Elizabeth Vintzileou

Three-Leaf Masonry in Compression, Before and After Grouting: A Review of Literature

This article summarizes the available experimental results related to the behavior of three-leaf masonry: The behavior and the failure mechanism of this type of masonry under compression is studied. The effect of the mechanical properties of ternary and hydraulic lime-based grout on the mechanical properties of masonry in compression is investigated. Simple formulae are proposed for the estimation of the compressive strength of three-leaf masonry after grouting.

Seismic behavior of three-leaf stone masonry buildings before and after interventions: Shaking table tests on a two-storey masonry model

The aim of this work is to reach a better understanding of the seismic behaviour of historic three-leaf stone masonry buildings with timber floors, before and after interventions. For this purpose, shaking table tests were performed on a building model (scale 1:2). Initially, the dynamic characteristics of the model were identified. Subsequently, biaxial earthquake tests were performed with the base acceleration increased step-wise until the occurrence of repairable damages. Afterwards, the masonry was strengthened by means of grouting and the diaphragm action of the floors was enhanced. Then, the strengthened model was re-tested. The comparison of the performance of the model under earthquake actions before and after strengthening shows that the selected intervention techniques significantly improved the seismic behaviour of the structure.

Testing Historic Masonry Elements and/or Building Models

This paper provides an overview of the Literature on the behaviour of historic masonry elements and building models. The purpose of this paper is to identify the main parameters affecting the seismic behaviour of historic masonry buildings, as illustrated through the experimental campaigns carried out by numerous researchers. Furthermore, aspects of the seismic behaviour that are not sufficiently studied to-date are identified. Thus, selected publications are evaluated related to the behaviour of historic masonry elements in compression, in diagonal compression, in in-plane shear and simultaneous compression, out-of-plane bending, as well as publications related to the behaviour of subassemblies and building models subjected to monotonic, pseudo-dynamic or dynamic tests on earthquake simulator. The available experimental results illustrate the main weaknesses of historic masonry elements and bearing systems, namely the vulnerability to in-plane shear and to out-of-plane bending, the limited ductility, the negative effect of the flexibility of timber floors and roofs, etc. On the other hand, the beneficial effect of adequate connection between horizontal and vertical elements, as well as the connection among walls is also evident. Moreover, the variety of the construction types of masonry tested by various researchers, the scale of the models, the variety of experimental setups and loading histories do not allow, in most cases, a direct comparison of the experimental results. This is so especially as far as properties related to the deformations of masonry elements are concerned. Thus, the effort to develop sound physical models and to calibrate them is not yet satisfactorily assisted by the available experimental results. Yet, this is a prerequisite for a reliable assessment of the current state of historic structures and, by way of consequence, for the selection of adequate intervention techniques for their preservation.

New Titanium Connectors for the Columns Capitals of the Classical Temple of Apollo Epikourios

ABSTRACT The columns of monumental buildings in ancient Greece were provided with a pair of timber “empolia” (plugs) and a “pole” (pin), at interfaces between stone members (drums, capital). In order to reinstate this connection system, in columns capitals that were repaired, during the ongoing restoration of the classical temple of Apollo Epikourios (Greece), new poles and empolia made of titanium were installed. The titanium elements were designed to have similar shape and shear strength to the estimated respective characteristics of the ancient poles and empolia. Moreover, their effect on the seismic behaviour of the temple columns was numerically investigated. The investigation showed that, within the range of strong earthquakes which are anticipated in the area of the monument, the installation of a single pole at the interface between the capital and the uppermost drum leads to limited reduction of the expected maximum and residual deformations of the column, without altering significantly the main characteristics of its rocking response. Furthermore, poles located at every column interface ensures significant limitation of the column residual deformations. Prior to implementation of the titanium poles and empolia, the main aspects of their design were verified through specially designed experiments.

The Use of Radar Techniques and Boroscopy in Investigating Old Masonry: The Case of Dafni Monastery

This article summarizes the results obtained from the application of two investigation techniques, namely radar and boroscopy, in the masonry of the Katholikon of Dafni Monastery (Attica, Greece). The two techniques were applied with the aim to investigate the type of construction of the monuments perimeter masonry. The application of these two techniques proved to be quite efficient because their results offered reliable information regarding the thickness of stones and thus the thickness of the internal filling material in the monuments three-leaf stone masonry. This article presents and comments on difficulties encountered during the application of these techniques, as well as problems that arose during the interpretation of measurements and observations.

Grouts for strengthening two- and three-leaf stone masonry, made with earthen mortars

ABSTRACT Earth was used in the past to produce mortars either on its own or in combination with other materials (such as lime and sand). Earth mortars were used both in adobe and in stone masonry structures. This article aims to study stone masonries made with earth mortar and their strengthening by grouting. Six wallettes were constructed, in order to study the mechanical properties of the two- and three-leaf stone masonry before and after grouting. In parallel, several compositions of grouts, having different ratios of hydraulic lime (NHL5), earth and water, were designed and evaluated regarding their injectability properties (fluidity-penetrability, stability tests). Moreover, flexural and compressive strength tests were performed. Thus, this project led to the development of a number of suitable mixes that satisfy the performance criteria set for their design. The suitability of those mixes from the mechanical point of view was checked by injecting them to wallettes, subsequently tested in compression.

Unreinforced Masonry Walls Subjected to In-Plane Shear: From Tests to Codes and Vice Versa

According to Eurocode 6, the lateral capacity of unreinforced masonry walls is calculated using a simple equation, accounting exclusively of a shear failure mode and based on the shear strength of masonry (friction analogy). With the purpose of checking the efficiency of the Code formula, experimental results are collected from the Literature and an effort is made to predict the lateral capacity of the tested walls. This comparison between predicted and experimental shear resistances shows that the Code formula systematically overestimates the lateral capacity of shear walls. The interpretation of this inconsistency is attempted, a qualitative re-evaluation of selected test results is offered and, finally, proposals for further actions within relevant Code Committees are submitted.

DESIGN OF GROUTS FOR STRENGTHENING THREE OR TWO LEAF MASONRY WITH MUD MORTARS

This paper presents the experimental procedure that has been followed, with main goal to develop various grout compositions adequate for strengthening stone masonry constructed with poor quality mortars. Two or three-leaf masonry frequently met in historic masonry structures is very vulnerable to environmental and seismic actions, especially when made with mud (very low strength) mortar. Although significant research effort is devoted to the development of grouts adequate for strengthening masonries made with lime or limepozzolan mortar, the respective studies on masonries made with mud mortar are scarce and inconclusive. Within the present work, a comprehensive investigation on mud mortars was conducted on samples that have been selected and sampled from three different buildings and sites, in order to identify their physicochemical and mineralogical properties, as well as their grain size distribution. Based on the studied samples of the aforementioned historical buildings with mud mortars, six wallettes were constructed, in order to study the mechanical properties of the two and three stone masonry before and after grouting. After the construction, nondestructive techniques (radar and boroscopy) were applied for the calibration of the methods and the comparison of the results before and after grouting, with main goal to develop various grout compositions according to the parameters which determine the efficiency of the intervention. Based on the characterization results, various grout mixes will be produced and will be examined in terms of compatibility between the mortar and the grout, as well as 4277 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 4277-4287

Assessment of Innovative Solutions for Non-Load Bearing Masonry Enclosures

Eurocode 8 imposes the use of reinforced solutions in order to ensure that the in-plane and out-of-plane damage of masonry infill walls due to seismic actions complies with given performance level requirements. Nevertheless, Eurocode 8 does not provide design rules or methodologies for the detailing of such reinforcement. An experimental programme was thus defined for assessing the response of innovative solutions for non-load bearing masonry enclosures using LNEC’s triaxial shake table. Two reinforcement solutions were tested on single leaf clay brick infill walls: (i) horizontal reinforcement in the bedding planes of the masonry units and (ii) reinforced mortar coating. Furthermore, a testing device for masonry infill panels was specifically conceived for this project. A detailed description of the methods used is given and the experimental results are partially presented and interpreted on the basis of the structural response and its evolution with damage.