Aided diagnosis of structural pathologies with an expert system

Sustainability and safety are social demands for long-life buildings. Suitable inspection and maintenance tasks on structural elements are needed for keeping buildings safely in service. Any malfunction that causes structural damage could be called pathology by analogy between structural engineering and medicine. Even the easiest evaluation tasks require expensive training periods that may be shortened with a suitable tool. This work presents an expert system (called Doctor House or DH) for diagnosing pathologies of structural elements in buildings. DH differs from other expert systems when it deals with uncertainty in a far easier but still useful way and it is capable of aiding during the initial survey 'in situ', when damage should be detected at a glance. DH is a powerful tool that represents complex knowledge gathered from bibliography and experts. Knowledge codification and uncertainty treatment are the main achievements presented. Finally, DH was tested and validated during real surveys.Peer ReviewedPostprint (author's final draft

Study of the compressive response of masonry using non-conventional joint materials

Winner of the International Journal of Masonry Research and Innovation IJMRI Best Paper Award 2017The compressive response of masonry is influenced by geometric, material and execution variables. In addition, the nature of bricks and mortar typically introduces uncertainty to the experimental results. In order to reduce this uncertainty, an experimental campaign has been carried out to analyse the influence of the properties of the joints. Four non-conventional masonry typologies including resin, EPS and rubber joints have been considered for this purpose. In all, 60 compressive tests and 50 deformability tests on five stacked bricks prisms were performed. Obtained data are compared with data from the literature. A comparison with the current European standard is also carried out. The obtained results point out that the modulus of linear deformation of the joint is the most influent variable on the compressive response of masonry. Finally, it seems that current formulation (Eurocode-6) tends to overestimate the modulus of linear deformation of masonry.Peer ReviewedAward-winningPostprint (author's final draft

Refuerzo a cortante de vigas de hormigón armado con tejidos y matrices base cemento. Análisis y comparativa

El principal objetivo de la presente investigación es realizar un estudio comparativo sobre la capacidad de diversos tipos de TRM actuando como refuerzo a cortante en vigas de hormigón armado de características actuales1. Para lograr este propósito, se han definido unos objetivos parciales que servirán de guía en todo el proceso de elaboración y realización de la investigación.Postprint (published version

Assessing the performance of CFRP strengthening on masonry walls using experimental modal analysis

Strengthening masonry structures using FRP laminates has been widely studied from a resistance point of view. However, there is a need of a non-destructive technique to validate strengthening interventions. In this paper, experimental modal analysis is proposed as a technique to assess practitioners’ works. Fifteen brick masonry walls were built and strengthened with five different patterns of carbon-FRP laminates. Experimental modal analysis was performed before and after strengthening interventions. Different vibration modes were compared to select the more sensitive one depending on the strengthening configuration. The change in the vibration frequency was analysed and correlated with cross-section stiffness modification. The obtained results showed changes up to 30% on the vibration frequencies due to strengthening installation. On the overall, the proposed experimental methodology is supported by theoretical analytical calculations with an error under 5% in most of the cases.Peer ReviewedPostprint (author's final draft

Effect of Sporosarcina Pasteurii on the strength properties of compressed earth specimens

Microbial biodeposition of calcite induction for improving the performance of rammed earth is a research area that must be analysed in a representative environment. This analysis must consider the compaction force, particle size distribution and curing process as production variables. This paper investigates the effects of adding specific bacteria, Sporosarcina Pasteurii, into compressed earth cubes and the effect of production variables. Uniaxial compressive tests and direct shear tests have been conducted for 80 specimens. The results indicate that calcite precipitation interacts with the drying process of clay/silt resulting in reducing the compressive strength, the apparent cohesion and the friction angle. Finally, bacterial activity, which is more likely in samples cured in a high humidity environment, tends to reduce the dilatancy effect.Peer ReviewedPostprint (published version

Experimental comparison of reinforced concrete beams strengthened against bending with different types of cementitious-matrix composite materials

© 2018. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Fabric-reinforced cementitious matrix (FRCM) materials overcome some hazard limitations of organic resins and are becoming a competitive technology on retrofitting reinforced concrete structures. In this work, five types of FRCM applied as flexural reinforcements are compared. The results show that there is a correlation between the strengthening materials and the cracking patterns developed by the tested beams. Further, FRCM contributed to an increase the flexural capacity and flexural stiffness of the strengthened beams, but their ductility decreased. Finally, a new methodology to study the cracking process is presented.Peer ReviewedPostprint (author's final draft

Analysis of different types of cementitious-based composites used as shear strengthening system for reinforced concrete beams

The global tendency to apply sustainable criteria in most of the productive fields and the limited durability and the pathologies that reinforced concrete elements suffer are aspects that explain the increasing necessity of strengthening this type of structures. The evolution of strengthening techniques has consisted in the development of new technologies that ease the application of the solution and minimise the time structures are out of service. In this way, using composite materials in construction has represented a revolution in the strengthening of structures. The textile-reinforced mortar (TRM) is a composite material that combines textiles, made of high strength tensile fibres, with cementitious matrix. A remarkable feature of this solution is that it does not require organic resins for its manufacturing and application, unlike the techniques as fibrereinforced polymer (FRP). The present work has consisted in the analysis of the mechanical and structural behaviour of reinforced concrete beams strengthened against shear stresses using different types of TRM. To fulfil this aim, an experimental campaign has been carried out. Nine reinforced concrete beams have been subjected to experimental tests, eight of them shear strengthened with four different combinations of textiles and mortars. Using the experimental data, an analytical study has compared the ultimate capacity of the reinforcements with the predictions obtained from three analytical models included in design standards of FRP and TRM. The results show that the strengthening system is able to increase an average of 33.7% the shear capacity of reinforced concrete beams. On the other hand, the results of analytical studies indicate that models adapted from FRP standards might show a better prediction capacity than the obtained with the code specifically developed for TRM reinforcements, which has performed significantly conservative.Peer ReviewedPostprint (published version

Insights into the controversy over materials data for the comparison of biomechanical performance in vertebrates

Mechanical comparison of different species is performed with the help of computational tools like Finite Element Analysis FEA. In palaeobiology it is common to consider bone like an isotropic material for simulations but often real data of bone materials is impossible to know. This work investigates the influence of choice of bone materials properties over the results of simulations, showing when and why the materials data are relevant and when the selection of these data becomes irrelevant. With a theoretical approach from continuum mechanics and with a practical example the relationship between material data and comparative metrics like stress, strains and displacements is discussed. When linear and elastic material properties are assumed in a comparative analysis, the effect of the elastic modulus of the material is irrelevant over stress patterns. This statement is true for homogeneous and inhomogeneous materials, in this last case the proportion between the different materials properties must kept constant. In the case of the strains and displacements, there is an inverse proportionality kept constant, between the values of the metrics and the changes in the elastic modulus. These properties allow comparative studies without considering the real elastic materials properties.Peer ReviewedPostprint (published version

Experimental and analytical flexural performances of reinforced concrete beams strengthened with post-tensioned near surface mounted basalt composite laminates

© 2018. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Near surface mounted (NSM) is a technique that improves the strengthening capacity of composite laminates. The use of a post-tensioning technique modifies the performance of the strengthening because it is active bearing loads from the very beginning. This study compares the performances of three beams: one without strengthening, one with passive NSM laminate, and a third with post-tensioned NSM laminate. The experimental approach compares the pre-cracking and post-cracking performance until failures, showing that the post-tensioned solution withstands larger loads in pre-cracking and presents less deformation in post-cracking. Moreover, post-tensioning is an effective technique that can prevent loss of stiffness even after cracking. Finally, simple analytical equations based on the plane cross-section for pre-cracking and failure analysis are proposed, showing good agreement with the experimental results.Peer ReviewedPostprint (author's final draft

Comportamiento mecánico de compuestos de matriz cementicia y tejidos de fibras vegetales

Los compuestos de matriz cementicia reforzados con fibras (fibre reinforced cementitious matrix: FRCM) han demostrado ser un material de refuerzo con un prometedor futuro, debido a su facilidad de aplicación, resistencia al fuego y su capacidad de disipar energía a través de un patrón de multifisuras. El auge que viene desarrollando el estudio de fibras vegetales como refuerzo dentro de los materiales compuestos debido a su bajo costo, baja densidad, reciclabilidad y biodegradabilidad, hace que estas fibras se presenten como una opción de refuerzo a considerar dentro los materiales compuestos. En este estudio se han elaborado especímenes FRCM de diferentes fibras vegetales (lino, cáñamo, sisal y algodón), utilizando un tratamiento a base de poliéster para evitar la degradación de las fibras y mejorar su eficacia dentro de los compuestos cementicios. Estos especímenes fueron sometidos a ensayos de tracción directa, donde los resultados mostraron una excelente interacción entre los tejidos y la matriz utilizada, pues el poliéster además mejorar las propiedades mecánicas de los hilos, aumenta la adherencia con la matriz, y con ello mejora las prestaciones mecánicas del FRCM. Los resultados presentan los FRCM de fibras de cáñamo y lino como los compuestos que alcanzaron mayor resistencia a traccion, y a los FRCM de fibras de algodón como los de mayor capacidad de alargamiento y multifisuración.Peer ReviewedPostprint (published version