Estimation of tensile mechanical parameters of existing masonry through the analysis of the collapse of Volterra’s urban walls

Abstract

In this work, numerical analyses on the Volterra's ancient walls are performed to understand the causes of a collapse occurred after an extreme rainfall (2014) and to identify the mechanical parameters that most influenced it. The stretch of collapsed wall is modelled with finite elements by distinguishing the material composing the multi-leaf wall. Non-linear static analyses are carried out with the DIANA software considering different levels of hydraulic head up to reach the collapse of the structure. The impact on the failure modes of the involved parameters, such as tensile strength, fracture energy and shear strength, are discussed. Tensile strength is found as the most relevant parameter in the failure mode. Finally, a 3-dim model is presented, and the results show a very good agreement with the failure mode actually occurred in terms of both failure modes and displacement fields. The safety evaluation is performed in the as-built and the retrofitted configuration, consisting in the wall restrained by tie-rods. The results show a significant increasing of the safety level of the retrofitted configuration showing a considerable improvement not only in terms of limit equilibrium but also in terms of structural capacity of the wall.

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

“…As for the symbols, is the polar inertia moment with respect to the pivot point O or O' equal to , whereas . The term assumes the form: (2) in which where is a position angle dependent on the position coefficient (Figure 1). The tie-rod can behave either as elastic or as plasticized.…”

“…Masonry structures can be seen as an assembly of macro-elements. Independently on the masonry type [1] and mechanical properties [2], these macro-elements that can be considered as a rigid system, provided that the masonry is monolithic. The rocking analysis of rigid blocks is a non-linear dynamic analysis capable of simulating the behavior of masonry walls rocking out-of-plane.…”

In-Plane Behaviour of Masonry Walls: Numerical Analysis and Design Formulations

“…In general, local failures mean the activation of out-of-plane mechanisms involving masonry elements that are exposed to seismic actions orthogonally to their plane. Several studies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] and experiences from past earthquakes have shown that the vulnerability of masonry buildings to out-of-plane mechanisms is emphasized by the lacking or weakness of connections between elements (i.e., between walls or between walls and horizontal diaphragms). On the other hand, global failure modes only occur in masonry buildings when the in-plane strengths of their earthquake-resistant elements can be activated, i.e., when the connections are able to guarantee a ‘box’ behaviour for the whole building such that seismic actions are, thus, mainly transferred to the walls parallel to each other.…”

“…Generally, the first two approaches are used to identify, in detail, the behaviour of regular masonry walls, while the third is more suitable for irregular/rubble masonry structures. Nevertheless, the macro-modelling approach is the most-used modelling strategy in the literature to assess the seismic behaviour of masonry structures, both when simulations regard whole structures and local behaviours [ 7 , 25 ], because it requires the assessment of very few parameters. Conversely, macro-modelling approaches based on the finite element method are not able to predict failure modes related to sliding mechanisms along unit-mortar joints, which need the use of the micro-modelling approach and the assessment of suitable interface-constitutive constraints.…”

Influence of Boundary Conditions on Cracking of Sanxingdui Moon Bay City Wall

“…Masonry and earthen structures constitute a majority of the global historic buildings and are often referred to as unreinforced masonry and unfired Earth. ese structures are highly vulnerable to damage such as rain erosion, cracking, undercutting, crumbling, and collapsing [1][2][3]. e cracking is the most common damage, which can be caused by desiccation, lack of drainage, earthquake, and structural deformation and is found in various types of historical structure spreading in both arid and humid regions [4][5][6][7].…”