Comparative study of the geometric incompatibilities in the dinamica of expandable structures

Expandable meshes are structures built by bars articulated at the extremes and with a passing articulation at the central knot. The calculation of these structures presents numerous difficulties, but furthermore, in many typologies the deployment is influenced by geometric incompatibilities in the intermediate positions that add new and complex factors to their analysis. Although the compatibility limitations have already been studied by several authors for slow-deployable grids by means of a static or quasi-static approach, it is obvious that for temporary structures, speed of erection and dismantling is an important part of the functionality of the product. For the study of such phenomena, the authors present a dynamic model of the structural movement, analysing the deployment by means of calculations in the time domain and idealising the actual structure as a model of rigid bars with elastic joints between them. Thus, in our model a bar has 6 co-ordinates corresponding to both end nodes and 5 co-ordinates corresponding to the three displacements and two rotations of the central rod

Scissor-Hinged Deployable Structures Supported Perimetrally on Rectangular Bases

[Abstract] Deployable bar structures on a rectangular base present the problems of closing the ends and longitudinal stabilization. Some proposals have been made to resolve them, mainly by creating mouths, but their application to composite geometries is problematic. On-the-bias deployable structures adequately solve both problems as they are supported around their entire perimeter, have a strong three-dimensional operation and only use load-bearing bars. The text analyses this type of deployable structures, their requirements and possibilities. A study on the combination of polar and translational units in a single deployable structure is then carried out, focusing on the study of on-the-bias deployable structures with perimeter polar modules that allow the effective height of the designs to be increased. Finally, the architectural possibilities of the system are studied, which make it possible to resolve overhangs, vertical openings in the roof, and T- or L-shaped ground plans, guaranteeing the modularity of the system.This research was carried out as a part of the Spanish Research Project on Deployable and Modular Constructions for Situations of Humanitarian Catastrophe, CODEMOSCH (Reference BIA2016-79459-R), funded by the Spanish Ministry of Industry, Energy, and Competitiveness (MINECO)

Modified Bistable Modules for Bias Deployable Structures

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Bias deployable grids are meshes with two directions of rotation on the ground plan with respect to the edges. They offer benefits such as three-dimensional resistance with supports around the entire perimeter of a rectangular layout, and consist exclusively of load-bearing scissors as opposed to the usual combinations of load-bearing scissors and bracing scissors. However, their resistance to angular distortion is limited, and they require auxiliary elements to maintain the fully deployed position. Nevertheless, they are very promising solutions for medium-span emergency buildings. This paper proposes a bistable module adapted to bias deployable structures. The geometrical incompatibilities of several modules are analysed together with their behaviour based on the kinematic models that were built, which alternate different types of nodes and different geometries of the perimeter scissors, making it possible to calibrate the level of incompatibility introduced. The dimensions of the nodes are also taken into account. The tests are checked against the results of several series of dynamic calculations.This research was carried out as a part of the Spanish Research Project on Deployable and Modular Constructions for Situations of Humanitarian Catastrophe, CODEMOSCH (Reference BIA2016-79459-R), funded by the Spanish Ministry of Industry, Energy, and Competitiveness (MINECO). Financing of the open access fee: Universidade da Coruña / CISU

Selección y diseño de las medidas de corrección de un talud inestable

[SPA] La sobre-excavación de un talud de grandes dimensiones, con problemas de estabilidad, aparece como la medida más utilizada para corregir esta situación. En un proceso de rotura a gran escala los taludes buscan de forma natural el equilibrio trasladando parte de sus materiales a la zona anterior al pie, como si establecieran una barrera de tierras, eliminando además peso de la parte superior, de la que proceden estos materiales. Al haberse superado los valores pico, la superficie de rotura ya solamente colabora al equilibrio con la resistencia residual. Una de las medidas que reproduce ese comportamiento es la de rellenar el pie del talud creando una barrera natural de tierras en esa posición y descargando o sujetando parte de la masa superior. La ventaja, en relación con la situación de rotura, se encuentra en la conservación de la resistencia intacta de los materiales, lo que proporciona una mayor seguridad. En este trabajo, apoyado en un conjunto de ejemplos prácticos, se plantea una metodología para seleccionar una variedad de medidas que pueden utilizarse, sobre la condición de que la situación final de diseño cumpla con las garantías de seguridad. Tal como se plantea en la minería en muchas ocasiones, se puede asumir cierta movilidad de los bloques que constituyen el macizo de roca, y remodelar las tierras inestables para buscar la geometría del talud más adecuada y evitar los riesgos de deslizamientos o desprendimientos sobre el área de trabajo.[ENG] The re-excavation of a large slope, with stability problems, appears as principal measure used to correct its instability. In a large slope failure, terrain naturally seek balance by transferring part of it mass to the foot slope area, establishing a land barrier, also eliminating the weight of the upper part, where these materials come from. Once the peak shear strength values have been overtaken, the breaking surface only contributes with its residual resistance. One of the measures that can reproduce this behavior is the filling of the slope’s foot creating a natural barrier of lands in that position and unloading or holding part of the upper mass too. The advantage, in relation to the breaking situation, lies in the preservation of the intact strength of the materials, which provides greater security. In this paper, supported by a set of practical examples, the methodology proposed is to select among a variety of measures that can be used, searching that the final design situation complies with the security guarantees. As is usually suggested in mining, it is possible to assume a certain mobility of the blocks that make up the rock mass, and to remodel the unstable lands in order to find the most appropriate slope geometry to avoid the risks of landslides or rock falls on the work area

Adding value to natural clays as low‑cost adsorbents of methylene blue in polluted water through honeycomb monoliths manufacture

natural Moroccan illite–smectite was used as an adsorbent for the removal of methylene blue (MB) from aqueous solutions. The clay was characterized by FTIR spectroscopy, TGA, SEM–EDS, X-ray fluorescence, XRD and N2 physisorption. The influence of pH, temperature and time on the MB adsorption by the clay was investigated. The maximum equilibrium adsorption capacity was 100 mg g−1 at 45 °C. The kinetic behavior and the isotherms better-fitted with the pseudosecond- order and Langmuir models, respectively. Clay honeycomb monoliths (50 cells cm−2) were obtained by means of extrusion from the starting material without any additive except water. The structured filters exhibited better performance under dynamic conditions than the powdered clay, adding value to the application of this low-cost adsorbent

Influencia de la no linealidad del material en la dinámica de estructuras articuladas de madera

This paper studies the effect of the non-linear behavior of the material in the movement of an articulate structure made of wooden bars, by means of an iterative of calculation method with lumped masses in the nodes.Se estudia el efecto del comportamiento no lineal del material en el movimiento de una estructura de barras de madera articuladas, mediante un método de cálculo iterativo con masas concentradas en los nodos

A New Approach To Expandable Structures: Crossed Expandable Frames (X-Frames)

The use of expandable structures in the field of building began in the 1960s, based on the pioneering work of Emilio Pérez Piñero. They underwent significant developments at the end of the 20th century, with typologies based on scissors or bundle modules. Until now, this typology has not been further enhanced, despite some very interesting contributions. These studies are usually based on straight bar expandable structures, although there are some interesting proposals based on the deployability of parallel arc systems, even in real buildings. However, other possible types of expandable structures have not been explored to date. In this paper, a new system for expandable structures is proposed, which opens new and interesting design possibilities based on the same folding principle. The system consists of deploying elements such as arches or frames with multiple intersections. Solutions for cylindrical vaults with horizontal axis joints and more complex geometries such as conoids are proposed, as well as domes with vertical and horizontal axis joints. Finally, other structures with special kinematic compatibility difficulties, such as concentric domes or toroids, are also studied.MINECO; BIA2016-79459-

A New Type of Reciprocal Structures: Deployable Yurts for Emergency Situations

[Abstract] Deployable structures are a good solution for emergency buildings due to their lightweight and compact characteristics that allow them to be transported to wherever they are needed, especially in emergency situations. Generally, folding structures have been designed with modules comprised of straight bars, forming a scissor joint. They are efficient systems, although they have the disadvantage of being excessively deformable, requiring the use of large and consequently heavier sections. Recently, interesting proposals have been made based on deployable systems with parallel arches and also with arches or frames with multiple intersections. Dome solutions have been proposed with vertical and horizontal axis joints with reciprocal support in the linkages that increase their efficiency. In this document, a new system is proposed for deployable structures based on a similar system of multiple intersections, but composed of straight bars. This allows them to be applied to a traditional and highly effective design, the yurt. The deployable yurts developed have multiple applications for common types of structures used in emergency situations.This study is part of the research project "Deployable and modular constructions for situations of humanitarian catastrophe", funded by the Ministry of Economy and Competitiveness of the Kingdom of Spain with reference BIA2016-79459-R

Deployable Bundle Modulus Structures With Reciprocal Linkages for Emergency Buildings

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Deployable structures are an ideal solution for emergency buildings because of their lightness and compactness, allowing them to be transported to wherever they are needed. Generally the most frequent solutions use Scissor-like-Elements (SLE), but in this case the use of bundle modules is proposed. These systems were developed by Pérez Piñero, but have hardly been used since then. The article analyses the problems they present, as well as their advantages in reducing the number of bars and linkages required, which allows for the design of simpler and more economical structures. The geometrical and mechanical conditions of the linkages for triangular and square modules are analysed, as well as the typologies that may arise. A calculation method is also developed to analyse this type of structure. Finally, the performance of a flat grid is analysed in an analytical and experimental way using reciprocal links at its ends. Both theoretical calculations and experimental tests allow us to demonstrate the viability and efficiency of this new type of structure.This study is part of the research project “Deployable and modular constructions for situations of humanitarian catastrophe”, funded by the Ministry of Economy and Competitiveness of the Kingdom of Spain with reference BIA2016-79459-