João Miranda Guedes

Experimental testing, numerical modelling and seismic strengthening of traditional stone masonry: comprehensive study of a real Azorian pier

Stone masonry is one of the oldest building techniques used worldwide and it is known to exhibit poor behaviour under seismic excitations. In this context, this work aims at assessing the in-plane behaviour of an existing double-leaf stone masonry pier by experimental testing. Additionally, a detailed 3D finite element numerical analysis based on micro-modelling of the original pier is presented (fully describing the geometry and division of each individual elements, namely infill, blocks and joints) aiming at simulating the experimental test results. This numerical strategy can be seen as an alternative way of analysing this type of constructions, particularly useful for laboratory studies, and suitable for the calibration of simplified numerical models. As part of a wider research activity, this work is further complemented with the presentation of an effective retrofit/strengthening technique (reinforced connected plaster) to achieve a significant improvement of its in-plane cyclic response which is experimentally verified in the results presented herein.

Structural rehabilitation of old buildings

Introduction and Rehabilitation: Aims & Scopes.- Construction Systems.- Building Materials and Components.- Laboratorial and In-field Tests.- Modeling.- Vulnerability Assessment.- Construction Maintenance.

NON-LINEAR BEHAVIOUR OF REINFORCED CONCRETE BEAMS : FROM 3D CONTINUUM TO 1D MEMBER MODELLING

Abstract Various levels of modelling of reinforced concrete beams are presented and compared. Their complementary character is outlined in some simple cases. Further studies are proposed.

Characterization and Reinforcement of Stone Masonry Walls

Stone masonry is one of the oldest “structural materials” known to man. It is made by the superposition of stones, mortar and, very often, with infill material between leaves. The components present complex links and interactions and, in most cases, unknown geometry and high variability of their mechanical properties. These characteristics make stone masonry a highly heterogeneous material for which it is difficult to define realistic behaviour laws, a challenge that still demands further research, either through laboratory or onsite experimental campaigns. In reality, the mechanical characteristics of a stone masonry element strongly depend on the geometry and geometrical distribution of the stones along the facade and cross-section of the element and, therefore, on the layout of the interfaces, i.e. the joints. Studies developed in Italy have defined a series of parameters that try to quantify the level of fulfilment of good practice constructions rules with the expectable performance of a stone masonry wall under static and dynamic loading, in particular under seismic type loadings. This chapter discusses construction typologies and materials, assessment methodologies, earthquake induced failure mechanisms and strengthening intervention techniques on stone masonry structures, in particular walls.

Applications of Sonic Tests to Masonry Elements: Influence of Joints on the Propagation Velocity of Elastic Waves

AbstractThe authors applied sonic tests to study the propagation of sonic waves through stone masonry walls. In particular, tests were made to study the effect of the joints and the influence of the characteristics of the stones surface, rough or smooth, on the measurement of the sonic velocities on granite masonry specimens. A series of direct, indirect, and impact echo sonic tests were performed on single stones and on columns of stones with dry and mortar joints to obtain P- and R-wave velocities. The results allowed a better understanding of the influence of the stones characteristics and the samples geometries, namely the number of joints, to the global response of the masonry to the propagation of sonic waves. This study also allowed verifying the complementarity of the different sonic test configurations and the interest to cross information from more than one technique to obtain more reliable information. Finally, significant results were also achieved concerning the relationship between the param...

Experimental assessment of in-plane mechanical behavior of tabique walls

ABSTRACT Tabique Walls (TWs) are slender walls, rather common in old masonry constructions, made of a timber-resistant skeleton covered by clay-based mortar. The skeleton consists of a layer of vertical boards and (or) props, sometimes intersected, or superimposed by diagonal elements with gaps filled in by earth-based mortar. Few studies still exist about TWs mechanical performance, a fact that contributes to the frequent decision of replacing them by new walls during rehabilitation work. Because it is quite a valuable technical, material, and cultural construction process that should be preserved, an experimental campaign was carried out at the Faculty of Engineering of Porto University (FEUP) to assess the mechanical behavior of TWs under in-plane vertical and horizontal forces. The campaign involved eight full-scale specimens and allowed for the evaluation of the walls’ strength, stiffness, and deformation modes, valuable information that helps to understand the contribution TWs have to a building’s global structural performance.

Experimental Characterization of Mechanical Behaviour of Existing Tabique Walls Under Compressive and Shear Loading

The construction of old buildings made using tabique walls is one of the most relevant examples of vernacular architecture in Portugal. It exists throughout the country and is particularly relevant in the region of Viseu. However, the knowledge about this traditional building technique is still insufficient. On the other hand, survey campaigns carried out, showed an expressive variability of construction techniques associated with the tabique walls. Thus, it’s essential to know the materials applied, their main properties and the way they interconnect. Following an investigation carried out in old buildings (19th century) of Viseu city [1], this paper presents an experimental work for structural characterization of tabique walls, including references to the setup used to perform the lab tests on 4 samples deemed representative such wall types. The main objective was to characterize the mechanical properties of these walls under in-plane compression and shear forces. The obtained results and the main conclusions are presented. This work aims at providing contributions for a better understanding of the structural behavior of tabique walls.

Assessment of the Mechanical Behaviour of Tabique Walls Through Experimental Tests

The option for substituting timber structures by other materials when renovating old constructions often leads to more invasive solutions, less compatible with the existing structure, being often the cause for more damage. On the contrary, low invasive procedures, such as preservation actions, generates more sustained and respectful interventions, closer to the recommendations expressed in international charts and documents. However, such procedure simply having a good knowledge on the materials (properties and characteristics) and behaviour of the elements (mechanical, static, dynamic, long term, short term…). The present research aims contributing to this knowledge, by assessing, experimentally, the compression mechanical behaviour of a particular type of timber walls commonly found in old masonry constructions in Portugal and referred to tabique walls; the lack of data on the behaviour of this type of walls is probably the main reason why interventions quite often consider their full substitution by new elements. The work consisted on constructing 4 full scale specimens that were tested at the Laboratory of Earthquake and Structural Engineering of the Faculty of Engineering of Porto University to assess the compression strength and behaviour of these elements under no initial damage conditions. The results were also compared to numerical simulations using SAP2000 software.

Assessment of the Mechanical Characteristics of Timber Floors Through Simple Dynamic Identification

The non-destructive in situ characterization of timber floors is difficult and may involve expensive procedures, such as loading tests. Alternatively, it is possible to estimate some mechanical properties by assessing the characteristics of timber beams through sonic or penetration tests (e.g. pilodyn and resistograph); however, the existing correlations are still not very reliable. Thus, this project aims assessing the characteristics of timber floors using dynamic identification procedures, a simple and low cost technique when compared to loading tests. In particular, and through the identification of the main frequencies, this research aims estimating the mechanical behaviour of timber floors, including the characteristics of the beams to walls connections.