5^th International Conference on Steel and Concrete Structures August 29-30, 2018 Tokyo, Japan

Dr.N.Umamaheswari is currently working as Associate Professor in Department of Civil Engineering at SRM Institute of Science and Technology in INDIA. She possesses more than 25 years of professional experience. Her research areas include steel-concrete composite structures, cold-formed steel structures and finite element analysis of structures. She has published about 30 research articles in journals and conferences.

Statement of the Problem: Double-skin steel tubes filled with concrete in between are considered as the extended version of Concrete-filled steel tubes. These columns are preferable since they possess better structural properties such as strength and stiffness, fire resistance and cyclic performance compared to conventional reinforced cement concrete or steel columns. Concrete-filled double-skin steel tubular (CFDST) columns consist of two concentrically placed steel tubes, an outer and an inner, with concrete sandwiched between them and a hollow space at their centre. It is observed from earlier researches that the parameters influencing behaviour of CFDST columns are length to diameter ratio, diameter to thickness ratio/thickness of outer and inner steel tubes, concrete and steel strengths. The significant aspects related to the performance of composite columns are the interaction between steel tube and concrete and confinement effect and these aspects need to be analyzed in short composite columns.

Findings: This paper deals with the analysis of results obtained from finite element analysis carried over by the author, on axial load carrying capacity of circular CFDST short columns. The evaluation of concrete confinement effect on axial load capacity of CFDST short columns is performed with respect to current international standards such as Eurocode 4 and AISC. Furthermore the influence of geometric and material properties of CFDST short columns on the confinement effect and hence on axial load carrying capacity is discussed. The results obtained from experiments conducted by previous researchers, as available in literature are also included.

The results show that diameter-to-thickness ratio of steel tubes and concrete compressive strength will have significant influence.

During the engineering investigations of destructive earthquakes like 1966 TaÅŸkent(Uzbekistan), 1976 Gazlı(Uzbekistan), 1981 Ä°zmit(Turkey), 1999 Düzce(Turkey), different damage characteristics have been encountered. As the height of these buildings increases, the degree of damage increases. Furthermore, the length of building increases the length and thickness of the cracks also increases. Collapsing of the masonry buildings exterior walls to the outside of the buildings and heavly damage at the corner columns of the carcass buildings have been encountered.These cracking characteristics have been studied and interpreted by different manner by different researchers.In our opinion, these damages are related to prestress-strain situation of the buildings structural systems before the earthquake occured. In addition structural system is deformed before earthquake effect.Analysis of the behavior of the structural system with involvement of prestressing state of the load resisting system into account take place at different sources.The analysis of the structural system due to its deformed condition is still actual.This papers presents the result of the investigation of the behavior of steel structural systems of industrial buildings, under the influence of horizontal and vertical loads in case of seasonal variation of temperature. Structural system behavior was investigated by using ANSYS program depending on numerical calculation results. It is also given here that the effect of deformed shape of the structural system on the behavior of load resisting systems of building and design of structural members.

 

 

 

 

 

 

 

Composite materials have gained wide importance in various industrial, civil, mechanical, aerospace, naval and military applications. Higher stiffness along with light weight give composite materials an edge over other traditional materials for such applications. However, composites are very sensitive to defects, induced during manufacturing or service period. Delamination is one of the major defects commonly encountered in composite materials. Once induced in the structure, it can propagate very fast leading the structure to a cataclysmic failure in later period. So, this kind of damages need to be detected in an early stage to avoid such occurrences. Throughout the years many researchers have tried to detect delamination damages by solving the vibrational response based inverse problem. Here, the authors have formulated the composite beam structure using 8-noded isoparametric elements based on layer-wise theory. Heaviside step function has been used to model the delaminated part. Combined natural frequencies and modeshapes are used as damage indicator. Instead of using finite model updating based inverse technique, Response Surface Method (RSM) is used. First the frequency and modeshapes based objective function is calculated for varying size and location of delmaintions using the finite element method. The interface of damage is kept constant. Then, MINITAB software is used to fit a surface of the response (objective function) as a function of location and size of the delmination. Lastly, unified particle swarm optimization (UPSO) is used to minimize the fitted surface to locate the location and size of the delamination. Present method is capable of reducing the computational effort significantly by eliminating the use of rigorous finite element model updating in every iteration during the optimization stage. Although at present this method is capable of handling only single delamination, it has greater potential in the field of damage detection in composite structure.   

He did B.E. in civil engineering from Bengal Engineering College, Shibpur under Calcutta University. Subsequently he acquired M.Tech and PhD degrees from Department of Aerospace Engineering, IIT Kharagpur. After a short stay at IIT Bombay as Senior Research Engineer he worked at Aeronautical Development Agency, Bangalore as scientist for over six and half years. He joined department of Aerospace Engineering, IIT Kharagpur as a faculty member since October 2004. He has published over 70 international journal papers, over 60 national and international conference papers handled several research projects and guided several PhD students. His primary research areas are analysis of composite structures employing various higher-order shear deformation theories, smart structures, aeroelasticity, structural health monitoring, etc.