Keywords: earthquake simulation, object-oriented integration, message passing interface, kernel, numerical experiment, ground motion, structural damage.

The occurrence of earthquakes, their consequent impact on people and on the facilities they live and work in, the evaluation and interpretation of damage caused by sever ground motion, are the principal items for both structural and geotechnical engineers designing structures in seismic areas. The attempts to find the answer to the question: "why does damage occur, after a wide amount of research work?" is an ethical duty of the specialist. The huge studies which have been conducted to the destructive damages that have been occurred in Northridge earthquake [1], U.S.A. on 1994, and Kobe earthquake [2], Japan on 1995, are proof for that current seismic analysis and design procedures for structures have their shortcomings.

Any structure to be built it has to pass through three major stages: analysis, design, and construction. It is also fact that each stage contributes in structure damage during an earthquake. Contribution of construction stage and design stage are beyond the scope of this study and usually addressed throughout improving design codes and providing provisions for seismic design; moreover, quality control in construction site is the key factor to assure constructing a provisions-compliant structure. On the other hand, contributions of analysis stage, seismic analysis stage, in structure damage during an earthquake are in the concern of the authors. In seismic analysis stage two main requirements are necessary: the first one is the input earthquake ground motion and the second one is the numerical technique which is employed in modelling and analysis of structure under a given earthquake ground motion. Those two requirements are representing earthquake causes and effects.

In this study authors are aiming to integrate earthquake causes and effects in one simulation to simulate earthquake disaster in a large scale domain, e.g. complete city. Earthquake causes are represented in earthquake ground motion (EGM) which in turn highly dependent on underground soil structure (UGSS). Sub-simulators have been provided to model UGSS and simulate the dependent EGM. Interaction among UGSS and EGM sub-simulators is important to resolve the mentioned dependency and result in the desired at-site ground motion which in turn has the at-site characteristic. Earthquake effects are represented in different structures which could be stroked by an earthquake: bridge piers, buildings, earth structures, pipelines...etc. Sub-simulators [3,4,5] have been provided to conduct modelling and seismic analysis for those structures based on the simulated at-site ground motion. Consequently, resulted seismic response for all structures in the domain of interest would be able to represent a global dynamic image as well as structural damage distribution which are in turn able to simulate the earthquake scenario.

The aforementioned large scale domain has been named as global domain. This global domain has been decomposed into domains which in turn represent earthquake causes and effects. Each domain has its relevant sub-simulator which is employed for modelling, analysis, or both. Consequently, to develop IES two major problem statements exist. The first problem statement is the need for an object-oriented integration technique which would be employed to design the desired integrated system. Hence, a constitution has been defined to set up the required concepts that allow domains to interact under prescribed control and schedule. This constitution is the kernel that based on which integration design accomplished. The second problem statement is the resulted huge run-time for simulation execution. To overcome this problem Message Passing Interface (MPI) technique [6] has been employed to parallelize computations in IES simulation and enable decomposition.

The contribution of IES simulation can be summarized as follow: it recovers the shortcomings of current seismic analysis methods, supports decision making on the governmental and individual level through out damage distribution in domain of interest, and supports the concept of performance based design technique based on structure seismic performance assessment. Numerical experiment has been conducted for part of Kobe city with (700x500[M]) domain size under different cases of input earthquake wave using multiprocessors computer architecture, eight node clusters. Spatial variation of ground motion has been resulted taking into account effect of local site condition and incidence direction of earthquake wave.

1

Gates, W., Morden, M., "Lessons from Inspection, Evaluation, Repair and Construction", Report SAC 95-06, Sacramento, Dec. 1995.

2

Earthquake Engineering Research Institute, "The Hyogoken-Nanbu Earthquake: Great Hanshin Earthquake Disaster, January 17, 1995; Preliminary Reconnaissance Report", Oakland, California, 1995.

3

Ichimura, T., "Basic Research for Simulator of Strong Motion Distribution", graduate thesis, civil engineering Dept. in the University of Tokyo, 1998.

4

Yang, F., Ichimura, F., Hori, M., "Earthquake Simulation in Virtual Metropolis Using Strong Motion Simulation and Geographic Information System", Journal of Applied Mechanics, JSCE, Vol.5, pp.527-534, 2002.

5

Nakamura, H., Higai, T., "Evaluation of 3-D Effects on RC Structures under Seismic Loads", Proceedings of the 2002 Structures Congress, USA, pp.83-84, 2002.

6

Quinn, M.J., "Parallel Programming in C with MPI and OpenMP", McGraw-Hill, 2004.

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