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Many developing countries are looking to scale-up what works through major systems strengthening investments. With leadership, conviction and commitment, systems thinking can facilitate and accelerate the strengthening of systems to more effectively deliver interventions to those in need and be better able to improve health in an equitable way. Systems thinking is not a panacea. Its application does not mean that resolving problems and weaknesses will come easily or naturally or without overcoming the inertia of the established way of doing things. But it will identify, with more precision, where some of the true blockages and challenges lie. It will help to: 1) explore these problems from a systems perspective; 2) show potentials of solutions that work across sub-systems; 3) promote dynamic networks of diverse stakeholders; 4) inspire learning; and 5) foster more system-wide planning, evaluation and research. And it will increase the likelihood that health system strengthening investments and interventions will be effective. The more often and more comprehensively the actors and components of the system can talk to each other from within a common framework --communicating, sharing, problem-solving - the better chance any initiative to strengthen health systems has. Real progress will undoubtedly require time, significant change, and momentum to build capacity across the system. However, the change is necessary - and needed now. This report therefore speaks to health system stewards, researchers and funders and maps out a set of strategies and activities to harness these approaches, to link them to these emerging opportunities and to assist systems thinking to become the norm in design and evaluation of interventions in health systems. But, the final message is to the funders of health system strengthening and health systems research who will need to recognize the potential in these opportunities, be prepared to take risks in investing in such innovations, and play an active role in both driving and following this agenda towards more systemic and evidence-informed health development.

Ground motion selection is one of the most important phases in the derivation of fragility curves through non-linear dynamic analyses. In this context, an easy-to-use software, namely S&M—Select & Match, has been adopted for the selection and spectral matching of recorded ground motions approaching a target response spectrum in a broad period range. In this paper, after a brief description of the key features of the S&M tool, two sets of 125 accelerograms, separately for stiff (i.e. site classes A and B according to the Italian code) and soft soil (i.e. site classes C and D) conditions, have been selected on the basis of the elastic design spectra of the Italian seismic code defined for different return periods. The selected ground motions have been analysed and used for non-linear dynamic analysis of a case study representative of a common Italian RC building type designed only to gravity loads. Results have been analysed in order to check the capability of the considered signals to adequately cover all the damage levels generally adopted in seismic risk analyses, as well as the effects on seismic response due to the selection criteria permitted by the proposed tool.

The goal of this study is to investigate the behavior and failure mechanism of historical Irgandi Bridge located in Bursa City under earthquake loads by using linear and nonlinear dynamic analysis. Dynamic characteristics of the bridge is investigated by using in-situ Operational Modal Analysis (OMA) tests. The finite element model is updated according to the OMA tests. Three different artificial earthquake records from weak to very strong are applied to the model for understanding the damage zones and the failure mechanism of the historical bridge. The results show that the bridge does not reach the failure mechanism under weak earthquakes for nonlinear dynamic analysis. However, under strong earthquake even if damage zones are occurred and the stiffness of the bridge is decreased, there is no failure mechanism observed according to the nonlinear dynamic analyses. Under very strong earthquake loads the bridge reaches the failure mechanism according to the nonlinear dynamic analysis. As the earthquake level increases, the difference between linear and nonlinear dynamic analysis results increases due to structural damages. In addition, considering the soil-structure interactions, it is concluded that the dynamic characteristics could be reflected more accurately.

This paper presents a novel method for rapidly addressing the earthquake-induced damage identification task in historic masonry towers. The proposed method, termed DORI, combines operational modal analysis (OMA), FE modeling, rapid surrogate modeling (SM) and non-linear Incremental dynamic analysis (IDA). While OMA-based Structural Health Monitoring methods using statistical pattern recognition are known to allow the detection of small structural damages due to earthquakes, even far-field ones of moderate intensity, the combination of SM and IDA-based methods for damage localization and quantification is here proposed. The monumental bell tower of the Basilica of San Pietro located in Perugia, Italy, is considered for the validation of the method. While being continuously monitored since 2014, the bell tower experienced the main shocks of the 2016 Central Italy seismic sequence and the on-site vibration-based monitoring system detected changes in global dynamic behavior after the earthquakes. In the paper, experimental vibration data (continuous and seismic records), FE models and surrogate models of the structure are used for post-earthquake damage localization and quantification exploiting an ideal subdivision of the structure into meaningful macroelements. Results of linear and non-linear numerical modeling (SM and IDA, respectively) are successfully combined to this aim and the continuous exchange of information between the physical reality (monitoring data) and the virtual models (FE models and surrogate models) effectively enforces the Digital Twin paradigm. The earthquake-induced damage identified by both data-driven and model-based strategies is finally confirmed by in-situ visual inspections.

The paper presents an assessment framework aimed at evaluating seismic fragility and residual capacity of masonry infilled reinforced concrete (RC) frames subject to mainshock/aftershock sequences. A double incremental dynamic analysis (D-IDA) approach is used, based on the combination of a mainshock (MS) signal at different intensities with a set of spectrum-compatible aftershocks (AS) scaled in amplitude with respect to peak ground acceleration. Limit state functions, specifically defined for infilled frames, are used to detect chord-rotation exceeding and shear collapse of RC members during standard and double incremental dynamic analyses. Intact and aftershock fragility curves are obtained for a reference full-scale RC frame specimen, by simulating seismic response with and without infills through a fully fiber section model developed in OpenSees. D-IDA results allow also defining aftershock residual capacity domains and loss diagrams, which are used to compare responses of bare and infilled frames subject to increasing MS intensities. Results show that masonry infills can drastically reduce seismic fragility of RC frame structures during main events and AS, and also limit and economic losses for the mid-low intensity earthquakes. Such beneficial contributions, however, depend on the capacity of RC members to support additional shear demand due frame-infill interaction and avoid sudden failures which conversely occur.

An insufficient separation distance between adjacent buildings is the main reason for structural pounding during severe earthquakes. The lateral load resistance system, fundamental natural period, mass, and stiffness are important factors having the influence on collisions between two adjacent structures. In this study, 3-, 5- and 9-story adjacent reinforced concrete and steel moment resisting frames (MRFs) were considered to investigate the collision effects and to determine modification factors for new and already existing buildings. For this purpose, incremental dynamic analysis was used to assess the seismic limit state capacity of the structures using a developed algorithm in OpenSees software including two near-field record subsets suggested by FEMA-P695. The results of this paper can help engineers to approximately estimate the performance levels of MRFs due to pounding phenomenon. The results confirm that collisions can lead to the changes in performance levels, which are difficult to be considered during the design process. In addition, the results of the analyses illustrate that providing a fluid viscous damper between adjacent reinforced concrete and steel structures can be effective to eliminate the sudden changes in the lateral force during collision. This approach can be successfully used for retrofitting adjacent structures with insufficient in-between separation distances.

This paper aims to investigate the nonlinear dynamic response of steel steep wave risers (SSWRs) considering the excitation of internal solitary waves (ISWs). Considering ISWs and the combined excitation of vessel motion (VM), surface wave (SW), this paper proposes a three-dimensional nonlinear dynamic model of the SSWRs based on the slender rod model. The finite element method and the Newmark-β method are applied to discretize the governing equations and solve the dynamic response of the SSWRs, respectively. Then, a computational program, DRSSWR, was developed in this paper. The accuracy of DRSSWR is verified with experimental data and published results. Further, the nonlinear dynamic response of the SSWR is obtained. Analysis results indicate that ISW causes extremely large displacements and shear deformations in the X, Y, and Z directions of the SSWR like a slow, massive shock load, particularly in the Y direction. Extreme values of displacement and stress occur mainly around critical points (i.e., seawater interface, arc bend point, sag bend point). ISW shows both “weakening effect” and “strengthening effect” on the dynamic response induced by VM and SW.

The seismic performance and stability analysis of slopes are important in predicating damage and mitigating potential losses in landslide-prone areas. Fragility functions can give results of slope performance assessment that are more comprehensive and richer. This study presents a procedure of constructing seismic fragility functions for slope stability analysis with various vulnerability states based on incremental dynamic analysis (IDA). IDA is a performance-based earthquake engineering analysis based on a series of dynamic time history analyses conducted for suitable multiple-scaled seismic records. IDA not only estimates the seismic demand and capacity of systems but also provides basic data for the estimation of fragility functions. Firstly, an ensemble of seismic records meeting the requirements of specific site conditions of a slope is selected to consider the randomness of ground motion. A series of seismic stability analyses of the slope are performed to obtain the dynamic safety factor time history of the slope. Each minimum safety factor and corresponding seismic intensity measure is then extracted to develop a set of IDA curves. On the basis of IDA results, analytical seismic fragility functions of a slope are developed considering the prescribed various vulnerability states of the slope in terms of the safety factor. The failure probabilities of exceeding different specific vulnerability states for a given intensity measure of the earthquake are finally obtained.

This paper presents numerical simulations within the frame of the project SERA—AIMS (Seismic Testing of Adjacent Interacting Masonry Structures). The study includes blind pre-diction and post-diction stages. The former was developed before performing the shaking table tests at the laboratory facilities of LNEC (Lisbon), while the latter was carried out once the test results were known. For both, three-dimensional finite element models were prepared following a macro-modelling approach. The structure consisted of a half-scaled masonry aggregate composed by two units with different floor levels. Material properties used for the pre-diction model were based on preliminary tests previously provided to the participants. The masonry constitutive model used for the pre-diction study reproduced classical stress–strain envelope, whereas a more refined model was adopted for the post-diction. After eigenvalue analysis, incremental nonlinear time history analysis was performed under a unique sequence based on the given load protocol to account for damage accumulation. In the post-diction, the numerical model was calibrated on the data recorded during the shaking table tests and nonlinear dynamic analysis repeated under the recorded accelerogram sequence. The interaction between the two units was simulated through interface elements. Moreover, the timber floors were accounted following different strategies: not modelling or considering nonlinear wall-to-floor connections. Advantages and disadvantages are then analysed, comparing the pre-diction and post-diction results with the experimental data. Numerical results differ from the experimental outcomes regarding displacements and interface pounding, although a clear improvement is visible in the post-diction model.

The increasing size and weight of deep-water topside modules necessitate reliable and efficient installation methods. The twin-barge float-over technique presents a viable alternative to conventional heavy-lift operations; however, its critical tri-vessel load transfer phase involves complex hydrodynamic interactions and continuous load redistribution that are not adequately captured by traditional staged analyses. This study develops a fully coupled time-domain dynamic model to simulate this process. The framework integrates multi-body potential flow hydrodynamics, mooring and fender systems, and Deck Support Units (DSUs). A novel continuous mass-point variation method is introduced to replicate progressive ballasting and the dynamic load transfer from single- to dual-barge support. Numerical simulations under representative sea states reveal significant narrow-gap resonance effects, direction-dependent motion amplification, and transient DSU load peaks that are overlooked in conventional quasi-static approaches. Beam-sea conditions are found to induce the largest lateral DSU loads and the highest risk of barge misalignment. The proposed framework demonstrates superior capability in predicting motion responses and load transitions, thereby providing critical technical support for the safe and efficient application of twin-barge float-over installations in complex marine environments.