摘要:

AbstractThis paper describes a comprehensive study of the attenuation of Modified Mercalli intensity in New Zealand earthquakes, which has resulted in significantly different and new findings when compared with those of earlier work. The current study used recently revised magnitudes for the 30 events in the carefully selected data set. Magnitudes ranged fromML= 5.0 toMs= 7.8. Special effort was also put into establishing the depths of the events, which ranged from very shallow to 65 km. An expression of a form also used in peak ground acceleration attenuation studies was adopted,I=a+bM+cr+dlog10rwithrbeing taken as the mean distance from the centre of the fault rupture surface to each isoseismal. A two‐step stratified regression analysis was used because it results in more realistic estimates of standard errors, although its mean curves were virtually the same as those derived from the standard one‐step method. It was found possible to model accurately the attenuation of the deepest events from regressions of the data of the shallowest events, but the inverse was not true. In a study of the influence of source mechanisms it was found that the attenuation was the same for events with normal and strike‐slip faulting. In contrast, events with reverse fault mechanisms were found to have higher intensities (for the sameMandr) than normal and strike‐slip events, by a factor corresponding to that found by Campbell in a study of peak ground accelerations, although the statistical test was narrowly short of the conventional significanc

ISSN:0098-8847    

DOI:10.1002/eqe.4290210301

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA design equation is proposed to prevent shear failure after flexural inelastic deformation. This equation is based on the truss‐strut model. Inelastic hinge rotation is assumed to reduce the effective strength of concrete and to increase the inclination of truss action inside hinge regions. The proposed equation is confirmed on the basis of existing experimental data. This equation is accepted in the 1990 Japanese Design Guideline

ISSN:0098-8847    

DOI:10.1002/eqe.4290210302

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn order to reduce the size of problems involving analysis of the dynamic response of structural systems, a transformatio based on appropriately selected Ritz shapes is commonly employed. The lower mode shapes may at times serve a effective Ritz shapes. However, the computation of mode shapes is a time consuming task; in addition, the mode shapes may not form the best basis for representing the spatial distribution of loads. The recently developed load dependent vectors, which are derived from a static solution for the applied loads, address some of the problems inherent in the use of mode shapes. However, both the natural mode shapes and the load dependent vectors fail to account for the frequency content of the loading, a parameter that may influence strongly the response, particularly for loading with a high frequency content. A procedure is presented here for the generation of frequency dependent vectors. A combination of load dependent and frequency dependent vectors will often form a very efficient basis for the representation of the response, as illustrated by several examples presented here.

ISSN:0098-8847    

DOI:10.1002/eqe.4290210303

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractOptimal control of base‐isolated and non‐base‐isolated buildings subjected to earthquake excitation is considered. The control force at any instant is determined on‐line through minimizing a quadratic time‐dependent performance index based on the total energy imparted to the structure and the control effect. This control algorithm is based upon the use of discrete actuators and sensors that exert the control force and monitor the response of the building. Having constant gain matrices makes this algorithm efficient and easy to implement. The effect of time delay on the efficiency of the algorithm is investigated. Comparisons have been made to demonstrate the effectiveness of the propos

ISSN:0098-8847    

DOI:10.1002/eqe.4290210304

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPounding of adjacent buildings is modelled by an impact oscillator subjected to harmonic excitation. Non‐linear impact stiffness is represented by a Hertz‐type relationship. Spectra of impact velocity are presented for a range of model parameters. These spectra are characterized by a strong peak near a period equal to one half the natural period of a similar non‐impacting oscillator. Bands of response are found in which periodic multiple impacts and non‐periodic or chaotic impact

ISSN:0098-8847    

DOI:10.1002/eqe.4290210305

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY