The practical structural health monitoring system is suggested aiming to detect certainly the occurrence of damage and to identify the portion with the degree of damage. Our system is highly reliable and simple of low cost adopting new sensors which translate the measurements to the damage indices and transmit in the minimum amount of data. The developed smart AE(acoustic emission) sensor is useful for local monitoring detecting the crack of concrete, and new smart VA(vibration analyzing) sensor is used for global monitoring by arresting the change in dynamic properties of the building structure. The wireless network using the standard ZigBee provides with the reduced consumption of electricity, and is expected to realize multi-hop transmission and mutual communication of sensors in the near future.

, Spatial incoherence of an earthquake ground motion may result in reduction in high-frequency components of the input motion for a building or a structure. Two-dimensional finite element method is used for heterogeneous soil medium. Through Monte Carlo simulation, the spatially correlated soil model shows more reducing effect in the average input with increasing frequency and with increasing correlation distance. Such effect is caused by the scattering damping and depends on the wavelength, the correlation distance, the traveling distance and the deviation of the soil properties.

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This paper presents the three − dimensional responses on soft semi − sphericai alluvial deposits under incidence of plane SH waves ． In し his analysis ， we modify the wave potential functions to estimate the exact solution without great computational capacity and cost ． The computed results show that 出 e seismic responses depend strongly on the aUuvial deposit depth varying along the curved boundary ． It is found that the scattering waves due to the curved boundary induce surface waves in alluvial deposits ， which are more developed as the incident angle decreases． Seismic responses show significant variations with the incident angle ， station location and impedance contrast ratio even for the simple idealized deposit model ． ． The above results suggest the formation of seismic ground motions in three − dimensional soft alluvial deposits with topographic irregular boundary ． Keyweizts ：three −dimensional resPonse ， 5 ε加 一 3 カ ゐ θ厂加 ！6 〃麗 擁 α 1 伽 ∫1 ε ∫ ， S万 wave ， Ztnne Potential ftinc − tions ， scattering wave ， imPeeinnce contrast ratio 3