Barbara Pintucchi

Effectiveness of nonlinear static procedures for slender masonry towers

This paper investigates the accuracy of pushover-based methods in predicting the seismic response of slender masonry towers, through comparison with the results from a large number of nonlinear time-history dynamic analyses. In particular, conventional pushover analyses, in both their force- and displacement-based variants, are considered, and seismic assessment through the well-established N2 method is also addressed. The study is conducted by applying a simple non-linear elastic model recently developed and implemented in the computational code MADY to represent slender masonry structures. The model enables both pushover analyses and non-linear dynamic analyses to be performed with a minimum of effort. A multi-record incremental dynamic analysis carried out for a quite large number of structural cases, each of which is subjected to a comprehensive set of dynamic nonlinear analyses, is used to evaluate the accuracy of pushover methods in predicting the global structural response, as represented by the usual capacity curve together with a damage curve, both of which are compared with dynamic envelopes. Local responses, in terms of lateral displacements and the distribution of damage along the tower height are also compared. The results reveal that the key issue in the accuracy of pushover methods is the nature of the lateral load applied, that is, whether it is a force or a displacement. Different ranges of expected deformation are suggested for adopting each type of lateral load to better represent the actual behaviour of masonry towers and their damage under seismic events through pushover methods.

Numerical Verification of the Effectiveness of the “Alpha” Method for the Estimation of the Maximum Rotational Elastic Response of Eccentric Systems

In previous research works, the authors have identified a key system parameter which controls the maximum rotational response under free and forced vibrations of one-story linear-elastic systems representative of asymmetric seismic base-isolated building structures. This parameter (called “ALPHA”) has also led to the identification of a simplified procedure (called “ALPHA method”) for the estimation of the maximum rotational response of such systems. The main goal of this article is to verify the properties of the ALPHA parameter and the predictive capabilities of the ALPHA method, when applied to one-story systems representative of generic asymmetric building structures. The verification is carried out through a comprehensive set of 11,600 numerical simulations developed with reference to different representative structures subjected to historically recorded ground motions, with special attention devoted to the identification of the sensitivity of the ALPHA parameter and the ALPHA method upon the fundamental period of vibration of the structure (not yet considered in previous research works). The results obtained: (a) confirm the effectiveness of the ALPHA parameter to capture the intrinsic propensity of an eccentric system to develop a torsional response; (b) confirm the capacity of the ALPHA method to effectively estimate the maximum rotational response of a given eccentric system under seismic excitation; and (c) indicate that the ALPHA method is only weakly sensitive upon the period of vibration of the structure. The article also introduces a simple code-like provision for conservative estimations of the maximum rotation developed under seismic input by asymmetric structures based upon the confidence interval concepts.

Epistemic Uncertainties in Structural Modeling: A Blind Benchmark for Seismic Assessment of Slender Masonry Towers

AbstractThe paper reports the results of a blind benchmark developed as a part of the preliminary activity of the research project RiSEM (Italian acronym for Seismic Risk on Monumental Buildings). ...

Dynamic Analysis of FRP-Reinforced Masonry Arches via a No-Tension Model with Damage

A FE beam model to perform static and dynamic analysis of fiber-reinforced masonry arches is presented. Based on a constitutive equation formulated for no-tension masonry beams, the model accounts for a limit to the material deformability and provides for irreversible damage occurring under compression. In order to capture any possible FRP debonding, a procedure is also formulated to reduce the performance of the fiber when the tangential and normal stresses at the masonry-composite interface reach a critical value. Some dynamic analyses are performed on a case study with the aim of evaluating the effectiveness of FRP-retrofitting in improving seismic performances.

Bartolomeo Ammannati’s Fountain: Comparisons Between Different Numerical Models

This paper focuses on the evaluation of the seismic performance of Venus, the central sculpture of Bartolomeo Ammannati’s Juno Fountain. A 3D geometrical model based on a laser scanner survey has been obtained and employed to build the finite element model (FEM) used in the analyses. The seismic response of the sculpture has been checked by performing different dynamic analyses, applying a spectrum-compatible ground motion and using different computer codes and assumptions. The considered numerical models differ from each other regarding the material behavior (linear and non-linear) and the connection between the statue and its base. Information useful for the seismic assessment of the artefact has been provided, thanks to the different models used.

A 3D Masonry-Like Model with Bounded Shear Stress

This paper deals with non linear elastic materials for which not all the stresses are admis-sible but only those which belong to the stress range, i.e. a closed and convex subset of the spaceof all symmetric tensors. The constitutive equation that has been formulated and explicitly solved issufficiently general to include, besides the so-called masonry-like materials, many others whose stressrange is obtained experimentally or is theoretically defined. The model, implemented into the finiteelement code MADY, has been used to analyze a masonry panel under a bi-directional monotonicallyincremental load and the obtained numerical results have been discussed.