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Uplifting of a structure is a seismic isolation technique: it works as a structural fuse limiting the maximum base moment (rocking foundation) or base shear (rocking podium) transferred to the foundation. To use uplifting in performance-based seismic design, the interaction between rocking and flexure must be understood well. Ideally, surrogate models to predict the seismic response of such systems should be also available to facilitate design. This paper presents the equations of motion and an analytical expression to calculate the uplifted vibration properties of a dynamic surrogate model that features rocking-flexure interaction.

Functional recovery of buildings following earthquakes requires resources and services shared among damaged buildings on a community or regional level. Tools that can identify the relation between community’s pre-disaster supply of such resources and services and the recovery time of its built environment can inform disaster preparedness measures. This paper presents how community disaster recovery models based on the iRe- CoDeS framework can be used to identify such a relation and provide probabilistic estimates of resource and service quantities a community requires for an efficient post-earthquake recovery. Such capabilities of the iRe-CoDeS recovery models are illustrated using a regional recovery simulation for the region of Kraljevo, Serbia, following the M5.4 2010 earthquake. Results show that 200 workers are sufficient to repair residential buildings that experienced major structural damage in less than 550 days after the earthquake.

Seismic isolation is a well-established method of seismic protection. However, applications of this technology in low-income countries are limited due to the associated high costs. An experimental study of rubber spheres rolling on concave or flat concrete surfaces is presented herein. The cost of the proposed devices is sufficiently low to make them applicable in low-income countries. The application of the system in a residential building would comprise a large number of closely-spaced rubber spheres placed below the walls of the structure. This would allow for significantly reducing the thickness and the steel reinforcement of the concrete slab at the isolation level. Avoiding the construction of a heavily reinforced isolation diaphragm is necessary to make seismic isolation affordable in low-income countries. The rubber spheres isolators were subjected to monotonic uniaxial compression to examine their behavior under vertical loading. Subsequently, a total of 488 shake-table tests was performed to investigate the behavior of the system under seismic loading. Parameters of investigation were the geometry of the concrete plates (i.e., flat or concave), the diameter of the rolling sphere (i.e., 50 or 100 mm), and the applied compressive load (i.e., 2.08, 3.23, or 4.74 kN/sphere). Results showed that the isolators substantially reduced the acceleration transmitted to the superstructure while sustaining zero residual displacements. The dynamic behavior of the system mainly depends on the axial load and the diameter of the spheres. The governing parameter for the design of the rubber spheres is not material failure but excessive compressive deformation that would reduce the efficiency of the isolators.

Communities need to be resilient to minimize direct and indirect losses due to earthquakes. To develop and compare effective resilience improvement measures, tools that quantify community earthquake resilience are needed. The iRe-CoDeS framework quantifies resilience by monitoring the post-disaster supply, demand and consumption of a community, viewed as a system-of-interdependent-systems, for various resources and services. Lack of Resilience is defined as the unmet demand of a community for a certain resource or service during the recovery period. This study illustrates the application of the iRe-CoDeS framework to quantify housing resilience of Kraljevo, Serbia, following the M5.4 2010 earthquake. Furthermore, damage prediction models are updated using the early arriving inspection data and the effect of updated damage assessment on the estimated resilience metrics is studied. Resilience quantification results obtained using the iRe-CoDeS model are compared to data collected after the event to validate the proposed resilience quantification model.

Squat-reinforced concrete shear walls are used as a gravity and lateral load resisting system in structures such as buildings and nuclear power plants. Due to their low aspect ratio, they are prone to shear or sliding failure. A shear wall was subjected to a cyclic test at the new Multi-Axis Sub-Assemblage Testing (MAST) facility at ETH Zurich. The shear to span ratio was 0.51 and a vertical load of 5.61% of the axial capacity of the wall was applied. The wall had a sliding failure, with a peak load capacity of 2760 kN. Digital Image Correlations (DIC) results show how the shear crack developed until sliding started and, from this point on, the majority of the wall deformation originated in the wall-foundation interface. Sliding displacements consisted of more than 50% of the total displacements of the specimen in large-amplitude cycles., Proceedings of the Third European Conference on Earthquake Engineering and Seismology – 3ECEES, ISBN:978-973-100-533-1

A high-fidelity, 3D finite element model consisting of a realistic, nonlinear code-conforming reinforced concrete moment-frame building surrounded and protected by seismic resonant metamaterials is developed in Real-ESSI Simulator to study the metamaterial-soil-structure interaction (meta-SSI) in nonlinear soil. The main objective of the study is to verify the most critical components of the complex numerical model and, in addition, to demonstrate the effectiveness of resonant metamaterials as a novel seismic risk mitigation method for existing structures. To that end, the structural model is initially verified both at material and system level. Verification of the inserted seismic wave field (SH waves generated using the Domain Reduction Method) and of the model size follows. The results indicate that for the case of a relatively soft soil profile, a significant reduction of the interstory drift ratios and of the accumulated—in the structure—plastic energy dissipation can be achieved by using properly tuned metamaterials; that is, the resonating masses are oscillating out-of-phase with the soil at excitation frequencies close to the first resonant frequency of the inelastic structure.

Hybrid simulation is a method used to investigate the dynamic response of a system subjected to a realistic loading scenario. The system under consideration is divided into multiple individual substructures, out of which one or more are tested physically, whereas the remaining are simulated numerically. The coupling of all substructures forms the so-called hybrid model. Although hybrid simulation is extensively used across various engineering disciplines, it is often the case that the hybrid model and related excitation are conceived as being deterministic. However, associated uncertainties are present, whilst simulation deviation, due to their presence, could be significant. In this regard, global sensitivity analysis based on Sobol’ indices can be used to determine the sensitivity of the hybrid model response due to the presence of the associated uncertainties. Nonetheless, estimation of the Sobol’ sensitivity indices requires an unaffordable amount of hybrid simulation evaluations. Therefore, surrogate modeling techniques using machine learning data-driven regression are utilized to alleviate this burden. This study extends the current global sensitivity analysis practices in hybrid simulation by employing various different surrogate modeling methodologies as well as providing comparative results. In particular, polynomial chaos expansion, Kriging and polynomial chaos Kriging are used. A case study encompassing a virtual hybrid model is employed, and hybrid model response quantities of interest are selected. Their respective surrogates are developed, using all three aforementioned techniques. The Sobol’ indices obtained utilizing each examined surrogate are compared with each other, and the results highlight potential deviations when different surrogates are used. ISSN:2504-4990

Uplift of a structure is a seismic isolation technique: it works as a structural fuse limiting the maximum base moment (rocking foundation) or base shear (rocking podium) transferred to the foundation. To use uplifting in seismic design, the interaction between rocking and flexure must be understood well. Ideally, surrogate models to predict the seismic response of such systems should be also available to facilitate design. This paper presents the equations of motion of a building mounted on a rocking foundation and on a rocking podium in modal coordinates, then surrogate models are developed by applying component mode synthesis. Analytical equations for calculating the uplifted frequency and modal shapes are derived and used to compare how uplift affects both systems.In the following, it is shown that the overturning moment in both systems is dominated by the first mode, therefore a surrogate model with two degrees of freedom (2DOF surrogate), namely the rocking angle and the first mode coordinate, is considered adequate to represent the entire system. Finally, a hundred different buildings, with varying periods, aspect ratios and number of stories, are generated and the maximum dynamic response of the complete system is compared to the 2DOF surrogate ones, the coefficient of determination between all the responses is greater than 0.81 for all cases, thus the 2DOF surrogate is considered adequate to represent the response of the full model.

Earthquakes can cause widespread damage to the built environment, disrupt the function of many residential buildings to provide safe housing capacities and thus, potentially induce severe long-term societal consequences. Rapid recovery significantly improves the short-term resilience of communities after an earthquake. However, time pressure and scarce information on the severity and the spatial distribution of damage complicate the decision-making. Therefore, early damage estimates are produced using regional earthquake risk models with rapid earthquake intensity data and typological building vulnerability functions. While the precision of the former depends, amongst other issues, on the density of seismic network stations and the region-specific geological knowledge, the typological classification of buildings often involves attribution models correlating exposure data, such as building height and age, with typological seismic vulnerability classes. Typological attribution models are approximate and locally add to the uncertainties resulting from the average representation of buildings forming one building class. Employing probabilistic machine-learning tools, the continuous inspection data inflow is leveraged to dynamically update initial regional earthquake risk predictions by updating simultaneously the functions that govern typological attribution and building damage. Hence, while completing inspection of all affected buildings may take several weeks, the limited information becoming available in the first days following an earthquake helps constraining underlying uncertainties. This leads to more reliable rapid estimates of losses of building functions and their respective spatial distribution. The framework is demonstrated on a region in Switzerland subjected to a fictitious earthquake scenario.