3. Producción
Browse
Search Results
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental validation of frequency and modal shape of two buildings under ambiental displacements using drone videos without fiducial markers(International Association for Earthquake Engineering, 2024-01-01)In civil engineering, accelerometers are widely used for vibration-based Structural Health Monitoring (SHM) analysis. While both wired and wireless accelerometers offer high sensitivity and resolution, wired sensors are constrained by installation requirements, and wireless sensors need individual power sources, making them susceptible to interference and data transmission issues. Additionally, sensor installation is time-consuming and can lead to damage or calibration problems. To address these challenges, camera-based vibration measurement has gained attraction. Cameras, whether can be installed on fixed supports (stationary) or drone-mounted, have been used to measure dynamic and static displacements in structures such as bridges, antennas, and suspension cables. Many studies rely on fiducial markers for tracking, but marker placement hinders convenience. Targetless measurement, which only requires the camera, has emerged as a practical solution, particularly for capturing large displacements. In this study, we filmed two buildings—a nine-story and a 54-story structure—using a commercial drone equipped with an integrated camera (20MP camera, 4K videos with 30fps for 5 min). The recordings were made without fiducial markers under ambient vibrations. By employing computer vision techniques, we tracked the buildings' distinctive features over time in the video footage. We separated the resulting time series into low and high-frequency components using Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). We expected the low-frequency component to represent the drone's displacement, while the high-frequency component contained the building's displacement under ambient excitation and noise. We further analyzed the high-frequency time series using a robust algorithm that consider the large number of observed displacements in several regions of interest. We use Covariance-based Stochastic Subspace Identification (SSI-COV) to extract frequency, modal shape, and damping ratio. Comparing these results with data from accelerometers on the structures, we found accurate frequency and modal shape identification, with slight discrepancies in damping estimation. This approach shows promise for enhancing the accuracy of frequency, damping, and modal shape analysis in future SHM investigations, particularly when capturing substantial structural displacements. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Additive construction using enhanced earthen-based composites: Improvement of the mechanical strength and water durability using chitosan and agave fibers(Elsevier Ltd, 2024-01-12)3D printing has emerged as a revolutionary technology with potential applications in the construction industry. However, the prevalent use of ordinary cement in most 3D printing formulations results in significant greenhouse gas emissions during 3D printing construction. In contrast, earthen-based composites are an eco-friendly alternative for building materials. However, as a construction material, earth presents poor mechanical strength and low durability against water erosion. This study aims to obtain earthen-based composites with suitable mechanical and durability properties to investigate their extrudability and buildability in tests. It also explores the effects of incorporating short sisal fibers (l/d ratio = 138.7) and chitosan (DD = 91%, Mw = 598 kDa) to improve strength and water durability in earthen-based composites for 3D printing purposes. Chitosan is a natural macromolecule derived from a waste product from the food industry, whereas sisal fibers are obtained from the Agave sisalana plant. The change in compressive strength was analyzed through uniaxial compression. Water durability was evaluated by measuring the water contact angle, total and capillary water absorption, and accelerated erosion tests. The results indicate that the use of 3.0% (w/v) aqueous solution of chitosan and 1.0% (w/w) of sisal fibers have an important effect on the hardening and water durability properties of earthen-based composites. This study suggests that these materials could serve as natural additives to enhance the mechanical properties and water durability of new eco-friendly construction materials for 3D printing. In conclusion, this study demonstrates that appropriate formulations with natural and eco-friendly additives can lead to stabilized earthen-based composites with suitable printing, mechanical and durability properties for 3D printing applications in construction materials. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Development and characterization of a printable concrete made with construction and demolition waste aggregates(Springer Science and Business Media B.V., 2024-01-01)To address the environmental challenges associated with Construction and Demolition Wastes (CDW) disposal and the depletion of natural sand resources by the construction industry, this paper investigates the potential use of fine aggregates from CDW as a complete replacement for natural sand in concrete formulations tailored for 3D printing applications. The study begins by physically characterizing fine aggregates produced by crushing and sieving CDW from concrete and fired clay brick residues. This stage includes water content and water absorption capacity tests, specific gravity tests and unit weight tests, and particle size analysis. Then, a 3D printable concrete mix formulated entirely with CDW fine aggregates, replacing 100% of natural sand, is developed using mortar flow and rotational rheology tests. This formulation is validated by printing a medium-sized wall using a 3D printing system developed in-house. Finally, compression tests are performed on printed filaments to examine mechanical properties such as compressive strength and modulus of elasticity. Fresh-state and hardened-state properties are compared with control concrete samples made with natural sand (0% of CDW fine aggregates). The study demonstrates the feasibility of formulating printable concretes with a total replacement of sand by CDW for real-size applications. However, special attention must be given in large-scale projects to the rate of workability loss caused by the high water absorption capacity of CDW fine aggregates. The research findings offer valuable insights into the potential and performance of CDW aggregates in 3D-printed concrete applications within the context of a circular economy. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Comprehensive investigation into the influence of soil composition and water content on cracking due to drying shrinkage in 3D-printed earthen structures(Springer Science and Business Media B.V., 2024-01-01)As a raw material for additive construction, earth offers a multitude of benefits, from environmental and economic to social points of view. However, the fresh-state properties of printable materials and the curing conditions of additively manufactured elements make large-scale 3D-printed earthen structures susceptible to suffering severe cracking from shrinkage during drying. This project investigates the effect of soil composition and water content on the development of drying shrinkage cracking in 3D-printed earthen structures. This article presents two strategies for minimizing those cracks: decreasing the clay content of the soil by adding fine sand and decreasing the required water content for printability by using a clay dispersant agent. Earth-based mix designs with different soil/fine-sand ratios and sodium hexametaphosphate (SHMP) contents were subjected to flow table, rotational rheology, and shrinkage cracking tests. The results indicate that the clay and water content are determining factors that minimize the appearance of cracks due to drying shrinkage. Two earthen-based formulations with zero cracks due to shrinkage resulted from replacing 50% wt. of the soil with fine sand and the addition of 0.55 and 2.20% wt. of SHMP. Further research is needed to confirm the validity of these findings across diverse soil types and curing conditions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Additive construction of concrete deep beams using low-cost characterization methods and FEM-based topological optimization(Elsevier Ltd, 2024-03-08)Additive manufacturing using concrete for large-scale construction purposes has demonstrated economic, social, and environmental benefits compared to conventional building procedures. These advantages stem from the capabilities of concrete 3D printing, which facilitates a rapid, accurate, and low-waste construction process with substantially less labor and energy requirements compared to traditional casting procedures such as formwork fabrication and stripping, concrete pouring, and concrete consolidation. This technology can pave the way for sustainable and cost-effective housing solutions when coupled with low-carbon concrete formulations and optimized structural designs. However, scientific and industrial experiences have shown that formulating printable concrete requires extensive testing and costly equipment to reach appropriate fresh and hardened-state properties. Therefore, accessible and practical mix-design protocols for the evaluation of printable concrete formulation are needed to enable in-situ control and broader adoption of 3D printing. Once a printable material is developed, innovative design methods, such as topology optimization, that exploit robot-controlled construction to fabricate efficient, safe, and free-form elements can be explored. In this context, this article presents a methodology based on a set of low-cost and accessible experimental tests to develop cement-based matrices with low binder content suitable for layer-by-layer deposition. Furthermore, a framework to design and fabricate efficient structural elements based on numerical-based topological optimization and concrete additive manufacturing is proposed and validated. The systematic experimental campaign carried out indicates that the yield strength obtained from shear vane tests, initially designed for geotechnical field tests, is a reliable reference value for proportioning extrudable, pumpable, and buildable concretes. Employing the proposed framework, four formulations with excellent printing capabilities are presented. These formulations are successfully utilized for additive manufacturing of a topologically optimized deep beam, achieving a remarkable 52% mass reduction compared to a solid element. This showcases the possibility of 3D printing structurally efficient elements with intricate geometries while minimizing material usage, all without the need for formworks.Principio del formulario. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Damage assessment via time history analysis of the massive earthen pyramid of Huaca de la Luna (Huacas de Moche, Perú)(International Association for Earthquake Engineering, 2024-01-01)Huaca de la Luna is a monumental religious complex located in the north coast of Perú built in different stages from 100 to 650 CE by the Moche civilization using millions of adobe blocks. The specific focus of this study is the main stepped pyramid at the centre of the complex, and the present objective is to use time history analyses simulating an actual earthquake to investigate how an accumulation of seismic damage affects its structural response. Built on the slopes of Cerro Blanco Mountain, this monument consists of superimposed horizontal platforms added on top of each other during historical renovations. On the east side, the pyramid is supported on sloping bedrock while the west side is built directly on layers of soft soil. The pyramid presents severe structural damage near the northwest corner. Previous work has focused on 2-and 3D continuum models, with the goal of determining a lateral capacity limit. These models of the structure and its foundation are derived from a detailed evaluation of available archaeological, material, and geotechnical data. Nonlinear analysis is performed in Abaqus/CAE Explicit 2022. The foundation of soft soil is modelled with a Mohr-Coulomb formulation. Using a macro-modelling approach, the adobe masonry is represented as a continuum of concrete damaged plasticity (CDP) material with damage parameters. In this material model, plastic strains represent fractures. This artefact of the material formulation allows us to follow the development of local damage conditions up to structural collapse by separation of the adobe structure into discrete sections by observing the time-evolution of elastic strain, kinetic, and plastic dissipation energies. A 2D FE plane strain model selected from previous research as the most critical case is used to perform and correlate dynamic pushover and time history analyses. The present study supports the conclusions that a) current damage to the pyramid’s northwest corner is unlikely due to gravitational loading, b) horizontal accelerations cause damage similar to that which is extant at the northwest corner of the pyramid, and c) seismic acceleration of considerably higher magnitude than the highest recorded may have occurred to produce such damage. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Sustainable and collaborative solutions for the long-term care of heritage earthen sites in seismic areas in Peru(Taylor and Francis Ltd., 2024-01-01)The challenges posed by conserving historical earthen structures in seismic-prone regions prompted the initiation of the Seismic Retrofitting Project (SRP) by the Getty Conservation Institute (GCI) and the Ministry of Culture of Peru. Since 2009, the SRP has aimed to enhance the structural performance and safety of historic earthen buildings while preserving their historical fabric by combining traditional techniques, local materials, and technical expertise with advanced computational tools. The project has focused on four Peruvian earthen buildings as case studies, including the seventeenth-century adobe church of Kuñotambo. An intervention was carried out between 2016 and 2019 by the regional branch of the Ministry of Culture in Cusco based on techniques developed by the SRP. The GCI is now working on a monitoring and maintenance plan for the site, collaborating with local stakeholders, including the Ministry of Culture of Peru in Cusco, the Archdiocese of Cusco, and the community of Kuñotambo. This paper primarily discusses the practical aspects of on-site monitoring, including the tools and techniques used to track changes in the building and its decorated surfaces. It also outlines the implementation of a structural health monitoring system and the development of capacity-building activities for Latin American engineers. The overarching goal is to provide a sustainable framework for the long-term preservation of historic earthen structures in seismic-prone regions, highlighting the importance of community involvement and multidisciplinary collaboration. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Nonlinear 2D and 3D finite element static and dynamic analyses of the main pyramid of Huaca de la Luna, Peru(Springer Science and Business Media B.V., 2024-01-01)Huaca de la Luna is a monumental earthen complex near Trujillo in north coastal Peru built from 200 AD to 850 AD by the Moche civilization. Its principal structure – a stepped pyramid built with millions of adobe bricks on sloping bedrock and soft soil – presents severe structural damage at the NW corner. The static and dynamic response of the pyramid is systematically analyzed using 2D and 3D nonlinear FE models derived from a detailed evaluation of archaeological, material, and geotechnical data. The analyses are performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. A critical cross-sectional configuration is identified through 2D FE plane strain sensitivity analysis of the static and lateral capacity to (a) pyramid stepped west side profile, (b) underlying bedrock configuration, and (c) adobe tensile strength. 3D models derived from the 2D critical configuration are then evaluated in terms of static stability, lateral capacity, and failure mechanisms. Results indicate that horizontal accelerations produce large structural failure at the pyramid northwest corner similar in extent and location to the present damage.