Válter Lúcio

Rubble stone masonry walls in Portugal strengthened with reinforced micro-concrete layers

This paper describes and analyses the performance of two structural strengthening solutions for rubble stone masonry walls. The strengthening solutions are characterised by: sprayed micro-concrete steel reinforced layers on both lateral faces of the walls, with transversal steel ties through the thickness of the specimens, not in contact with the base of the loading systems; sprayed micro-concrete steel reinforced layers on lateral faces of the specimens, without transversal steel ties but in contact with the base of the loading systems. For the first solution three specimens were tested under axial compression load and three under compression-shear load, and for the second solution three specimens were tested under axial compression load. The results are compared with unstrengthened (reference) specimens. Strengthening solutions of this nature have been used in the rehabilitation of old masonry walls in Portugal, particularly in Lisbon downtown, and in the rehabilitation of some Azores buildings after the 1998 earthquake.

Rubble Stone Masonry Walls Strengthened by Three-Dimensional Steel Ties and Textile-Reinforced Mortar Render, Under Compression and Shear Loads

This article addresses the results of a structural strengthening solution for rubble stone masonry walls. The strengthening includes inserting three-dimensional steel ties across the thickness of the walls and a 30-mm layer of air-lime and cement mortar render reinforced with glass fiber mesh (textile-reinforced mortar), on both sides of the wall. The strengthening solution was found to be efficient for rehabilitating ancient rubble stone masonry walls due to the “three-dimensional” confinement, provided by the steel wires, by offsetting the low cohesive capacity of the mortar used in the walls and thus improving the mechanical resistance and delaying the collapse mechanisms. This study is part of an experimental research program carried out in Universidade Nova de Lisboa, to evaluate structural strengthening solutions for ancient rubble stone masonry buildings. To this end, three specimens of rubble stone masonry walls without strengthening (unreinforced masonry) and other three, with the mentioned strengthening solution, were subjected to compression and shear load tests. Building materials were also tested in order to characterize physical, chemical and mechanical properties.

Rubble Stone Masonry Walls Strengthened by Three-Dimensional Steel Ties and Textile Reinforced Mortar Render, Under Compression

This article concerns the results of a structural strengthening solution for rubble stone masonry walls. The strengthening involved inserting three-dimensional steel ties through the thickness of the walls and applying a 30 mm layer of air-lime/cement mortar render, reinforced with glass fiber mesh (textile reinforced mortar), on both sides of the wall. This study was part of an experimental research program carried out in Universidade Nova de Lisboa, to evaluate a number of structural strengthening solutions for ancient rubble stone masonry buildings and it was sponsored by several industrial companies. In this research program, specimens of rubble stone masonry walls without strengthening (reference specimens) and others with the specified strengthening solution were subjected to compression tests. The strengthening solution was found to be efficient for rehabilitating ancient rubble stone masonry walls due to confinement, which offsets the low cohesive capacity of the mortar used in the walls, thus improving the mechanical resistance and delaying collapse mechanisms.

Rubble Stone Masonry Walls in Portugal Material Properties, Carbonation Depth and Mechanical Characterization

ABSTRACT A significant proportion of Portuguese ancient buildings have structural masonry walls. Therefore, it is important to study this building typology in order to define appropriate structural rehabilitation interventions, whenever necessary. This article presents the results of research carried out at Universidade NOVA de Lisboa on the material properties, of rubble stone masonry walls, including the evolution of carbonation depth over time and mechanical characterisation under compression and shear load tests. It was found that the mechanical behavior of the unreinforced masonry specimens is mostly influenced by the reduced compression and tensile strength of the air-lime mortar. A formulation to estimate the carbonation depth and the masonry compressive strength as a function of time is proposed and the Strut-and-Tie Method is used to estimate the resistance of specimens under compression and shear forces. The results of this study are part of a major research project studying the mechanical behavior of unreinforced rubble stone masonry walls (unreinforced masonry—URM), evaluating different strengthening solutions for ancient rubble stone masonry walls (Pinho 2007; Pinho et al. 2012a, 2014a, 2014b) and characterizing the building materials used in both URM and strengthened walls.

Numerical Simulation of Blast Effects on Fibre Grout Strengthened RC Panels

The present paper aims to examine the potential of the Applied Element Method (AEM) in simulating the blast effects in RC panels. The numerical estimates are compared with the results obtained in an experimental campaign designed to investigate the effectiveness of fibre grout for strengthening full scale RC panels by comparing the effects that a similar blast load produces in a reference and the strengthened panel. First, a numerical model of the reference specimen was created in the software Extreme Loading for Structures and calibrated to match the experimental results. With no further calibration, the fibre reinforced grout strengthening was added and the resulting numerical model subjected to the same blast load. The experimental blast effects on both reference and strengthened panels, despite the lack of high speed measurement equipment (pressure, strains and displacements sensors), compare well with the numerical estimates in terms of residual and maximum displacements, showing that, once calibrated, the AEM numerical models can be successfully used to simulate blast effects in RC panels.

Experimental analysis of rubble stone masonry walls strengthened by transverse confinement under compression and compression-shear loadings

ABSTRACT Stone masonry walls of ancient buildings have reasonable resistance to vertical loads but lower resistance to shear forces and reduced tensile strength. However, to achieve such compressive strength the masonry must not disaggregate when subjected to loading. This can be achieved if during the construction of the walls larger stones, usually referred as “through stones”, are used, spanning the thickness of the wall, making it possible to improve the transverse confinement of the masonry. For rehabilitation projects and structural reinforcement of such buildings, the transverse confinement can be achieved by fixing steel elements perpendicular to the wall. This confinement technique is often part of a more comprehensive rehabilitation solution, which includes the application of mortar or concrete reinforced layers applied to the wall surface. This article presents results of an experimental research on material properties and mechanical characterisation of stone masonry specimens strengthened by two transverse confinement solutions (independent steel reinforcing rods and continuous steel ribbons wrapping the specimen). Specimens were tested under compression and compression and shear loadings. This experimental work is part of a major research project to study the mechanical behavior of URM and strengthened walls, and the characteristics of the building materials of such specimens.