Masonry is a construction material that has been used throughout the years as a structural or non-structural component in buildings. Masonry can be described as a composite material made up of ...different units and diverse types of arrangements, with or without mortar, that is used in many ancient public buildings, as well as with the latest technologies being applied in construction. Research in multiple relevant fields, as well as crossing structural with non-structural needs, is crucial for understanding the qualities of existent buildings and to develop new products and construction technologies. This book addresses and promotes the discussion related to the different topics addressing the use of masonry in the construction sciences and in practice, including theory and research, numerical approaches and technical applications in new works, and repair actions and interventions in the built environment, connecting theory and application across topics from academia to industry.
•Nonlinear static analyses for the seismic assessment of masonry buildings.•Seismic assessment of existing complex masonry buildings with flexible floors.•Vulnerability assessment of mixed ...masonry–reinforced concrete buildings.•Reliable models and strength criteria for masonry pier and spandrel elements.•An advanced modelling tool useful both at research level and engineering practice.
The seismic analysis of masonry buildings requires reliable nonlinear models as effective tools for both design of new buildings and assessment and retrofitting of existing ones. Performance based assessment is now mainly oriented to the use of nonlinear analysis methods, thus their capability to simulate the nonlinear response is crucial, in particular in case of masonry buildings. Among the different modelling strategies proposed in literature, the equivalent frame approach seems particularly attractive since it allows the analysis of complete 3D buildings with a reasonable computational effort, suitable also for practice engineering aims. Moreover, it is also expressly recommended in several national and international codes. Within this context, the paper presents the solutions adopted for the implementation of the equivalent frame model in the TREMURI program for the nonlinear seismic analysis of masonry buildings.
► We introduce a innovative approach for simulating nonlinear seismic response of masonry buildings. ► The computational cost of the proposed approach is greatly reduced, compared to nonlinear FEM. ► ...The basic plane element is able to reproduce the typical in-plane collapse behaviour of a masonry wall. ► This approach provides a powerful tool for the seismic assessment of masonry building. ► The model can be used for modelling large real structures in practical engineering.
The evaluation of the nonlinear seismic response of masonry buildings represents a subject of considerable importance whose resolution is nowadays a main research topic in earthquake engineering. Refined nonlinear finite element models require a huge computational cost that makes these methods unsuitable for practical application. In this paper an innovative discrete-element model, conceived for the simulation of the in-plane behaviour of masonry buildings, is presented. The basic idea of the proposed approach is to approximate the in-plane nonlinear response of masonry walls by an equivalent discrete element. This element is able to reproduce the typical in-plane collapse behaviour of a masonry wall subjected to earthquake loading. The reliability of the proposed approach has been evaluated by means of nonlinear incremental static analyses performed on masonry structures, for which theoretical and/or experimental results are available in the literature. The proposed computational strategy provides a relatively simple and practical tool which could be of significant value for the design and the vulnerability assessment of unreinforced masonry structures in seismic areas.
•The in-plane drift capacity of rocking unreinforced masonry piers is discussed.•A dataset of tests on calcium silicate and clay masonry is created and analysed.•Parameters affecting the ultimate ...drift capacity are identified.•A new empirical model specifically suited to Dutch masonry piers is proposed.•The proposed equation improves the prediction of the ultimate drift of the piers.
In recent years, seismic assessment of existing unreinforced masonry (URM) structures is being increasingly based on nonlinear methods. The in-plane displacement capacity represents one of the most crucial yet still debated features of the nonlinear behaviour of URM piers. International codes often employ empirical models to estimate the pier ultimate drift. These models usually depends on the failure mode (flexure or shear) and on the properties of the pier (such as geometry, material properties, boundary or loading conditions).
The present work focuses on the displacement capacity of Dutch masonry piers, or walls comparable to those, failing after the activation of a rocking mechanism. As a consequence, a dataset of 38 quasi-static tests on URM piers representative of the Dutch masonry is constructed and statistically analysed. The dataset, that includes also new laboratory tests recently performed at Delft University of Technology, consists of both calcium silicate and clay brick masonry piers characterised by low axial compressive loads and limited thickness. The displacement capacity of calcium silicate masonry is of special interest because it was not investigated in the past as extensively as for clay brick masonry. The analysis of the dataset highlights the influence of axial load ratio, aspect ratio and pier height on the drift capacity of Dutch rocking URM piers, whereas the other parameters do not appear to have a remarkable impact. Subsequently, a new empirical equation is derived and calibrated against the dataset. The accuracy of the proposed equation is assessed by comparing it to empirical models recommended in international standards and in the literature. For the considered dataset, representative of Dutch rocking URM piers, the proposed equation improves the accuracy of the predictions and fairly reproduces the dependence of the experimental drift capacity on the principal wall parameters.
•A unified model governed by ten parameters is proposed for modeling masonry walls.•The identification procedure for each parameter of the proposed model is presented.•Four wall specimens are ...cyclically loaded to validate the proposed approach.•A half-scale building structure is tested to verify the effectiveness of the model.
A significant portion of the building stock in seismic regions all over the world is constituted by brick masonry structures that are well known to be prone to damage under seismic excitations. For evaluating the dynamic performance of masonry buildings, efficient numerical models are required. In this paper, considering the typical hysteretic behavior of brick masonry walls, a unified model for the static and dynamic analysis of masonry structures governed by ten key parameters is proposed. The model is able to simulate different kinds of walls such as unconfined unperforated and perforated walls, as well as confined unperforated and perforated walls subjected to horizontal reverse cyclic loadings and vertical compression. The identification procedure of each key parameter, that includes, among the others, lateral strength, loading and unloading stiffness, accumulated damage factor, shrinkage factor, as well as slipping factor, is presented by analyzing over one hundred results collected from literature. In order to validate the proposed approach, four different types of wall specimens were tested under cyclic loads. Furthermore, a two-storey half-scale structure was tested to verify the effectiveness of the presented model in reproducing the deformation response and global hysteretic behavior of the structure.
Cracks are the most important source of information about the damage that occurs to unreinforced masonry piers under seismic actions. To predict the structural state of unreinforced masonry piers ...after an earthquake, research models have been developed to quantify important features of crack patterns. One of the most used crack features is the width, but this can be influenced by several parameters such as the axial load ratio, the shear span ratio, and the loading protocol, which have not been fully studied in previous research studies.
In this study, we use experimental data to investigate the evolution of cracking in stone masonry piers during the application of cyclic shear–compression loading. The data consists of gray-scale images taken during quasi-static shear–compression tests performed on six plastered rubble-stone masonry walls subjected to constant axial force and cycles of increasing drift demand. Through the combined use of digital image correlation and a pre-trained deep learning model, crack pixels are identified, post-processed, and quantified based on their width. The dependency of the crack width on the axial load ratio, the shear span ratio, and the loading protocol at the peak force and ultimate drift limit states of the piers is clarified by a displacement vector field analysis, histogram of the crack width, and the concentration of deformation in the cracks.
We show that, as opposed to flexural cracks, diagonal shear cracks do not fully close when moving from the applied drift demand to the residual drift measured upon removal of the lateral load. Furthermore, we provide the maximum residual crack width at peak force and ultimate drift limit states. This study will improve the decision making abilities of future models used to quantify earthquake-induced damage to stone masonry buildings.
•Automated computation of crack width from DIC measurements.•Automated computation of crack orientation from segmented crack pixels.•Investigating flexural and shear crack width at various drift demands and residual drifts.•Determining influence of axial load, shear span and loading protocol on crack width.•Computing residual crack width at peak force and ultimate drift.
Methods employed for surveying buildings for condition have traditionally been reliant upon visual assessment and manual recording. Survey of traditional masonry also ostensibly conforms to this ...approach but, due to the sheer volume of masonry units composing walls, it is often prohibitively time consuming, exceptionally complex and ultimately costly. Notable features of such survey work for ashlar stone types require each stone to be labelled and overlaid with information relative to condition. Further hindering these already costly operations, it has been shown that the accuracy of reporting, including labelling the manifestation of defects and defect diagnosis, is subjective, depending upon the expertise and experience of those evaluating the fabric. Moving beyond these preliminary survey and reporting stages, this situation gives rise to variable repair and maintenance strategies that can have significant cost implications and can debase fundamental conservation activities.
The development of digital technologies, such as terrestrial laser scanning, and advancements in novel computer vision statistical techniques can help produce accurate representation of buildings that can be subsequently rapidly processed, achieving many tangible survey functions with greater inherent objectivity. In this paper, an innovative strategy for automatic detection and classification of defects in digitised ashlar masonry walling is presented. The classification method is based on the use of supervised machine learning algorithms, assisted by surveyors' strategies and expertise to identify defective individual masonry units, through to broader global patterns for groups of stones. The proposed approach has been tested on the main façade of the Chapel Royal in Stirling Castle (Scotland), demonstrating its potential for ashlar masonry forms of wall construction. It is important to recognise that the findings are not limited to this culturally significant building and will be of high value to almost innumerable ashlar-built structures worldwide. The research ultimately attempts to reduce the degree of subjectivity in classifying defects, on a scale and rapidity hitherto beyond traditional project cost constraints. Importantly, it is recognised that through automation more effective utilisation of resources that would have been traditionally spent on survey can be redeployed to support fabric intervention or routine maintenance operations.
•We present a novel strategy for automatic detection and classification of defects.•The developed algorithm has been applied to digitised ashlar masonry walling.•It identifies loss of material defects and discolouration on walls.•The method has been validated through experiments in an important heritage building.•Results prove the potential of the method toward more objective & accurate surveys.
•Experiments on shear anchors embedded into brick and stone masonry.•Analytical exact model that predicts the shear strength of any anchorage embedded into masonry.•Discussion about the mechanical ...behavior of the shear anchor.•Comparisons between model predictions and both experimental results and code provisions.•Optimal technical solution prompted by the model.
This paper focuses on any straight bar, herein called “anchor”, inserted within a hole drilled into a masonry structure, installed orthogonally to the masonry surface, and bonded to the masonry either with an anchoring material or without (adhesive or mechanical anchors). The anchor is subjected to a transverse force applied at the end that protrudes from the masonry (i.e., a shear force having direction parallel to the masonry surface), while no appreciable axial force is applied to the anchor (shear anchor). In brief, the paper is devoted to the post-installed horizontal anchor that transfers vertical loads from a horizontal structure to a vertical masonry structure.
On site experiments on real anchors allowed the author to establish the mechanical assumptions that govern the behavior of the shear anchor. Based on those assumptions, an analytical (closed form) model was created. The model is comprised of a function that gives the ultimate contact pressures, and a two-equation system whose solution is the maximum shear force that the anchor can bear, therefore called “shear strength”. The model also provides the elastic limit shear strength. The data to be entered into the model is composed of the geometry of the anchor and the strength of the masonry.
The paper presents the experimental campaigns, the model, the application of the model to case studies, and a comprehensive discussion. The results put forward the optimal technical solutions for the masonry shear anchor, which are described.
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