ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING)
Year:2006 | Volume:7 | Issue:4|Papers Count:9

In this paper experimental and computational modeling methods for studying multiphase flows in porous and fractured media are studied. Particular attention was given to the flows in a laboratory-scale flow cell model. It is shown that the gas-liquid flows generate fractal interfaces and the viscous and capillary fingering phenomena are discussed. Experimental data concerning the displacement of two immiscible fluids in the lattice-like flow cell are presented. The flow pattern and the residual saturation of the displaced fluid during the displacement are discussed. Numerical simulations results of the experimental flow cell are also presented. The numerical simulation results for single and multiphase flows through rock fractures are also presented. Fracture geometry studied was obtained from a series of CT scan of an actual fracture. Computational results show that the major losses occur in the regions with smallest apertures. An empirical expression for the fracture friction factor is also described. Applications to CO2 sequestration in underground brine fields depleted oil reservoir stimulation are discussed.    

In this paper, some recent advances and a few novel concepts are presented for motion control of highrise building and bridge structures under dynamic wind and earthquake loading. Recent research performed by the authors in the areas of smart structures, hybrid control, tuned liquid column damper, and wavelets is reviewed.      

An investigation procedure is proposed by the authors to study the vulnerability of the diffuse historic building patrimony in seismic area previously considered as minor, but meaningful testimonies of cultural heritage. The research suggests a "minimal" investigation program, which can support the designers in their projects. The knowledge of existing buildings is approached by considering different analysis levels: history, materials, structural morphology of the wall section, observed damage mechanisms, effectiveness of retrofitting techniques. The methodology, calibrated on four historic centres situated in Umbria (Italy), allowed defining an abacus of the aother similar centres and to critically evaluate the past and future repair techniques.      

The recent studies on the stability of the French Pantheon [1], commissioned by the French Ministry of Culture and Communication, enabled to spot the causes of the structural disorders, thanks to a balanced fusion of historical analysis, precision surveys, experimental inspections and numerical modeling. The interest in these studies arouses also from the fact that the French Pantheon, designed by Souffiot with slender structures and innovative techniques and finished by Rondelet in 1790, can be considered as the first building for whom tests on materials and "modern" structural calculations have been carried out in a systematic manner.    

On this day, any single country cannot alone deal with vast problems caused by large natural disasters. Underneath this unprecedented internationalization of disaster problems is economic globalization that captures every country on earth. This capitalism at work, while intensifying and complicating disaster risk of nations has produced at the same time mass quantities of potential resources for disaster reduction. This fundamental transition offers challenge as well as opportunity for disaster reduction efforts of nations. Our science and technology must accommodate this process through nimbly detecting emerging risks and resources and utilizing them wisely. For this purpose, some seemingly informative materials are reviewed below based on recent experiences in Japan.    

Taking advantage of computer technology and science that enable us to carry out a large scale numerical simulation, the authors have been simulating the whole phases of an earthquake, i.e., the generation and propagation of an earthquake, the response and damage of structures, and the human and society actions against the earthquake damages. This is the integrated earthquake simulation (IES). With the aid of the latest geographical information system (GIS), IES is able to automatically construct a compute model for a city of some hundred meter scale. This paper presents the development of IES, focusing the simulation of strong ground motion and structure responses; the structure response simulation is made by several numerical analysis methods and the data exchange between each method and IES is controlled by an interpreter program. Discussions are made on the usefulness of IES. It is pointed out that IES provides vital information to form common recognition of possible earthquake hazards and disasters among government officials and residents.      

The aim of the present work is two fold. In one hand it shows to mathematicians how the apparently pure mathematical concepts can be applied to the efficient solution of problems in structural mechanics. In the other hand it illustrates to engineers the important role of mathematical concepts for the solution of engineering problems. In this paper a number of applications of graph theory in structural mechanics are presented. These applications simplify the analysis of structures and make their optimal analysis feasible. For each case, the main problem is stated and then the formulation together with illustrative examples is presented.      

A method is presented which permits the geometrically nonlinear analysis of structures undergoing arbitrarily large displacements, rotations and strains. This method is based on the general nonlinear theory of elasticity and can be applied consistently to different types of structural elements such as beams and plates. The method has so far been implemented for two-dimensional trusses and frames. For several examples of structures with very large displacements and rotations as well as snap-through, the results which are obtained with the method are compared to exact solutions. The convergence of the method to the exact results is demonstrated.      

This paper describes three-stage mitigation of earthquake-induced hazards with special attention to geotechnical and liquefaction problems. Different from the conventional factor-of- safety approach, this approach requires more knowledge on damage mechanisms and choice of an appropriate mitigation measure. By practicing mitigative measures and assessing analytically the effect of mitigation, it will be possible to save cost as well as to achieve safety in a broader range in the public. At the end, geotechnical achievements in the field of post-earthquake emergency action will be described.