Retrofit Solutions Research Articles

Performance of historical ferrocement specimens subjected to corrosive environments

AbstractFerrocement is a type of thin wall‐reinforced concrete composed of hydraulic cement mortar reinforced with several layers of steel wire mesh. The material is used as a low‐cost construction and retrofit solution and allows the creation of very thin elements. In the past, the material was also used to build some structural engineering masterpieces that currently face preservation challenges. Despite the use of the material, few studies have analyzed its durability with respect to corrosion and its evaluation for preservation purposes. The paper presents the results of a testing campaign on ferrocement replica specimens subjected to a corrosive environment. After an aggressive aging procedure, where the specimens are exposed to chloride ingress, the specimens are tested through a four‐point bending test to compare their performances. Results of the mechanical behavior are compared to the results from the half‐cell potential monitoring carried out during the aging process and optical microscope acquisitions regarding the cross‐sectional corrosion‐loss area in the wires. The aim is to assess the performance of historical ferrocement exposed to degradation due to corrosion; this can be useful in identifying the best procedures to protect and preserve it, as well as in evaluating its performance over time.

Retrofitting of an existing residential structure

Retrofitting of any given structure is done to improve its strength and performance. In most scenarios, retrofitting is done to improve seismic resilience and performance, however in this investigation retrofitting techniques are utilized to increase the structural strength. In order to encompass the additional load parameters, instead of complete reconstruction, retrofitting solutions are to be adopted, which reduces cost, labor and is very energy and environment conscious. The said structure was modeled using the E- Tabs software, with appropriate load parameters. Furthermore, the altered load parameters for the data center would likewise be examined to understand the extent of failure and would help in indicating the appropriate retrofitting solution to ameliorate the situation. This project is cutting edge in the sense that a sustainable approach in the construction industry is sought to, looking at the need for energy efficiency.

Influence of masonry infills on seismic performance of BRB‐retrofitted low‐ductile RC frames

AbstractReinforced concrete (RC) frames with masonry infills represent a prevalent construction typology across the globe, including moderate to high seismic regions. Such structures are often characterized by high seismic vulnerability, and consequently, there is an urgent need for retrofit solutions to effectively improve their seismic performance. Buckling‐restrained braces (BRBs) represent one such solution. They are a type of dissipative device that can be included within the frames of an existing structure to increase its strength, stiffness, and energy dissipation capacity. Although a substantial amount of research has already been performed to understand the effectiveness of BRBs as a retrofit strategy, these studies have often neglected the contribution of masonry infills and the interactions between the infills and the BRBs. While masonry infills are usually overlooked in the analysis and design stage (owing to their brittle nature), past studies indicated that their strength and stiffness may significantly alter the structure's seismic performance, leading to undesirable and unexpected results. This study presents a detailed investigation of the impact of masonry infills on the seismic response and fragility of BRB‐retrofitted RC frames. A three‐story, three‐bay, low‐ductile RC frame has been selected for case study purposes. High‐fidelity finite element models are developed in OpenSees for combinations of infilled and non‐infilled structures—with and without BRBs. Nonlinear static and dynamic analyses are performed to evaluate the seismic response of the different configurations at local and global levels. Successively, cloud analyses are conducted by considering a set of 150 ground motion records to account for the record‐to‐record variability and develop seismic fragility curves. The present study sheds some light on the mutual interaction between the infill panels and BRBs retrofit intervention and highlights the critical aspects that must be considered in the design.

Cybersecurity in Prognostics and Health Management

PHM continues to show its value by improving operational efficiencies, increasing safety, reducing downtime, and decreasing cost of operations. PHM technologies are therefore not only being deployed as retrofit solutions but are being integrated into new systems as standard practice. Deployment covers areas such as medical equipment, nuclear power plants, aeronautics applications, oil and gas, mining, and many others. As the impact of PHM increases, it is imperative to also consider the potential vulnerabilities that are being exposed. Hackers have famously used Supervisory Control and Data Acquisition (SCADA) and Programmable Logic Controller (PLC) systems to sabotage industrial facilities. As such, it is important to understand the exposure to malfeasance to ensure that PHM does not end up being the enabling mechanism for unauthorized access to the system it is meant to keep in running order. It is also important to understand the measures that need to be taken to avoid or respond to an attack. These range from extensive penetration testing to conducting extensive counter-social engineering training, setting up a PHM-specific CERT plan and team in place. This paper discusses various threats that are emerging and that may have to be considered when designing a PHM solution. Additionally, the NIST cybersecurity framework is discussed in the context of PHM. Finally, this paper looks at the diagnostic capabilities of PHM systems to detect cyber security attacks and to contain these threats.

An updated multi-criteria decision-making method for the sustainable renovation of buildings including environmental, economic and social life-cycle metrics

The ambitious targets of carbon emission reduction set worldwide for the coming years entail the commitment of structural engineers towards the sustainable renovation of existing buildings. The life cycle thinking (LCT) approach offers a holistic perspective for the design of sustainable retrofitting strategies. It envisages the reduction of the environmental impact at all building life cycle phases, while also addressing economic and social issues. Multi-criteria decision-making (MCDM) approaches support the choice of optimal retrofitting solutions, thus being relevant tools for boosting the actual adoption of LCT in current practices. In this study, a previously proposed MCDM approach is enriched with additional LCT-inspired decision parameters (module D beyond-life impacts, environmental payback period, invasiveness), and is then scrutinised and discussed through its application to a case-study building. Four integrated retrofitting scenarios are investigated using state-of-art seismic loss and energy performance assessment methods, including four different types of exoskeletons, made of timber, steel, and concrete. The end-to-end integrated assessment shows that the inclusion of additional LCT-inspired decision criteria effectively favours LCT-based retrofitting interventions over more traditional ones.

Analyzing Passive Design Retrofits using Pareto Front Optimization to Reduce Operational Carbon in Commercial Laboratory Spaces

Buildings are one of the leading sources of carbon emissions in the world. Most of the carbon emissions are released during the operation phase of the building. It is essential for buildings to provide thermal and visual comfort for the users. In the case of existing buildings, it is necessary to offer retrofit solutions so that the operational carbon emissions can be reduced without compromising on the other essential factors. In this study a Multi-Objective Optimization (MOO) of passive design strategies was conducted for a commercial laboratory in India situated in a moderate climate zone. The design variables considered for the study are wall and roof insulation, glazing material, window-wall ratio (WWR), depth of shading device and the number of shading devices used. The objective functions are: 1. reduced energy use intensity and operational carbon emissions, 2. increased thermal comfort hours and 3. increased daylight autonomy. Rhinoceros and grasshopper software along with Ladybug and Honeybee plug-ins were used for the study which resulted in 1296 iterations. MOO technique namely Pareto front optimization was used to optimize the objective functions. Out of 1296 solutions (excluding base case), 72 solutions were non-dominated. Two methods are described in the study to identify the recommendations for retrofit. The first method describes a Heuristic method of selection using Design Explorer recommending 5 good solutions. In the second method a factor is evolved to identify the 5 best solutions in sequential order. The overall study recommends the use of EPS insulation for the RCC roof, WWR of 20% on all sides, 3 horizontal shading devices of depth 0.75 m for all window openings. When compared with the base case scenario, this solution minimizes the EUI by 3.7%, maximizes average TCH by 106.6% and maximizes average DA by 66.9%. The overall operational carbon emissions are reduced by 7095.6 kgCO2.

An energy analysis methodology for residential heat pump retrofits

The government has targets to upscale domestic heat pump retrofit as part of the strategy to decarbonise heat. There are significant barriers to uptake including installation cost together with a lack of expertise in predicting and reporting energy and carbon performance. As a result, end user confidence in heat pumps can be low. This paper presents analysis of two monitored domestic properties using high resolution data. The aim is to develop reliable prediction and in-use diagnostic tools to improve transparency and reliability of heat pump performance. This paper focuses on a method drawn from theory as set out in CIBSE TM41, and shows how real building heat loss coefficients can be determined from regression analysis over different time frame resolutions. Practical application This research aims to provide residential heat pump retrofit providers with cost effective methods for assessing the suitability of dwellings to accept heat pump retrofit solutions, and to extend these techniques for the effective monitoring and performance evaluation of heat pumps post installation.

Energy Efficiency and Sustainability in Food Retail Buildings: Introducing a Novel Assessment Framework

One of the primary global objectives is to decrease building energy consumption to promote energy efficiency and environmental sustainability. The large-scale food retail trade sector accounts for over 15% of total primary energy consumption in Europe, posing a significant challenge to the transition towards green energy. This study proposes a simple method for energy efficiency, environmental sustainability, and cost-saving assessment and improvement in large-scale food retail trade buildings. It aims to analyze the energy and environmental performance of building–plant systems, establishing an interactive network to assess intervention potential for the energy transition. The investigation focuses on the proper selection and analysis of the benefits of retrofit solution implementation, emphasizing potential energy savings in current and future climate change scenarios. Dynamic simulation with the Building Energy Model (BEM) was used to evaluate the impacts of building–plant system retrofit solutions, such as high thermal insulation, photovoltaic (PV) panels, Light Emitting Diode (LED) installation, waste heat recovery, and improvement in refrigeration units. The results show a reduction in annual energy consumption for the PV panel installation by up to 29% and lighting systems with high-quality LED to 60%. Additionally, CO2 emissions can be decreased by up to 41% by combining these two strategies.

Comparative Studies on In-Plane Shear Behavior of Masonry Wallettes Retrofitted with Mortar, UHPC, and ECC Ferrocement: Shotcrete and Prefabricated Panels

Masonry walls, prevalent in many historical and contemporary structures, often require retrofitting to meet modern safety and performance standards. Motivated by the need for efficient and reliable retrofitting solutions, this research investigates the potential of various types of ferrocement, reinforced with high-strength steel meshes, to enhance the in-plane shear behavior of brick masonry walls. Through rigorous diagonal compression tests on nine masonry wallettes, the study evaluated the performance of ferrocement overlays in terms of overlay configuration (asymmetric or symmetric), cementitious material type (mortar, ECC, or UHPC), the presence or absence of steel mesh, and construction method (shotcrete or prefabricated panels). The results indicated that UHPC and ECC overlays significantly enhanced post-cracking deformation capacity. Compared to the asymmetric retrofit, the symmetric retrofit led to more uniform deformation in the retrofitted wallette, effectively improving the maximum shear by up to 119 %. While UHPC shotcrete was more effective in improving the shear strength, ECC shotcrete led to the highest rupture shear strain and pseudo-ductility for the retrofitted wallette, reaching 0.83 % and 17.2, respectively. Moreover, although steel mesh inclusion in the ferrocement overlay was crucial in enhancing post-peak ductility, its impact on shear strength of the retrofitted wallettes was minimal. The test results also demonstrated that the developed prefabricated UHPC panels emerged as an effective retrofitting solution to simultaneously improve the strength, deformation capacity, and ductility for masonry wallettes. In addition to the experimental investigation, a new strength model, accounting for various key design variables, was developed, offering reliable shear strength predictions for the retrofitted wallettes.

Seismic Retrofit Case Study of Shear-Critical RC Moment Frame T-Beams Strengthened with Full-Wrap FRP Anchored Strips in a High-Rise Building in Los Angeles

This paper discusses the iteration of a seismic retrofit solution for shear-deficient end regions of 19 reinforced concrete (RC) moment-resisting frame (MRF) T-beams located in a 12-story RC MRF building in downtown Los Angeles, California. Local strengthening with externally bonded (EB) fiber-reinforced polymer (FRP) fabric was chosen as the preferred retrofit strategy due to its cost-effectiveness and proven performance. The FRP-shear-strengthening scheme for the deficient end-hinging regions of the MRF beams was designed and evaluated through large-scale cyclic testing of three replica specimens. The specimens were constructed at 4/5 scale and cantilever T-beam configurations with lengths of 3.40 m or 3.17 m. The cross-sectional geometry was 0.98 × 0.61 m with a top slab of 1.59 m in width and 0.12 m in thickness. Applied to these specimens were three different retrofit configurations, tested sequentially, namely: (a) unanchored continuous U-wrap; (b) anchored continuous U-wrap with conventional FRP-embedded anchors at the ends; and (c) fully closed external FRP hoops made of discrete FRP U-wrap strips and FRP through-anchors that penetrate the top slab and connect both ends of the FRP strips, combined with intermediate crack-control joints. The strengthening concept with FRP hoops precluded the premature debonding and anchor pullout issues of the two more conventional retrofit solutions and, despite a more challenging and labor-intensive installation, was selected for the in-situ implementation. The proposed hooplike EB-FRP shear-strengthening scheme enabled the deficient MRF beams to overcome a 30% shear overstress at the end-yielding region and to develop high-end rotations (e.g., 0.034 rad [3.4% drift] at peak and 0.038 rad [3.8% drift]) at strength loss for a beam that, otherwise, would have prematurely failed in shear. These values are about 30% larger than the ASCE 41 prescriptive value for the Life Safety (LS) performance objective. Energy dissipation achieved with the fully closed scheme was 108% higher than that of the unanchored FRP U-wrap and 45% higher than that of the FRP U-wrap with traditional embedded anchors. The intermediate saw-cut grooves successfully attracted crack formation between the strips and away from the FRP reinforcement, which contributed to not having any discernable debonding of the strips up to 3% drift. This paper presents the experimental evaluation of the three large-scale laboratory specimens that were used as the design basis for the final retrofit solution.

An interface-based microscopic model for the failure analysis of masonry structures reinforced with timber retrofit solutions

This paper presents a refined Finite Element (FE) modeling strategy for analyzing the failure behavior of regular masonry structures reinforced with timber-based retrofit solutions. The proposed model schematizes the masonry as brick units, modeled using two-dimensional linear elastic plane stress elements, mutually joined through zero-thickness cohesive interface elements. These interface elements serve to reproduce the nonlinear behavior of masonry because of the occurrence of failure mechanisms of the mortar joints. Reinforced timber frame elements are modeled using truss elements that exhibit elastic brittle fracture behavior. The interaction between the masonry sub-structure and the reinforced timber frame system is accounted for using special constraint conditions that simulate the mechanical behavior of anchorage connections. The reliability of the proposed model in reproducing the failure behavior of masonry is assessed through comparisons with experimental and numerical data available in the literature. Additionally, the efficacy of the retrofit technique based on timber frame structures is investigated in detail through pushover analyses on a two-story masonry wall representative of real-life masonry buildings. The results indicate that the proposed retrofitting strategy is an effective and eco-friendly retrofit solution to enhance the in-plane bearing capacity of masonry structures subjected to horizontal forces.

Cross‐laminated timber for seismic retrofitting of RC buildings: Substructured pseudodynamic tests on a full‐scale prototype

AbstractThis paper presents an experimental study on an innovative timber‐based retrofit solution for reinforced concrete (RC) framed buildings, with or without masonry infills. The intervention aims to enhance seismic resistance through a light, cost‐effective, sustainable, and reversible approach integrating energy efficiency upgrades. The method employs cross‐laminated timber (CLT) panels as infills or external retrofitting elements, mechanically connected to the RC frame through steel fasteners. The system is combined with thermal insulation for improved energy efficiency. The seismic performance of the proposed retrofit technique was assessed experimentally on a full‐scale building model at the European Laboratory for Structural Assessment (ELSA). The experiments included tests on two five‐story building configurations: a masonry‐infilled RC building as a reference and the same structure strengthened with CLT panels. Each building was subjected to unidirectional earthquake simulations of increasing intensity using the pseudodynamic (PsD) testing method with substructuring. The physical substructure of the hybrid model consisted of the first story of a two‐story mockup built and retrofitted in the laboratory, while stories two to five were simulated numerically. The paper discusses major observations from the tests, comparing the damage evolution and hysteretic responses of the two configurations. The experiments yielded promising results, showing that the suggested retrofit solution significantly increased displacement and energy dissipation capacity. The retrofitted building survived earthquake intensities up to 50% higher than the non‐retrofitted counterpart, exhibiting only slight structural damage. These pioneering experiments provide compelling data on the high effectiveness of the proposed CLT‐based retrofit system in enhancing the seismic performance of full‐scale RC buildings.

Modeling wave dynamics with coastal vegetation using a smoothed particle hydrodynamics porous flow model

Coastal vegetation serves as an effective nature-based solution for protecting shorelines from erosion and storm surges. A detailed understanding of the dynamic interactions between waves and vegetation is crucial for quantifying the mitigation potential of coastal vegetation during extreme climatic events. This study investigates wave dynamic interactions with coastal vegetation by developing a numerical model using the weakly compressible Smoothed Particle Hydrodynamics (WCSPH) method. The model simulates the effects of vegetation by incorporating vegetation porosity, drag, and inertia forces into the momentum equations. By integrating porosity information at specific background points, the SPH interpolation method effectively treats the interfaces between fluid and vegetation regions, allowing versatility in modeling various vegetation layouts without explicitly simulating their solid structures, which is computationally prohibitive. The numerical model is validated using laboratory-based measurements and analytical models for both submerged and emergent scenarios involving cylindrical and strip-type vegetation. The model is then utilized to investigate the effects of vegetation as both a natural line of defense and a retrofitting solution in front of a sea dike, to quantify the performance of nature-based solutions for enhancing climate resilience in natural and hybrid coastal protection infrastructures. The results reveal that canopy density significantly impacts solitary wave run-up and energy dissipation. For the configurations tested in this study, high-density vegetation reduces normalized wave run-up by 52% compared to simulations without vegetation, while low-density vegetation achieves a 17% reduction. These findings demonstrate the potential of vegetation, particularly at higher densities, to mitigate solitary wave energy and reduce run-up hazards. Furthermore, simulation results indicate that using vegetation as a retrofitting solution effectively mitigates overtopping rates, achieving a 37% reduction with minimal forest density (∅ = 0.023). These results underscore the effectiveness of nature-based interventions in enhancing coastal protection and resilience.

Experimental study on the pullout behavior of steel rebars in masonry shotcreted layer

Unreinforced masonry (URM) buildings are quite popular worldwide due to their low construction costs, despite being susceptible to significant damage even from moderate earthquakes. In many cases, reconstruction may not be the most viable option due to financial and time constraints. Among the available retrofit solutions, steel-reinforced shotcrete (SRS) proves to be a cost-effective, straightforward, yet effective method for repair/retrofitting. This paper presents the results of an experimental study aimed at evaluating the effects of various construction conditions on the rebar pullout resistance of steel-reinforced shotcrete used as a retrofit method for URM walls. To achieve this, a total of 46 full-scale URM specimens were manufactured and tested, each consisting of a one-sided 50 mm-thick shotcrete layer with a single 8 mm steel rebar. The variables examined included the condition of the URM surface before the shotcrete application (wet/dry, with/without finishing including plaster/scratched plaster/oil paint), the condition of the rebar surface (rusty/clean), the type of rebar (plain/ribbed), rebar cover in the shotcrete layer (20/25/30 mm), and the URM substrate temperature before application of shotcrete (20 °C/-16 °C). The results indicate that there is an increase in pullout resistance of the specimens under the following conditions: when the wall's finishing is removed, the wall's surface is wetted before shotcrete application, ribbed steel rebar is utilized, and the temperature of URM before shotcrete application is 20 °C, there is an increase in pullout resistance of the specimens by 58 %, 56 %, 32 %, and 13 %, respectively. Additionally, when the steel rebar cover is sufficient, ribbed steel rebar is utilized, and this rebar is rusted, there is an increase in pullout resistance of the specimens by 55 %, 10 %, and 6 %, respectively.

Internet of things and deep learning-enhanced monitoring for energy efficiency in older buildings

Retrofitting older buildings for energy efficiency is paramount in today's sustainability and environmental awareness era. Older buildings contribute greatly to energy waste since they typically lack new energy-efficient technology. Reducing carbon emissions, lowering energy bills, and extending the life of these historic landmarks all depend on fixing the energy inefficiency that plagues these buildings. Despite advanced technologies' remarkable progress, the potential of the Internet of Things and deep learning in older buildings has not been unexplored. Major obstacles include expensive and out-of-date infrastructure and the difficulty of incorporating new technology into historically significant structures. Existing research has mostly ignored older infrastructures' unique requirements and limitations in favour of current or newly built services. In addition, comprehensive research on integrating deep learning with the Internet of Things in this specific environment has been lacking. Smart building energy management is made possible by the Internet of Things (IoT) and deep learning. Architectural limitations, outmoded infrastructure, and the necessity for non-invasive retrofitting solutions all contribute to the difficulty of energy monitoring and improvement in older buildings. This research proposes combining the IoT with Deep Learning-enhanced Predictive Energy Modeling (DL-PEM) to make an energy management system that can change and adapt to the needs of older buildings. Data from IoT sensors is collected on occupancy, temperature, lighting, and equipment usage and then analyzed using Deep Learning models to determine the most efficient energy consumption patterns. Beyond its energy-saving potential, this method has many potential uses. Spotting and fixing structural problems before they become major can improve occupant comfort, reduce maintenance costs, and pave the way for predictive maintenance. Integration with the Smart grid and demand response programs can be facilitated, too, improving the reliability of the power system as a whole. Our IoT and Deep Learning-based energy management solution optimizes energy usage, reduces expenses, and mitigates environmental impact in older buildings, as shown by extensive simulation studies. The system's performance is compared to more conventional methods, and its flexibility is evaluated in various building and usage contexts. The experimental outcomes show the suggested DL-PEM model increases the energy demand forecasting analysis, energy consumption analysis, thermal comfort optimization analysis, seasonal variation analysis, and occupancy data analysis.

HAPPENING: an efficient cascade heat pump system for multifamily buildings

An innovative hybrid heat pump system is presented as a novel solution for multifamily building heating system retrofitting. This system is very efficient on the one hand thanks to its innovative configuration in cascade, minimum thermal losses and on the other hand, the maximization of local solar energy self-consumption due to decoupling generation and consumption and applying smart control strategies. It is aimed at facilitating retrofitting of existing heating systems in multifamily buildings, enabling an efficient decarbonization. Three variations of the system have been designed, installed, and tested in real buildings across Europe, within the H2020 project “HAPPENING”. The project is now under monitoring phase and the preliminary results are positive, demonstrating the high efficiency of the concept

Noise control for curtain wall construction in residential buildings - a retrofit solution

In modern high-rise residential buildings, designers and architects utilize curtain wall construction either for the entire building or a portion of the building to achieve the desired visual impact in an urban setting. This poses significant challenges to satisfy the building code acoustical requirement (e,g., sound transmission class) between residential suites on adjacent floors. Apparent sound transmission class tests were completed after the curtain wall system was installed and concluded non-compliance with the Ontario Building Code acoustical requirement. A retrofit noise mitigation option was proposed and implemented. The ASTC field test was repeated and concluded compliance with the building code acoustical requirement.

ANALISIS AIR CONDITIONER PADA KOMPLEK PERUMAHAN DI KOTA DENPASAR

Green building retrofit is an approach that involves modifying or enhancing existing buildings to achieve higher standards of sustainability and energy efficiency. By conducting an energy audit first, it's possible to identify potential energy savings in the housing, as well as components that need to be upgraded to reach the desired level of sustainability. Retrofit solutions may include the use of implementation of efficient HVAC systems, energy-saving lighting, and better energy management. The aim of this research is to explore the potential improvements that can be applied through Green Building Retrofit with a focus on energy efficiency and sustainability in Jadi Pesona II Barat Housing, comparing the energy consumption conditions of houses before and after the energy audit, as well as calculating the payback period for occupants after the retrofit implementation. After the energy audit and Green Building Retrofit, daily energy usage in homes in Perumahan Jadi Pesona II Barat decreased from 47.45 kWh per day to 36.91 kWh per day. This indicates a reduction of 10.54 kWh per day or approximately 22.22% from the previous conditions, and the payback period analysis results show that almost all air conditioners show values in line with the project investment feasibility parameter, which is below 4.2 years.

Integration of moisture transfer through walls into an urban climate model and application to the medieval city centre of Cahors (France)

Moisture transfer is a key phenomenon for simulating the energy balance of the walls of historical buildings as it has an impact on indoor and outdoor comfort, energy consumption and the durability of the walls. It is therefore essential to consider moisture transfer through walls when simulating old city centres, in order to properly assess the impact of different retrofit solutions on building and city energy balances. However, urban climate models neglect this phenomenon. The objective of this paper is to integrate the coupled mass and heat transfers into the urban climate model Town Energy Balance (TEB). A specially designed numerical method for solving hygrothermal transfers at the urban scale is updated and the hygrothermal transfer through walls is integrated using an IMplicit/EXplicit (IMEX) discretization scheme with large spatiotemporal scales. The reliability of this modified version of TEB for representing a historical district is verified by comparing the simulated results with in-situ measurements in a building of the medieval city centre of Cahors (France). The comparison is carried out for several points in the wall and for indoor conditions, running from June to December 2021. The integration of the moisture transfers through the walls greatly improves the moisture estimation inside the building. This new version of the model gives a good representation of the hygrothermal behaviour of a historical building and could therefore be used to compare several renovation scenarios for the medieval centre of Cahors, with regard to durability, energy and microclimatic issues.

Seismic fragility of unbraced industrial steel pallet racks

Past Italian earthquakes revealed the high seismic vulnerability of steel pallet racks designed for gravity loads only, which are still the most widespread industrial storage system. This study aims to derive the seismic fragility of these structures to enable more refined estimates of enterprise risk and the definition of effective retrofit solutions. For this purpose, 3D non-linear models of 27 unbraced pallet racks, representative of the Italian context, were analysed in Time-History under 268 bidirectional events, representative of Italian seismicity. Multiple fragility models were then derived, based on various engineering demand parameters and seismic intensity measures, through a cloud approach.