A digital tool to design structurally feasible semi-circular masonry arches composed of interlocking blocks

This work deals with a digital tool to design stable semi-circular masonry arches composed of interlocking blocks which are kept together by interlocking connectors on their faces. These blocks, comparing to conventional blocks, increase the sliding resistance and reduce the workmanship. However, the current digital tools were developed mostly to design arches with conventional blocks. The proposed tool tries to fill this gap by addressing the work in three stages. First, a heuristic method is developed to define the relationships between the geometry of an interlocking face and the sliding resistance. Then, a structural analysis procedure is developed based on limit analysis and a heuristic method to define the stability condition of the arch. Finally, optimization algorithms are developed to find the thinnest arch by means of two minimization strategies dealing with the relationship between the sliding resistance of the blocks and the geometry of the interlocking faces, differently. The algorithms consider some control points on a given thrust line and automatically adjust them to minimize the thickness, while the stability condition checks the structural feasibility during the geometry adjustment. To evaluate the accuracy of the proposed heuristic method, the results obtained with FE analysis are used for comparison

Environmental and economic impact of retrofitting techniques to prevent out‐of‐plane failure modes of unreinforced masonry buildings

This paper presents an innovative methodology to assess the economic and environmental impact of integrated interventions, namely solutions that improve both structural and energy performance of existing masonry buildings, preventing out‐of‐plane modes and increasing their energy efficiency. The procedure allows the assessment of the environmental and the economic normalized costs of each integrated intervention, considering seismic and energy‐saving indicators. In addition, the work introduces in relative or absolute terms two original indicators, associated with seismic displacement and thermal transmittance. The iso‐cost curves so derived are thus a powerful tool to compare alternative solutions, aiming to identify the most advantageous one. In fact, iso‐cost curves can be used with a twofold objective: to determine the optimal integrated intervention associated with a given economic/environmental impact, or, as an alternative, to derive the pairs of seismic and energy performance indicators associated with a given budget. The analysis of a somehow relevant case study reveals that small energy savings could imply excessive environmental impacts, disproportionally increasing the carbon footprint characterizing each intervention. Iso‐cost curves in terms of absolute indicators are more suitable for assessing the effects of varying acceleration demands on a given building, while iso‐cost curves in terms of relative indicators are more readable to consider a plurality of cases, located in different sites. The promising results confirm the effec-tiveness of the proposed method, stimulating further studies

Stochastic assessment of rocking masonry façades under real seismic records

This contribution assesses in stochastic terms the safety level of masonry façades potentially subjected to out-of-plane loading and the beneficial effect offered by horizontal restraints – such as steel tie rods - under earthquakes. A parametric analysis is performed on façades of different slenderness and size to state their influence on the response in probabilistic terms, showing that velocity and energy based Intensity Measures are optimal since they usually re-spect the efficiency and practicality criteria. In case of retrofitting interventions, the univariate FCs can be plotted in the two configurations (with and without steel tie rods). In order to ef-fectively present the results, the graph of the difference of conditional probability is elaborat-ed, which directly gives the information on the earthquake intensity for which the level of im-provement is more relevant. Univariate and bivariate curves are also compared and the for-mer may be not in favor of safety, especially for stronger seismic records. This probabilistic procedure is ideal for applications in earthquake engineering, assessing in stochastic sense the level of improvement obtained with traditional retrofitting solutions

In-plane behaviour of masonry walls: Numerical analysis and design formulations

This paper presents the results of several numerical analyses aimed at investigating the in-plane resistance of masonry walls by means of two modelling approaches: a finite element model (FEM) and a discrete macro-element model (DMEM). Non-linear analyses are developed, in both cases, by changing the mechanical properties of masonry (compressive and tensile strengths, fracture energy in compression and tension, shear strength) and the value of the vertical compression stress applied on the walls. The reliability of both numerical models is firstly checked by means of comparisons with experimental tests available in the literature. The analyses show that the numerical results provided by the two modelling approaches are in good agreement, in terms of both failure loads and modes, while some differences are observed in their load-displacement curves, espe-cially in the non-linear field. Finally, the numerical in-plane resistances are compared with the theoretical formulations provided by the Italian building code for both flexural and shear failure modes and an amendment for the shape factor ‘b’ introduced in the code formulation for squat walls is proposed

Literature review of the in-plane behavior of masonry walls: Theoretical vs. experimental results

In-plane strength of masonry walls is affected by the resistant mechanisms activated in the walls, i.e., related to flexural or shear behavior. The latter one can occur in the walls according to different failure modes depending on both mortar and unit strengths and on the type of assembling, i.e., ‘regular’ or ‘irregular’ texture. In this paper, a critical review of the existing design formulations for the in-plane strength of masonry walls is firstly presented, with important information on the achievable failure modes depending on the geometrical and mechanical features of the masonry fabric. Then, experimental tests are collected from the literature and a comparison between theoretical and experimental results is carried out. The presented analyses are aimed to highlight the differences between the existing formulations and to identify the most suitable ones

Role of science in ecosystem management

Roberts argues that in order to implement ecosystem management, resource management must switch its ecological perspective from an individual-and population-based focus to ecosystem-and landscape-based ecology; from an object (form) to context (function) approach; and adopt a multi-scalar modeling approach. A major role for science in EM is to predict ecosystem behavior under alternative management strategies. Wilcox, Risbrudt, Thomas, and Kessler all emphasized the critical role of a higher level of science, although Daniels pointed out that there is a risk of creating a politics of expertise. Thus participating scientists have a strong responsibility to communicate their knowledge to the public in understandable ways

Damage assessment in single-nave churches and analysis of the most recurring mechanisms after the 2016–2017 central Italy earthquakes

Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage

Experimental Investigation on the Torsion-Shear Behaviour at the Interfaces of Interlocking Masonry Block Assemblages

This paper presents an experimental investigation on the initial shear (cohesion) and torsion-shear strengths at the interface of an interlocking masonry block. An interlocking block is a rigid unit with locks avoiding the block to slide. This improves the seismic response of dry jointed assemblages of masonry structures subjected to in-plane and out-of-plane loading. The experimental investigation is designed and carried out for the corrugated interface having one lock with rectangular cross section, i.e. the specimen is an interlocking unit composed of a main body and a lock located on the upper face of the main body. Cement- based mortars are selected to reproduce the specimen, casted using a mould provided by a 3D printer, and both the lock and the main body are kept rigid during the tests. The initial shear and torsion-shear capacities of the interface at which the lock is connected to the main body are assessed together with its quasi-brittle fracture and registered in terms of load- displacement curves. In the designed setup, the horizontal force is applied to the rigid lock until it is disjointed from the rigid main body of the block, while the effect of rocking during the shear test is avoided. The force and the displacements are measured using a load cell and Linear Variable Displacement Transducers (LVDTs), respectively. The experimental programme includes four different sets with different load application points and different load directions, each set repeated on a number of similar specimens. Empirical formulations between the initial shear and compressive strengths of the lock interface are also evaluated

In-plane Behaviour of an Iron-Framed Masonry Façade: Comparison between Different Modelling Strategies

The ‘baraccato’ system is a construction technique with genius earthquake resilient features, used for the reconstruction of the historical city centres in the South of Italy after the catastrophic events occurred in the 18th-19th centuries. A very interesting example of such a building typology is represented by the Church of Santa Maria Maddalena, located in the municipality of Casamicciola Terme of the Ischia Island and built in 1896, after the catastrophic earthquake of 1883. The church is characterized by a mixed ‘baraccato’ system mainly made of yellow tuff block masonry walls strengthened by iron profiles or wooden elements. The reduced damage suffered by the church after the seismic event of 21st August 2017 evidenced the good behaviour of such a mixed structural system, especially into avoiding out-of-plane mechanisms. The presence of the iron-framed system is even more challenging in the definition of the modelling strategies for the structural analysis of the church. Thus, the choice of an appropriate numerical strategy to be used for nonlinear simulation should be properly investigated since the interaction between the frame elements and the elements representing the masonry walls has to be considered. As a first step of the structural analysis of the whole church, the in-plane behaviour of the main façade of the Church of Santa Maria Maddalena is analysed in this paper, with the aim to evaluate the efficacy of different modelling strategies. In particular, the study considers different models according to Finite and Discrete Element strategies available within DIANA FEA [1] and 3DMacro [2] software, respectively. Non-linear static analyses are carried out by means of both software and the obtained results are compared and discussed with the aim of extending them to the study of the whole church