Abstract: The effect of the strength and stiffness characteristics of a previously proposed novel column base on the seismic performance and collapse capacity of steel self-centering moment-resisting frames is evaluated in this paper. This is done through three normalised parameters that represent the initial stiffness, post-yield stiffness, and strength of the column base, which can be independently adjusted. For these evaluations, a prototype steel building, which serves as a case study, is designed with sixteen different cases of a self-centering moment-resisting frame with different column base stiffness and strength characteristics (SC-MRF-CBs). A self-centering moment-resisting frame with conventional column bases and the same members and beam-column connections as those of the SC-MRF-CBs, named SC-MRF, serves as a benchmark frame. A set of 44 ground motions was used to conduct non-linear dynamic analyses and evaluate the seismic performance of the frames. Incremental dynamic analyses were also performed with the same ground motions set to evaluate the collapse capacity of the frames. Collapse capacity fragility curves and adjusted collapse margin ratios of the frames were derived and used for the comparison of the seismic risk of the frames. The results show that the new self-centering column base significantly improves the seismic performance of the SC-MRF, demonstrating the potential of the SC-MRF-CBs to be redesigned with smaller member sections. Moreover, the SC-MRF-CBs achieve significant reduction in collapse risk compared to the SC-MRF. Finally, the results show that increasing the base strength and stiffness improves the seismic performance and collapse capacity of the SC-MRF-CBs.
Abstract: This work is an effort to join, for the first-time, multifractal analysis and damage detection in civil structures subjected to strong ground seismic motions. Specifically, based on the singularity spectrum quantitative and qualitative criteria are proposed. The qualitative criteria are based on the concave of singularity spectrum of damage and undamaged structure. The proposed quantitative criterion is based on calculation of damage index taken the parameters of singularity spectrum. In order to achieve the above goal, a robust signal processing method, which is known as multifractal wavelet leader (MFWL) is used. The multifractal analysis is a tool to calculate fractal properties as well as scaling behavior of the structural response excited by an earthquake. The singularity spectrum is obtained from the Legendre-transformation to Holder exponents. In this paper, a parameter which is based on the shape of singularity spectrum and can identify the damage in the structure is proposed. The proposed method is an output-only approach for damage detection. Considering that the dynamic behavior of an inelastic system subjected to strong ground motion appears to be a non-stationary process, the above procedure of multifractal wavelet leader is suitable to retrieve the simulation response data. The findings from the analysis show that the MFWL is an appropriate scheme for structural damage detection.
Από την 6η έως την 19η Ιουλίου 2020 πρόκειται να διεξαχθεί το Θερινό Σχολείο που διοργανώνει το Ελληνικό Ανοικτό Πανεπιστήμιο - ΕΑΠ με τίτλο «Φυσικές και ανθρωπογενείς καταστροφές και τεχνικά έργα» για την πρόληψη, διαχείριση και αντιμετώπιση των φυσικών και ανθρωπογενών κινδύνων. Οι συμμετέχοντες στο Θερινό Σχολείο θα εκπαιδευτούν στους πιθανούς τρόπους αντιμετώπισης των κινδύνων και των προκλήσεων και θα μάθουν να σχεδιάσουν/προτείνουν τρόπους πρόληψής τους. Επίσης, θα εκπαιδευτούν στις πλέον πρόσφατες τάσεις που αφορούν επιστημονικά και κοινωνικά σημαντικά ζητήματα σχετικά με τους φυσικούς κινδύνους. Έμφαση σε όλα τα παραπάνω θα δοθεί στην επίδραση που έχουν πάνω στα τεχνικά έργα και σε όλες τις φάσεις που τα διέπουν, δηλ. μελέτη, κατασκευή, χρήση και κύκλος ζωής τους. Εκτός από το εκπαιδευτικό υλικό, θα δημιουργηθεί πλατφόρμα ανταλλαγής απόψεων, ιδεών και προσωπικών προοπτικών στην οποία θα συζητηθούν πολύ σημαντικά ζητήματα όπως, π.χ., γιατί τείνουμε να μειώσουμε ορισμένους φυσικούς κινδύνους ενώ αυξάνεται η επικινδυνότητα σε άλλους; Τι μπορούμε να κάνουμε στο μέλλον, βραχυχρόνια και μακροχρόνια, για να προστατευτούμε από φυσικούς κινδύνους;
Το εν λόγω Θερινό Σχολείο απευθύνεται σε όλες τις κατηγορίες επιστημόνων οι οποίοι θέλουν στον τομέα της ειδικότητάς τους να εντάξουν τα προαναφερθέντα φαινόμενα. Παρακάτω παρουσιάζεται το περίγραμμα που αφορά στο Θερινό Σχολείο διάρκειας 10 ημερών και το οποίο χωρίζεται σε ισάριθμες Θεματικές Ενότητες.
Abstract: This work is focused on comparatively assessing the cost-effectiveness of three seismic retrofit approaches for non-code-conforming frame buildings with steel-concrete composite columns. The first two of the assessed retrofit approaches aim in indirectly enhancing structural system performance by strengthening individual composite columns using reinforced concrete jackets or concrete-covered steel cages. The third retrofit approach considered aims in upgrading the composite building frame at hand by installing steel bracings at selected bays. A specially developed structural optimization procedure is used to perform an objective comparison of the cost-effectiveness of the three retrofit approaches. The objective of the optimization procedure is to minimize the total retrofit material cost, while constraints are imposed to ensure the satisfaction of design requirements for the retrofitted structure regarding member capacities (according to Eurocodes 3 and 4 for steel beams and composite columns, respectively), structural system performance under horizontal loading (based on interstorey drifts calculated by pushover analyses) and fundamental periods (obtained from eigenvalue analyses). By defining 30 cases of under-designed 2-storey, 4-storey and 6-storey composite buildings (i.e. buildings with steel-concrete composite columns), an extensive numerical investigation involving 120 retrofit optimization runs was conducted. The results obtained provide insight into the relative cost-effectiveness of the three seismic retrofit approaches and reveal certain conditions under which each approach is economically most viable.
Eurosteel has consistently attracted more than 500 delegates from countries across the world, and is now an essential event for academic researchers at all levels, as well as designers and fabricators. It provides a great opportunity for industry and academia to meet and discuss real-world problems where research is needed, as well as the opportunities provided by leading-edge research.
In Sheffield we hope to increase the number of sessions in which both academia and industry can learn from one another. Hence we are particularly interested in paper proposals from practitioners in design, fabrication and construction, as well as the mainstream research specialities. Invited keynote lectures will cover major themes in current research, as well as the real-world context of current steel construction.
Young researchers will particularly benefit from attending. The conference will allow them to present of their research findings and discuss them with the leading experts in their fields, to appreciate the state of the art in other areas of research and practice, and to generate ideas by interacting with practitioners. The conference has traditionally attracted delegates from academia and industry world-wide.
Abstract: This work investigates and compares the cost-effectiveness of seismically designed buildings having either pure steel or steel-concrete composite columns. In order to ensure an objective comparison of these two design approaches, the assessed building designs are obtained by a structural optimization procedure. Thus, any bias that would result from a particular designer’s capabilities, experience, and subjectivity is avoided. Hence, a discrete Evolution Strategies optimization algorithm is employed to minimize the total cost of materials (steel and concrete) used in a structure subject to constraints associated with: (a) Eurocode 4 provisions for safety of composite column-members, (b) Eurocode 3 provisions for safety of structural steel members, and (c) seismic system behaviour and resistance. Extensive assessments and comparisons are performed for a variety of seismic intensities, for a number of building heights and plan configurations, etc. Results obtained by conducting 154 structural design optimization runs provide insight into potential advantages attained by partially substituting steel (as a main structural material) with concrete when designing the columns of earthquake-resistant buildings.
On the occasion of the 20th anniversary of the catastrophic earthquake in 1999, the Hellenic Department of Earthquake Engineering and the Technical Chamber of Greece co-organize the 4th Hellenic National Conference on Earthquake Engineering and Technical Seismology. The aim of the conference is to bring together the scientific and professional community of Greek engineers and seismologists and to present the progress that has been made in the last 20 years in the assessment and mitigation of seismic risk in our country. The Conference will take place at Hellexpo's premises in Marousi between 5-7 September 2019 and will provide a platform for a meaningful exchange of views, knowledge and experience for the efficient management of the critical issue of Earthquake Protection by the State.
COMPDYN 2019 is the seventh edition of the International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering and one of the Thematic Conferences of the European Community on Computational Methods in Applied Sciences (ECCOMAS) and a Special Interest Conference of the International Association for Computational Mechanics (IACM). It has also been promoted by the European Committee on Computational Solids and Structural Mechanics (ECCSM) of ECCOMAS. COMPDYN 2019 will be held in conjunction with the 3rd International Conference on Uncertainty Quantification in Computational Sciences and Engineering (UNCECOMP 2019), also an ECCOMAS Thematic Conference.
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The Conference is a highly-anticipated event, held every four years, and is considered to be the leading activity of the European Association for Earthquake Engineering (EAEE), member of the International Association for Earthquake Engineering (IAEE), as well as the baseline and meeting point for the scientific and professional sector at an international level, with more than 1000 delegates from Europe and worldwide.
The conference, which takes place often, organised by the Greek Division for Concrete of the TCG in the past 40 years, is intended for engineers in Greece, industry, design and construction companies, higher education institutes, public services such as organisations working on research and innovation on concrete technology, design and construction of concrete structures.
The Steel Structures Research Society and the Central - Western Thessaly Section of the Technical Chamber of Greece are organizing the 9th Hellenic National Conference on Steel Structures to take place in Larisa on 5-7 October 2017.