Architects throughout the ages have looked to nature for answers to complex questions about the most appropriate structural forms for their buildings. This is the case of Jørn Utzon and the design of roof shells of the Sydney Opera House, in which the search for natural references was constant, from the nautical references in the initial design phases to the final spherical solution based on the analogy with an orange. This paper analyzes the influence of nature as a source of inspiration in this World Heritage building, assessing through FEM calculation models the suitability of the different solutions proposed and weighing up the influence of certain factors such as scale in this type of process. Through the calculation models developed, it has been possible to verify the poor performance of the initial designs compared to the power of the final solution, which, after more than 5 years of research by the design team headed by Utzon, was able to solve the enormous problem with a “simple” typological and geometric change.

RESUMENLa Ópera de Sídney puede considerarse un paradigma en relación a la influencia que los métodos de representación gráfica y análisis estructural ejercen en la concepción y construcción de las obras de arquitectura. Se plantean posibles esquemas estructurales para las cubiertas de dicho edificio respetando la forma propuesta originalmente por Utzon, forma que se vio modificada durante el proceso de proyecto para hacer viable su construcción, poniendo en evidencia el impacto que los avances científicos y tecnológicos acaecidos durante la segunda mitad del siglo pasado han tenido en la manera de concebir y construir edificios.Palabras clave: Ópera de Sídney; diseño paramétrico; análisis estructural; láminas de hormigón. ABSTRACT

This article describes a model based on concepts of Fracture Mechanics to evaluate the flexural strength of fiber-reinforced concrete (FRC) sections. The model covers the need by structural engineers to have tools that allow, in a simple way, the designing of FRC sections and avoiding complex calculations through finite elements. It consists of an analytical method that models FRC post-cracking behavior with a cohesive linear softening law (σ − w). We use a compatibility equation based on the planar crack hypothesis, i.e., the assumption that the crack surfaces remain plane throughout the fracture process, which was recently proven true using digital image correlation. Non-cracked concrete bulk follows a stress–strain law (σ − ε) combined with the Bernoulli–Navier assumption. We define a brittleness number derived from non-dimensional analyses, which includes the beam size and the softening characteristics. We show that this parameter is key to determining the FRC flexural strength, characterizing fiber-reinforced concrete, and reproducing the size-effect of sections in flexure. Moreover, we propose an expression to calculate the flexural strength of FRC as a function of the cited brittleness number. The model also gives the ratio between the residual strength in service conditions and the flexural strength. Model results show a good agreement with tests in the scientific literature. Finally, we also analyze the brittle–ductile transition in FRC sections.

The Matadero Madrid cultural center is located in an old slaughterhouse and livestock market built between 1908 and 1928 in the Arganzuela district. The project was designed by architect Luis Bellido and it was structured around a number of pavilions with various purposes and services, covering a surface area of approximately 165,000 m 2. The complex was characterized by its constructive rationality and conceptual simplicity, however it also incorporates some Neo-Mudejar features. With the arrival of the new century, an important set of interventions were initiated by Madrid City Council in order to transform the space into a cultural hub. Thus, it became a place of new architectural experimentation, following the criteria of the Special Plan which focused on conservation and reversibility, allowing the buildings to be reconverted into their original states. This paper describes the structural restoration of pavilions 15 and 16 for their new uses. These two pavilions, restored between 2009 and 2011, are twin pavilions in terms of structure (brick wall perimeter and steel columns and trusses interior) and volumetry. Pavilion no. 15 was transformed by Langarita-Navarro Architects and became the new "Music Pavilion" now hosting the Red Bull Music Academy headquarters in Madrid. Pavilion no. 16 was transformed into a new cultural and contemporary multi-functional space (concert hall, exhibition space, conference room, etc.) by ICA Architects. Mecanismo Ingeniería undertook the structural refurbishment-including the micropile underpinning of the existing foundations-of both pavilions, which have received numerous international architectural awards including the Mies Van der

No abstract