ANALYTICAL MODEL OF THE BEHAVIOUR A MASONRY STRUCTURE REINFORCED WITH COMPOSITE MATERIALS

U radu je prikazan pokušaj opisivanja i prilagodbe modela rada zidanih konstrukcija podvrgnutih postupcima ojačanja kompozitnim materijalima. Formiranje određenog modela sloma je povezano s vrstom ojačanja i njegovim položajem (ekstradosi, intradosi). Dani modeli nisu predviđeni da se koriste za proračune, već da pokažu ponašanje konstrukcije, i mogu činiti osnovu za procjenu djelovanja ojačanja primijenjenog u drugim slučajevima.The paper presents an attempt to describe and adapt models of work of masonry structures subjected to reinforcement treatments with composite materials. The formation of a particular failure model is related to the type of reinforcement and its location (extrados, intrados). The models given are not intended to be used for calculations but to illustrate the behaviour of the structure, and may form the basis for assessing the effects of reinforcement applied in other cases

Seismic performance of a masonry arch viaduct subjected to foreshocks and a mainshock

The main objective of this work is to present the results of seismic numerical investigation which was conducted for a masonry arch viaduct. The viaduct which was chosen as a case study, was subjected to foreshock-mainshock sequence. For the numerical evaluation a 3D finite element model (FEM) of the structure was assembled with the ABAQUS/Standard software program. In the numerical simulations a Barcelona Model (BM) was applied as a constitutive material model to represent nonlinear behaviour of the masonry arches of the investigated viaduct under the seismic actions. Taken into consideration the results of calculations the evident nonlinear behaviour of the masonry arches was detected under the earthquakes. The plastic strains as well as the cracking were achieved in some areas of the arches of the viaduct after seismic foreshock-mainshock sequence. Also proposed methodology for strengthening and monitoring of the structure of the viaduct in the future

FINITE ELEMENT SIMULATIONS FOR THE COMPREHENSION OF PHYSICAL PHENOMENA INVOLVED IN ELECTRIC IMPEDANCE TOMOGRAPHY OF MASONRY STRUCTURES

The paper describes the preliminary studies of University of Minho on the use of Electric Impedance/Resistance Tomography to assess masonry structures. The study is focused on the analysis of values of current and voltage resulting from the use of an electrical source with voltage and frequency values from a distribution network. The analysis is made from results obtained through computer simulations, using a three-dimensional model of the idealized masonry structures. A finite element program was used for the simulations. Three types of electrodes were used in simulations, and the analysis of the results led to significant conclusions. Later masonry specimens were built and a series of preliminary tests were carried out in the laboratory. The comparative analysis of simulated and experimental results allowed identifying the factors that have influence on the physical results

Structural and health assessment of historic timber roofs from the Convent of Christ in Tomar

Before coming up with any important decision of intervention in the restoration process of existing buildings, the assessment of the conservation state is required as regards heritage timber structures and especially for those that suffered a lack of maintenance in their service life. In that context, three timber roof structures from the Convent of Christ in Tomar, Portugal, were selected and investigated. To this end, a research methodology was introduced and applied to these case studies into four main steps: (1) visual inspection; (2) non-destructive wood diagnosis; (3) structural safety evaluation; (4) prevention and intervention measures. For the visual inspection, every element and joint constituting the roof structures received scrutiny through assessing the wood species, the different construction stages and, last but not least, their respective geometry. As regards the encountered pathologies, structural disorders (e.g. accidental failure, serviceability defects…) and wood deteriorations due to biological agents (e.g. wood-destroying fungi or insects), which ineluctably leads to a likely decrease of the mechanical performances of the roof structure, were reported. To estimate the residual element cross section and elastic modulus, wood diagnosis was carried out using three relevant non-destructive tests: (1) ultrasonic pulse velocity; (2) drilling resistance; (3) impact penetration. From the collected data, the three timber roof structures were modelled on a commercial software to check their safety and integrity. Based on those outcomes, some prevention and intervention measures haves been lastly proposed case by case.This work was financed by FEDER funds through the Competitively Factors Operational Programme—COMPETE and by national funds through FCT—Foundation for Science and Technology within the scope of the research project INVISIBLE WOODS PTDC/EPH-PAT/2401/2014, and the PhD Scholarships SFRH/BD/128580/2017. Besides, we would also like to acknowledge Prof. Cristina Nabais, from the University of Coimbra, for her collaboration dealing with the dendrochronological part and, last but not least, the DGPC for opening the doors to the wonderful Convent of Christ in Tomar and for the permission to investigate the timber roof structures in the dormitory Room 68 and Knights’ Hall