Dottorato in INGEGNERIA STRUTTURALE E GEOTECNICA

Titolo della tesi: Performance-Based Design of Integrated Building Systems

As a result of global warming and climate change, natural disasters occur more frequently around the world. In Italy, earthquakes, floods, and volcanic eruptions are a continuous threat to social stability. In particular, the socio-economic impact of moderate-to-strong earthquakes and requirement for low embodied carbon buildings have further highlighted the urgent need to enhance community resilience and upgrade the national building stock. A new prototype of high-performance building, relying on advanced seismic and energy efficiency concepts, is needed to satisfy the societal expectations of engineered seismic performance and to build up a sustainable building portfolio. Within this context, many research studies have been carried out to better investigate the seismic performance of buildings, mainly focusing on structural systems while often neglecting the high seismic vulnerability of non-structural components. Whereas, economic seismic losses associated with non-structural damage are usually larger when compared to the structural skeleton. Moreover, these components can compromise the functionality and operability of the building even for low-intensity seismic events. Therefore, the current performance-based seismic design should more explicitly focus on the development of an integrated design approach involving the performance of the overall building system, including skeleton, architectural elements (e.g. facades, internal partitions and ceilings), equipment and building contents. Nevertheless, advanced seismic design methodologies as well as more reliable analytical/numerical procedures should be more often considered to design/assess the overall building system. In addition to advanced design methodologies, damage-mitigation technologies should be implemented to reduce the seismic risk of modern buildings. Following this goal, research efforts have been made in recent years to develop innovative low-damage technologies for both structural and non-structural components. The final aim is to design a cost-affordable integrated “earthquake proof” building system, thus setting a new high-performance building standard. Furthermore, the increasingly demand for low embodied carbon buildings is moving the interest on the environmental sustainability, representing a key aspect in new building design as per EU regulation. For this reason, a paradigm shift is required in terms of advanced technologies for the overall building to define energy efficient, safer and resilient systems. Considering the previous background, this Thesis firstly aims to raise awareness on the seismic potential of high-performance integrated structural/non-structural building systems. Experimental shake-table seismic tests on a half-scale timber-concrete low-damage structure, including facades and partitions, have been carried out to prove the high efficiency of such solution. An overview of the full experimental campaign, comprising the design of the test specimen, construction phases, the instrumentation plan and preliminary experimental results, is provided. The development of a 3D lumped-plasticity numerical model describing the non-linear behavior of the test specimen is then presented and analytical vs. numerical vs. experimental comparisons are carried out to prove the reliability of the specimen design methodology as well as the capacity of capturing the high performance of the structure. The Thesis also highlights the cost/performance benefits due to the implementation of such technologies, as well as advanced design methodologies, when compared to traditional design systems and code-compliant methods. Analytical/numerical, parametric and probabilistic, seismic analyses and loss assessments, based on the rigorous Performance-Based Earthquake Engineering (PBEE) methodology, have thus been developed. The weakness of the current code-based design approach, leading to uncontrollable and less reliable results, while the resilience of the integrated low-damage solution is proved. The study has been carried out through the implementation of a Python-based workflow able to automatize the seismic design, loss assessment (non-linear static and dynamic approach) and fragility analysis (Bayesian Cloud). Finally, the Thesis presents a novel probabilistic-based assessment to evaluate the integrated seismic and energy losses as well as to derive fragility curves for the energy performance. These assessment procedures provide more reliable estimations of the building performance and might be adopted as supporting tool when making investments decisions for both new buildings and retrofit/refurbishment of existing structures.