Mean Annual Frequency Research Articles

A more rational selection of the behaviour factor for seismic design according to Eurocode 8

The main objective of the research presented in this paper is to assess the influence of a more rational selection of the behaviour factor (q) for the seismic design of steel moment-resisting frames (MRFs) according to Eurocode 8 (EC8). To this end, a large set of steel MRFs were designed using for code-prescribed behaviour factors as well as using the Improved Force-Based Design (IFBD) methodology for a more consistent selection of q. The seismic performance of the archetypes was assessed through nonlinear static and response-history analysis. The results point to the discrepancy between the design assumptions and the real response of the structures, as significant differences between the design base shear and the lateral strength of the frames were observed for frames designed with code-prescribed behaviour factors. Moreover, it is shown that IFBD-designed steel frames exhibit more uniform inelastic demands over the building height, as well as ductility demands more compatible with the design assumptions. Finally, the fragility and seismic risk assessment conducted shows that all building archetypes, regardless of the q-scenario considered, exhibit values of mean annual frequency of collapse that comply with limits available in the literature.

Collapse capacity of reinforced concrete skewed bridges retrofitted with buckling-restrained braces

This study assesses the collapse capacity and failure modes of skewed bridges retrofitted with buckling-restrained braces (BRBs) at the column bent. The asymmetric configuration of these bridges requires a three-dimensional numerical model that considers uncertainties in the seismic ground motions. The factors controlling the seismic performance of these bridges are obtained from a case study of a three-span reinforced concrete box girder skewed bridge with varying skew angles of 0°, 18°, 36°, and 54°. Numerical models with distributed plasticity and concentrated plasticity are created considering material deterioration and plastic deformation properties. A numerical distributed plasticity model with strength and stiffness deterioration is calibrated with a concentrated plasticity model by performing two-dimensional incremental dynamic analyses (IDAs) on the straight bridges (i.e., 0° skew angle), using 21 far-field ground motions. Then, the collapse capacity of original and retrofitted skewed bridges is obtained from three-dimensional IDAs using the distributed plasticity model. The collapse capacity and failure modes of BRB components are summarized based on investigations from experimental data. Nonlinear time history analyses indicate that the BRB retrofit greatly improves the seismic performance of skewed bridges, but it has negligible effects on the bridge’s collapse capacity after BRB failure. However, the use of BRB greatly reduces the bridge’s probability of failure, and the mean annual frequency of global collapse, since the BRB components dissipate seismic energy as structural fuses. The proposed method of parameter calibration, including BRB failure, is found to be sufficiently reliable to perform satisfactory results.

Collapse risk assessment of a Chilean dual wall-frame reinforced concrete office building

Several code-conforming reinforced concrete buildings were severely damaged during the 2010 moment magnitude (Mw) 8.8 Chile earthquake, raising concerns about their real collapse margin. Although critical updates were introduced into the Chilean design codes after 2010, guidelines for collapse risk assessment of Chilean buildings remain insufficient. This study evaluates the collapse potential of a typical dual system (shear walls and moment frames) office building in Santiago. Collapse fragility functions were obtained through incremental dynamic analyses using a state-of-the-art finite element model of the building. Site-specific seismic hazard curves were developed, which explicitly incorporated epistemic uncertainty, and combined with the collapse fragility functions to estimate the mean annual frequency of collapse (λc) values and probabilities of collapse in 50-years (Pc(50)). Computed values of λc and Pc(50) were on the order of 10−5–10−4, and 0.1–0.7%, respectively, consistent with similar studies developed for buildings in the US. The results also showed that the deaggregation of λc was controlled by small to medium earthquake intensities and that different models of the collapse fragility functions and hazard curves had a non-negligible effect on λc and Pc(50), and thus, propagation of uncertainty in risk assessment problems must be adequately taken into account.

Spatio-temporal variations in extreme drought in China during 1961–2015

Understanding the past variations in extreme drought is especially beneficial to the improvement of drought resistance planning and drought risk management in China. Based on the monitoring data of meteorological stations from 1961 to 2015 and a meteorological drought index, the Standardized Precipitation Evapotranspiration Index (SPEI), the spatio- temporal variations in extreme drought at inter-decadal, inter-annual and seasonal scales in China were analyzed. The results revealed that 12 months cumulative precipitation with 1/2 to 5/8 of average annual precipitation will trigger extreme drought. From the period 1961–1987 to the period 1988–2015, the mean annual frequency of extreme drought (FED) increased along a strip extending from southwest China (SWC) to the western part of northeast China (NEC). The increased FED showed the highest value in spring, followed by winter, autumn and summer. There was a continuous increase in the decadal-FED from the 1990s to the 2010s on the Tibetan Plateau (TP), the southeast China (SEC) and the SW. During the period 1961–2015, the number of continuous drought stations was almost the same among 4 to 6 months and among 10 to 12 months of continuous drought, respectively. It can be inferred that drought lasting 6 or 12 months may lead to more severe drought disasters due to longer duration. The range of the longest continuous drought occurred in the 21st century had widely increased compared with that in the 1980s and the 1990s. Our findings may be helpful for water resources management and reducing the risk of drought disasters in China.

Probabilistic seismic performance assessment of seismically isolated buildings designed by the procedures of ASCE/SEI 7 and other enhanced criteria

Recent studies have shown that seismically isolated buildings designed by the minimum criteria of ASCE/SEI 7 may have unacceptable probabilities of collapse in the MCER. Acceptable probabilities of collapse in the MCER are achieved when the isolation system displacement capacity and the strength of the superstructure are increased. The same studies have shown that conventional buildings designed by the minimum criteria of ASCE/SEI 7 have acceptable probabilities of collapse in the MCER, and that the collapse probabilities may be much lower than those of minimally designed seismically isolated buildings and may even be lower than those of seismically isolated buildings designed by enhanced collapse performance criteria. This paper investigates what isolated buildings offer in terms of performance criteria other than collapse performance. Based on a probabilistic approach, mean annual frequencies of exceedance of story drift, residual story drift and floor acceleration are computed for a number of isolated and non-isolated buildings that meet the minimum criteria of ASCE/SEI 7 and other enhanced criteria. Based on the mean annual frequencies, probabilities of exceeding response limits that relate to damage are computed for a lifetime of 50 years. It is shown that seismically isolated buildings designed by the minimum or enhanced criteria generally have lower probabilities to develop damage or to be in need of demolishing in 50 years of lifetime than any minimally designed non-isolated building.

Long-Term Ground-Based Measurements of Aerosol Optical Depth over Kuwait City

We analyze ten years (2008–2017) of ground-based observations of the Aerosol Optical Depth (AOD) in the atmosphere of Kuwait City, in Middle East. The measurements were conducted with a CIMEL sun-sky photometer, at various wavelengths. The daily average AOD at 500 nm (AOD500) is 0.45, while the mean Ångström coefficient (AE), calculated from the pair of wavelengths 440 and 870 nm, is 0.61. The observed high AOD500 values (0.75–2.91), are due to regional sand and dust storm events, which are affecting Kuwait with a mean annual frequency of almost 20 days/year. The long-term record analysis of AOD500 and AE, shows a downward and upward tendency respectively, something which could be attributed to the continuous expansion and industrialization of the main city of Kuwait, in combination with the simultaneous increase of soil moisture over the area. By utilizing back trajectories of air masses for up to 4 days, we assessed the influence of various regions to the aerosol load over Kuwait. The high aerosol loads during spring, are attributed to the dominance of coarse particles from Saudi Arabia (AOD500 0.56–0.74), a source area that contributes the 56% to the mean annual AOD500. Other dust sources affecting significantly Kuwait originated from the regions of Iraq and Iran with contribution of 21%.

Probabilistic models for structures with bilinear demand‐intensity relationships

SummaryAn extension to the existing SAC/FEMA expressions to estimate mean annual frequency of exceedance (MAFE) for a given limit state is described. In specific, this study pertains to structural systems whose demand versus seismic intensity relationship cannot be reasonably represented by a linear fit in logspace, but rather a bilinear fit over the entire range of structural response. Using a predefined limiting intensity, the median demand is separated into two distinct zones of response. These expressions are derived using a second‐order polynomial hazard model fit and can be considered a further extension of the closed‐form expressions available in the literature. The steps in the derivation are described along with an example application of the proposed expressions. Comparing different models shows that the MAFE can be significantly misrepresented when using a linear demand‐intensity model for systems whose behaviour deviates from this assumption in logspace. Similarly, a logarithmic function demand‐intensity fit is examined and seen not to be suitable in the specific situations focused on here. Furthermore, significant underestimation or overestimation is observed when using local fits in the vicinity of the behaviour transition point, which highlights the need for such a bilinear model when assessing the structural performance at the transition point's vicinity. Adopting a bilinear model is shown to better represent structural systems with complex response characteristics, also allowing the use of a single demand model for the entire range of response. This is at the same time still compatible with the existing framework for performance‐based seismic design and assessment.

Probabilistic seismic assessment of non-ductile RC buildings retrofitted using pre-tensioned aramid fiber reinforced polymer belts

The current manuscript presents a probabilistic seismic assessment of non-ductile RC structures retrofitted by pre-tensioned aramid fiber reinforced polymers (AFRP). Three RC buildings with different heights (4-, 6- and 8-stories) are designed according to older construction practice and the poorly detailed columns of each model are then retrofitted using pre-tensioned AFRP belts. The numerical finite element models are developed in OpenSees using concentrated plastic hinge models that can capture shear weakness of original columns and deterioration of beams’ stiffness and strength. Incremental dynamic and nonlinear static analyses are performed to quantify structures’ performance in terms of both global- and component-level metrics. The structures’ global response is evaluated using fragility curves, mean annual frequency of collapse, and collapse margin ratios. Furthermore, statistical analyses are performed to obtain median inter-story drift distribution along the height of the structure, structural members’ ductility and dissipated energy under three different seismic hazard levels. The results indicate that retrofitting by pre-tensioned AFRP improves the structure’s global-level ductility and reduces the collapse probability significantly. Moreover, it can prevent weak story formation by engaging a larger number of stories in collapse mechanism. From a component-level perspective, pre-tensioned AFRP increases columns’ ductility and dissipated energy and enhances their performance, particularly at near-collapse-limit states.

Seismic Collapse Risk Assessment of Code-Conforming RC Moment Resisting Frame Buildings Designed With 2014 Canadian Standard Association Standard A23.3

This paper presents collapse risk assessment of code-conforming reinforced concrete moment resisting frame (RC MRF) buildings located in Vancouver, Canada. This assessment investigates the three- and six-storey of regular RC MRF building systems, with and without unreinforced masonry infill wall, representing low- to mid-rise structures. These buildings are designed according to the current National Building Code of Canada and detailed based on the 2014 Canadian Standards Association A23.3 standard provision for high seismic regions. Two different ductility classes of seismic building design, namely ductile and moderately ductile, are considered to identify the capability, equality and/or difference of the seismic performance of these designed buildings. Nonlinear dynamic analysis is applied in the performance-based seismic assessment procedures to assess the collapse response of structural for the set of 50 pair ground motion records. Next, the seismic fragility curves are developed through incremental dynamic analysis. Finally, mean annual frequency of collapse is calculated through combination of fragility curve and hazard curve. The results indicate that the bare RC buildings are vulnerable to earthquake-induced collapse when the number of the story increased. The presence of the URM infill walls significantly influence the collapse behavior of the frame structure. Compared to moderately ductile MRF buildings, ductile MRF buildings show a better collapse performance, is strongly influenced by the capacity of the building system.

Comparative seismic fragility estimates of steel moment frame buildings with or without superelastic viscous dampers

Superelastic viscous damper is a passive hybrid control device that combines shape memory alloy cables and a viscoelastic damper to mitigate dynamic response of structures subjected to multi-level seismic hazards. In the hybrid device, shape memory alloy cables that exhibit a nonlinear but elastic response are used mainly as re-centering unit, while the viscoelastic damper composed of high-damped butyl rubber compounds is employed to augment the equivalent viscous damping provided by the device. This study evaluates the effectiveness of superelastic viscous dampers in mitigating seismic response of steel frame structures through a probabilistic framework. First, a nine-story steel frame building is designed and modeled with and without superelastic viscous dampers, and extensive nonlinear response-history analyses are conducted. Then, probabilistic demand models are developed for selected engineering demand parameters. To quantitatively compare the performance of the designed buildings, seismic fragility curves and mean annual frequency of exceeding different performance levels are developed. In particular, the structural performance is evaluated using both peak inter-story drift and residual drift responses. Results indicate that superelastic viscous dampers can significantly improve structural performance; thus, it has the potential to lower the post-earthquake losses, as the better structural performance leads to less loss in relocation, rental, and economic loss.

Probabilistic residual drift assessment of SMRFs with linear and nonlinear viscous dampers

Maximum Residual Interstory Drift Ratio (MRIDR) is one of the most important Engineering Demand Parameters (EDPs) for evaluating the safety of structures after the occurrence of an earthquake. This EDP is used as an index to decide about the retrofit or demolition of structures. The main purpose of this study is to evaluate the effects of using linear and nonlinear Fluid Viscous Dampers (FVDs) on the MRIDR response of steel Special Moment Resisting Frames (SMRFs) with FVDs. Moreover, two vertical distributions of damping coefficients including Uniform Distribution (UD) and Interstory Drift Proportional Distribution determined based on the first mode deformations (IDPD) are compared for the structures considered. The values of median MRIDR capacity, median SaRD, corresponding to different MRIDR levels are determined by performing Incremental Dynamic analyses (IDAs). After computing the median SaRD for a specified MRIDR level and its corresponding logarithmic standard deviation, the Mean Annual Frequency (MAF) of exceeding that MRIDR level (λRD) is computed. Based on the results, the values of median SaRD for structures with linear FVDs are higher than those for structures with nonlinear FVDs, and hence the values of λRD corresponding to structures with linear FVDs are lower than those for structures with nonlinear FVDs. In addition, for structures with a soft story, using IDPD to determine damping coefficients results in higher median SaRD values, and hence lower λRD values.

Aboveground carbon sequestration in dry temperate forests varies with climate not fire regime.

The storage of carbon in plant tissues and debris has been proposed as a method to offset anthropogenic increases in atmospheric [CO2 ]. Temperate forests represent significant above-ground carbon (AGC) "sinks" because their relatively fast growth and slow decay rates optimise carbon assimilation. Fire is a common disturbance event in temperate forests globally that should strongly influence AGC because: discrete fires consume above-ground biomass releasing carbon to the atmosphere, and the long-term application of different fire-regimes select for specific plant communities that sequester carbon at different rates. We investigated the latter process by quantifying AGC storage at 104 sites in the Sydney Basin Bioregion, Australia, relative to differences in components of the fire regime: frequency, severity and interfire interval. To predict the potential impacts of future climate change on fire/AGC interactions, we stratified our field sites across gradients of mean annual temperature and precipitation and quantified within- and between-factor interactions between the fire and climate variables. In agreement with previous studies, large trees were the primary AGC sink, accounting for ~70% of carbon at sites. Generalised additive models showed that mean annual temperature was the strongest predictor of AGC storage, with a 54% near-linear decrease predicted across the 6.1°C temperature range experienced at sites. Mean annual precipitation, fire frequency, fire severity and interfire interval were consistently poor predictors of total above-ground storage, although there were some significant relationships with component stocks. Our results show resilience of AGC to frequent and severe wildfire and suggest temperature mediated decreases in forest carbon storage under future climate change predictions.

From landslide susceptibility to landslide frequency: A territory-wide study in Hong Kong

Rain-induced shallow landslide is the major type of landslide that happens on natural terrain in Hong Kong due to its high seasonal rainfall and deep weathering soil profile. The Geotechnical Engineering Office has been in a leading role to steer the risk management of natural terrain landslides in Hong Kong. Recently, the territory-wide rainfall-based landslide susceptibility model (in terms of landslide density per year) has been developed to predict the number of natural terrain landslides that may occur in an anticipated rainfall event. Subsequently, the storm-based landslide density has been transformed to the annual landslide frequency to compile the territory-wide landslide frequency map by incorporating the mean annual frequency of occurrence of different probable rainfall scenarios. The annual rainfall frequency of a particular rainfall scenario is derived from its return period, determined based on the abundant real-time rainfall data at a five-minute interval from 110 automatic raingauges across Hong Kong at an average density of 10 km2/gauge. The transformation is discussed in this paper, together with the evaluation of the performance of the landslide frequency map. In addition, the potential applications of the map in Hong Kong and the pitfalls of the common evaluation methods, including the receiver operating characteristic curve and the success-rate curve, are highlighted.

PCN189 - Hepatocellular Carcinoma In The Brazilian Public Health System: A Burden Of Illness Model

Estimate and project Hepatocellular carcinoma costs to the Brazilian Public Health System (SUS). The study was a retrospective analysis of DataSUS, a Brazilian Public Health System medical claims database. Patients were tracked by the ICD between July 2011 and June 2016. The disease costs were segmented between diagnostic and treatment costs, for each disease status, according to SUS list of procedures. The total costs of HCC were calculated by multiplying the mean annual frequency per patient of each performed procedure at each stage of the disease by its cost and added to the cost of the diagnostic procedures performed in the respective year. The costs were also projected for the next 5 years. Costs expressed in 2016 prices, exchange rate 1.00 USD = 3.19 BRL. 28,822 patients were identified. 11% of the sample was on initial stage, 13% on intermediate, 9% on advanced and 67% were already diagnosed on terminal stages, receiving only palliative care. In 2016, the costs for treating HCC were USD 7.6 million for 9,028 patients, reaching USD 8.7 million for 10,042 patients in 2021. The stage with the greatest economic impact was the intermediate, with average annual costs estimated at USD 3.04 million, followed by the advanced stage, with an average annual cost of USD 2.33 million. Regarding the economic impact per patient, the advanced stage had the higher costs (USD 2,821). More than 75% of the patients are already diagnosed in late stages, where there are no more curative treatment options, and 67% are already diagnosed in the terminal stage of the disease. Thus, the development of screening strategies for patients with hepatopathies and early diagnosis are essential to increase the number of patients diagnosed under curative conditions, where there may be optimization of health resources.

Radiographic Analysis of Fractures of the Proximal Femur in Patients Over 50 Years Old at Hospital Universitario De Los Andes, Merida, Venezuela, 2008-2012

AIM: An observational, retrospective analysis of the XR is presented. Preoperative tests performed on patients older than 50 years of age treated surgically for fractures of the proximal femur at the University Hospital of the Andes (Merida, Venezuela). MATERIALS AND METHODS: These XRs were analyzed with reference to age, sex and fracture modality according to the AO/ASIF alphanumeric classification, which considers A the trochanter fractures and B the femoral neck ones. The mean annual frequency for the Hospital Universitario de Los Andes was estimated according to age, sex and fracture type strata. RESULTS: Between 2008 and 2012, in people over 50 years of age, 463 hip fractures were present, affecting 334 women and 129 men (2.6/1). Hip fractures are 7.3 times more frequent after age 80, compared to strata between 50 and 60 years of age. The average annual frequency is 0.12%: 0.15% for ladies and 0.09% for gentlemen. Trochanteric fractures represent 76.4% of the total and are more common in women, with a mean age of 80.4 years. About 70% of these hip fractures are considered unstable injuries. CONCLUSION: In the city of Merida (Venezuela), hip fractures affect women over 80 and more commonly in the trochanteric area with high indices of instability.

Seismic intensity measures for above‐ground liquid storage tanks

SummaryA series of scalar and vector intensity measures is examined to determine their suitability within the seismic risk assessment of liquid storage tanks. Using a surrogate modelling approach on a squat tank that is examined under both anchored and unanchored support conditions, incremental dynamic analysis is adopted to generate the distributions of response parameters conditioned on each of the candidate intensity measures. Efficiency and sufficiency metrics are used in order to perform the intensity measure evaluation for individual failure modes, while a comparison in terms of mean annual frequency of exceedance is performed with respect to a damage state that is mutually governed by the impulsive and convective modes of the tank. The results reveal combinations of spectral acceleration ordinates as adequate predictors, among which the average spectral acceleration is singled out as the optimal solution. The sole exception is found for the sloshing‐controlled modes of failure, where mainly the convective period spectral acceleration is deemed adequate to represent the associated response due to their underlying linear relationship. A computationally efficient method in terms of site hazard analysis is finally proposed to serve in place of the vector‐valued intensity measures, providing a good match for the unanchored tank considered and a more conservative one for the corresponding anchored system.

Development of BP-based seismic behavior optimization of RC and steel frame structures

The present study develops and numerically verifies a new methodology for the seismic behavior enhancement of reinforced concrete (RC) and steel frames incorporating BP (Back Propagation) algorithm and performance-based estimation. The proposed optimization flow allows automatic correction of the assumed damage weighting coefficients of the components with a series of prepared local and global damage indices defined as required. On the basis of the revised coefficients, modification of the sectional dimensions and corresponding reinforcement ratio of a six-story RC frame is carried out. The exceeding probability of each limit state and the Mean Annual Frequency (MAF) are reduced, leading to a better safety margin of the RC structure. And the mechanical model of a user defined element of self-centering energy dissipation brace (SCEDB) is experimentally confirmed. Meanwhile, the installation strategy against the normal continuous arrangement of the SCEDBs in a nine-story benchmark steel frame is proposed as well. As a result, the story drift ratio and local damage of the steel frame are effectively decreased. The BP-based optimization results demonstrate that the seismic performance of the two structures has been improved without any cost increase, resulting in an effective structural optimization method.

Diagnostic nuclear medicine procedures in Germany between 1996 and 2002: application frequencies and collective effective doses.

Man-made radiation exposure to the German population predominantly results from the medical use of ionizing radiation. It was therefore the aim of the present study, to provide public health information concerning diagnostic nuclear medicine procedures carried out in Germany between 1996 and 2002. Application frequencies for 10 groups of procedures were estimated from official reimbursement data provided by the German health insurance companies. Mean effective doses for these examinations were estimated from data provided by 14 clinics and 10 practices concerning the radiopharmaceuticals in use and the activities administered. During the period 1996-2002, a total of (3.83 +/- 0.31) million nuclear medicine procedures were performed in average per year, which corresponds to a mean annual application frequency of approximately 47 examinations per 1 000 inhabitants. More than 90% of the examinations were scintigraphies of the thyroid (37%), skeleton (25%), myocardium (13%), lungs (8%) and kidneys (8%). The averaged collective effective dose was (10.2 +/- 1.4) . 10(3) mSv per year, which corresponds to a mean annual per caput effective dose of about (0.12 +/- 0.02) mSv. Three types of procedures were responsible for about 80% of the total collective effective dose: scintigraphies of the myocardium (36%), skeleton (33%) and thyroid (10%). Averaged over all procedures carried-out, the mean effective dose per examination was (2.7 +/- 0.8) mSv. The average effective dose per inhabitant and year caused by nuclear medicine examinations is markedly lower than that resulting from medical X-ray procedures (0.12 vs. 1.8 mSv). Reduction of patient exposure may be achieved, for example, by replacing (201)Tl-labeled radiopharmaceuticals by (99m)Tc-labeled compounds.

Dynamics of intense rainfalls in the southern half of European Russia for the period 1960-2015

Two time periods (1960-1986 and 1986-2015) were compared in terms of mean annual frequency and mean annual sum of warm season rainfalls to quantify general trends in the changing regime of heavy precipitation over the southern part of European Russia, which is the area of the most intensive agricultural activity. The identified trends were compared with the published assessment of the intensity trends of soil erosion processes. The prevalence of the increasing tendency in the frequency and amount of precipitation is demonstrated, which undergoes against a decrease in the rate of eroded sediment accumulation and against a decrease of linear growth rate of gullies. This result rather proves the crucial contribution of the snowmelt to the soil erosion over the studied area.

Improvement of Relative Survival in Elderly Patients with Acute Myeloid Leukemia Emerging from Population-Based Cancer Registries in Switzerland from 2001-2013

Introduction: Acute Myeloid Leukaemia (AML) is a rare disease with increasing frequency in the elderly and an emerging impact on health care resources. Trends of classification, incidence, mortality, and survival of AML patients have not yet been reported for Switzerland. Given the demographic ageing, we were mainly interested to investigate whether elderly patients have benefited on a population-based level from the recent changes in AML management.Methods: We performed a population-based, observational analysis of AML cases reported to Cantonal Cancer Registries in Switzerland. Data was aggregated by the National Institute for Epidemiology and Cancer Registration and stratified for the two time-periods 2001-2007/2008-2013. The Swiss Federal Statistics Office provided canton-specific mid-year estimates of the size of the general population and mortality statistics. Data from transplanted patients was provided from the registry of the Swiss Blood Stem Cell Transplant Group .Results: 2'351 new AML cases were registered within the observation time at a median age of 68/67 yrs (range 0-96 yrs). The extrapolated mean annual frequency increased from 275 to 305 AML cases (+10.8%) in the two time periods. In contrast, the age-standardized incidence and mortality rates remained stable (3.0 [95 CI: 2.8-3.2] and 1.9-2.0 [1.8-2.1] per 100'000 person-years, respectively). Incidence was up to 1.4-fold more frequent in males and increased up to 7 fold in patients >75 yrs of age. The fraction of non-classifiable AML cases decreased over time (54.6%/41.8%), but remained high in elderly patients (75-84 yrs: 54.1%, 85+ yrs: 59.1%). As expected, 5-year relative survival (RS) correlated directly with AML risk classes (favorable: 61.7-68.4%, intermediate: 14.9%-27.3%, adverse: 11.4%-20.4%, non-classifiable: 11.4%-14.7%) and inversely with age (<65 yrs: 42.6-42.7%, 65-74 yrs: 5.2%-13.5%, 75-84 yrs: 2-3%; 85+ yrs: 0%). RS improved only modestly in all age classes over time (19.2%/23.3%). Most interestingly, a trend towards improved RS was found in AML patients aged 65-74 yrs (5.2%/13.5%) and with intermediate (20.4%/27.3%) as well as adverse risk (11.4%/ 21.9%). This trend was multifactorial and only partially explained by an increased referral to allogeneic HSCT (1.4%/7%) or inclusion in clinical trials of patients ≥65 yrs.Conclusions: AML incidence remained stable during the observation period, indicating that the 10.8% raise in annual case-frequency is mainly related to population growth and ageing and not to an increase of age-specific risk. AML classification improved over time, but non-classifiable AML cases remained high in elderly patients, suggesting that diagnostics and reporting is less accurate with increasing age. A trend towards improved RS was found in AML patients aged 65-74 yrs and with intermediate as well as adverse risk. These trends were caused by multiple factors and mainly based on the general changes of treatment management of AML patients ≥65 yrs. Survival of elderly AML patients remains dismal. Nevertheless, recent progress in clinical management of elderly AML patients resulted in an emerging improvement of survival on a population-based level in Switzerland. The demographic trend will further increase AML burden and has to be taken into account for structural as well as financial considerations for future health care systems. [Display omitted] DisclosuresGregor:AbbVie: Other: Personal Fees; Celgene: Other: Personal Fees, Non-Financial Support; Gilead: Other: Personal Fees; GlaxoSmithKline: Other: Personal Fees; Janssen: Other: Personal Fees, Non-Financial Support; Mundipharma: Other: Personal Fees; Novartis: Other: Personal Fees, Non-Financial Support; Roche: Other: Personal Fees, Non-Financial Support.