The growing concern over environmental impact and the significant improvement in the quality of engineered wood products have led to the rapid growth of the timber building industry in the last decades. Although traditional, yet recent, mass timber structural systems, such as cross-laminated timber walls, can provide satisfactory seismic performance during earthquakes in terms of life-safety, the crucial need for more resilient timber buildings has prompted the development of low-damage high-performance self-centring and dissipative solutions based on unbonded post-tensioned hybrid connections, referred to as Pres-Lam technology. The flexibility of design and construction speed, combined with the enhanced seismic performance, create a unique potential towards an earthquake-proof sustainable building system. Despite the growing popularity of the technology, a comprehensive framework for the fragility analysis, to be used in risk and loss modelling applications, has not yet been developed for both component and building levels.@en

The severe socio-economic impact of recent earthquakes has represented a tough reality check, further confirming the mismatch between society expectations and reality of seismic performance of modern buildings. Life-safety code-compliant design criteria are not enough when dealing with new structures. To raise the bar in terms of structural safety and overall performance objectives, the renewed challenge is defining high-performance buildings able to sustain a design-level earthquake with minimum disruption of business and limited economic losses. To achieve this goal, alternative strategies might be adopted: (a) implementing more advanced design methodologies, (b) increasing the seismic design level, (c) adopting low-damage earthquake-resistant technologies. However, the common perception is that these strategies would lead to unaffordable costs. To support decision-makers, the paper develops a comprehensive parametric study to compare the cost–benefit of reinforced concrete multi-storey buildings designed for increasing levels of seismic intensities (representing a higher seismicity zone or Importance Class) and according to alternative design approaches (Force-based vs. Displacement-based) and technologies (traditional vs. low-damage). Analytical/numerical investigations are carried out to determine the building performance, and loss assessment analyses are performed to compute the Expected Annual Losses of all the parametric configurations. Results, further elaborated through a machine-learning technique, highlight the convenience of implementing more advanced design methodologies, such as a displacement-based approach allowing for a better control of the building response, and the remarkable benefits of applying low-damage technologies, leading to a very high performance and significantly reduced economic losses (> 50%) for a small increase (< 5–10%) of the initial investment cost.

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In the last decades, recent earthquakes have further highlighted the high vulnerability of non-structural components. Post-earthquake damage due to building envelope, equipment and building contents can lead to substantial economic losses in terms of repair costs and daily activity interruption (downtime). Moreover, non-structural damage can represent a life-safety threat for both occupants and pedestrians. These considerations confirm the crucial need for developing low-damage systems for either structural or non-structural elements. This paper aims to assess the seismic performance of glazed facade systems, widely adopted in modern buildings, focusing on point fixed glass facade systems (PFGFSs), also referred to as “spider glazing”. In this work, a numerical investigation is developed to study the seismic performance of such systems at both local-connection level through a 3D FEM in ABAQUS as well as at global system level through a simplified lumped plasticity model in SAP 2000 to assess the overall in-plane capacity of the facade. Based on the local connection and global facade system behavior, a novel low-damage connection system is herein proposed, and a parametric study is carried out on the key parameters influencing the facade capacity. The benefits of implementing low-damage connection details are highlighted by an increase of the in-plane capacity of the facade system when compared to a traditional solution. To further investigate the potential of the proposed low-damage details in preserving the integrity of the facade system itself, non-linear time history analyses have been carried out on a case-study building equipped with the innovative PFGFSs.

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This article presents a numerical study on the influence of the anchorage shear hysteresis on the seismic response of nonstructural components (NSC) connected to multi-storey reinforced concrete (RC) buildings, and of the anchorage itself. To cover a variety of different types of shear hysteresis shapes, this contribution considered the experimental results obtained for five types of post-installed anchors. The results were used for calibrating the hysteresis model of the anchorage connecting an ideal NSC with rigid fixture and a 12-storey RC building host-structure. Using a suit of 40 earthquake records and assuming a single NSC at each storey level anchored by a single fastener, a series of non-linear dynamic analyses of the structure-fastener-nonstructural system was carried out. The results showed significant differences in terms of maximum acceleration and force of the NSC and anchorage, respectively, depending on the type of anchor. These seismic demands were sometimes larger than those required by the reviewed code provisions for rigid NSC, but also for the most restrictive code-case for flexible NSC. The results presented different amounts of scatter, mostly related to the size of the annular gap and of the loading stiffness of the anchorage. It is shown that the maximum force achieved by the anchorage is directly related to the peak relative velocity of the NSC within the gap region. It was concluded that the shape of the shear hysteresis of the anchorage highly influences the response of the NSC and the anchor itself and should not be neglected in practice.

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Different low-damage technologies have recently been developed to meet society's growing expectations for earthquake-proof buildings. Among others, the PRESSS (PREcast Seismic Structural System) technology has proved its capability to withstand earthquakes with minimal damage, effectively mitigating socio-economic losses. However, applying loss assessment methodologies can pose challenges due to the lack of data regarding fragility functions for low-damage structural components. This paper aims to propose a method for computing numerical fragility curves for rocking dissipative structural components. To achieve this, archetypes of precast concrete structures were analyzed to develop fragility models for this technology.

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Since the 1980s, calcium silicate element masonry has been commonly used in Dutch buildings, and vertical continuous joints have been usually located at the corner of perpendicular walls. Since the shear failure of these joints may significantly reduce the seismic performance of the flanged wall and therefore of the entire building, the assumption of rigid connection may be inaccurate, unlike for the traditional interlocking of bricks in running bond textures. In this paper, analytical and numerical approaches to study the failure of vertical joints in the seismic assessment of URM buildings are presented. The first part of the work focuses on two different numerical models to study the nonlinear behaviour of the vertical connection; the related critical numerical issues are then discussed. The second part introduces an analytical method able to estimate the lateral force–displacement curve of a flanged wall, which considers the possible failure of the connection. In particular, the method is derived from the section analysis approach developed for controlled rocking deformable systems. The comparison between the numerical simulations and the analytical method proves the capacity of the latter to provide a quick but sufficiently accurate estimate of the force–displacement curve of a URM U-Shaped wall.

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Terraced houses built in the Netherland after 1980 are often characterized by the use of large units connected at corners by continuous thin layer mortar joints. Unlike the running bond pattern, usually modelled as a rigid connection, the vertical continuous connection may fail in shear and influence the global seismic capacity of the entire building. This work aims at investigating and comparing different numerical modelling approaches for simulating the vertical connections. Two different constitutive models are adopted to simulate the quasi-brittle nonlinear behaviour of the continuous joint, and their advantages and limitations are pointed out in terms of robustness and accuracy. The study considers both the component level in terms of U-shaped pier-wall configuration, and the full-scale structural level in terms of the global capacity for a two-storey masonry house assemblage, characterized by a running bond arrangement. The results of this work show that the shear failure involving the continuous joint usually reduces the strength capacity of the structure. Both the selection of constitutive models for the connection interface and masonry material are demonstrated to affect the results significantly. Decoupled direct traction-displacement relations for the interfaces appear to provide more robust results than coupled plasticity-based Coulomb friction laws. The selection of either a pre-fixed orthotropic smeared crack model for the masonry or a standard isotropic concrete-like rotating smeared crack formulation is demonstrated to strongly influence the activation of the different failure mechanisms and hence the response of the structure.

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Unitized curtain walls are glazing facade systems widely used in modern architecture for mid and high rise buildings, due to their benefits in terms of lightness, quality control, ease of construction and quick installation. However, recent earthquake surveys have shown damages to these non-structural elements. Slight-to-moderate damage can cause loss of facade functionality, moderate-to-major damage can provoke severe post-earthquake economic losses and pose a life-threatening danger to both building occupants and pedestrians. Despite recent studies on the seismic behavior of unitized curtain walls, research in this field is still limited and experimental investigations typically neglect the study of the overall facade performance as well as the identification of the full sequence of damage states and the ultimate resistance of the facade components. This paper presents the extensive experimental campaign carried out at the laboratory of Permasteelisa Group, in Vittorio Veneto (Italy), to investigate the seismic behaviour of full-scale unitized curtain walls from a holistic and multi-performance perspective. The research aims at providing information about the serviceability performance and the ultimate limit state of alternative facade designs. The tests involve various facade configurations consisting of dry (gasket) vs. wet (structural silicone) glazing systems with different construction details for glass, frame and joints (dimensions and type). The testing sequence consists of displacement-control dynamic cyclic loading and/or time histories at increasingly seismic intensity levels, accounting for in-plane, out-of-plane and vertical movements. Air infiltration tests, water leakage tests and wind resistance tests are performed before and after the low-intensity seismic tests to study the post-earthquake facade serviceability. This paper discusses the research objectives, the specimen details and the test setup, and provides preliminary experimental results.@en

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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When dealing with seismic risk assessment at a large scale, the collection of relevant building data is still deemed a challenging task, often leading to limited building knowledge and, consequently, high uncertainties. Therefore, innovative yet standardized frameworks and adaptive tools are needed to support the seismic risk assessment of buildings. Towards this goal, this paper proposes a simplified multi-knowledge seismic assessment methodology involving the analytical-mechanical SLaMA (Simple Lateral Mechanism Analysis) method. An ad-hoc data collection form is first developed to identify the building vulnerabilities by merging and building on existing institutional forms at the international level and integrating new input data. The data are then used to implement the SLaMA-based methodology, at different building knowledge levels, to assess the seismic safety and the economic losses of buildings. The proposed data structure and approach is planned to be included in the “Seismic-Response” module for PELL (Public Energy Living Lab)-School platform, aiming to become a standardized and interoperable database for relevant data of Italian schools and a dashboard for allowing stakeholders to continuously monitor their energetic and static/seismic conditions. The paper discusses the potential and effectiveness of the proposed procedure for large-scale applications and its integration into platforms assessing the energy efficiency of buildings.

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High-rise buildings have large impact on the community and a significant economic value, considering the resources involved from the design through construction and use. Due to the increasing demand for renewable construction materials, the use of mixed timber-concrete solutions for high-rise structures is attracting more interest: concrete provides adequate stiffness, while timber reduces the embodied carbon of the building, including reductions in construction and demolition waste and improved recyclability. Nevertheless, in earthquake-prone countries, advanced technologies should be used to mitigate the seismic risk of high-rise buildings, considering that slight-to-moderate level of damage can produce substantial economic losses and significant environmental impact. This paper investigates the application of timber-concrete post-tensioned dissipative connections for high-rise buildings in seismic zones. These low-damage connections are able to reduce the post-earthquake residual drift and minimize the damage, thereby reducing direct and indirect losses. Furthermore, dry jointed connections allows for a flexible design approach and advantages in the construction phases. This approach is investigated through two designed case studies: a traditional concrete monolithic (cast-in-situ) building vs. a low-damage timber-concrete solution. Nonlinear dynamic analyses are performed to compare the structural/seismic responses of the case studies. A life-cycle analysis of the two buildings is developed to assess the environmental footprint, also accounting for the probable maximum losses associated with seismic damage. Results demonstrate the great efficacy of the low-damage technology for high-rise buildings: both the post-earthquake economic losses and the environmental impact are reduced by more than 40% when compared to the traditional building system.

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In recent years, the seismic risk in the north of the Netherlands has increased due to gas extraction. Since 2014, the Delft University of Technology started a research program to assess the seismic response of unreinforced masonry (URM) buildings. The Dutch URM buildings are characterized by slender piers and transverse walls. In common practice, the connections between piers and transverse walls are often modelled as rigid, but in real structures these connections may exhibit different behaviour. Especially, since the 1980s, calcium silicate element masonry has been commonly used in Dutch buildings, and vertical continuous joints are present between transverse walls. For this reason, it appears essential to assess the connection strength properties, since its failure can significantly reduce the seismic performance of the entire structure. The first part of this work investigates and compares different numerical approaches to describe the nonlinear behaviour of masonry under lateral loads, simulating seismic action. The second part specifically focuses on the critical issues related to the modelling of vertical connections of Dutch URM buildings. A sensitivity study of the frictional parameters is performed to analyze the influence of the strength of the glued connection on the global response of the URM structure.@en