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Combining seismic retrofit with energy refurbishment for the sustainable renovation of RC buildings: a proof of concept

Authors:
Alessandra Marini at University of Bergamo
Alessandra Marini
Chiara Passoni at University of Bergamo
Chiara Passoni
Andrea Belleri at University of Bergamo
Andrea Belleri
Francesca Feroldi at University of Brescia
Francesca Feroldi
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In this paper, an integrated approach targeting sustainability, safety and resilience is envisioned for the renovation of the post-Second World War RC buildings clustered in urban outskirts. The solution stems as an enhancement of the widespread camou age practice, which targets energy e ciency and architectural restyling by complementing the building with a technological double skin, self-supported on an independent exoskeleton. Based on this integrated approach, the exoskeleton can be further engineered to also enable structural safety and resilience. Life cycle thinking is addressed to re- conceive traditional structural design approaches, guaranteeing safety, while minimising costs and environmental impacts over the building life cycle. Accurate selection of materials and dry technologies enables adaptability, reparability and maintenance, and total recyclability/reuse at end-of-life. The intervention is carried out from outside, avoiding relocation of the inhabitants and possible building downtime. The paper introduces a possible framework for engineers, technologists and architects to design new holistic renovation interventions, for which innovative solution sets are required. Possible structural techniques to be coupled with energy refurbishment are proposed. As a proof of concept, the envisaged holistic renovation strategy is applied to a reference building, and bene ts entailed in combining structural safety measures within an integrated intervention are commented.
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The Version of Record of this manuscript has been published and is available in
European Journal of Environmental and Civil Engineering, 03/09/2017,
http://www.tandfonline.com/10.1080/19648189.2017.1363665
Alessandra Marini , Chiara Passoni, Andrea Belleri , Francesca Feroldi, Marco Preti, 1
Giovanni Metelli, Paolo Riva, Ezio Giuriani & Giovanni Plizzari (2017): Combining 2
seismic retrofit with energy refurbishment for the sustainable renovation of RC 3
buildings: a proof of concept, European Journal of Environmental and Civil 4
Engineering. http://dx.doi.org/10.1080/19648189.2017.1363665 5
6
Free download (50 copies available) at: 7
http://www.tandfonline.com/eprint/rA2tAnhGXhETP97q2Hyh/full 8
9
Post-print version available at author personal webpage: 10
https://sites.google.com/a/unibg.it/abelleri/publications 11
12
13
Combining seismic retrofit with energy refurbishment for the 14
sustainable renovation of RC buildings: a proof of concept 15
By 16
Alessandra Marini , Chiara Passoni, Andrea Belleri , Francesca Feroldi, Marco Preti, 17
Giovanni Metelli, Paolo Riva, Ezio Giuriani & Giovanni Plizzari 18
19
In this paper, an integrated approach targeting sustainability, safety, and resilience is envisioned 20
for the renovation of the post-World War II RC buildings clustered in urban outskirts. The 21
solution stems as an enhancement of the widespread camouflage practice, which targets energy 22
efficiency and architectural restyling by complementing the building with a technological 23
double skin, self-supported on an independent exoskeleton. Based on this integrated approach, 24
the exoskeleton can be further engineered to also enable structural safety and resilience. Life 25
cycle thinking is addressed to re-conceive traditional structural design approaches, guaranteeing 26
safety, while minimizing costs and environmental impacts over the building life cycle. Accurate 27
selection of materials and dry technologies enables adaptability, reparability and maintenance, 28
and total recyclability/reuse at end-of-life. The intervention is carried out from outside, avoiding 29
relocation of the inhabitants and possible building downtime. The paper introduces a possible 30
framework for engineers, technologists, and architects to design new holistic renovation 31
interventions, for which innovative solution sets are required. Possible structural techniques to 32
be coupled with energy refurbishment are proposed. As a proof of concept, the envisaged 33
holistic renovation strategy is applied to a reference building, and benefits entailed in combining 34
structural safety measures within an integrated intervention are commented. 35
Keywords: Sustainable building renovation, seismic and energy refurbishment, modern RC 36
buildings, engineered exoskeletons, life cycle thinking, building retrofit from outside, 37
enhancement of camouflage practice 38
2
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... Timber exoskeletons are particularly suited to the sustainable and integrated rehabilitation [18] of post-war masonry or RC buildings of low architectural value. However, their applicability may be limited by building geometry, irregularities, and size or strength constraints related to the use of CLT panels. ...
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... In recent years, innovative integrated intervention solutions have been proposed ( [7], [8]) that are based on the principles of life cycle thinking. These solutions not only overcome obstacles to retrofitting, but also take several aspects into account at the same time: structural safety, living comfort, architectural and energy aspects as well as environmental sustainability. ...
Integrated renovation of reinforced concrete buildings through cold-formed steel panels with burring holes
Conference Paper
  • Aug 2024
Decarbonisation is a crucial imperative in the global effort to mitigate climate change and promote sustainable development. To achieve these ambitious goals, a profound transformation of the building sector is needed, requiring a systematic renovation of the existing building stock, which is characterised by both poor energy efficiency and poor structural performance. In recent years, integrated and sustainable renovation solutions based on the principles of life cycle thinking have been proposed. This study aims to investigate the suitability of cold-formed steel panels with burring holes as earthquake resistant elements in integrated interventions. First, a numerical study was carried out to reproduce the experimental behaviour of the panel through an FE model. Then, a simplified procedure was proposed to design a retrofit system with such panels. Finally, the validation of the work was carried out using a case study building. The results show the suitability of the numerical model and the effectiveness of the panels as a retrofit system. © Fédération Internationale du Béton–International Federation for Structural Concrete.
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... Different construction techniques and materials have been proposed for the second skin. For example, Takeuchi et al. [10] developed a steel dissipative façade, Marini et al. [11] proposed a second skin with steel shear walls and the possibility of introducing dissipative members, Ferrante et al. [12] investigated an integrated solution based on steel exoskeleton. RC second skin has been developed as well, such as the new RC infilled frame connected to the existing structure proposed by Manfredi and Masi [9] or the cast-in-site RC frame system endowed with EPS modules developed by Pozza et al. [13]. ...
Dissipative CLT‐Based Seismic Upgrading System for RC‐Framed Structures: Experimental Characterization, Numerical Modelling, and Design Guidelines
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Full-text available
This paper investigates a seismic retrofit technique named e‐CLT, which is part of the solution for integrated seismic and energy rehabilitation of buildings developed in the framework of the research project e‐SAFE funded by the European Union's Horizon 2020 research and innovation program. According to this technique, the RC structure is cladded by means of CLT panels equipped with friction dampers, to increase lateral stiffness, strength, and energy dissipation capacity. The effectiveness of the e‐CLT system has been proved by a full‐scale experimental test. A finite element numerical model of the RC frame with e‐CLT system has been developed and calibrated based on the experimental results. Hence, guidelines for the design of seismic strengthening of multi‐storey RC framed building structures by e‐CLT system have been drawn based on the results of a parametric analysis conducted on a set of RC case study frames representative of a variety of existing buildings not designed for seismic resistance.
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... It is noteworthy that, in a context in which sustainability aspects in the construction sector have received great attention from the scientific and professional community [23][24][25][26], this solution has the potential to align with the Life Cycle Thinking principles [27,28]. Furthermore, as demonstrated by several real-world application case studies [29,30], the design of a holistic intervention with exoskeletons is often practicable [31,32], addressing the structural safety [33] while simultaneously enhancing the energetic performance [34,35], and aesthetic value [36][37][38] through the creation of a second façade of the building [39,40]. ...
Performance-based optimization of steel exoskeletons: An alternative approach to standard regulations
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Full-text available
  • Mar 2025
Among the various seismic retrofitting techniques, steel exoskeletons are distinguished as a valuable retrofitting approach to mitigate structural vulnerability under lateral loads while simultaneously preserving the buildings’ functionality and activities’ full operability. However, they are not a commonly selected option by designers, as several standard regulations recommend a design approach based on the relative stiffness between the exoskeletons and the building. They establish a restrictive limit for this ratio, resulting in costly and heavy designs. This paper proposes a paradigm shift in exoskeleton design, moving from the control of the stiffness ratio to a performance-based design approach. Different inter-story drift thresholds are adopted as performance constraints of an innovative optimized design procedure where the number, position, and sizing of the exoskeletons are assumed as design variables. Based on the outcomes of the optimization processes conducted on three real-world inspired case studies, a sensitivity analysis is performed. In all scenarios, the results demonstrate that the performance-based approach allows for greater utilization of the building’s capacity in the elastic field to resist horizontal actions while preserving structural safety. Consequently, in contrast with the conservative designs obtained following standard regulations, the proposed approach leads to lighter and more economically efficient designs, which make the exoskeletons a more attractive alternative.
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... The use of renewable energy technologies, such as photovoltaic panels and solar shading devices, can improve the energy performance of buildings. Furthermore, despite steel representing a material with greater embodied energy, around 32-35 MJ/kg [61], the lightweight nature of steel construction and its high structural strength per square meter compared to other construction materials reduces the carbon footprint associated with transportation and installation [62]. When comparing the embodied energy of potential exoskeleton materials, such as steel, aluminum, and structural timber, steel exhibits a higher embodied energy than timber but a lower energy demand compared to aluminum production. ...
From energy-intensive buildings to NetPlus targets: An innovative solar exoskeleton for the energy retrofitting of existing buildings ☆
Article
  • Feb 2025
  • ENERG BUILDINGS
The retrofitting of existing buildings is a challenging strategic objective towards achieving the European climate neutrality target by 2050. According to the Renovation Wave plan, the European Union aims to renovate around 35 million existing inefficient buildings to the highest energy efficiency level by 2030, requiring innovative technological solutions to succeed in this ambitious goal. Along this line, this paper proposes a prototype of a novel solar exoskeleton for the energy and architectural retrofitting of existing buildings, called "en-SʘLEX". The system comprises a self-supporting external steel frame that envelops buildings like a double skin. It combines passive solar gain control, such as shading and greening, with high-efficiency active solar systems, including PV panels. The system's modular and flexible design makes it easy to install, allowing for retrofitting from the outside without affecting occupancy, reducing the time and cost of its implementation. The energy-saving potential of the system, thermal and daylight comfort, and payback period with different façade configurations were evaluated on a multi-family residential building in a Mediterranean climate. The energy simulations demonstrate that the proposed solution can significantly reduce the energy required for space heating and cooling, by 33.4% and 25.5% respectively. A maximum reduction of 80.7% and 60.5% for heating and cooling is achieved by integrating the "en-SʘLEX" system with generator replacement. The integration of renewable energy sources leads to surplus electricity generation, which causes the building to exceed its average annual electricity demand regardless of the building orientation, thus transforming the existing building into a NetPlus one.
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... Integrating seismic and energy retrofit interventions has been increasingly investigated by researchers over the last years, highlighting that in earthquake-prone areas, integrated solutions can lead to overall cost reductions and improvements in the longevity of energy upgrading investments [21][22][23][24][25]. A recent overview of the state-of-the-art research on this topic [26] highlighted, however, that despite the increasing interest in the topic of combined or integrated retrofitting, there is only limited experimental work assessing the actual feasibility of such schemes. ...
Pre‐fabricated TRC Panels Versus TRM Jacketing for Integrating Seismic and Energy Retrofitting: Bi‐Directional Shaking Table Tests on Three Masonry‐Infilled RC Buildings
Article
Full-text available
Two novel integrated seismic and energy retrofitting solutions for existing buildings are experimentally assessed in this study. Three 60%‐scaled, two‐storey infilled reinforced concrete buildings underwent a series of bi‐directional shaking table tests. The control building represented a part of a typical Korean school building with seismic design deficiencies and suffered out‐of‐plane (OOP) failure of the second‐storey infill panels at maximum considered earthquake. Two retrofitting schemes based on textile‐reinforced cement‐based composites were evaluated as follows: (1) newly developed ‘textile capillary‐tube panels’ (TCPs), namely pre‐fabricated textile‐reinforced concrete (TRC) with integrated capillary tubes, and (2) a combination of textile‐reinforced mortar (TRM) with thermal insulation. Additionally, the presence of openings in the infills, as well as the effect of different types of anchorage of the textile reinforcement were studied. At the design level earthquake, both retrofitted buildings presented next to no damage, compared to the control structure that was in a state of near‐collapse. The retrofitted structures reached double the intensity of the design earthquake, with the shaking table reaching its maximum acceleration capacity, yet no irreversible damage was observed. The strength increase for both retrofitted buildings was +110% compared to the un‐retrofitted building in the direction with openings, in which both buildings were retrofitted with TRM. For the fully infilled direction, the TRM‐retrofitted building recorded more than double the inter‐storey drifts compared to the TCP‐retrofit, and reached its peak strength (+120% compared to the control building). The TCP‐retrofitted building, instead, displayed a stiffer response with reduced deformations due to the carbon textiles employed in the precast panels. For both retrofits OOP damage was prevented, also demonstrated by the measured accelerations at the centre of the infills.
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... With respect to IP mechanisms, unlike other heavy [25] or framed [30] timber retrofits, the one proposed herein does not seek to equate or exceed the URM stiffness and/or increase the wall strength, nor to eliminate cracking, but it rather aims to increase the displacement capacity and delay/avoid disastrous brittle failures. As shown in the next sections, the proposed retrofit can help mitigate brittle diagonal shear failures to instead have much more desirable mixed shear sliding mechanism, creating a margin against the onset of partial or total collapse for easier post-earthquake repairs and safer building evacuationstherefore exponentially augmenting LS performance, often targeted for reuse projects [62]. ...
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Dissipative steel exoskeletons for seismic retrofit of RC buildings
Article
  • Apr 2025
This paper addresses the seismic retrofitting of highly vulnerable reinforced concrete (RC) buildings, with a focus on relevant and strategic structures such as schools, public offices, and cultural institutions. It proposes innovative retrofit solutions using external additive structures, or exoskeletons, designed for rapid, low-impact, and reversible interventions. These exoskeletons can be installed while the building remains operational, removed, replaced if damaged, and integrated with energy-efficient upgrades, reducing the time and cost of separate interventions. The research investigates two retrofit strategies for a school building: parallel exoskeletons with eccentrically braced frames (EBFs) and steel slit dampers (SSDs), and orthogonal exoskeletons with concentrically braced frames (CBFs) and shape memory alloy dampers (SMADs). A displacement-based design methodology ensures optimal energy dissipation and prevents premature buckling. Nonlinear time-history analyses validate the effectiveness of the retrofits across various earthquake scenarios. Peak inter-story drift ratio (IDR) responses are significantly reduced, remaining below the 2% collapse prevention limit. The parallel exoskeleton achieves IDR values of 0.66% and 0.86% in the X- and Y-directions, while the orthogonal exoskeleton records 0.63% and 1.06%, respectively. Additionally, the self-centering capability of SMA braces minimizes residual inter-story drifts, with permanent drifts as low as 0.0321% in the X-direction and 0.0090% in the Y-direction, ensuring repairability even after severe seismic events. These findings highlight the efficacy of dissipative exoskeletons in enhancing structural resilience while maintaining practicality and cost-efficiency for retrofitting critical infrastructure in earthquake-prone regions.
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Dissipative Roof Diaphragm for the Seismic Retrofit of Listed Masonry Churches
Article
Full-text available
  • Aug 2017
  • J EARTHQ ENG
In the seismic retrofit of existing masonry buildings, dissipative and deformable roof diaphragms could offer an efficient solution in cases where both the adoption of steel ties or stiff diaphragms would be ineffective. An innovative deformable, dissipative and lightweight roof diaphragm for the seismic retrofit of masonry churches is proposed. Such a diaphragm prevents the overturning of the side walls whilst allowing the onset of a controlled rocking mechanism. The specific diaphragm elasto-plastic response caps the seismic actions transferred by the roof diaphragm to the seismic resistant walls, in contrast with a rigid and with a stiffened diaphragm. This effect is meant to mitigate the overload of the head walls thus preventing their collapse or the need for their strengthening, which could require interventions invasive of the historical structure. The feasibility of the proposed retrofit strategy is assessed through the experimental characterisation of a prototype diaphragm sub-assembly and non-linear dynamic analyses of the global response of two retrofitted reference buildings.
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Reality-check and renewed challenges in earthquake engineering: Implementing low-damage systems - From theory to practice
Article
Full-text available
  • Dec 2012
Earthquake Engineering is facing an extraordinarily challenging era, the ultimate target being set at increasingly higher levels by the demanding expectations of our modern society. The renewed challenge is to be able to provide low-cost, thus more widely affordable, high-seismic-performance structures capable of sustaining a design level earthquake with limited or negligible damage, minimum disruption of business (downtime) or, in more general terms, controllable socio-economical losses. The Canterbury earthquakes sequence in 2010-2011 has represented a tough reality check, confirming the current mismatch between societal expectations over the reality of seismic performance of modern buildings. In general, albeit with some unfortunate exceptions, modern multi-storey buildings performed as expected from a technical point of view, in particular when considering the intensity of the shaking (higher than new code design) they were subjected to. As per capacity design principles, plastic hinges formed in discrete regions, allowing the buildings to sway and stand and people to evacuate. Nevertheless, in many cases, these buildings were deemed too expensive to be repaired and were consequently demolished. Targeting life-safety is arguably not enough for our modern society, at least when dealing with new building construction. A paradigm shift towards damage-control design philosophy and technologies is urgently required. This paper and the associated presentation will discuss motivations, issues and, more importantly, cost-effective engineering solutions to design buildings capable of sustaining low-level of damage and thus limited business interruption after a design level earthquake. Focus will be given to the extensive research and developments in jointed ductile connections based upon controlled rocking & dissipating mechanisms for either reinforced concrete and, more recently, laminated timber structures. An overview of recent on-site applications of such systems, featuring some of the latest technical solutions developed in the laboratory and including proposals for the rebuild of Christchurch, will be provided as successful examples of practical implementation of performance-based seismic design theory and technology.
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Does seismic risk affect the environmental impact of existing buildings?
Article
Full-text available
  • Oct 2015
  • ENERG BUILDINGS
The building sector significantly impacts on the environment during every stage of the building life cycle. The necessary transition toward a carbon-neutral society is driving a growing attention toward the refurbishment of old buildings, fostering intervention measures with the twofold objective of reducing operational energy consumption, typically upgrading the thermal insulation, and ensuring the quality of the consumed energy by adopting renewable and sustainable energy in the supply chain, such as thermal and photovoltaic solar energy.In seismic prone areas the vulnerability of existing buildings, not designed according to modern building codes, could hamper the efficiency of the solely energy refurbishment, besides representing a safety hazard. The present paper investigates a framework to quantify the influence of seismic events on the environmental impact assessment of buildings.The investigated framework is applied to a selected building, considering the building as alternatively located in regions with different seismicity. As an example, the building environmental impact is evaluated, in terms of carbon footprint, in the case of two different scenarios: upon completion of an energy refurbishment only, and after a coupled intervention targeting energy refurbishment and seismic retrofit. The results show that, in case of energy refurbishment only, the building located in a high-seismicity region presents an expected additional annual embodied equivalent carbon dioxide due to seismic risk, which almost equals the annual operational carbon dioxide after thermal refurbishment.
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Experimental testing of engineered masonry infill walls for post-earthquake structural damage control
Article
Full-text available
  • Jul 2014
The paper presents the results of an experimental campaign on the behaviour of engineered masonry infill walls subjected to both in- and out-of-plane loading. The aim of the research was to develop a design approach for masonry infill walls capable of solving their vulnerability and detrimental interaction with the frame structure when exposed to seismic excitation. Tests on two large-scale specimens and sub-assemblies were performed in order to evaluate the infill deformation capacity, the damage associated with different drift levels, and the mechanical properties of the components. A design solution with sliding joints to reduce the infill-frame interaction and ensure out-of-plane stability, which was proposed in a previous study, was developed and refined with focus on construction details. The aim of sliding joints is to ensure a predetermined mechanism in the infill wall, which is governed by hierarchy of strength and is capable of ensuring ductility and energy dissipation that can be taken into account in the design practice, thanks to the predictability of the response. The two infill wall specimens, one of them including an opening, reached up to 3 % in-plane drift with very little damage and supported an out-of-plane force equivalent to a horizontal acceleration four times the acceleration of gravity. The force-displacement hysteretic curve, sliding at the joints and crack pattern show the efficiency of the construction technique, based on affordable and tradition-like construction processes and materials. The technique, presented here for hollow fired-clay masonry units, can be extended to different masonry infill typologies.
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Dynamic Behavior of Rocking and Hybrid Cantilever walls in Precast Concrete Building
Article
Full-text available
  • May 2014
  • ACI STRUCT J
http://aisberg.unibg.it/bitstream/10446/31172/1/111-S55%20-%20Author%20post-print%20copy.pdf This paper discusses the dynamic response of precast, post-tensioned, rocking and hybrid cantilever walls that provided lateral force resistance to a three story precast concrete building built at half-scale. The building was subjected to extensive shake table testing on the NEES Large High-Performance Outdoor Shake Table at the University of California, San Diego. The tests provided a landmark opportunity to observe the dynamic response of this type of lateral force resisting system. Excellent performance was observed overall. Comparison between the assumptions made during the wall’s design and the experimental results allowed the validation of the presented design procedure and of the reinforcement detailing in the critical region at the base of the walls.
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Seismic Retrofit Using Rocking Walls and Steel Dampers
Conference Paper
Full-text available
  • Dec 2009
A retrofit system of prestressed concrete rocking walls and steel dampers is used to control the seismic damage mode and increase the strength and energy dissipating capacity of an 11 story steel reinforced concrete frame in Japan. Important details of the retrofit design are introduced. The seismic performance of the structure before and after the retrofit is evaluated through extensive nonlinear time history analysis. Results show that the rocking system can significantly reduce both the seismic responses to different earthquake ground motions and their scattering. This makes the damage mode and the seismic performance of the retrofitted building more predictable, leading to a possibility of more reliable performance-based seismic design.
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Seismic Retrofitting Using Energy Dissipation Façades
Conference Paper
Full-text available
  • Dec 2009
Building Façade has various functions, not only being suitable for placing additional seismic reinforce elements, but affecting on architectural appearance and running energy efficiency. For improving all of these performances, the authors have proposed the concept of "Integrated Façade", which treats structural design, façade design and environmental design combined together, including improvements on seismic performances using seismic energy dissipation devices. The practical application of this concept to the 40-years aged building is reported, which requires improvement in seismic performance allowing continuous tenant occupancy along the retrofit works.
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Seismic response of a case study soft story frame retrofitted using a GIB system
Article
Full-text available
This paper presents results from a numerical investigation into the seismic retrofit of a soft story frame using a novel gapped‐inclined brace (GIB) system. The GIB system consists of a pinned brace and a gap element that is added to the first story columns of the frame. The inclusion of GIB elements in addition to increasing the lateral capacity of columns at the first story increases the post‐yield stiffness ratio of the system and reduces the P‐delta effects on the columns, while not increasing the first story lateral resistance or stiffness. This allows for the isolating benefits of the soft story to protect the upper floors of the structure from damage while avoiding excessive deformations and reducing the propensity for collapse. A six‐story RC frame with masonry infills on all floors except for the first floor is studied. The dynamic response of the retrofitted building using the GIB system is investigated numerically and is compared with the response of the original un‐retrofitted building and the same building in which masonry infills are added to the first story to mitigate the soft story response. Results from the nonlinear time‐history analyses indicate that the GIB system could provide a reliable seismic retrofit mechanism for soft story buildings, which greatly reduces the likelihood of collapse by increasing the displacement capacity of the soft storey and by reducing P‐delta effects, while minimizing the overall damage and losses in the building by taking advantages of the isolation that is provided by the soft story to the rest of the structure located above. Copyright © 2014 John Wiley & Sons, Ltd.
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Thin Folded Shell for the Renewal of Existing Wooden Roofs
Article
  • Aug 2015
In this article, a technique for the renewal of historic building wooden roofs is presented. The solution can be used for the strengthening of existing wooden roofs against excessive lateral thrusts on the peripheral wall or for the recovery of the attics, as it allows removing the existing structural elements, such as possible wooden truss-works of no artistic value. With minor adaptations, the solution can be addressed to enhance the building seismic performance. The technique is minimally impairing on existing buildings and can be applied also in new constructions. The technique is based on the construction of a thin folded shell, overlaying the existing pitches. Emphasis is given to lightweight folded shells, obtained by overlaying thin plywood panels on the existing roof rafters and planks, without modifying the overall architectural layout. The technique conceptual design is discussed and a simplified analytical method is proposed, which allows for the clarification of the role of each structural component and can be adopted for the folded shell proportioning and design. The analytical results are validated against numerical results obtained with reference to some case studies. Ultimately, emphasis is given to the detailing, whose correct execution is mandatory for the success of the proposed structural intervention.
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Influence of Infill Panels and their Distribution on Seismic Behavior of Existing Reinforced Concrete Buildings
Article
  • Oct 2012
  • Open Construct Build Tech J
Infills can highly influence the seismic response of a Reinforced Concrete (RC) building: generally speaking, their presence leads to an increase in global stiffness and strength, but their brittle behavior can result in an increase of displacement demand if a certain threshold of seismic intensity is overcome. Moreover, presence of infills often leads to a change in the collapse mechanism compared with the bare structure, leading, for instance, to column-sway storey mecha- nisms characterized by a detrimental localization of inelastic displacement demand. In this paper, a numerical investiga- tion of the influence of infills on the seismic behavior of a case-study existing gravity load designed RC building is car- ried out. Different infill configurations are considered (Bare, Uniformly infilled and Soft-storey infilled). Seismic capacity assessment is carried out by means of Static Push-Over analyses, within the N2 spectral assessment framework. A sensi- tivity analysis is carried out, thus evaluating the influence of main material and model parameters on seismic response at different Limit States, namely Damage Limitation and Near Collapse, mainly due to the change in parameters as effective period of vibration, base shear and displacement capacity.
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