The first decade of the 21st Century can easily be labelled the most active in the 125 year history of the tall building typology, with more, and taller, skyscrapers being constructed than at any other time. This boom in construction has coincided with a global recognition for the need to reduce anthropogenic greenhouse gases with climate change becoming arguably the greatest challenge of the modern world. In light of this, attention has turned towards the environmental impact of tall buildings which are still seen by many as inherently unsustainable. The year 2008 presented a unique standpoint in global history, as for the first time half the world’s population – some 3.3 billion people – lived in urban areas. According to the United Nations, 193,107 new city dwellers are added to this figure every day, meaning urban populations will nearly double by 2050. Where will these people live, work, play? It is clear the tall building could play a role in this, providing dense sustainable living and compact cities with reduced transportation emissions. However, despite this potential, the majority of tall buildings completed today continue to be designed with too little consideration of environment and sustainability. The importance of improving tall building sustainability then cannot be denied and frenzied research has – and continues to be – undertaken in order to improve their sustainable credentials. Much of the research to date has focussed on reducing the environmental impacts associated with the operation of tall buildings, that is reducing the energy required for (and emissions released from) activities such as space conditioning, lighting, equipment operation, water supply and water heating that occur on a day-to-day basis. Out of this research has emerged numerous tall building proposals and built projects that claim to have significantly reduced operating energy requirements. Whilst these advancements are vital for creating sustainable tall buildings, they are in themselves not enough. Energy is also required, and emissions also released, through the production, transportation and assembly of materials and components into functioning buildings (known as embodied energy / carbon), and little work has been undertaken to establish the importance of these environmental impacts in the high-rise typology. Sustainability is a holistic concept, encompassing economic, social and environmental issues, so clearly the challenge to create truly sustainable tall buildings goes far beyond energy efficiency alone. This thesis then explores sustainability in tall buildings in the broader sense, encompassing environmental, social and economic issues, examining the links between these areas and how changes driven by the influence of one can impact the others. It consists of an Extended Abstract and five published papers which together describe the quest the author has undertaken to identify opportunities and challenges for the creation of more sustainable high-rise architecture. Note: For copyright reasons, only the Extended Abstract document is included here in this online version.

Στόχος της παρούσας διατριβής είναι η εξαγωγή συμπερασμάτων σχετικά με την απόκριση πολυώροφων κατασκευών ενισχυμένων με εμφάτνωση από οπλισμένο σκυρόδεμα και η αναλυτική προσέγγιση αυτών υπολογίζοντας τις χαρακτηριστικές ιδιότητες δυσκαμψίας, αντοχής και ικανότητας παραμόρφωσης του νέου τοιχώματος. Βεβαίως, ελέγχεται και η επίτευξη μονολιθικής σύνδεσης μεταξύ φατνώματος και μελών του περιμετρικού πλαισίου. Για το λόγο αυτό, κατασκευάζεται και δοκιμάζεται πειραματικά μέσω της υβριδικής μεθόδου με υποκατασκευές, ένα τετραώροφο πλαίσιο εμφατνούμενο από οπλισμένο σκυρόδεμα εξασφαλίζοντας την επαρκή σύνδεση του κορμού του τοιχώματος με το υφιστάμενο πλαίσιο. Ακολουθεί η διεξαγωγή μη - γραμμικής δυναμικής ανάλυσης προκειμένου να υπάρξει προσέγγιση των πειραματικών αποτελεσμάτων από τα αναλυτικά, καθώς και ο υπολογισμός των χαρακτηριστικών παραμορφώσεων και δυσκαμψίας του δοκιμίου σύμφωνα με τον Κανονισμό Επεμβάσεων (ΚΑΝ.ΕΠΕ.)και την υιοθέτηση ορισμένων παραδοχών, η αξιοπιστία των οποίων εξετάζεται μέσω της αναλυτικής προσέγγισης εναλλακτικού πειραματικού φορέα. / The aim of this thesis is to reach in conclusions about the response of existing multistorey reinforced concrete structures, retrofitted by reinforced condrete infill wall and also analytically approach that response computing the characteristic properties of stiffness, strength and deformation capacity of the new composite wall. Moreover, the effectiveness of the connection between the web and the surrounding frame members is under investigetion. For the aforementioned purposes, a 4-storey RC frame converted into slnder wall is constructed and tested by pseudo-dynamic method with substructures. In order to compare the experimental with the analytical results, a non-linear dynamic analysis is conducted and the deformation and stiffness of the specimen are determined by the use of some computtional assumptions, which derive from the computational procedure of the characteristic response parameters of the composite wall. Finally, the overall reliability and correctness of those assumptions is examined through the analytical procedure of a different exprimental project.