Micro-modeling of stack bond masonry in compression using a plasticity law

A set of experimental tests to determine the compressive strength of masonry stack prisms has been numerically simulated using a combined plasticity-smeared crack constitutive law employed in three-dimensional analysis

Case study of the effect on foundation of changing an arch bridge to a slab and girder bridge

This paper presents the case study of the effect on the foundation of changing the structural system of a bridge from a plain concrete multi-arch bridge to a slab and girder one. The bridge was built in 1940 over the Cardener river and was designed according to a typology commonly used in that period: plain concrete ribbed arches without centering, with three arches spanning 11.5, 26.5 and 11.5 m. Piles that supported piers between arches were designed to balance the excess of horizontal force induced by the thrust of the main arch. In 1965, arches were substituted by a deck of precast girders with cast-in-situ slab. The forces and the barycenter of the vertical forces on the foundation changed in a radical way. Some of the piles resulted overstressed and other, almost completely discharged. Repair intervention was designed to assure good behavior and durability of the foundation.Postprint (published version

3D analytical prediction of building damage due to ground subsidence produced by tunneling

Tunnel construction entails the generation of ground settlements, which can endanger the adjacent buildings. The prediction of damages in buildings is usually based on the classical Gaussian profiles for the approximation of the subsidence trough and the equivalent beam method for modeling the response of building walls. Current available expressions refer to walls aligned transversally with respect to the tunnel axis, which usually represents the worst-case scenario. However, approximations must be done for other building alignments, since no analytical expressions are available for these cases. We propose a novel equation for the determination of the horizontal ground strain, which departs from the equations of the classical Gaussian settlement profiles. The novel formulation allows the application of the equivalent beam method in 3D and the modeling of the tunnel advance. The results show significant variations of the estimated damage depending on the wall position with respect to the tunnel axis. The paper reviews also certain relevant aspects of building damage predictions, such as the influence area of settlements and the possible contribution of ground horizontal strain to damage reduction. A parametric analysis is further performed to create a non-linear regression model that allows direct estimation of the maximum tensile strain in a building wall according to input values of geological conditions and wall and tunnel geometries.Peer ReviewedPostprint (author's final draft

Comportament resistent dels revestiments de túnel realitzats amb dovelles prefabricades de formigó

La present ponència mostra l’activitat investigadora duta a terme en l’àmbit de la resposta resistent dels revestiments de túnels realitzats a base d'anells de dovelles prefabricades de formigó. L’activitat s’inicià amb la realització d’una prova de càrrega in situ sobre un tram experimental ubicat dins la línea 9 del metro de Barcelona. Les conclusions obtingudes sobre el seu comportament van permetre desenvolupar models de simulació numèrica tant 2D com 3D ben contrastats amb els resultats experimentals de l'assaig. Aquesta recerca també inclou l’estudi del comportament longitudinal del revestiment,on es determina fins a quin punt la compressió longitudinal inicialment introduïda per la tuneladora es va dissipant en el temps per efecte de la fluència del revestiment, fet que condiciona la capacitat d'interacció longitudinal entre anells successius

Distribution of fibers in SFRC segments for tunnel linings

This paper presents research results regarding the distribution of steel fibers in concrete used to build precast tunnel segments for Line 9 of the Barcelona Metro. The fiber distribution was studied using the actual fiber contents obtained by means of crushed cores drilled from different points of three full-scale tunnel lining segments. A statistical analysis determined that the fiber content in the ends of segments tends to be greater than in the central zone. The way of transporting, pouring and compacting concrete influences the fiber content and the fiber distribution across the thickness of the segment. In addition, cores with a diameter of 150 mm were found to have a lower scatter in the fiber content than smaller diameter specimens. Finally, based on probabilistic approaches, a minimum of 11 cores is proposed to control the fiber content in FRC segments.Peer ReviewedPostprint (author's final draft

Eina interactiva per a l'autoaprenentatge del formigó estructural

L’objectiu principal de l’assignatura Estructures de Formigó, que s’imparteix a quart curs d’enginyeria de camins, canals i ports és que l’estudiant sigui capaç de dissenyar les estructures de formigó, amb el seu ampli ventall de condicions funcionals i ambientals, de forma competent. Per aquesta raó cal que l’estudiant pugui veure l’aplicació dels coneixements de Formigó Estructural en els diferents àmbits on es troben estructures d’aquest material, a través d’exercicis que permetin aplicar els conceptes generals, podríem dir més teòrics, a múltiples casos concrets i, si és possible, extrets de la pràctica professional. Amb la intenció de donar a l’estudiant eines que li permetin aprendre l’aplicació real dels coneixements a múltiples casos, s’ha desenvolupant una eina d’autoaprenentatge interactiva del formigó estructural, utilitzant les tecnologies de la informació, que ajuda a l'alumne a dissenyar les estructures de formigó, amb el seu ampli ventall de condicions funcionals i ambientals, de forma competent. Això es desenvolupa a través d’una col·lecció de 160 exercicis autoavaluables de 5 a 30 minuts de durada que permeten aplicar els conceptes generals (teoria) a múltiples casos concrets. L’existència de l’eina permet al professor abordar les classes pràctiques centrant-se més en els aspectes globals. L’acollida de l’eina d’autoaprenentatge per part dels estudiants ha estat molt favorable, com demostren els resultats de les enquestes fetes als estudiants

Use of BCN test for controlling tension capacity of fiber reinforced shotcrete in mining works

Fiber reinforced shotcrete (FRS) is widely used for tunnel construction. However, the systematic control of FRS properties is hampered by the complexities of the experimental procedures used. The experiments are normally based on the load-deflection response obtained from flexural tests with third-point loading performed under displacement control. These types of tests are characterized by instability when the cracking load is reached and, subsequently, errors occur in the deflection measurements, increasing the dispersion of the results. An alternative test, the Barcelona test, has some experimental advantages for FRS control as the use of much smaller specimens, an easy procedure and a lower scatter. Using the mean crack opening, correlations were established between the Barcelona test and the flexure test to estimate the toughness and residual strengths at a deflection of 3.0 mm. Equivalences between the two tests were obtained based on the laboratory results and were validated based on work site results, with differences of less than 5% of the residual strength. These relationships and advantages have allowed the Barcelona test to be proposed to control the properties of the FRSs used in the Chuquicamata Underground (Chuquicamata Subterránea) Project developed by the mining company CODELCO-Chile.Peer ReviewedPostprint (author's final draft

Robust estimation of axial loads sustained by tie-rods in historical structures using Artificial Neural Networks

[EN] Widely used simplified analytical methods for estimating the tensile force in tie-rods are clearly not applicable when they contain significant discontinuities or irregularities. A common example for which this fact becomes relevant in practice is the use of connectors to unify historical ties consisting of several segments. To address this challenge, a robust hybrid methodology is proposed which can be applied to any historical tie by employing a data-driven approach to a dataset generated using the finite element method. The methodology is applied to a real case study involving two historical ties.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Servei del Patrimoni Arquitectònic of the Generalitat de Catalunya through a project (managed by the City Council of Sant Cugat) aimed at monitoring the church of the Monastery of Sant Cugat (grant number C-10764); the Ministry of Science, Innovation and Universities of the Spanish Government and the ERDF (European Regional Development Fund) through the SEVERUS project (Multilevel evaluation of seismic vulnerability and risk mitigation of masonry buildings in resilient historical urban centres) (grant number RTI2018-099589-B-I00); and the AGAUR agency of the Generalitat de Catalunya in the form of the predoctoral grant of the first author.Makoond, NC.; Pelà, L.; Molins, C. (2023). Robust estimation of axial loads sustained by tie-rods in historical structures using Artificial Neural Networks. Structural Health Monitoring. 22(4):2496-2515. https://doi.org/10.1177/147592172211233262496251522

Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design

The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms.Peer ReviewedPostprint (author’s final draft