Circular concrete-filled tubular columns: state of the art oriented to the vulnerability assessment

The vulnerability of framed structures has been analyzed until recently from two different perspectives: Structural and socio-economical. For the sake of assessing the former, indexes and objective measurements have been proposed in the literature. These indexes include relatively accurate assessments of the strength, ductility, energy absorption, fire, blast response and resilience of the elements in order to define a higher-level structural magnitude. Similar approaches are performed with the latter when it comes to assessing damage, economical aspects, social and other important factors. On the other hand, concrete-filled tubes (CFT) have proven structurally efficient due to their relatively high strength-toweight ratio. Considerably complete state-of-the-art reviews are available for these members when it comes to analyzing their strength and overall or local buckling in static and/or dynamic responses. Reviews concerning important issues related to the structural vulnerability of those members are, however, scarce. In this paper, a state-of-the art dealing with the behavior of concrete-filled tubes is presented. The novelty of such approach is to present research concerning CFT but, in this case, from a structural vulnerability perspective (not socioeconomical), that is to say, summarizing references concerning seismic response, fire resistance, impact response and other main characteristics that are further used when defining the aforementioned indexes. Relevant numerical, experimental and theoretical studies presented in recent years are pinpointed as well as potential research trends.Peer ReviewedPostprint (published version

Learning path for Construction 4.0 based on tinkering and STEAM

This article describes the outcomes of a completed study of practice in civil engineering education. The study is aimed at infusing Construction 4.0 content to a Bachelor degree on Civil Engineering. A set of STEAM-rich activities are created in the form of an individual learning path. These activities are conceived with a threefold perspective: i) Construction 4.0-related, ii) STEAM vision by-design and iii) hardware-software independent (open-source, accessible, affordable). Cornerstone and capstone projects as well as a set of workshops represent some demonstrators of these activities. All these demonstrators are knitted together in a single path in that is pegged to the traditional curriculum The STEAM perspective provides completeness to the whole development. During the last two years, design, development and implementation of several demonstrators have been completed. Some results related to the application of some activities are already available. In the years to come, it is expected that an improved systematic deployment of such activities will allow assessing the evolution between tools, pedagogies and the needs of the sector. In this paper, the description of the activities together with the discussion on the potential of tinkering on Construction 4.0-based curriculum is addressed.Objectius de Desenvolupament Sostenible::4 - Educació de QualitatPostprint (published version

Open-source digital technologies for low-cost monitoring of historical constructions

This paper shows new possibilities of using novel, open-source, low-cost platforms for the structural health monitoring of heritage structures. The objective of the study is to present an assessment of increasingly available open-source digital modeling and fabrication technologies in order to identify the suitable counterparts of the typical components of a continuous static monitoring system for a historical construction. The results of the research include a simple case-study, which is presented with low-cost, open-source, calibrated components, as well as an assessment of different alternatives for deploying basic structural health monitoring arrangements. The results of the research show the great potential of these existing technologies that may help to promote a widespread and cost-efficient monitoring of the built cultural heritage. Such scenario may contribute to the onset of commonplace digital records of historical constructions in an open-source, versatile and reliable fashion.Peer ReviewedPostprint (author's final draft

Web crippling strength of longitudinally stiffened steel plate girder webs subjected to concentrated loading

Currently, the AISC code provides guidance for the calculation of the ultimate strength of unstiffened plate girder webs subjected to concentric edge loads. Specifications consider three categories: local web yielding, web crippling, and sideway web buckling. Based on previous studies, the presence of longitudinal stiffeners in the web has not been considered in the calculation procedures. Longitudinal stiffeners in steel plate girders are primarily used to increase bending and shear strength. In the last two decades, a number of projects regarding the positive effect of longitudinal stiffening on the strength of plate girder webs to concentrated load have been conducted around the world. The results have shown that this type of stiffening enhances ultimate strength for web crippling depending on the position of the stiffener that modifies the slenderness of the directly loaded panel; and flexural and torsional rigidities of the stiffener. This paper presents a methodology for the consideration of longitudinal stiffening on the ultimate strength of plate girders webs subjected to concentrated loads. The methodology is based on the plastic collapse mechanism observed experimentally, in which plastic hinges are formed in the loaded flange and yield lines result in the portion of the web limited by the loaded flange and stiffener. Then, a closed-form solution accounting for the influence of the stiffener is developed following the current expression available in the AISC specifications. Theoretical predictions are compared with available test results, showing that the predicted ultimate loads are in good agreement with experimental results.Postprint (published version

Designing experiments using digital fabrication in structural dynamics

In engineering, traditional approaches aimed at teaching concepts of dynamics to engineering students include the study of a dense yet sequential theoretical development of proofs and exercises. Structural dynamics are seldom taught experimentally in laboratories since these facilities should be provided with expensive equipment such as wave generators, data-acquisition systems, and heavily wired deployments with sensors. In this paper, the design of an experimental experience in the classroom based upon digital fabrication and modeling tools related to structural dynamics is presented. In particular, all experimental deployments are conceived with low-cost, open-source equipment. The hardware includes Arduino-based open-source electronics whereas the software is based upon object-oriented open-source codes for the development of physical simulations. The set of experiments and the physical simulations are reproducible and scalable in classroom-based environments.Peer ReviewedPostprint (author's final draft

Effect of uncertainty in localized imperfection on the ultimate compressive strength of cold-formed stainless steel hollow sections

Stainless steel has excellent corrosion resistance properties, considerable long-term durability, and good mechanical strength. Hollow sections are a versatile and efficient form for construction applications. The use of cold-formed stainless steel rectangular hollow section (RHS) and square hollow section (SHS) in construction industry grasps the attention of designers conceiving long-term, cost-effective structures. For cold-formed RHS and SHS, localized imperfection (ω) resulting from rolling and fabrication process is inevitable. ω has inherent variability and has no definitive characterization. In this paper, statistical analysis of the maximum value of ω collected from available experimental data is conducted. A new approach utilizing Fourier series to generate the three-dimensional (3D) models of members with random ω is proposed. Probabilistic studies based on the proposed 3D models are then carried out to evaluate the effect of uncertainty in ω on the ultimate compressive strength of stainless steel columns with cold-formed RHS and SHS. A total of 21 columns that are prone to local buckling reduction are studied. The results show that uncertainty in ω has a considerable influence on the columns with relatively higher cross-sectional slenderness.Peer ReviewedPostprint (published version

Vigas armadas híbridas de acero: estado del conocimiento

Una viga armada se considera híbrida cuando se utilizan diferentes límites elásticos de acero en las chapas de alas y alma que la conforman. Un diseño estructural de una viga armada híbrida puede resultar más eficiente que el de una viga homogénea, tanto desde un punto de vista resistente como desde un punto de vista económico y sostenible. Para una capacidad a flexión dada, se utilizarán chapas de acero de viga armada de menor espesor que su equivalente de viga homogénea. Las vigas armadas híbridas han sido estudiadas a nivel teórico, experimental y numérico bajo solicitaciones de flexión, de inestabilidad por cortante, de interacción flexión-cortante, de cargas concentradas y de fatiga. Los estudios realizados han demostrado que dicho diseño puede ser especialmente atractivo en la construcción de puentes metálicos de tipo bijácena-mixtos. En el presente artículo, se presenta una descripción de las diferentes investigaciones realizadas a nivel mundial en las que se aborda la temática mencionada.Postprint (published version

Respuesta estructural de pilas metálicas circulares rellenas de hormigón (CFT) en puentes integrales

En este estudio se presenta el análisis de la respuesta estructural de pilas metálicas tubulares rellenas de hormigón (CFT) sometidas a solicitaciones de flexo-compresión. El objetivo principal de este estudio es el de valorar los mecanismos resistentes de las pilas cuando se someten a un desplazamiento en cabeza. Estos desplazamientos, conjuntamente con las cargas correspondientes al peso propio, representan las acciones a las cuales se ven sometidos los elementos de este estudio. Para estudiar dicha respuesta estructural, se utiliza una herramienta numérica ampliamente contrastada con la experimentación sobre una base hipotética de prototipos de pilas de dimensiones realistas. Se hace especial hincapié en el estudio de la ductilidad de las pilas para diferentes configuraciones geométricas. Finalmente, se busca proponer una expresión de diseño que recoja de manera simplificada una predicción teórica de la ductilidad de las pilas. Por otro lado, se proponen expresiones de diseño relativas a la capacidad seccional de los CFT teniendo en cuenta el efecto del confinamiento y se comparan con los resultados que se derivan de la actual formulación de EN1994. Se demuestra que los resultados derivados de las expresiones propuestas se acercan más a los resultados obtenidos numéricamente. Asimismo, se estudian los límites planteados en EN1994 para tener en cuenta el efecto de la abolladura local de los tubos. Como resultado de este estudio, se demuestra que los límites que se plantean en EN1994 son conservadores desde el punto de vista de la resistencia de los elementos

Open-source terrestrial laser scanner for the virtualization of geometrical entities in AEC classrooms

This paper depicts a case study that shows an open-source Terrestrial Laser Scanner (TLS) for use on the virtualization of simple yet precise geometrical entities in AEC classrooms. For bringing this technology to AEC classrooms, an open-source TLS was developed. The physical model was built using digital fabrication, its connectivity was established using accessible, affordable, open-source sensors and actuators and its digital representation was developed using generative design tools. All elements together are synchronized in real-time and the TLS becomes live, digitally twinned, geometry generator. The points that are generated by the TLS are gathered in a 3D virtual space in the form of virtual points. The present digitally twinned vision of laser scanning has thus three identified educational uses: (i) illustration of the measuring principle using open-source hardware together with mathematics and statistics, (ii) illustration of the generation and visualization of point clouds in real-time within a CAD environment, and (iii) perhaps with a vaster scope in AEC classrooms, illustration of the usage, analysis and identification of these point clouds. The development of this tool belongs to a vaster project for infusing Construction 4.0 technologies in AEC classrooms under development at the School of Civil Engineering of UPC-BarcelonaTech. The illustration to students of all these concepts with accessible technological tools is expected to enlarge their vision of more advanced constructional technologies such as cyber-physical systems for monitoring and surveying as well as digital technologies for reproducing “As-Built” models.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::4 - Educació de QualitatPostprint (published version

Numerical validation of the incremental launching method of a steel bridge through a small-scale experimental study

The final publication is available at Springer via http://dx.doi.org/10.1007/s40799-016-0037-5This article presents an experimental and a numerical study of an incremental launching process of a steel bridge. The former is deployed in a scale-reduced laboratory,whereas the latter is performed using the finite elementmethod. The numerical simulation is based upon realistic transient boundary conditions and accurately reproduces the elastic response of the steel bridge during launching. This numerical approach is validated experimentally with the scale-reduced test performed at the laboratory. The properly validated numerical model is subsequently systematically employed as a simulation tool of the process. The proposed simulation protocol might be useful for design and monitoring purposes of steel bridges to be launched. Results concerning strains, stresses, and displacements might be inferred from the model and thus compared to field measurements obtained in situ. The conditions presented at the end of the article are potentially useful for researchers and practice engineers alike.Peer ReviewedPostprint (author's final draft