Day 1 :
University of Birmingham, UK
Keynote: Entrainment Defects in Steels
Time : 10:00-10:45
John Campbell has spent most of his life in the casting industry. He set up the Cosworth Casting Process for Al alloy automotive blocks for racing engines in 1980, which is still the world’s fastest and soundest production technique. From 1989 to 2004, he was Professor of Casting Technology at Birmingham University, UK. He currently works with steel and investment foundries, including Castings Research International, UK. He is the author of a number of books on castings including “Complete Casting Handbook” which is not for the faint hearted, but otherwise recommended for those who want to get their castings right.
The entrainment of the oxide film on the surface of metals during melting and pouring leads necessarily to the incorporation of crack-like defects into the liquid, which are frozen in as crack-like defects in the solid. These are bifilms; doubled-over oxide films, often only a few nanometers thick, across which, between the ceramic oxide-to-ceramic oxide interface, there is no bonding. Although it seems a few steels are naturally free from such cast-in cracks, other constructional steels, including many stainless and bearing steels, are particularly damaged. The current fatigue failures of wind turbine bearings, and cracks in the steels of power plants and helicopter drive shafts are common examples. Ni-based alloys are usually even more susceptible to these defects, greatly affecting the process ability of Ni alloys and their final properties. Simple, low cost improvements to melting and casting process could revolutionize the strength and reliability of steels and Ni alloys, to the point that failure by cracking of an engineering structure would not be possible. It would be a revolution in metallurgy and engineering.
University of Arizona, USA
Time : 11:05-11:50
Achintya Haldar completed his PhD from University of Illinois. He worked for Bechtel Power Corporation after graduation. After returning to academic career, he worked at Illinois Institute of Technology, Georgia Tech, and now at the University of Arizona. He is a Distingusihed Member of ASCE and a Fellow of SEI. He developed the Stochastic Finite Element Method and many reliabile evaluation concepts applicable to many engineering disciplines. His most recent research is on structural health assessment. He proposed several Kalman filter-based concepts. He received numerous reserach and teaching awards listed at haldar.faculty.arizona.edu. He authored over 575 technical articles including several well accepted books.
Catasprophic failures of structures in some recent seismic events indicate that there is room for improvement. Major weaknesses in current practices are the inability of the profession to incorporate major souces of uncertainty in the formulation, realistic structural behavior leading to failure, and most importantly predicting the exact design earthquake time histrory for a specific site. It is well known that the absolute safety of structures can not be assured but the associated risk needs to be mitigated appropriately. To address excessive economic losses, the performance based seismic design (PBSD) concept is being advocated particularly for steel structures. This risk-based concept is expected to be incorporated in future design guidelines. The speaker and his team proposed several novel conecpts to estimate the underlying risk considering major sources of nonlinearity and uncertainty and applying the seismic loading in time domain. To make design more seismic load tolerant, multiple earthquake time histories need to be considered to incorporate uncertainty in the frequency content. Similar requirements are being introduced in recent design guidelines. After the Northridge earthquake of 1994, to address brittle failures in beam to column connections, several new concepts/features were introduced to design steel structures. Some of these concepts were validated by conducting experiments. The methods proposed by the speaker’s team can quantify significant reduction of risk in the presence of these features. Several related topics to make steel structures more sesimic damage tolerant will be presented.
Eastern Mediterranean University, North Cyprus
Time : 11:50-12:35
Dr. Celikag has completed her PhD in 1990 from University of Sheffield, UK. She then worked with reputable international companies in UK, Singapore and UAE. In 1994 she became Chartered Engineer in UK (MICE). She worked as an Adjunct Professor at UAE University before she joined Eastern Mediterranean University (EMU) in 2000. Besides she is the director of ROBUST Engineering and Consultancy Ltd, at EMU Techno Park. She has been the author of around 35 research articles/book chapters and supervised more than 40 postgraduate students. She is serving as reviewer to reputed ISI journals.
The effect of material properties and the geometrical configurations of reverse channel flush end-plate connections (RCC) on the moment-rotation (M-) relationship under monotonic loading are presented in this paper. The main focus of this research was on the stiffness, strength, sources of deformability, rotational capacity and failure mechanisms of the RCC. The investigations were based on parametric studies performed by using general finite element package ABAQUS (v.6.12) software. Hence, three-dimensional (3-D) FE models were developed for 268 specimens. The developed models were validated against the experimental results available from literature. All tests were able to achieve a rotational capacity beyond the minimum 0.03 rad. The results of the parametric study indicate that the key to the rotational capacity of RCC was found as the channel wall thickness to the flush end-plate thickness ratio. Furthermore, the ratio of channel depth to square hollow section (SHS) width was mainly responsible for the deformability of the column face and 0.72 is recommended as the minimum value of this ratio. On the other hand, the use of HSS (S690) reverse channel as part of the joint; compared to mild steel (S355), produced remarkable increase in both ultimate flexural resistance and the rotational capacity without compromise to the initial stiffness.
Universitat Politècnica de Catalunya, Spain
Time : 12:35-13:20
Jose TURMO (Spain, 1974) got his 6-year program degree in Civil Engineer (1998) from University of Cantabria (Santander, Spain) and his PhD (2003) in Construction Engineering from Technical University of Catalonia BarcelonaTech- UPC (Barcelona, Spain). At the moment, he is Professor in the School of Civil Engineering in Barcelona, BarcelonaTech (Spain), where he teaches Construction Engineering. His area of expertise is Bridge Engineering and Structures.
The need for structural system identification, model updating and health monitoring is constantly growing as the structural stock of modern societies is getting considerably bigger. In order to ensure that an already built construction is structurally sound, data can be gathered from nondestructive dynamic or static tests or dynamic behavior can be recorded from ambient vibration. Whereas the methods to study dynamic data have been thoroughly studied and developed, much less attention has been paid to the study of nondestructive static tests. A new parametric method for structural system identification which is based in a mathematical technique called observability will be presented. It is said that a subset of variables is observable when the system of equations implies a unique solution for this subset, even though the remaining variables remain undetermined. This leads to the observability problem that has a relevant role in many engineering problems, among them the structural system identification. The application of observability will lead to identify which are the relevant measurement sets to be used in order to identify a given set of targeted structural parameters. The applications of such method to identify structural unknowns, such as bending of axial stiffness’s, from measured deflections or rotations, will be outlined. The impact of measurement errors on the accuracy of the solution will be highlighted as well as different techniques to improve the results of the estimates for steel bridges and building frames.