Doing PhD studies under our supervision means to join the world of scientific research by studying and developing a research topic for three years until you will master it and will be able to compete with international experts in field, i.e. to become a “Philosophiae Doctor”. The research topic will be selected from those related to assessment and mitigation of the seismic risk of buildings. It may be based on advanced research projects in the field of seismic engineering in which we actively participate (e.g., the cycle of ReLUIS research projects and the e-SAFE research project) or it may be autonomous and based on a specifically created research project. A list of the PhD theses is reported in the following. A brief description is provided for each thesis, while you can download the pdf of the whole thesis clicking on its title. Candidates for the PhD programme are selected on competitive basis and the call is generally issued in July. Further information can be found on the webpages dedicated to the PhD programme of the University of Catania.
For the successful completion of PhD studies on topics in our field of expertise, you should preliminarily hold good knowledge of structural analysis and design of seismic-resistant structures. It is useful, but not mandatory, to have developed a master’s thesis on topics in the field of seismic engineering. Those who plan to apply for admission to PhD programme when asking for the degree thesis are advised to communicate it immediately; this will allow us to assign a thesis topic that may have future development in PhD studies and plan activities that can be also useful to train you to the competition for admission to the PhD programme.
Many countries in the world, including Italy, are in seismically-active areas. In spite of this, their building stock is often vulnerable to earthquake excitation due to the use of outdated construction techniques or inadequate structural design. The combination of these two factors leads to an unacceptable level of seismic risk for a society that wants to be modern, supportive and resilient. In this framework and complying with the targets of the PNRR, each of our PhD theses aims to provide a contribution to the achievement of the more general objective of improving the resilience of our cities. In order to allow the PhD student to complete the PhD thesis, his background will be completed through individual study activities and participation in courses for the training of specific skills under the constant guidance of the supervisors. The PhD student will be introduced into the national/international scientific community through participation in conferences, as attendant as well as speaker, involvement in our network of contacts and collaborations, and study/research experiences in foreign research institutions. The whole process will be planned so that the student can face each step having previously acquired the knowledge he needs. Through the PhD studies, the PhD student will learn advanced tools and methodologies in the field of modelling and structural analysis, will learn how to deal with complex structural problems by designing the solution and demonstrating its effectiveness, will interact with experts in the field recognized at international level and will learn how to present his work and defend it in front of a qualified audience.
William Leni, XXXVIII cycle, 2022-2025 – IN PROGRESS, (in co-supervisione with prof. Francesca Barbagallo): Seismic upgrading by dissipative steel exoskeletons.
Hosting foreign research institution: University of Birmingham, Birmingham, United Kindom, 3 months.
Hosting company: TECHNOSIDE, Catania (CT), Italy, 6 months.
Abstract: The research project aims at developing a seismic upgrading technique for buildings with RC structure by means of a steel exoskeleton and the related design procedure. The exoskeleton, which must prevent the formation of soft storey collapse mechanisms and mobilize the dissipation capacity of the existing structure, can be equipped with dampers to benefit from an additional source of energy dissipation. The effectiveness of the exoskeleton will be tested on buildings built in the 70s and 80s of the twentieth century (the majority in the RC building stock that needs seismic retrofitting). The research will involve study of the state of the art on steel exoskeletons, formulation and calibration of the design procedure, calibration of the design parameters. The proposed technique is part of a framework, that has long been the subject of study by the research group, that regroups seismic upgrading interventions with a common root represented by: (1) eco-compatible materials, to guarantee sustainable structural solutions from an environmental point of view, (2) use of engineered products, to minimize the implementation times of the intervention and (3) execution of the intervention from outside to minimize the disturbance to the occupants.
Erika Licciardello, XXXVIII cycle, 2022-2025 – IN PROGRESS, (in co-supervisione with prof. Francesca Barbagallo): Seismic upgrading by dissipative CLT panels.
Hosting foreign research institution: Laboratorio Nacional de Engenharia Civil, Unit of sesmic engineering and dynamics of structures, Lisbon, Portugal, 6 months.
Abstract: The research project aims at developing a seismic upgrading technique for buildings with RC structure by means of CLT panels equipped with dampers applied to the building façade and the related design procedure. CLT panels coupled to dampers act as bracing elements that provide the original RC frame with lateral stiffness and strength where it is deficient, thus promoting the formation of the global collapse mechanism. The activation of the dampers provides an additional source of energy dissipation. The effectiveness of the seismic upgrading technique will be tested on buildings built in the 70s and 80s of the twentieth century (the majority in the RC building stock that needs seismic retrofitting). The research will involve study of the literature in the field, formulation and calibration of the design procedure, calibration of the design parameters. The proposed technique is part of a framework, that has long been the subject of study by the research group, that regroups seismic upgrading interventions with a common root represented by: (1) eco-compatible materials, to guarantee sustainable structural solutions from an environmental point of view, (2) use of engineered products, to minimize the implementation times of the intervention and (3) execution of the intervention from outside to minimize the disturbance to the occupants.
Carola Tardo, XXXIV cycle, 2018-2021, (in co-supervisione with prof. Giuseppe Margani): Seismic and energy renovation of RC framed buildings with cross-laminated timber panels equipped with innovative friction dampers.
Hosting foreign research institution: Faculty of Science and Technology, Norwegian University of Life Sciences, Drøbakveien, Norway, 6 months (in smart working because of the COVID pandemic).
Hosting company: ADVECO, Villa Carcina (BS), Italy, 6 months from October 2019 to March 2020.
Abstract: In European seismic countries, most of the building stock is highly energy-intensive and earthquake-prone since it was built before the enforcement of effective energy and seismic codes. In these countries renovation actions that synergically integrate both energy-efficient and anti-seismic interventions are strongly needed, looking at the resilience of buildings against earthquakes as one of the main values of a sustainable city. However, the implementation of such interventions is currently limited by barriers that are mostly related to the excessive costs and the high invasiveness of traditional seismic retrofit actions. To overcome these barriers, a new holistic design approach to the building renovation is required, which should result in innovative and integrated retrofit interventions able to specifically meet the needs of cost-effectiveness, quick installation, reduced users’ disturbance, and low environmental impact. In this framework, this Ph.D. thesis aims at analysing the potential of a novel integrated retrofit technology for RC framed buildings. The proposed retrofit system consists in cladding the existing building envelope with a new prefabricated timber-based external shell that acts as seismic-resistant and energy-efficient skin, contributing also to renovate the architectural image of the building. The new skin combines structural Cross-Laminated Timber (CLT) panels – connected to the existing RC frame through innovative friction dampers – with non-structural panels that integrate high-performing windows. The potential of the proposed technology is analysed in terms of seismic and energy performance, and technical feasibility. Pushover analyses on a case study RC frame preliminarily demonstrate the high potential impact of the proposed seismic retrofit system (CLT panels equipped with novel friction dampers) on the response of existing buildings to be upgraded. Hence, different prototypes of the friction damper are tested under cyclic loading, identifying the most promising in terms of structural efficiency. Dynamic thermal simulations on multi-story buildings, at pre- and post-intervention state, show the relevant energy efficiency of the system, especially in the winter. Moreover, proper technical solutions are investigated to ensure the technical feasibility and versatility of the proposed retrofit technology.
Francesca Barbagallo, XXX cycle, 2014-2017: An overdamped multimodal adaptive nonlinear static procedure for seismic assessment of RC infilled frames.
Hosting foreign research institution: Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan, 12 months from May 2015 to May 2016.
Abstract: The seismic assessment of existing structures is considered the fundamental step to (i) estimate the seismic capacity of the initial structure (ii) predict the collapse mechanism and the structural weakness, (iii) select the most appropriate seismic retrofitting technique and determine the improved capacity of the upgraded building. In this framework, nonlinear static methods of analysis are tool that can predict the seismic behaviour of structures with a good accuracy but with a lower computational burden. Although existing methods of analysis are generally reliable, however they neglect the contribution of higher modes of vibration to the seismic response and do not consider the progressive reduction of the structural stiffness due to the nonlinear behaviour of the structure. Another important aspect regarding existing structures is the presence of infill panels. Although infill panels provide the structure with a much larger stiffness and their location and mechanical properties influence the dissipative mechanism of the structure, however they are considered non-structural elements, and their contribution to the seismic response is neglected. The thesis developed a nonlinear static method of analysis that can accurately estimate the seismic response of RC frames, with and without infill panels, keeping acceptable computation costs. Specifically, the thesis proposes a multimodal adaptive procedure named overDamped Displacement Adaptive Procedure (D-DAP). This method has been developed from the combination of the approaches proposed by Pinho et al. and by Ghersi et al. The multimodal adaptive procedure to update the load vector is taken from the first, while the method for the association of the peak ground acceleration to the displacement demand without the SDOF approximation is drawn from the second. In addition, the D-DAP is equipped with an equivalent damping to consider the increase of the energy dissipation due the cumulated damage in the structure. To this end, the value of the equivalent damping is updated at each step according to a new damping law that has been properly calibrated in this work for RC frames with and without infill panels. The accuracy of the D-DAP in the seismic assessment of RC frames was compared to that of the DAP by Pinho, the MPA by Chopra, the N2 method (EC8) and the CSM (FEMA 440). To this end, a set of 54 RC frames was designed to be representative of existing buildings with various levels of seismic deficiencies, and their seismic responses were predicted by those aforementioned methods of analysis. These comparisons showed that the D-DAP applied with the proposed damping law demonstrated an accuracy in predicting the seismic response of RC frames, with and without infills, generally higher than the other nonlinear static methods of analysis.
Paola Roberta Stramondo, XXVIII cycle, 2012-2015: Formulation of a design method for seismic upgrading of RC frames by buckling-restrained braces.
Abstract: Many existing RC buildings were designed considering gravity loads only or very low seismic action. Hence, these buildings require seismic upgrading to meet the performance requirements stipulated by current seismic codes. In this PhD thesis, a displacement-based method for the seismic upgrading of these structures by means of Buckling-Restrained Braces (BRBs) is proposed and validate. BRBs are dissipative steel braces that exhibit similar behaviour in tension and compression, stable hysteresis cycles and good energy dissipation capacity thanks to the high ductility demand they can sustain before fracture. Selected the target performance requirement, the proposed design method allows the designer to define stiffness and strength of the BRBs by choosing appropriate values for the cross-sectional area, length of the ductile segment and the yield stress of the steel. The design method is based on two requirement conditions: the storey drift condition and the BRB ductility demand condition. According to the first condition, story drift demand should be reduced below values compatible with the deformation capacity of the structure. Based on this requirement, the additional lateral stiffness to be provided by the BRBs at each storey is determined. The second condition requires that the maximum ductility demand sustained by BRBs during the earthquake should be not larger than their capacity, which provides the yield stress and, therefore, the axial resistance needed for BRBs. The proposed method is applied to three case studies representative of existing buildings that need seismic upgrading. The effectiveness of the method is investigated through nonlinear dynamic analyses conducted on RC framed structures upgraded by BRB considering the possible variation of the design parameters.
Giovanna A.F. Ferrara, XXIV cycle, 2007-2011: Prediction of the seismic response of in-plan asymmetric buildings by means of nonlinear static method of analysis.
Abstract: The aim of the thesis is the extension of a nonlinear static method of analysis, initially formulated for simplified asymmetric single-storey schemes, to multi-storey in-plan asymmetric buildings. It involves the execution of two nonlinear static analyses. For each analysis, seismic forces are applied with a different “corrective” eccentricity with respect the centres of mass. These corrective eccentricities are defined on the basis of the key parameters that govern the dynamic response of single-storey systems. The generalization of the method to multi-storey buildings require that some problems are overcome. First of all, the redefinition of the key parameters, for which there is not direct correspondence in the case of multi-storey buildings. Hence, the definition of a certain number of multi-storey structural systems representative of actual existing buildings to validate the proposed method is preliminarily done. In this regard, a set of multi-storey buildings with a RC framed structure was designed considering different design criteria and building regulations in force in the past. The building modelling, carried out with the OpenSEES software, is realistic and allows the simulation of all the most significant mechanical phenomena that characterize the inelastic behaviour of RC structural members, in particular, the degradation of strength and stiffness under cyclic loads. Furthermore, a procedure has been developed to determine an adaptive load pattern, which, due to its complexity, is not characterized as a proposal to be combined with the correction in plan of the response, but constitutes only a tool for carrying out pushover analyses in the scope of this study. Finally, alternative proposals to the originally suggested method were developed. These proposed methodologies can further improve the estimation of displacement demand and are easier to apply.