Stochastic linearization of multi-degree-of-freedom non-linear systems

An equivalent linearization technique to obtain the response of non-linear multi-degree-of-freedom dynamic systems to stationary gaussian excitations is developed. The non-linearities are assumed to be single-valued functions of accelerations, velocities and displacements. Using a property of gaussian vector processes, the closed forms of the coefficients of the equivalent linear system are obtained by the direct application of partial differentiation and expectation operators to the non-linear terms. It is shown that when the non-linearities possess potentials, the linear system has symmetric coefficient matrices. A geometrical interpretation of the linear coefficients, in connection with the original non-linearities, is presented. The accuracy is investigated by means of examples.     

A new tsunami runup predictor

Natural Hazards - We introduce a new parameter, tsunami runup predictor (TRP), relating the accelerating phase of the wave to the length of the beach slope over which the wave is travelling. We...     

Petrology of the Tekirova (Antalya) ophiolite (Southern Turkey): evidence for diverse magma generations and their tectonic implications during Neotethyan-subduction

The SW Antalya Complex is an assemblage of Mesozoic carbonate platform, margin and ophiolitic rocks which record the formation and tectonic emplacement of a small Mesozoic ocean basin. The late Cretaceous ophiolitic rocks are located at two localities, namely the relatively intact Tekirova ophiolite to the east of Kemer zone and the dismembered Gödene ophiolite to the west of Kemer zone. The Tekirova (Antalya) ophiolite comprises harzburgitic tectonites, ultramafic to mafic cumulates, isotropic gabbros and sheeted dikes. Numerous isolated dikes, ranging in thickness from 5 cm to 10 m, intruded the crustal rocks at different structural levels. The isotropic gabbros are represented by gabbro, diorite and quartz diorite rocks with granular to ophitic–subophitic textures. The isolated dikes are characterized by dolerite, diabase and microdiorite with ophitic, intersertal and microgranular textures. These rocks exhibit tholeiitic to alkaline compositions. New geochemical data presented in this paper from the isolated dikes and isotropic gabbros suggest that there are three main types of parental basic magmas that form the oceanic crustal rocks of the Tekirova (Antalya) ophiolite. These are (1) IAT series which can be referred to the Group I isolated dikes and isotropic gabbros; (2) low-Ti boninitic series characterized by the Group II isolated dike and isotropic gabbros; and (3) OIB-type including the Group III isotropic gabbros. The geochemical evidence suggests that the crustal rocks of the Tekirova (Antalya) ophiolite were generated from a progressive source depletion from island arc tholeiites (IAT) to boninites. Therefore, a fore-arc tectonic setting seems likely for the generation of the crustal rocks from the Tekirova (Antalya) ophiolite in the southern branch of Neotethys during the Late Cretaceous. The OIB-type alkaline isotropic gabbros are thought to have resulted from either (1) a late-stage magmatic activity fed by melts that originated within an asthenospheric window due to slab break-off or (2) subduction of a ridge system which generated OIB source across the asthenospheric window that has been no influence of fluids from the subducted slab into the overlying mantle wedge, shortly before the emplacement of the Tekirova (Antalya) ophiolite onto the Tauride platform.     

Assessment of rockfall hazard around Afyon Castle,Turkey

The Afyon Castle is a tourist destination and a historical site in the City of Afyon in Turkey. The Castle is located on a steep hill, with a height of 226 m. In close proximity to the Castle there are settlements. The hill consists of trachitic andesite. The rock contains columnar joints and flow layering. Owing to these discontinuities, blocks of varying sizes had fallen down. The settlement areas near the Castle are now in danger because of the rockfall risk. In this study, rockfall analysis was carried out along nine profiles of the hill. Fall-out distance, bounce height, kinetic energy and velocity of the rocks along each profile were investigated. The results of the analyses were evaluated, and the areas delineated as susceptible to rockfall risk are highlighted. Remedial measures including rock bolts and protective fences were suggested on the basis of the field observations and the rockfall risk evaluation.     

Potassium Permanganate Doped Geopolymers for Remedial Applications

This study investigates the use of KMnO₄ doped geopolymers as controlled‐release materials for remedial applications. The geopolymers were prepared by mixing alkali activated Na‐silicate solutions, metakaolin, and various amounts of granular KMnO₄. Samples were heat treated at 75 °C for 48 h. Concentrations of KMnO₄ in samples 1, 2, and 3 were 1.40 × 10^?1, 4.63 × 10^?1, and 6.07 × 10^?1 g/cm³, respectively. 1D column experiments showed that a high MnO₄^? release rate lasted for the first few hours, followed by a gradual decrease of MnO₄^? release. Neither cracks nor surface erosion of the geopolymers were observed throughout the experiments. Sample 1 approached exhaustion at the end of the Day 7. It took about 18 d for exhaustion of KMnO₄ releases in samples 2 and 3. Modeling of the observed KMnO₄ releases suggested diffusion and dissolution‐related fast transport as the most important mechanisms. This latter mechanism involves the creation of a connected secondary porosity in the geopolymers by dissolution of KMnO₄ granules. The contribution of Fickian diffusion to the total release decreased as the KMnO₄ content of the samples increased, and the dissolution mechanism became increasingly important.     

Teaching Structural Hazards Awareness for Preparedness and Community Response

Most successful search and rescue is performed by neighbors and household members during the first 24 h after an earthquake, before professional responders arrive on the scene. Many spontaneous responders become casualties in the process. Kandilli Observatory and Earthquake Research Institutes Disaster Preparedness Education Project with the support of the Earthquake Engineering Department has developed a training module for Community Disaster Responders to help them assess the level of damage for immediate citizen disaster response. Learning the signs of damage in both reinforced concrete and adobe buildings, they will be better able to distinguish the slight and moderately damaged buildings where their light search and rescue efforts will be effective, as opposed to the heavily damaged buildings where professional help is required for safe extrication. Incorporating citizens into the early stages of building collapse rescue is designed to make professional urban search and rescue efforts more effective. The program is being piloted in Turkey by the Civil Defense Directorate, Search and Rescue Brigade. It is expected that this will lead to a new demand for engineers to work in partnership with community-based organizations for planning and prioritizing disaster mitigation efforts, and to participate in immediate post-disaster damage assessment. Engineering recommendations will also be needed for post-earthquake building re-entry and re-habitation risk assessment.     

Evaluation of the twenty-first century RCM simulations driven by multiple GCMs over the Eastern Mediterranean–Black Sea region

In this study, human-induced climate change over the Eastern Mediterranean–Black Sea region has been analyzed for the twenty-first century by performing regional climate model simulations forced with large-scale fields from three different global circulation models (GCMs). Climate projections have been produced with Special Report on Emissions Scenarios A2, A1FI and B1 scenarios, which provide greater diversity in climate information for future period. The gradual increases for temperature are widely apparent during the twenty-first century for each scenario simulation, but ECHAM5-driven simulation generally has a weaker signal for all seasons compared to CCSM3 simulations except for the Fertile Crescent. The contrast in future temperature change between the winter and summer seasons is very strong for CCSM3-A2-driven and HadCM3-A2-driven simulations over Carpathians and Balkans, 4–5 °C. In addition, winter runoff over mountainous region of Turkey, which feeds many river systems including the Euphrates and Tigris, increases in second half of the century since the snowmelt process accelerates where the elevation is higher than 1,500 m. Moreover, analysis of daily temperature outputs reveals that the gradual decrease in daily minimum temperature variability for January during the twenty-first century is apparent over Carpathians and Balkans. Analysis of daily precipitation extremes shows that positive trend is clear during the last two decades of the twenty-first century over Carpathians for both CCSM3-driven and ECHAM5-driven simulations. Multiple-GCM driven regional climate simulations contribute to the quantification of the range of climate change over a region by performing detailed comparisons between the simulations.