As-Built 3D Heritage City Modelling to Support Numerical Structural Analysis: Application to the Assessment of an Archaeological Remain

Terrestrial laser scanning is a widely used technology to digitise archaeological, architectural and cultural heritage. This allows for modelling the assets’ real condition in comparison with traditional data acquisition methods. This paper, based on the case study of the basilica in the Baelo Claudia archaeological ensemble (Tarifa, Spain), justifies the need of accurate heritage modelling against excessively simplified approaches in order to support structural safety analysis. To do this, after validating the 3Dmeshing process frompoint cloud data, the semi-automatic digital reconstitution of the basilica columns is performed. Next, a geometric analysis is conducted to calculate the structural alterations of the columns. In order to determine the structural performance, focusing both on the accuracy and suitability of the geometric models, static and modal analyses are carried out by means of the finite element method (FEM) on three different models for the most unfavourable column in terms of structural damage: (1) as-built (2) simplified and (3) ideal model without deformations. Finally, the outcomes show that the as-built modelling enhances the conservation status analysis of the 3D heritage city (in terms of realistic compliance factor values), although further automation still needs to be implemented in the modelling process

Empleo de morteros estructurales eco-eficientes. Revisión crítica desde un análisis DAFO.

One of the main climate trigger are CO2 emissions. In the field of architecture and construction, one of the most harmful materials is the cement due to its employment and its polluting power (about 5 and 8% of the worldwide CO2 emissions). Thus, the search of an alternative material is essential. This paper shows the possibility of using eco-efficient mortars as structural materials, in order to guarantee both safety and environment preservation in the strengthening/refurbishment/retrofitting of structures. In those mortars, the binder can be substituted by organic or inorganic materials (e.g. fly ash, ground granulated blast furnace slag, rice husk ash, palm oil fuel ash). From this strategy, the waste reduction is promoted, as wastes are immobilised without polluting the environment essential. Thus, it is encouraged the re-use of architecture which is an essential factor to get a more sustainable habitat. The obtained results allow setting a guide that makes easier the selection of eco-efficient mortars (guaranteeing both structural safety and environment preservation) to the agents involved in processes of structural works.Uno de los principales detonantes del cambio climático son las emisiones de CO2. En el ámbito de la arquitectura y la construcción, uno de los materiales más perjudiciales en relación a su uso y su poder contaminante es el cemento (entre el 5 y 8% de las emisiones de CO2 en el mundo son generadas por éste). Por tanto, es fundamental buscar alternativas a su uso. Esta investigación muestra la posibilidad del uso de morteros eco-eficientes como materiales estructurales que garanticen tanto la seguridad de la construcción como la preservación del medioambiente en intervenciones de refuerzo/ rehabilitación/consolidación estructural. En estos morteros, el conglomerante o bien es un material distinto al cemento o se realiza la sustitución de parte de éste por materiales orgánicos o inorgánicos como cenizas volantes, residuos de altos hornos, cáscaras de arroz, cenizas de aceite de palma, entre otros, con lo que también se propiciaría la reducción de residuos que pasarían a inmovilizarse sin contaminar la naturaleza. Así, se fomenta el reciclaje de la arquitectura, siendo éste un factor clave para un hábitat sostenible. Los resultados obtenidos permiten establecer una guía que facilite a los agentes implicados en las actuaciones de intervención estructural la selección de morteros eco-eficientes óptimos, tanto para garantizar la seguridad como para preservar el medioambiente

Proyecto AURA: Vivienda social sostenible

El Proyecto Aura nace con el objetivo de desarrollar una línea de investigación enfocada en la vivienda social sostenible dentro de la Escuela Técnica Superior de Arquitectura de la Universidad de Sevilla en general y del grupo de investigación HUM-965_TRAnSHUMANCIAS en particular. La invitación recibida para participar en la competición de arquitectura sostenible “Solar Decathlon Latin America & Caribbean 2015”[2] se convierte en la plataforma perfecta para materializar en una propuesta construida, el trabajo desarrollado por el equipo de investigación, en el que también concurren investigadores de otros grupos, tanto de la Universidad de Sevilla, como del extranjero. En esta edición las premisas que tradicionalmente venían siendo los pilares fundamentales de esta competición entre Universidades de todo el mundo, y que orientaban a los equipos en la búsqueda de un prototipo eco-eficiente, dan un giro y se enfocan hacia la reflexión sobre la sostenibilidad en unas condiciones de contorno, situación y localización, muy concretas: El entorno de clima tropical y la problemática de vivienda social y crecimiento urbano en la ciudad de Cali. En esta ponencia, complementaria a la titulada “PROYECTO AURA: VIVIENDA SOCIAL SOSTENIBLE” se describe la estrategia para la caracterización constructiva del proyecto así como la planificación proceso constructivo real llevado a cabo del prototipo para el concurso

Efficient structural design of a Prefab concrete connection by using artificial neural networks

In the built environment, one of the main concerns during the design stage is the selection of adequate structural materials and elements. A rational and sensible design of both materials and elements results not only in economic benefits and computing time reduction, but also in minimizing the environmental impact. Nowadays, Artificial Neural Networks (ANNs) are showing their potential as design tools. In this research, ANNs are used in order to foster the implementation of efficient tools to be used during the early stages of structural design. The proposed networks are applied to a dry precast concrete connection, which has been modelled by means of the Finite Element Method (FEM). The parameters are: strength of concrete and screws, diameter of screws, plate thickness, and the posttensioning load. The ANN input data are the parameters and nodal stresses obtained from the FEM models. A multilayer perceptron combined with a backpropagation algorithm is used in the ANN architecture, and a hyperbolic tangent function is applied as an activation function. Comparing the obtained predicted stresses to those of the FEM analyses, the difference is less than 9.16%. Those results validate their use as an efficient structural design tool. The main advantage of the proposed ANNs is that they can be easily and effectively adapted to different connection parameters. In addition, their use could be applied both in precast or cast in situ concrete connection design

Activated sugarcane bagasse ash as efficient admixture in cement-based mortars: mechanical and durability improvements

Biomass ashes can be used in cementitious materials as cement or sand substitution. Nevertheless, ashes resulted from the combustion of biomass in generation plants present drawbacks that can reduce their potential use if they are not previously treated. In this research, industrial sugarcane bagasse ash (SCBA) was mechanically activated by grinding and its effects evaluated when used as mineral admixture in cementitious materials. Four different substitution rates (0%, 10%, 20% and 30%) where used to investigate the influence of the amount of ashes replaced on the durability and mechanical performance of mortars and identify the optimal substitution rate. To get a thorough comprehension, results were also compared to mortars containing untreated ashes. The combination of a performance-based testing campaign (compressive and flexural strength, open porosity, apparent density, water capillary absorption, surface electrical resistivity, rapid chloride migration coefficient) and a set of analytical techniques (XRD, FT-IR, SEM and TGA-DTA) enabled to characterise the mechanical and durability properties of mortars and identify the mechanisms behind the results. The research concluded that, at 28 days, the incorporation of ground SCBA enhances the compressive strength of mortars up to 62%, decreases the porosity of samples by 35%, highly improves the resistance to the diffusion of chlorides by 10 times and improve the interfacial transition zone by narrowing and closing the gap between aggregates and pastes

Hygro-thermo-mechanical analysis of brick masonry walls subjected to environmental actions

Masonry walls comprise an important part of the building envelope and, thus, are exposed to environmental effects such as temperature and moisture variations. However, structural assessment usually neglects the influence of these hygro-thermal loads and assumes ideal conditions. This paper presents a hygro-thermo-mechanical model and its application to simulate the impact of temperature- and moisture-related phenomena on the structural behavior of masonry walls. A fully coupled heat and mass transfer model is presented and a 2D finite element model is prepared to simulate the behavior of a brick masonry wall under various hygro-thermal scenarios. Two different mortars are considered: namely, cement mortar and natural hydraulic lime mortar. The results are evaluated in terms of temperature and moisture content distribution across the wall thickness. The hygro-thermal model is further extended to incorporate mechanical effects through the total strain additive decomposition principle. It is shown that the hygro-thermo-mechanical response of the brick masonry wall is a complex 2D phenomenon. Moreover, the environmental loads change the natural stress distribution caused by gravitational loads alone. Finally, the wall with cement mortar develops higher levels of stress when compared to the one with lime mortar, due to the dissimilar hygro-thermal behavior between the constituent materials

Simulation of moisture transport in fired-clay brick masonry structures accounting for interfacial phenomena

This paper presents a numerical study on moisture transport in brick masonry walls with a special focus on the simulation of their hygric performance as well as the hydraulic phenomena at the brick-mortar interface. A diffusivity model based on Fick's law is used to describe the moisture transport accounting for both liquid and water vapor movement. The necessary hygric parameters are obtained directly from experimental tests or determined by curve fitting. The proposed model is validated with respect to water absorption and drying tests. The good-fitness of the results is qualitatively assessed and an overall good agreement is found between the simulated and measured curves. It is demonstrated that the chosen liquid water diffusivity expression needs to be adjusted to represent drying processes; the necessary adjustment is made through a diffusivity factor implemented in the original analytical expression. The interface impact on water absorption is introduced as a hydraulic resistance. Moreover, it is hypothesized that the presence of successive interfaces entails an additive in-series effect. Conversely, the interfacial impact on drying is negligible. Finally, the proposed model is extended to different modeling approaches commonly used for mechanical studies of masonry. The necessary input data, modeling methodology, advantages and disadvantages associated with each modeling strategy are also discussed. The present study points out the need of studying water absorption in multi-layered structures made up of constituents with relatively similar hygric behavior. In such cases, the impact of imperfect contact at the interface between materials is not negligible

Pore structure and interdisciplinary analyses in Roman mortars: Building techniques and durability factors identification

Microstructural and compositional analysis of historical mortars is an active research field, not only to guarantee the use of compatible repair measures, but also to guide the design of novel efficient materials. Despite the crucial role of Roman mortars in building history, there is a significant lack of knowledge of their pore system in relation to building techniques and durability. From these premises, this research focuses on the structural mortars of the Realillo aqueduct (Archaeological Site of Baelo Claudia, Spain). This construction is especially interesting from a durability point of view, as in addition to being in a windy coastal area, the water-proof potential of the material is a major issue. Complementary experimental techniques (petrography, computed tomography, X-ray fluorescence, X-ray diffraction (micro and conventional), thermal analysis, pycnometry, physisorption, Hg porosimetry, and SEM-EDS) are applied within a multidisciplinary approach, including the Vitruvian guidelines and comparative analysis with coetaneous buildings. The size and shape of the pores and the porous volume distribution have been linked to hydraulicity, and to cohesion and weathering resistance. Total and open porosity can be related to waterproof worsening, and the entrapped air pores detected could indicate inadequate placement. The shrinkage cracks can be related to the sea sand aggregate. Thermal analysis and C-A- S-H gel indicate hydraulic phases, but with different hydraulicity levels. This variation could be related to the non-high-purity limestone and/or to the recipe. The differences in binder/aggregate ratios and petrographic classification confirm the distinct compositions. Non-standardized manufacturing or building stages could be related to compositional variations. This research has provided significant insights into durability and manufacturing issues by integrating a micro–macro pore structure study within multianalytical and interdisci- plinary research. The method may be used as a complementary procedure to characterize historical mortars. As upgrading/degrading durability factors were obtained, a conservation campaign could be designed. In addition, knowledge about historical building techniques and materials has been enriche

Investigación sobre morteros estructurales eco-eficientes

The main research goal is proving the possibility of using eco-efficient mortars as structural materials, to guarantee both safety and environment preservation in the strengthening/refurbishment/retrofitting of structures. After a comprehensive review on ecoefficient mortars, mechanical properties, rheological behaviour, setting times, durability, and environmental impact (GWP and EE) were analysed. Thus, a qualitative comparison between result obtained and OPC reference cement mortar was possible. Research is completed with an experimental characterisation of ashes, and mechanical test of mortar/concrete samples with plant biomass ashes. The research aims to demonstrate the feasibility and potential of plant biomass ashes in cement-based building materials. The performance from those mortars must be studied with static and dynamic loads as well as the resulting CO2 emission reduction. Finally, this research will propose a protocol selection of eco-efficient mortars based on an analytical hierarchy process (AHP)-based assessment method.Resumen: capacidades mecánicas suficientes para ser usados en refuerzos estructurales y que den resultados aceptables desde un punto de vista mecánico, económico y medioambiental. Tras realizar una exhaustiva revisión bibliográfica , se analizan las propiedades mecánicas, el comportamiento reológico, tiempo de fraguado, durabilidad e impacto medioambiental (GWP y EE), lo que permite realizar una comparativa cualitativa entre los resultados obtenidos y el mortero de cemento Portland de referencia. La investigación se completa con ensayos mecánicos realizados a morteros de cemento con sustitutivos de cenizas de biomasa vegetal obtenidas de plantas de producción de energía, las cuales han sido previamente caracterizadas. Con el desarrollo de la investigación se espera demostrar la viabilidad del uso de cenizas de biomasa vegetal como sustitutivo parcial del cemento con valores de resistencias suficientes, analizando el desempeño de estos morteros eco-eficientes desde la seguridad estructural, bajo cargas estáticas y dinámicas, acompañado del análisis de beneficios medioambientales para la reducción de las emisiones de CO2. Como objetivo final, se espera concluir con la elaboración de un protocolo de selección de dichos morteros eco-eficientes empleando el método de jerarquías analíticas (AHP)