摘要:

AbstractThe first passage problem for a sliding rigid block on a frictional foundation, subjected to Gaussian white noise through the foundation, is studied. A well‐posed boundary value problem is formulated from Markov process theory and solved for the ordinary moments of time to first passage by the finite element method. A range of parameters is studied representing a simple seismic base isolation system. Results of Monte Carlo simulation are given for compariso

ISSN:0098-8847    

DOI:10.1002/eqe.4290130303

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractWhen the finite element method is used to idealize a structure, its dynamic response can be determined from the governing matrix equation by the normal mode method or by one of the many approximate direct integration methods. In either method the approximate data of the finite element idealization are used, but further assumptions are introduced by the direct integration scheme. It is the purpose of this paper to study these errors for a simple structure. The transient flexural vibrations of a uniform cantilever beam, which is subjected to a transverse force at the free end are determined by the Laplace transform method. Comparable responses are obtained for a finite element idealization of the beam, using the normal mode and Newmark average acceleration methods; the errors associated with the approximate methods are studied. If accuracy has priority and the quantity of data is small, the normal mode method is recommended; however, if the quantity of data is large, the Newmark method is useful.

ISSN:0098-8847    

DOI:10.1002/eqe.4290130304

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA homogeneous and internally consistent body of regional magnitudes is needed not only for the statistical study of seismicity but also for the modelling of seismic sources and for the hazard assessment of engineering sites. Also the assessment of the design ground motions for engineering projects requires homogeneous magnitude estimates. The nature of the available data for U.K. and Northwestern European earthquakes, and of the events themselves, is such that we are concerned with the assessment of magnitudes at the lower end of the scale, and thus great importance focuses on the uniform calculation of magnitudes within a relatively narrow range ofMvalues. The purpose of this study is to present the uniform re‐assessment of magnitudes for British and Northwestern European earthquakes for the period 1900 to 1984. It is shown that, for the larger events, surface‐wave magnitudes can be estimated uniformly and that neither a period constraint at 20 seconds nor distance effects for the regional conditions considered appear to play an important role. For smaller events, crustal phases at short distances have been used to derive calibration curves for a magnitude which, at larger distances and longer periods would fit the magnitude scale of surface wa

ISSN:0098-8847    

DOI:10.1002/eqe.4290130305

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA simple approach to analyse the flexural vibration of grouped piles was developed. In this approach, a pile group is replaced by a single pile for the evaluation of the pile‐head flexibility matrix. Parametric studies were conducted for various conditions of grouped piles. Various features of flexural vibration of pile groups were found. The charts presented in this paper enable quick estimations of dynamic group effects to be made in a manner similar to that widely used for the evaluation of static group effect

ISSN:0098-8847    

DOI:10.1002/eqe.4290130306

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractRegional seismic characteristics in northeastern and southwestern China are quite different. Earthquakes are more frequent in SW China than in NE China and intensity attenuates faster in SW China than in NE China. Through regression analyses of data from these two regions we have found the attenuation of peak horizontal accelerations also to be noticeably different. For northeastern China the regression is log10(a) = −0.474 + 0.613M− 0.873 log10(R) −0.00206Rand for southwestern China, the regression is log10(a) = 0.437 + 0.454M− 0.739 log10(R) −0.00279Rwhereais acceleration in cm/sec2,Mis the Chinese surface wave magnitude (Institute of Geophysics, State Seismological Bureau), andRis the distance in kilometres. The formula for northeastern China has distance coefficients similar to those for Central United States as derived by Nuttli and H

ISSN:0098-8847    

DOI:10.1002/eqe.4290130307

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractFor coupled vibration analyses of prismatic shell structures immersed in an infinite fluid medium, a composite element consisting of a semi‐analytical infinite fluid element and a cylindrical shell strip element is proposed in this paper. The behaviour in the infinite direction can be accurately modelled with minimum effort and great saving in computational cost is achieved using this element. Unlike many other methods which tend to take advantage of axisymmetry to simplify the analysis, this method may be used to analyse the dynamic behaviour of prismatic shell structures with arbitrary cross‐sections in offshore engineer

ISSN:0098-8847    

DOI:10.1002/eqe.4290130308

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe purpose of this paper is to present the results of an evaluation of the seismicity of western Scandinavia. Intensities, with reference to the MSK scale, have been assessed for the larger earthquakes, in most cases from primary sources, and isoseismal maps have been constructed for the most important events, while for smaller shocks one or more isoseismal radii were estimated. In all, over 3,200 earthquakes have been retrieved for Northwest Europe including about 300 artificial events such as chemical explosions, rock‐bursts and mine explosions. Of these, 500 events occurred in western Scandinavia. Surface‐wave magnitudes were reassessed for 205 events, using surface‐wave amplitude‐period data, and all earthquakes recorded by more than 6 stations were relocated for the period prior to 1955. A calibration formula, obtained from the combination of macroseismic and instrumental data of the 20th century, has been used to assign magnitudes to all events for which there is macroseismic information available, thus deriving a homogeneous body of data covering a period of 180 years.It is shown that the largest earthquake in the region since 1800 occurred on land and that it had a magnitude in excess of 6.0. This is contrary to the current belief, based on short‐term data, that the larger events in western Fennoscandia occur offshore in the continental sh

ISSN:0098-8847    

DOI:10.1002/eqe.4290130309

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThree approximate models are considered for the evaluation of the first few natural frequencies and associated mode shapes of infilled frames, a commonly occurring composite structural system formed by the combination of plane frames and filler walls. The reasonableness of the models is checked with the available experimental results and with the corresponding finite element solutions. The multiple strut model, wherein the infills are replaced by a set of equivalent multiple struts, can account for the frame–infill separation and infill openings and this model is seen to be an improvement over the single equivalent diagonal strut models proposed by earlier investigators. The shear—flexure cantilever analogy, by rationally evaluating the fundamental frequency, aids the equivalent lateral load procedures of the earthquake analysis. For dealing with the frames with central infill openings an equivalent plane frame model is discussed.Besides presenting the approximate models, the effect of frame—infill separation in reducing the fundamental frequency is investigated and an empirical relation is presented in this regard. Also some of the factors influencing the frame—infill contact lengths are studied and this indicates that the contact lengths are highly sensitive and indeterminate. Some constructional methods for avoiding separation and ensuring effective composite action between the frame and infill are also su

ISSN:0098-8847    

DOI:10.1002/eqe.4290130310

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290130311

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290130313

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY