The effects of deterioration strongly impact the expected future service life and the structural ... more The effects of deterioration strongly impact the expected future service life and the structural performances of existing reinforced concrete structures. Currently, straightforward methodologies are required to include such effects in the assessment and renovation of the RC buildings’ heritage. A simplified protocol enabling the detection, evaluation, and modelling of corrosion effects is presented in this paper. The protocol provides the guidance for the design and management of the on-site diagnostic campaign, aimed at identifying a possible corrosion risk scenario. Then, equivalent damage parameters describing corrosion effects in the structural models can be calibrated. Structural performances over time can be assessed to predict the structural residual life, maintenance management criteria and timing, and major indications on the feasibility of the retrofit intervention, or the unavoidable need of demolition. The application of the proposed protocol to some case studies emphasi...
The decarbonization of the construction sector, which is one of the most impactful sectors worldw... more The decarbonization of the construction sector, which is one of the most impactful sectors worldwide, requires a significant paradigm shift from a linear economy to a circular, future-proofed and sustainable economy. In this transition, the role of designers and structural engineers becomes pivotal, and new design objectives and principles inspired by Life Cycle Thinking (LCT) should be defined and included from the early stages of the design process to allow for a truly sustainable renovation of the built environment. In this paper, an overview of LCT-based objectives and principles is provided, critically analyzing the current state of the art of sustainability and circularity in the construction sector. The effectiveness of applying such design principles from the early stages of the design of retrofit interventions is then demonstrated with reference to a case study building. Four seismic retrofit alternatives made of timber, steel and concrete, conceived according to either LCT...
Given the current climate emergency and the ambitious targets of carbon emissions reduction, retr... more Given the current climate emergency and the ambitious targets of carbon emissions reduction, retrofitting strategies on existing buildings typically include reducing energy demand, decarbonising the power supply, and addressing embodied carbon stored in materials. This latter point redefines the role of engineers in the transitions towards a sustainable construction sector, being they responsible for designing low impact, sustainable and carbon neutral solutions. A Life Cycle Structural Engineering (LCSE) approach, inspired by the principles of Life Cycle Thinking (LCT), should thus be adopted for the sustainable renovation of existing buildings. Only recently have pioneering approaches been proposed, tackling multifaceted buildings’ needs, such as those related to energy consumption as well as seismic safety, but often disregarding LCT principles. This study presents a redefinition of the concept of LCSE for sustainable construction and a comprehensive review of available methods a...
Abstract Failure and deterioration of structural interventions on masonry buildings demonstrated ... more Abstract Failure and deterioration of structural interventions on masonry buildings demonstrated the need for compatible repairs. Mechanical, chemical, transport properties and density of Portland Cement concrete are poorly compatible with lime mortar masonry structures. Several natural lime composites are developed in this study for compatible Historical Heritage rehabilitation. Two relevant interventions with different strength/density requirements are considered: masonry vault filling and wooden floor non-structural overlay. Density minimization is attained with various lightweight aggregate (LWA) types/contents; different LWAs in one same mortar are also employed. Composites’ density, strength, stiffness, cost, and carbon footprint are compared; the influence of different factors is discussed.
The seismic retrofit of the existing building heritage represents an urgent issue to be faced and... more The seismic retrofit of the existing building heritage represents an urgent issue to be faced and innovative solutions which allow to overcome renovation barriers are needed. In this scenario, pin-supported (PS) walls represent an eligible solution, enabling linearization of the deformation of the frame along its height and inhibiting soft storey collapse mechanisms. The PS wall can be connected to the existing building from outside, thereby avoiding disruption to occupants or their relocation, which are acknowledged as the main barriers to the renovation nowadays. Suitability of PS wall solutions in the seismic retrofit of the existing building stock has been investigated herein, particularly in the case of existing reinforced concrete (RC) buildings, preliminarily focusing on 2D RC frames. The paper shows the weaknesses and strengths of the PS wall solution in relation to the specific features of the considered buildings. An analytical closed-form formulation is proposed and appli...
The effects of deterioration strongly impact the expected future service life and the structural ... more The effects of deterioration strongly impact the expected future service life and the structural performances of existing reinforced concrete structures. Currently, straightforward methodologies are required to include such effects in the assessment and renovation of the RC buildings’ heritage. A simplified protocol enabling the detection, evaluation, and modelling of corrosion effects is presented in this paper. The protocol provides the guidance for the design and management of the on-site diagnostic campaign, aimed at identifying a possible corrosion risk scenario. Then, equivalent damage parameters describing corrosion effects in the structural models can be calibrated. Structural performances over time can be assessed to predict the structural residual life, maintenance management criteria and timing, and major indications on the feasibility of the retrofit intervention, or the unavoidable need of demolition. The application of the proposed protocol to some case studies emphasi...
The decarbonization of the construction sector, which is one of the most impactful sectors worldw... more The decarbonization of the construction sector, which is one of the most impactful sectors worldwide, requires a significant paradigm shift from a linear economy to a circular, future-proofed and sustainable economy. In this transition, the role of designers and structural engineers becomes pivotal, and new design objectives and principles inspired by Life Cycle Thinking (LCT) should be defined and included from the early stages of the design process to allow for a truly sustainable renovation of the built environment. In this paper, an overview of LCT-based objectives and principles is provided, critically analyzing the current state of the art of sustainability and circularity in the construction sector. The effectiveness of applying such design principles from the early stages of the design of retrofit interventions is then demonstrated with reference to a case study building. Four seismic retrofit alternatives made of timber, steel and concrete, conceived according to either LCT...
Given the current climate emergency and the ambitious targets of carbon emissions reduction, retr... more Given the current climate emergency and the ambitious targets of carbon emissions reduction, retrofitting strategies on existing buildings typically include reducing energy demand, decarbonising the power supply, and addressing embodied carbon stored in materials. This latter point redefines the role of engineers in the transitions towards a sustainable construction sector, being they responsible for designing low impact, sustainable and carbon neutral solutions. A Life Cycle Structural Engineering (LCSE) approach, inspired by the principles of Life Cycle Thinking (LCT), should thus be adopted for the sustainable renovation of existing buildings. Only recently have pioneering approaches been proposed, tackling multifaceted buildings’ needs, such as those related to energy consumption as well as seismic safety, but often disregarding LCT principles. This study presents a redefinition of the concept of LCSE for sustainable construction and a comprehensive review of available methods a...
Abstract Failure and deterioration of structural interventions on masonry buildings demonstrated ... more Abstract Failure and deterioration of structural interventions on masonry buildings demonstrated the need for compatible repairs. Mechanical, chemical, transport properties and density of Portland Cement concrete are poorly compatible with lime mortar masonry structures. Several natural lime composites are developed in this study for compatible Historical Heritage rehabilitation. Two relevant interventions with different strength/density requirements are considered: masonry vault filling and wooden floor non-structural overlay. Density minimization is attained with various lightweight aggregate (LWA) types/contents; different LWAs in one same mortar are also employed. Composites’ density, strength, stiffness, cost, and carbon footprint are compared; the influence of different factors is discussed.
The seismic retrofit of the existing building heritage represents an urgent issue to be faced and... more The seismic retrofit of the existing building heritage represents an urgent issue to be faced and innovative solutions which allow to overcome renovation barriers are needed. In this scenario, pin-supported (PS) walls represent an eligible solution, enabling linearization of the deformation of the frame along its height and inhibiting soft storey collapse mechanisms. The PS wall can be connected to the existing building from outside, thereby avoiding disruption to occupants or their relocation, which are acknowledged as the main barriers to the renovation nowadays. Suitability of PS wall solutions in the seismic retrofit of the existing building stock has been investigated herein, particularly in the case of existing reinforced concrete (RC) buildings, preliminarily focusing on 2D RC frames. The paper shows the weaknesses and strengths of the PS wall solution in relation to the specific features of the considered buildings. An analytical closed-form formulation is proposed and appli...
The refurbishment of the existing building stock is nowadays becoming a priority in order to meet... more The refurbishment of the existing building stock is nowadays becoming a priority in order to meet energy-saving and emission-control international targets and to foster safety and resilience of European communities. A new research recently introduced the concept of holistic seismic, energy, and architectural renovation of existing buildings targeting resilience, safety, and sustainability. Integrated retrofitting techniques have been proposed, and a new structural design procedure has been studied rethinking existing approaches by including sustainability principles. With reference to post-WWII RC buildings, which are often mid-rise isolated buildings located at the city outskirts, additional exoskeletons implementing the technologies and devices for an integrated upgrade have been proposed. Exoskeletons are entirely built from outside, thus avoiding the temporary dismissal of the buildings and the relocation of the inhabitants. Both ‘shear wall’ or ‘shell’ solutions, either dissipative or over-resistant, can be envisioned for structural retrofitting. In the first solution, shear walls can be integrated in the new exoskeleton, whereas energy efficiency upgrading is guaranteed by the envelope, thus the two structure-energy systems work in parallel. In the ‘shell’ solution, the building envelope has both energy and structural functions. In this paper, both over-resistant and adaptive diagrids are introduced for the holistic refurbishment of existing buildings. Over resistant diagrids are conceived for the seismic upgrade of those buildings having stiff masonry infill walls and staircase walls, for which dissipative solutions may be ineffective unless massive preliminary interventions are carried out to downgrade the existing building initial stiffness. Adaptive diagrids are conceived as over resistant ‘shell' structures to avoid any damage at the operational limit state, while dissipation is triggered through dissipative rigid-plastic supports to reduce shear at the grid foundations at the life safety limit state. Selection of materials and technologies, enabling maximum adaptability, reparability and maintenance, and total demountability-recyclability/reuse at end-of-life is also discussed.
The reinforced concrete constructions built after World War II represent almost half of the Europ... more The reinforced concrete constructions built after World War II represent almost half of the European building stock. Such buildings are characterized by low energy efficiency, living discomfort and may be inherently vulnerable to seismic actions, having been designed before the enforcement of modern building codes. A global integrated intervention for the sustainable restoration of the considered building stock is proposed in this paper. The conceived approach overcomes the shortcomings of the traditional renewal practice, targeting uncoupled solution of single deficiencies. The solution also stems as an enhancement of past pioneering techniques, such as the double skin, focusing on architectural restyling and energy efficiency upgrade. In the proposed approach energy efficiency and structural upgrading measures are coupled, and the exoskeleton is complemented with ad-hoc systems and devices to increase structural safety and seismic resilience. The intervention is carried out from the outside, with reduced impairment of the inhabitants and building downtime. Unlike traditional energy efficiency interventions, the structural upgrade entails a series of co-benefits: it allows lengthening the building service life, thus representing a viable and more sustainable alternative to the building demolition and reconstruction practice; it increases seismic resilience at district level, reduces life cycle costs and minimizes environmental impact over the building life cycle. Despite the research work be multidisciplinary, in this paper emphasis is made on the sole structural issues. The exoskeleton conceptual design is discussed and both over-resistant and dissipative solutions are proposed. Main principles of performance based design are presented, which allow minimizing the damage on the existing building. Finally, the case study of a typical residential building is presented, in which the possible use of the engineered double skin is proposed as an alternative to the basic double skin.
Uploads
Papers by Chiara Passoni
A new research recently introduced the concept of holistic seismic, energy, and architectural renovation of existing buildings targeting resilience, safety, and sustainability. Integrated retrofitting techniques have been proposed, and a new structural design procedure has been studied rethinking existing approaches by including sustainability principles.
With reference to post-WWII RC buildings, which are often mid-rise isolated buildings located at the city outskirts, additional exoskeletons implementing the technologies and devices for an integrated upgrade have been proposed. Exoskeletons are entirely built from outside, thus avoiding the temporary dismissal of the buildings and the relocation of the inhabitants.
Both ‘shear wall’ or ‘shell’ solutions, either dissipative or over-resistant, can be envisioned for structural retrofitting. In the first solution, shear walls can be integrated in the new exoskeleton, whereas energy efficiency upgrading is guaranteed by the envelope, thus the two structure-energy systems work in parallel. In the ‘shell’ solution, the building envelope has both energy and structural functions.
In this paper, both over-resistant and adaptive diagrids are introduced for the holistic refurbishment of existing buildings.
Over resistant diagrids are conceived for the seismic upgrade of those buildings having stiff masonry infill walls and staircase walls, for which dissipative solutions may be ineffective unless massive preliminary interventions are carried out to downgrade the existing building initial stiffness.
Adaptive diagrids are conceived as over resistant ‘shell' structures to avoid any damage at the operational limit state, while dissipation is triggered through dissipative rigid-plastic supports to reduce shear at the grid foundations at the life safety limit state.
Selection of materials and technologies, enabling maximum adaptability, reparability and maintenance, and total demountability-recyclability/reuse at end-of-life is also discussed.
A global integrated intervention for the sustainable restoration of the considered building stock is proposed in this paper. The conceived approach overcomes the shortcomings of the traditional renewal practice, targeting uncoupled solution of single deficiencies. The solution also stems as an enhancement of past pioneering techniques, such as the double skin, focusing on architectural restyling and energy efficiency upgrade. In the proposed approach energy efficiency and structural upgrading measures are coupled, and the exoskeleton is complemented with ad-hoc systems and devices to increase structural safety and seismic resilience. The intervention is carried out from the outside, with reduced impairment of the inhabitants and building downtime. Unlike traditional energy efficiency interventions, the structural upgrade entails a series of co-benefits: it allows lengthening the building service life, thus representing a viable and more sustainable alternative to the building demolition and reconstruction practice; it increases seismic resilience at district level, reduces life cycle costs and minimizes environmental impact over the building life cycle.
Despite the research work be multidisciplinary, in this paper emphasis is made on the sole structural issues. The exoskeleton conceptual design is discussed and both over-resistant and dissipative solutions are proposed. Main principles of performance based design are presented, which allow minimizing the damage on the existing building. Finally, the case study of a typical residential building is presented, in which the possible use of the engineered double skin is proposed as an alternative to the basic double skin.