Assessment of the seismic vulnerability of the building stock in the earthquake-prone Marmara region of Turkey is of growing importance since such information is needed for reliable estimation of the losses that possible future earthquakes are likely to induce. The outcome of such loss assessment exercises can be used in planning of urban/regional-scale earthquake protection strategies; this is a priority in Turkey, particularly following the destructive earthquakes of 1999. Considering the size of the building inventory, Istanbul and its surrounding area is a case for which it is not easy to determine the structural properties and characteristics of the building stock. In this paper, geometrical, functional and material properties of the building stock in the northern Marmara Region, particularly around Istanbul, have been investigated and evaluated for use in loss estimation models and other types of statistic- or probability-based studies. In order to do that, the existing reinforced concrete (RC) stock has been classified as 'compliant' or 'non-compliant' buildings, dual (frame-wall) or frame structures and emergent or embedded-beam systems. In addition to the statistical parameters such as mean values, standard deviations, etc., probability density functions and their goodness-of-fit have also been investigated for all types of parameters. Functionalities such as purpose of use and floor area properties have been defined. Concrete properties of existing and recently constructed buildings and also characteristics of 220 and 420 MPa types of steel have been documented. Finally, the financial effects of retrofitting operations and damage repair have been investigated. © 2007 Elsevier Ltd. All rights reserved.
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Post-earthquake structural damage shows that out-of-plane (OOP) wall collapse is one of the most common failure mechanisms in unreinforced masonry (URM) buildings. This issue is particularly critical in Groningen, a province located in the northern part of the Netherlands, where low-intensity induced earthquakes have become an uprising problem in recent years. The majority of buildings in this area are constructed using URM and were not designed to withstand earthquakes, as the area had never been affected by tectonic seismic activity before. OOP failure in URM structures often stems from poor connections between structural elements, resulting in insufficient restraint to the URM walls. Therefore, investigating the mechanical behaviour of these connections is of prime importance for mitigating damages and collapses in URM structures. This paper presents the results of an experimental campaign conducted on timber joist-masonry cavity wall connections. The specimens consisted of timber joists pocketed into masonry wallets. The campaign aimed at providing a better understanding and characterisation of the cyclic axial behaviour of these connections. Both as-built and strengthened conditions were considered, with different variations, including two tie distributions, two pre-compression levels, two different as-built connections, and one strengthening solution. The experimental findings underscored that incorporating retrofitting bars not only restores the system's initial capacity but also guarantees deformation compatibility between the wall and the joist. This effectively enhances the overall deformation capacity and ductility of the timber joist-cavity wall system.
While modern wind turbines have become by far the largest rotating machines on Earth with further upscaling planned for the future, a renewed interest in small wind turbines (SWTs) is fostering energy transition and smart grid development. Small machines have traditionally not received the same level of aerodynamic refinement as their larger counterparts, resulting in lower efficiency, lower capacity factors, and therefore a higher cost of energy. In an effort to reduce this gap, research programs are developing worldwide. With this background, the scope of the present study is 2-fold. In the first part of this paper, an overview of the current status of the technology is presented in terms of technical maturity, diffusion, and cost. The second part of the study proposes five grand challenges that are thought to be key to fostering the development of small wind turbine technology in the near future, i.e. (1) improving energy conversion of modern SWTs through better design and control, especially in the case of turbulent wind; (2) better predicting long-term turbine performance with limited resource measurements and proving reliability; (3) improving the economic viability of small wind energy; (4) facilitating the contribution of SWTs to the energy demand and electrical system integration; (5) fostering engagement, social acceptance, and deployment for global distributed wind markets. To tackle these challenges, a series of unknowns and gaps are first identified and discussed. Based on them, improvement areas are suggested, for which 10 key enabling actions are finally proposed.
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The Ph.D. candidate will investigate the seismic response of connection details frequently used in traditional Dutch construction practice, specifically in the Groningen area. The research will focus on the experimental and numerical definition of the complete load-deflection behaviour of each considered connection; specifically, the tests will aim at identifying stiffness, strength, ductility, and dissipative behaviour of the connections. The experiments will be conducted on scaled or full-scale components that properly resemble the as-built and retrofitted as well connection details. The tests will involve monotonic and cyclic loading protocols to be able to define the load and displacement response of the connection to reversal loads, such as earthquakes, as well as the development of failure mechanisms under such loading cases. Possibly, also dynamic tests will be performed. Numerical models will be created and calibrated versus the experimental findings. Characteristic hysteretic behaviours of the examined connection types will be provided for the use of engineers and researchers.
In recent years, human-induced seismicity in the northern part of the Netherlands increased rendering the seismic response of unreinforced masonry (URM) structures critical. Majority of the existing buildings in the Netherlands are URM, which are not designed to withstand earthquakes. This issue motivates engineering and construction companies in the region to research on the seismic assessment of the existing structures.The companies working in the structural engineering field in the region were forced to adapt very quickly to the earthquake related problems, such as strengthening of existing buildings after earthquake. Such solutions are of prime importance for the Groningen region due to the extent of the earthquake problems and need for strengthening the houses. The research published in the literature show that the connections play an important role in seismic resistant of the houses. Fixing or improving the poor wall-to-wall or floor-to-wall connections may have a large positive impact on the overall seismic behaviour. Some strengthening solutions are already provided by SMEs, and an extensive experimental campaign was carried out at TU Delft on retrofitted connections. In this project, a new experiment will be run on a large shake-table, unique in the Netherlands, that can simulate earthquake vibrations. These tests, together with the previous experience, will complement the overall knowledge on the strengthening solutions and their performance under real-time actual earthquake vibrations.
In recent years, human-induced seismicity in the northern part of the Netherlands increased rendering the seismic response of unreinforced masonry (URM) structures critical. Majority of the existing buildings in the Netherlands are URM, which are not designed to withstand earthquakes. This issue motivates engineering and construction companies in the region to research on the seismic assessment of the existing structures. The companies working in the structural engineering field in the region were forced to adapt very quickly to the earthquake related problems, such as strengthening of existing buildings after earthquake. Such solutions are of prime importance for the Groningen region due to the extent of the earthquake problems and need for strengthening the houses. The research published in the literature show that the connections play an important role in seismic resistant of the houses. Fixing or improving the poor wall-to-wall or floor-to-wall connections may have a large positive impact on the overall seismic behaviour. Some strengthening solutions are already provided by SMEs, and an extensive experimental campaign was carried out at TU Delft on retrofitted connections. In this project, a new experiment will be run on a large shake-table, unique in the Netherlands, that can simulate earthquake vibrations. These tests, together with the previous experience, will complement the overall knowledge on the strengthening solutions and their performance under real-time actual earthquake vibrations.
