Statistics for Spatial Data.

Structural systems often show nonlinear behavior under severe excitations generated by natural hazards. In that condition, the restoring force becomes highly nonlinear showing significant hysteresis. The hereditary nature of this nonlinear restoring force indicates that the force cannot be described as a function of the instantaneous displacement and velocity. Accordingly, many hysteretic restoring force models were developed to include the time dependent nature using a set of differential equations. This survey contains a review of the past, recent developments and implementations of the Bouc-Wen model which is used extensively in modeling the hysteresis phenomenon in the dynamically excited nonlinear structures.

The Hysteresis Bouc-Wen Model, a Survey

A substructure approach is used to estimate the stiffness and damping coefficients of structures from measurement of dynamic responses. The structures are decomposed into smaller subsystems for which state and observation equations are formulated and solved by the method of extended Kalman filter with a weighted global iteration algorithm. Substructural identification methods with and without overlapping members are proposed. In both methods, the convergence of the structural parameters to the optimal values is improved significantly with less computation time as compared to a complete structural approach. Numerical simulation studies are performed for three types of structures, namely a shear building, a plane frame building and a plane truss bridge. The effects of measurement noise and response observations required for identification of system parameters are also investigated.

Estimation of structural parameters in time domain: A substructure approach

A method for identifying the element properties of a truss is developed in this paper. The measured natural frequencies and modal shapes of the truss are used in the identification process. The finite-element method is used to formulate the eigenequation of the truss. The identification problem is then formulated as an optimization program in which the error norm of the eigenequation is minimized. It is shown that given sufficient modal data, the element properties can be directly attained without iterations. Further, the solution is unique and global minimal. The identifiability of the inverse problem is then studied in depth. The perturbation method is adopted to investigate the influence of measurement errors on the identification results. A numerical example is presented to demonstrate the effectiveness of the proposed method in property identification and damage detection.

Identification and Damage Detection of Trusses Using Modal Data

Analysis of gust winds in the United States has resulted in a new wind speed map for design-level winds. The map is based on 50-year peak gust speeds rather than fastest mile speeds used in the national wind load standard ANSI/ASCE 7-93. The change in gust duration is necessary because the fastest mile wind record has ended. A new technique was used to reduce variability due to sampling error in non-hurricane areas. Individual stations were demonstrated to be statistically independent and were combined as regional superstations. The purpose was to decrease sampling error by effectively increasing sample length. Wind speeds on the hurricane coast were converted from fastest mile to peak gust using new information on gusts in hurricanes. In addition, three Monte Carlo studies of hurricane speeds were considered in place of the one study available for the earlier map. Wind speeds for various return periods are presented.

Closure of "Design Gust Wind Speeds in the United States"

Identification problems on dynamic parameters of a running load and beam system were investigated, using the EK-WGI method, which is a weighted global iteration procedure incorporated with the extended Kalman filter. By suitably formulating a set of state vector equations and observation equations for the system on which this method was applied, dynamic parameters of both the running load and the beam were identified with high accuracy, where numerically simulated data were used as observation waves so that accuracy and convergency of estimated parameters might be examined.

Identification of Running Load and Beam System

Adaptive identification problems on coefficient matrices of an autoregressive model for multivariate and one‐dimensional nonstationary Gaussian random processes are investigated by applying the extended Kalman filter incorporated with a weighted global iteration. The major contributions of the present paper are the use of the extended Kalman filter for estimating time‐varying model parameters recursively, and the development of an effective method in terms of computer time. The results indicate that the coefficients of this recursive equation are identified simply, but extremely well, at the stage of their stable convergence to optimum. It is suggested that the method be applied for the analysis of multiple‐point array data of earthquake ground motion.

Adaptive Identification of Autoregressive Processes

This paper presents an improvement of the current wind zone map of the Philippines. The Generalized Extreme Value (GEV), Gumbel and point process models were used in characterizing the extreme wind speeds in the Philippines. Available daily maximum wind data from 50 stations in the Philippines were also used in the analysis. The results show that the standard errors in the point process model are lower than the GEV or Gumbel models making it a better model. Finally a regional wind zone map (6 zones) was developed using extrapolated 30, 40 and 50 year return wind speeds from the point process approach. Wind zone maps were developed using kriging interpolation method of ArcGIS Geostatistical Analyst.

https://www.jstage.jst.go.jp/article/jsceseee/22/1/22_1_15s/_pdf

Development of a regional map of extreme wind speeds in the philippines

Current seismic design guidelines in Japan are diverse in the seismic ground strain estimates, because the concepts on a horizontally propagating wave model are not consistent in various seismic design guidelines including gas, water and other underground structures. The purpose of this study is (a) to derive the analytical methods to estimate the ground strains for incident seismic waves, (b) to develop a statistical estimation technique of the ground strains, and finally (c) to compare the theoretical estimation with the observed data which was measured at 441 sites in the 1999 Chi-Chi Earthquake in Taiwan.

Osamu Maruyama

Papers

Identification of Running Load and Beam System

Adaptive Identification of Autoregressive Processes

Development of a regional map of extreme wind speeds in the philippines

Ground strain estimation for lifeline earthquake engineering

Identification of dynamic properties of existing structures by multivariate arma representation.