Seismic Vulnerability Assessment and Simplified Empirical Formulation for Predicting the Vibration Periods of Structural Units in Aggregate Configuration

Abstract

The present research aims at investigating the vibration period of structural units (SUs) of a typical masonry aggregate located in the historical center of Mirandola, a municipality in the province of Modena. The clustered building consists of eighteen SUs mutually interconnected to each other, which are characterized by solid brick walls and deformable floors. First of all, non-linear static analyses are performed by adopting the 3Muri software focusing on two distinct modelling techniques concerning the analyzed SUs in isolated and clustered configurations. Congruently to the procedure adopted, in order to evaluate a reliable seismic structural response of the SUs arranged in aggregate conditions, the contribution in terms of stiffness and mass derived from adjacent buildings is considered. The analysis results are represented in terms of risk factor, stiffness, and ductility. Secondly, the eigenvalue analysis is faithfully developed to identify the main vibration modes of the investigated SUs by proposing an empirical formulation, that allows for predicting the vibration period of structural units placed in aggregate configuration starting from the corresponding isolated ones. Finally, fragility functions are derived for both the heading and intermediate SUs to point out the expected damages under earthquakes with different intensities.

Post-Earthquake Assessment of a Historical Masonry Building after the Zagreb Earthquake—Case Study

“…All deformations are concentrated in piers and spandrels, and they are connected with rigid nodes. For the use of the software, official user manuals were used with a variety of useful tutorials and similar journal articles dealing with such case studies [18,[34][35][36][37][38]. The 3D model of the building and the equivalent frame made of macro-elements is shown in Figure 14.…”

Physics-Based Ground Motion Simulations for the Prediction of the Seismic Vulnerability of Masonry Building Compounds in Mirandola (Italy)

“…However, although Mirandola did not have a radial expansion, it is noted that the dimensional variation of the building aggregates is linked to the transition from the first expansion phase of the city with a quadrangular plan to the second one with an octagonal urbanized distribution [30,31]. In particular, the buildings located in the historic centre are mainly characterized by a construction uniformity of vertical structures, made of solid brick walls, with the presence of semi-rigid and deformable floors, which represents the most widespread construction typology of the historic centres of the Emilia-Romagna Region [10].…”

“…Buildings 2021, 11, x FOR PEER REVIEW 5 of 25 of solid brick walls, with the presence of semi-rigid and deformable floors, which represents the most widespread construction typology of the historic centres of the Emilia-Romagna Region [10].…”

“…The fragility curves define the probability that a given damage state, d Si , is equalled or exceeded by a specific intensity measure. The adopted methodology considers as intensity measure the spectral displacement, S d , according to the following Equation (3) [10,55,60]:…”

“…In general, it was observed that several historical centres are characterized by an ancient building heritage having an inadequate safety level against earthquakes. In the urban centres, the existing construction typologies are frequently grouped in aggregate configurations, and the constructive matrix of structural units (SUs) is the living representation of a well-consolidated design practice that is very vulnerable to seismic actions [7][8][9][10].…”