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The expression stiffness matrices used in the study of tensegrity structures has inherited a formulation initially conceived for the shape finding problems of tension structures. Nevertheless stiffness and geometrical stiffness matrices are well known concepts of structural analysis and all the formulations which are used need to be congruent. In this paper, we present a formal discussion about the formulations used in several publications showing that they are not equivalent. A classic example is presented, which has been solved using several expressions available in the relevant literature, the results have been compared with a classical finite element software, showing the discrepancies.

Tensegrity structures are composed by pre-stressed pin-jointed compression (struts) and tensión (cables) members that are self-equilibrated. They have had a great development in the last years owing to their ingenious forms, lightweight, deployability and controllability. A challenge related to the design of tensegrity structures is the determination of the force densities during the form-finding process that leads to a stable tensegrity. In this work, the octahedron tensegrity is used as a source of new tensegrity forms. A family of tensegrity structures is a group of them that share a common connectivity pattern. A set of force densities that achieve an equilibrium shape of tensegrities based on the octahedron family was computed analytically. Several examples are shown. Este trabajo ha sido financiado con una ayuda del Programa de Fomento e Impulso de la actividad Investigadora de la Universidad de Cádiz.

The assessment of the residual flexure capacity of existing reinforced concrete structures affected by corrosion is a key point for reparation and rehabilitation works. A procedure for the evaluation of the residual flexure capacity of corroded RC members due to steel-to-concrete bond deterioration and steel cross-section reduction taking into account the original reinforcement layout is presented. The approach is based on different models provided in the literature to account for the main corrosión effects.. Some examples are provided.

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015. The Force Density Method has been traditionally employed to seek the equilibrium shape of tension structures. Recently, the use of a process based on topology has been introduced to provide a first network in which the Force Density Method can be applied. Compression-only structures such as vaults and domes can also be modelled by means of the former approach if this is modified to get a design process similar to the Gaudí’s one based on hanging models. The conjunction of Topological Mapping and the Forced Density Method is first explained in the form-finding process of tension structures and, later on, the modifications to that approach are introduced so that an iterative procedure is obtained to get equilibrium shapes of compression-only structures. The versatility of this novel approach is presented by means of the analysis of some representative examples.

In recent years, there has been a tendency to increase the efficiency of existing welding processes. This is most commonly done by achieving higher molten metal deposition rates, which is extremely important for welding steel structures of significant thickness. The buried-arc methodology allows the welding of plates up to 30 mm in thickness by only using one pass. There is a lack of data on the applicability of this relatively new welding method and is necessary to investigate this procedure experimentally and numerically. Numerical simulations are increasingly used for predicting residual stress distributions and could replace expensive experimental measurements in the future. In this paper, a prescribed temperature approach was used in order to reduce model preparation and computation time. The obtained results are compared to the previous work of authors using the constant heat flux method for simulating heat input during welding. The influence of strain hardening on residual stress distribution was considered by using bilinear isotropic and kinematic hardening models.

Sensor placement optimization problem is a fundamental one in vibration measurement, structural health monitoring, and so on. Many different approaches have been proposed [1], from heuristic to approximations of the original problem [2]. We present an algorithm based on a series of the convex optimizations, where each iteration simultaneously minimizes a performance criteria and a sparsity-inducing term, as well as prioritizing grouping sensors in prescribed groups [3]. In the existing algorithms [4], [3], the non-convex sparsity inducing L_0 norm is replaced by a series of weighted L_1 relaxations [5], which doesn’t offer the ability of grouping the sensors. Grouping becomes important in multi-dimensional spaces to avoid eliminating a spatial coordinate from a potential sensor location. We approach grouping by using the L_2 norm alongside the relaxed L_0 norm.