Innovative damage-mitigation technologies have been recently developed to improve the seismic performance of structural and non-structural elements. The combination of these solutions can lead to a ...high-performance and cost-efficient building system, capable of sustaining earthquakes with limited damage and reduced socio-economic losses. This article investigates the convenience of implementing damage-control solutions through a cost/performance-based evaluation of multi-story-reinforced concrete buildings, comprising alternative combinations of traditional vs low-damage technologies for both structural skeletons (frames, walls) and non-structural elements (heavy/light facades, heavy/light partitions, suspended ceilings). The significant benefits of the innovative systems are investigated through loss assessment studies, implemented using a practical approach based on numerical pushover analyses and the capacity spectrum method. The parametric analyses confirm that the integrated low-damage structural/non-structural system can lead to significant savings, in these specific cases, in the range of 150-300 euro/m2 during the 50-year building-life and downtime reductions at ultimate limit state in the order of 2-7 months.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
A seismic loss-based design framework is proposed. It relies on the introduction of a multi-objective loss-performance matrix that attempts to set an innovative design approach directly associating ...loss measures to performance levels as a function of the design seismic intensity and the social importance of the building. This approach provides higher awareness about the economic consequences caused by structural and non-structural damage in the aftermath of an earthquake event. The design framework is applied to a case-study-reinforced concrete frame building designed as a traditional cast-in-situ moment resisting frame system, analyzing its performances within the new loss matrix.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Recent seismic events are a unique opportunity to monitor and collect details of direct repair costs and the downtimes associated with massive reconstruction processes. This paper focuses on the ...actual repair costs of five RC buildings damaged by the 2009 L'Aquila earthquake. The repair costs for structural and nonstructural components that experienced different types of earthquake damage are discussed and then used as a benchmark for the predictions. The comparison at both the building and component levels revealed that the FEMA P-58 methodology is suitable, in general, for application to different types of building stock. Ad hoc upgrades to the FEMA fragility database for components that are typical of the Mediterranean area are required. When implementing the proposed modifications, a reasonable level of consistency is achieved in terms of actual and predicted repair costs (differences in the range of 30-48%). A discussion on the actual repair costs and the main differences with the predicted costs for infills and partitions, structural subassemblies, floor finishes, and other acceleration-sensitive nonstructural components is provided, along with suggestions for further improving.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
•Seismic safety and environmental sustainability need to be considered simultaneously.•A probabilistic risk assessment is proposed to support building investment decisions.•Integrated seismic and ...energy economic losses are used as design decision variable.•Traditional vs low-damage seismic-resisting technologies are investigated.•Design solutions are assessed and compared in terms of reliability and risk values.
Structural safety and environmental sustainability are major factors in investment decisions for building systems, but are rarely considered simultaneously. Recent research efforts have redressed this by developing assessment methodologies and technical solutions for integrated energy efficiency and seismic performance. These studies are typically limited to existing buildings and retrofit interventions at global building scale, whereas an effective framework could and should be part of the design process of either new or existing buildings at both building and component scales. This paper proposes a probabilistic-based assessment framework to assess the building performance in terms of integrated economic losses and support the selection of resilience-enhanced solutions. The proposed methodology is validated through its application to reinforced concrete case-study buildings consisting of traditional vs low-damage earthquake-resistant technologies coupled with energy efficiency strategies. Seismic and energy risk assessment analyses are performed accounting for both modelling uncertainties and earthquake/weather variability. Probabilistic distributions of the integrated economic losses are finally derived to compare the design solutions in terms of risk and reliability. The research outcomes demonstrate the effectiveness of the probabilistic approach for decision-making in building projects. Specifically, it is found that the economic losses can be highly underestimated (greater than40 %) in the single domains (energy or seismic); greater savings and return on investment can be achieved when the seismic safety is involved in the design process; probabilistic distributions and reliability/risk values can represent an effective tool to assess and compare design solutions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the current practice, the design of energy refurbishment interventions for existing buildings is typically addressed by performing time-consuming software-based numerical simulations. However, ...this approach may be not suitable for preliminary assessment studies, especially when large building portfolios are involved. Therefore, this research work aims at developing simplified data-driven predictive models to estimate the energy consumption of existing school buildings in Italy and support the decision-making process in energy refurbishment intervention planning at a large scale. To accomplish this, an extensive database is assembled through comprehensive on-site surveys of school buildings in Southern Italy. For each school, a Building Information Modelling (BIM) model is developed and validated considering real energy consumption data. These BIM models serve in the design of suitable energy refurbishment interventions. Moreover, a comprehensive parametric investigation based on refined energy analyses is carried out to significantly improve and integrate the dataset. To derive the predictive models, firstly the most relevant parameters for energy consumption are identified by performing sensitivity analyses. Based on these findings, predictive models are generated through a multiple linear regression method. The suggested models provide an estimation of the energy consumption of the “as-built” configuration, as well as the costs and benefits of alternative energy refurbishment scenarios. The reliability of the proposed simplified relationships is substantiated through a statistical analysis of the main error indices. Results highlight that the building's shape factor (i.e., the ratio between the building's envelope area and its volume) and the area-weighted average of the thermal properties of the building envelope significantly affect both the energy consumption of school buildings and the achievable savings through retrofitting interventions. Finally, a framework for the preliminary design of energy refurbishment of buildings, based on the implementation of the herein developed predictive model, is proposed and illustrated through a worked example application.
Worth noting that, while the proposed approach is currently limited to school buildings, the methodology can conceptually be extended to any building typology, provided that suitable data on energy consumption are available.
•Time-consuming simulations are required for energy refurbishment of buildings.•Simplified methodologies may support the energy requalification of buildings.•The results of refined energy analyses of existing school buildings are considered.•A Multiple Linear Regression (MLR) model is trained to obtain a predictive tool.•A framework for a preliminary design of energy refurbishment interventions is proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Recent devastating earthquakes have shown that existing reinforced concrete (RC) buildings that rely on shear walls may exhibit damage and cracking. The majority of seismic actions are borne by shear ...walls; hence, the quantification of their residual post-earthquake capacity is critical. Moreover, the repair interventions that are typically implemented in practice may be insufficient to fully restore the original capacity of the undamaged system, particularly in terms of stiffness. This makes it difficult for stakeholders to decide on implementing either building repair or demolition and reconstruction. This article proposes a novel methodology to aid practitioners in quantifying the effect of earthquake damage and repair on the seismic performance of buildings with shear walls within a loss-assessment framework. A refined procedure relying on a validated nonlinear finite element numerical model capable of reproducing the shear response of RC walls is proposed along with an analytical approach. Parametric analyses of an RC case-study building are conducted, and the results are discussed and compared in terms of expected annual losses in the undamaged, damaged, and repaired configurations.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
•First ever experimental testing of a post-tensioned timber core wall structure.•Under SLS loads, wall panels can be assumed to be connected rigidly to each other.•Supplementary dissipative devices ...provide stable hysteretic energy dissipation.•Clamping forces from the PT prevent sliding between panels and at the foundation.•Displacement incompatibilities can be accommodated by simple connections details.
With the increasing demand for multi-storey timber buildings in areas with high wind loads and high seismic activity, stiff lateral load resisting systems are becoming a crucial design component. Post-tensioned Pres-Lam mass timber lift shafts and stairwell core walls not only provide a strong and very stiff lateral load resisting system, but also damage limiting response in the case of a large seismic event.
This paper describes the results of experimental tests on Cross-Laminated Timber (CLT) Pres-Lam core walls tested under bi-directional quasi-static seismic loading. In the first configuration the CLT wall panels were connected in the corners with screws, while in the second configuration, steel pivotal columns were introduced at the corners and the CLT wall panels were connected to the steel columns with dissipative U-shaped Flexural Plates (UFPs).
Overall the testing showed that the Pres-Lam system, when used for structural timber core walls subjected to bidirectional loading regimes, sustains nominal damage after large drift demands. By adding ductile screw-connections or steel columns with UFPs at the corners additional strength and dissipation capacity is obtained.
Friction between the CLT panels improved the seismic performance of the structure, which in Serviceability Limit State (SLS) conditions led to rigid behaviour of the splices between the panels. Displacement incompatibilities between the floor diaphragm and the core walls were accommodated by locating the connections at the centre of the walls, or by pinned connections in the corner pivotal columns. Relative displacements between orthogonally running connector beams were accommodated by using flexible connections out-of-plane. Under low axial forces there was horizontal sliding of the walls at the foundation level, but this was not observed when larger post-tensioning forces were applied.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•The increase in yield strength for Grade 300E is not dependent on the pre-strain.•At room temperatures, changes in mechanical properties are completed within 90 days.•Increase in UTS and reduction ...in ductility are proportional to the prestrain.•The increase in yield strength due to long term strain ageing is about 55 MPa.•Microalloyed high strength steel Grade 500E is not affected by strain ageing.
Modern seismic codes are based on capacity design and hierarchy of strength principles that allow the formation of plastic hinges in sacrificial elements within a structure. An accurate estimation of the mechanical properties of the steel reinforcement is required to achieve a ductile failure mechanism. After being subjected to plastic deformation, many types of low-carbon steel experience a time- and temperature-dependent phenomenon known as strain-ageing. This phenomenon causes changes in the mechanical properties such as increase in yield and reduction in ductility. Therefore, in the aftermath of an earthquake event, the hierarchy of strength between beams and columns in a subassembly and/or between flexure and shear within the same structural element of a damaged structural system could potentially be compromised. In this paper, the extent of strain-ageing in New Zealand Grade 300E and Grade 500E reinforcement is investigated through experimental testing in which reinforcing bar samples were pre-strained up to selected strain limits and then subjected to natural (at 15 °C) and accelerated ageing (at 100 °C), at different time intervals, up to one year. The changes in mechanical properties were monitored and quantified. These changes must be accounted for during post-earthquake assessments and repairing design and are recommended to be incorporated in future code provisions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Most of the experimental studies available in literature on the seismic assessment and retrofit of existing, poorly detailed, reinforced concrete (RC) beam-column joints, typical of pre-1970s ...construction practice, have concentrated on the two-dimensional (2D) response, using unidirectional cyclic loading testing protocol and constant axial load. Even more limited information is available on the performance of exterior (corner) three-dimensional (3D) RC beam-column joints with substandard detailing subjected to bidirectional loading regime. In this study, the results of a comprehensive experimental program is presented, aiming to show the effects of varying axial and bidirectional loading on the seismic performance of deficient exterior RC beam-column joints before and after retrofit. Ten exterior beam-column joint subassemblies are tested, including four as-built specimens and six retrofitted specimens using externally bonded glass fiber-reinforced polymer (GFRP) sheets. Test results are herein presented and conclusions are drawn on the basis of the observed global and local performance. The significance of the triaxial interaction of varying axial and bidirectional loading effects on the response of retrofitted corner joints is confirmed by the experimental findings. The proposed retrofit solution was shown to be capable of re-establishing an appropriate hierarchy of strength within the subassembly, protecting the panel zone region from shear failure while promoting the formation of a plastic hinge in the beam.
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FGGLJ, IZUM, KILJ, NUK, PILJ, SAZU, UL, UM, UPUK
