Conventional seismic design methods rely on structural inelastic hysteretic response to dissipate seismic energy. This approach often results in extensive damage and substantial direct and indirect losses following high-intensity earthquakes, thereby affecting the overall resilience of communities. To address this issue, modern earthquake engineering is facing an extraordinarily challenging era in providing affordable, high-seismic-performance structures able to minimise both seismic damage and repair time. To this end, the ERIES SC-RESTEEL (Self-Centring seismic-RESilient sTEEL structures) project examines the structural response, repairability, resilience, and performance recovery of low-damage self-centring steel Moment-Resisting Frames (MRFs) equipped with friction devices and post-tensioned bars with disc springs at column bases and beam-to-column joints. Shaking table tests will be conducted at LNEC (Laboratório Nacional de Engenharia Civil) in Lisbon, Portugal, to investigate the performance of a large-scale 3-storey steel MRF. Key objectives include evaluating the seismic performance of the structure, its reparability strategy, and the performance after repairs. This paper presents the test specimen design, advanced Finite Element analyses of various joint configurations, and the preparatory work for the tests. The findings offer valuable insights into the expected experimental outcomes.

Lessons from recent earthquakes have provided a tough reality check of the traditional seismic design approach and technologies, highlighting the urgent need for a paradigm shift of performance-based design criteria and objectives toward low-damage design philosophy and technologies for the whole building system. Modern society is asking for "earthquake proof" resilient buildings that are able to withstand seismic events without compromising their functionality. The EU-funded SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe Project) project discussed in this paper provided the opportunity to develop and validate within the European context an integrated seismic low-damage prototype, including main structure and non-structural elements, for the next generation of high-performance buildings. This paper presents an overview of the research, involving three-dimensional shake table tests of a two-storey 1:2 scaled timber-concrete post-tensioned dissipative low-damage structure "dressed" by earthquake-resistant gypsum/masonry partitions and glass/concrete facades. Specimen details, construction and assembly phases, test setup, and experimental results are discussed. After many cycles of input motions at increasing levels of seismic intensity (higher than Collapse Prevention Limit State), the integrated building system exhibited a very high seismic performance. The experimental campaign carried out at the National Laboratory of Civil Engineering in Lisbon confirmed the unique potential of low-damage technologies and the opportunity for their widespread implementation into design practice.

Different approaches are used to generate ground motion sets compatible with a target RotD100 spectrum following current ASCE7 requirements. The sets are used as input to perform bidirectional nonlinear response history analyses and evaluate the imposed deformation and energy demands. The structures studied are multistory buildings comprised of space frames designed to resist both gravity and earthquake forces. The influence of reinforcement detailing is explored by varying the ratios between the nominal moment capacities of beams and columns. A wide range of inelastic demands is investigated by scaling the intensity of the input motions. It was found that the marked disparities between the demands exhibited by the various sets can be explained by the differences in the spectral amplitudes along the expected periods of vibration. The traditional approach of spectral matching each horizontal component separately to the target RotD100 spectrum generates records with disproportionate intensities causing unrealistic large inelastic demands when compared to the results expected from amplitude-scaled records. On the other hand, the sets generated by simultaneous modification of the horizontal components to directly match the target RotD100 spectrum exhibited the tightest match to the target and the closest ground motion characteristics (Arias Intensity, significant duration, directionality, and spectral dispersion) to the amplitude-scaled sets. These sets also imposed the mean peak drift and mean total energy demands closest to the imposed by the amplitude-scale sets; however, the mean peak drift demand was slightly but consistently below the expected from amplitude-scaled sets. This unconservative bias vanished when the same approach was implemented using 110% the target spectrum to comply with the ASCE7 minimum spectral amplitude requirement for spectrally matched records.

Seismic risk mitigation in existing buildings requires an engineering assessment of the current condition and expected seismic performance and an identification of possible deficiencies that should be addressed. For heritage and historical buildings in particular, there is significant benefit in using the most detailed analysis methods available to avoid the conservatism inherent in simpler methods and thereby minimise unnecessary interventions and more precisely pinpoint where strengthening is required. On recent heritage projects, Arup has used the analysis software LS-DYNA and a new material model, calibrated against experimental tests on unreinforced masonry components and buildings to carry out (or supplement) seismic assessments. The analysis method (non-linear response history analysis) is not new, but its application on detailed finite-element models of complex historic structures has previously been computationally prohibitive and requires significant analyst experience to deliver reliable results. This paper summarises three of these recent Arup projects: Woltersum Church (the Netherlands), Procuratie Vecchie (Venice) and a building cluster in the historical centre of Appingedam (the Netherlands). The case studies show that these analyses allow complex features of seismic performance to be considered, such as damage or modifications to the building over time, pounding (separate buildings colliding into one another due to seismic movements) and load sharing between adjacent structures.

The development of seismic fragility functions for buildings generally relies on simplified modelling methods and the use of indirect engineering demand parameters (EDPs) for the determination of collapse or other damage states. The collapse response of real buildings, particularly those that have not been specifically designed for seismic resistance, can often be driven by local failures that may not be captured in simplified models. Furthermore, the use of EDP thresholds to indicate damage states may not be consistent with multiple possible failure modes, which may be triggered by different characteristics of the ground shaking or variations in model parameters. This paper demonstrates the use of non-linear finite element models including explicit progressive collapse simulation for the development of fragility functions. It presents an overview of the method developed and its application to an unreinforced masonry (URM) building typology in the Groningen region of the Netherlands, where induced seismicity risk is currently being evaluated. Multiple index buildings were selected to represent the variations in geometry, material properties, and connection types found within the typology. For each index building, Latin Hypercube sampling was used to generate batches of several hundred realisations of an LS-DYNA time-history analysis, each selecting from a set of 100 hazard-consistent ground motions, and varying material properties and other uncertain variables according to pre-assigned probability distributions. Automation was used in model generation, running analyses and in post-processing to allow the required computation with minimal analyst intervention. The main output from each analysis was a normalised debris cover estimate, which describes the extent of damage observed in the model and is correlated with life safety risk. Regression analyses were carried out directly on threshold levels of debris cover identified building collapse. Fragility functions were developed for the URM terraced house typology by combining results from the individual index buildings together.

A parametric mathematical form of vulnerability function is developed that gives a full probabilistic description of losses as a function of earthquake ground shaking intensity. The model is intended to be used with any loss measure that can take values between 0% and 100%, inclusive, including normalized financial losses (damage ratios), human casualty rates, or debris cover. It is a mixed discrete-continuous probability distribution, in that it assigns a discrete probability mass to experiencing exactly 0% or 100% loss, and a continuous probability density to values in between. The model can be used with empirical or analytical loss data. Two possible regression approaches are presented and Monte Carlo analysis is used to demonstrate that the regressions give unbiased estimates of the model parameters. Finally, the model is applied to a data set of debris cover percentages estimated from detailed finite element analysis of Dutch unreinforced masonry buildings.

In an effort to incorporate building fragility into seismic risk assessment, simple formulations of fragility functions are developed, such as a cumulative lognormal distribution, which describe the probability of damage of a building experiencing a given ground motion. We show here that when a lognormal fragility function is empirically estimated from data with uncertainty on the intensity of ground motion experienced by buildings, the estimate is biased towards fragility functions with larger variances. We show that this bias, due to the uncertainty on the ground motion, can be semi-analytically determined and we devise a methodology to correct for it.

Foreword by Professor Robin Spence 1 The lessons from earthquake damage, 1.1 Damage studies, 1.2 Ground behaviour, 1.3 Structural collapse, 1.4 Important categories of damage, 1.5 Reinforced concrete, 1.6 Structural steelwork, 1.7 Masonry, 1.8 Timber, 1.9 Foundations, 1.10 Non-structural elements, 1.11 Bibliography Ground motion, 2.1 Primary and secondary sources of earthquake damage, 2.2 Earthquake basics, 2.3 Earthquake probability and return periods, 2.4 Performance objectives under earthquake loading, 2.5 Representation of ground motion, 2.6 Site effects, 2.7 Quantifying the risk from earthquakes, 2.8 Design earthquake motions, 2.9 References The calculation of structural response, 3.1 Introduction, 3.2 Basic principles of seismic analysis, 3.3 Linear elastic forms of seismic analysis, 3.4 Non-linear analysis, 3.5 Analysis for capacity design, 3.6 Analysis of building structures, 3.7 References Analysis of soils and soil-structure interaction, 4.1 Introduction, 4.2 Soil properties for seismic design, 4.3 Liquefaction, 4.4 Site-specific seismic hazards, 4.5 Soil-structure interaction, 4.6 References Conceptual design, 5.1 Design objectives, 5.2 Anatomy of a building, 5.3 Planning considerations, 5.4 Structural systems, 5.5 Cost of providing seismic resistance, 5.6 References Seismic codes of practice, 6.1 Role of seismic codes in design, 6.2 Development of codes, 6.3 Philosophy of design, 6.4 Code requirements for analysis, 6.5 Code requirements for strength, 6.6 Code requirements for deflection, 6.7 Load combinations, 6.8 Code requirements for detailing, 6.9 Code requirements for foundations, 6.10 Code requirements for non-structural elements and buildingcontents, 6.11 Other considerations, 6.12 References Foundations, 7.1 Design objectives, 7.2 'Capacity design' considerations for foundations, 7.3 Safety factors for seismic design of foundations, 7.4 Pad and strip foundations, 7.5 Raft foundations, 7.6 Piled foundations, 7.7 Retaining structures, 7.8 Design in the presence of liquefiable soils, 7.9 References Reinforced concrete design, 8.1 Lessons from earthquake damage, 8.2 Behaviour of reinforced concrete under cyclic loading, 8.3 Material specification, 8.4 Analysis of reinforced concrete structures, 8.5 Design of concrete building structures, 8.6 Design levels of ductility, 8.7 Design of reinforced concrete frames8.8 Shear walls, 8.9 Concrete floor and roof diaphragms, 8.10 Unbonded prestressed construction, 8.11 References Steelwork design, 9.1 Introduction, 9.2 Lessons learned from earthquake damage, 9.3 The behaviour of steelwork members under cyclic loading, 9.4 Materials specification, 9.5 Analysis of steelwork structures, 9.6 Design of steel building structures, 9.7 Design levels of ductility, 9.8 Concentrically braced frames (CBFs),9.9 Eccentrically braced frames (EBFs),9.10 Moment-resisting frames, 9.11 Steel-concrete composite structures, 9.12 References Masonry, 10.1 Introduction, 10.2 Forms of masonry construction and their performance inearthquakes, 10.3 Designing masonry for seismic resistance, 10.4 Analysis of masonry structures, 10.5 Simple rules for masonry buildings 10.6 References Timber, 11.1 Introduction, 11.2 Characteristics of timber as a seismic-resisting building material, 11.3 The lessons from earthquake damage, 11.4 Design of timber structures, 11.5 References Building contents and cladding, 12.1 Introduction, 12.2 Analysis and design of non-structural elements for seismicresistance, 12.3 Electrical, mechanical and other equipment, 12.4 Vertical and horizontal services, 12.5 Cladding, 12.6 References Seismic isolation, 13.1 Introduction, 13.2 Lessons from 30 years of seismic isolation, 13.3 Seismic isolation systems, 13.4 Design considerations, 13.5 Analysis of seismic isolation systems, 13.6 Testing of bearing systems, 13.7 Active and semi-active systems, 13.8 References Assessment and strengthening of existing buildings, 14.1 Introduction, 14.2 Performance of

La Sagrada Familia in Barcelona is currently 135 years into its construction, with an expected completion date of 2026. Since its inception by Antoni Gaudí in 1882, radical analysis and design methods have been required to imagine its architectural form and understand the engineering performance of what will be, once complete, the tallest church in the world. Gaudí famously used hanging chain models to realise the catenary form of his structures, a method which pre-empted modern form-finding software and enabled him to devise an organic optimised form long before this could be achieved with computers.

Seismic base isolation is examined as a design alternative for supporting industrial facility liquid storage tanks against earthquake loading. A 160,000m3 liquid storage tank is adopted as a case study, for which two designs are assessed, one with and one without base isolation. Using a nonlinear surrogate model and a set of ground motion records selected using the conditional spectrum approach for the average spectral acceleration intensity measure, Incremental Dynamic Analysis is employed to derive seismic fragility curves. Consequences of damage are evaluated in terms of downtime, considering the characteristics of petrochemical storage tanks, whereby any repair requires a lengthy list of actions dictated by health and safety requirements. The results reveal considerable benefits when base-isolation is employed, by drastically reducing downtime when sufficient displacement capacity is provided in the isolators.

The Kyrgyz Republic is located in a highly seismic region subjected to devastating earthquakes that have caused loss of life, destroyed homes and ruined livelihoods in historical and recent times. In order to better understand the risk from earthquakes across the entire country, a nationwide seismic hazard and risk management study for buildings was undertaken. Across the Kyrgyz Republic, there are 150,000 residential buildings with an estimated portfolio value of 60 billion USD, 5,500 school buildings with an estimated value of 1.5 billion USD, 333 fire station buildings with a value of 500 million USD and 185 hospital buildings with a value of 9 billion USD. In this study, direct earthquake losses due to ground shaking have been quantified for each building asset portfolio using a probabilistic hazard and risk assessment for the entire country as well as twelve (12) selected credible scenario earthquake hazard and risk calculations. Risk assessments were performed independently for each building portfolio, using exposure and vulnerability models specifically tailored to the characteristics of each group of assets. The probabilistic seismic hazard and risk assessment confirmed that the country is subjected to moderate to high seismic hazard across most of the country and that significant average annual losses are expected (for example, up to 4% of GDP for the residential buildings portfolio). For the considered scenario events, the estimated monetary losses (mean) range from 138 million to 11 billion USD (i.e. up to 150% of GDP while fatalities range from 200 to 10,300 people. These findings will allow stakeholders to make informed decisions for upgrades and investment to reduce losses, better plan for emergency response and inform longer term recovery after earthquake disasters.