Analytical and numerical seismic assessment of heritage masonry towers

Abstract

The new Italian building code, published in 2018 [MIT in NTC 2018: D.M. del Ministero delle Infrastrutture e dei trasporti del 17/01/2018. Aggiornamento delle Norme Tecniche per le Costruzioni (in Italian), 2018], explicitly refers to the Italian "Guidelines for the assessment and mitigation of the seismic risk of the cultural heritage" [PCM in DPCM 2011: Direttiva del Presidente del Consiglio dei Ministri per valutazione e riduzione del rischio sismico del patrimonio culturale con riferimento alle norme tecniche per le costruzioni, G.U. n. 47 (in Italian), 2011] as a reliable source of guidance that can be employed for the vulnerability assessment of heritage buildings under seismic loads. According to these guidelines, three evaluation levels are introduced to analyse and assess the seismic capacity of historic masonry structures, namely: (1) simplified global static analyses; (2) kinematic analyses based on local collapse mechanisms, (3) detailed global analyses. Because of the complexity and the large variety of existing masonry typologies, which makes it particularly problematic to adopt a unique procedure for all existing structures, the guidelines provide different simplified analysis approaches for different structural configurations, e.g. churches, palaces, towers. Among the existing typologies of masonry structures there considered, this work aims to deepen validity, effectiveness and scope of application of the Italian guidelines with respect to heritage masonry towers. The three evaluation levels proposed by the guidelines are here compared by discussing the seismic risk assessment of a representative masonry tower: the Cugnanesi tower located in San Gimignano (Italy). The results show that global failure modes due to local stress concentrations cannot be identified if only simplified static and kinematic analyses are performed. Detailed global analyses are in fact generally needed for a reliable prediction of the seismic performance of such structures.

Assessment and Fragility of Byzantine Unreinforced Masonry Towers

“…Their heights vary between approximately 20 m to 25 m. Given that our aim is a statistical treatment of the vulnerability and not a specific case-study, a very detailed model is out of the scope of the analysis. Simplified models have been applied to tackle the aforementioned difficulties: (i) simple mechanical models; and (ii) limit analysis [59,60].…”

Implementation of Pushover Analysis for Seismic Assessment of Masonry Towers: Issues and Practical Recommendations

“…The role of the geometry is also represented here by the presence of openings, which is demonstrated by an apparent vertical cracking passing through the openings, see Figure 6. This result implies the necessity to address a more detailed numerical approach model, where the simplified ones, as proposed in [9,10], could fail to distinguish the most prone active mechanism.…”

“…Masonry towers are very peculiar structural typologies, and they are typically conceived to withstand only vertical loads, as it occurs for all historical masonry constructions [7][8][9][10][11][12][13][14][15][16]. Therefore, their seismic vulnerability is expected to be high and particular attention should be paid to their seismic assessment toward a preservation approach.…”

A “Smartly Functional” Urban 3D Model: A New Way to Preserve the State of Health and Quality of a Complex Masonry Structure

“…It is on the basis of this concept that the Ministerial Circular no. 617 of 2 February 2009, implementing the Ministerial Decree of 14 January 2008 "New Technical Standards for Construction" in chapter 8, introduced the concept of "Level of knowledge" to the "Existing Constructions", which defines the procedures for the geometric-structural survey, structural details, the mechanical characterization of materials, and the analysis method to be used [21].…”