -to model the global behavior due to poor connections between structural elements [6]. In this case, local analyses are more significant [7]- [11]. From an energy point of view, there is an analogous gap between the availability of calculation methods and the real knowledge of the components inside the walls.…”

Masonry Walls Retrofitted with Vertical FRP Rebars

“…The effectiveness of the intervention is analysed in terms of level of seismic improvement, defined as the ratio between the seismic capacity of the reinforced and unreinforced walls.Buildings 2020, 10, 72 2 of 17 with the current state of the art, the masonry element, when subjected to out-of-plane actions, assumes a monolithic behaviour and cracks subdividing into distinct macro-elements. A model of rigid body excited into a rocking motion can be adopted to simulate the behaviour of the masonry element [12][13][14], whose effectiveness has been recently proved through dynamic tests performed on real walls [15] and by the subsequent comparison with analytical and numerical models [16].Depending on the typology of restraints and on the location of the masonry element within the structure, different mechanisms may take place [17]. It is nowadays well assessed that, in presence of poor connections with external or internal perpendicular walls, out-of-plane behaviour of masonry piers and spandrels represents the greater structural vulnerability of existing masonry building [18][19][20][21][22].…”

“…It is nowadays well assessed that, in presence of poor connections with external or internal perpendicular walls, out-of-plane behaviour of masonry piers and spandrels represents the greater structural vulnerability of existing masonry building [18][19][20][21][22]. Advanced analysis techniques, involving both theoretical approaches [15,[23][24][25][26][27][28][29][30][31] and numerical models [11,16,[32][33][34], allow to accurately evaluate the seismic capacity of the masonry element and to direct engineers to the definition of proper retrofitting interventions, required to ensure an adequate safety level in case of low structural capacity. Well-designed classical retrofitting interventions can improve the seismic strength of the masonry macro-element but, on the other hand, they can change the collapse mode, inhibiting the simple overturning mechanism and then modifying the structural behaviour of the entire structure.…”

“…Buildings 2020, 10, 72 2 of 17 with the current state of the art, the masonry element, when subjected to out-of-plane actions, assumes a monolithic behaviour and cracks subdividing into distinct macro-elements. A model of rigid body excited into a rocking motion can be adopted to simulate the behaviour of the masonry element [12][13][14], whose effectiveness has been recently proved through dynamic tests performed on real walls [15] and by the subsequent comparison with analytical and numerical models [16].…”