摘要:

AbstractThis paper presents uniformly calculated surface‐wave magnitudes of over 400 earthquakes in the European area and adjacent regions associated with strong‐motion recordings. Seismic moments and body‐wave magnitudes are estimated also, so that they may be used in the derivation of attenuation laws. Using a more complete set of data the attenuation law derived for western North American earthquakes is modified for surface‐wave mag

ISSN:0098-8847    

DOI:10.1002/eqe.4290190103

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA series of numerical experiments on the performance of different base isolation systems for a non‐uniform shear beam structure is carried out. Several base isolation systems are considered and the peak relative displacements and the maximum absolute accelerations of the base‐isolated structure and its base raft under a variety of conditions are evaluated. Several sensitivity analyses for variations in properties of the base isolator and the structure are carried out. A number of different earthquake excitations are also used in the study. The results show that performances of the base isolation systems are not sensitive to small variations in their natural period, damping or friction coefficient. The presence of a frictional element in the isolators reduces their sensitivity to severe variations in frequency content and amplitude of the ground acceleration. In particular, the resilient‐friction base isolators with or without sliding upper plate perform reasonably well under a variety of loading conditions. The rubber bearing type, however, leads to the lowest peak transmitted accelerations for moderate intensity earthq

ISSN:0098-8847    

DOI:10.1002/eqe.4290190104

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractOptimum strong‐motion array geometry for source inversions is again determined for each of three types of earthquake faults: strike‐slip, dip‐slip and offshore subduction thrust. The method is the same as employed in a previous study;1however, use of a complete Green's function in an elastic half‐space provides better results for engineering practice. It is found that the complete Green's function is capable of stabilizing the accuracy of an inversion solution obtained using theoretical seismograms, regardless of the differences in array configuration. The optimum strong‐motion array for a strike‐slip fault is characterized by stations well distributed in azimuth, while the optimum array for a dip‐slip event has stations arranged in a grid‐shaped form. The array geometries obtained here are grossly similar to those in the previous study,1which were derived using only the far‐field S waves, and are more consistent with those proposed at the 1978 International Workshop on Strong‐Motion Earthquake

ISSN:0098-8847    

DOI:10.1002/eqe.4290190105

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe non‐linear dynamic analysis of three‐dimensional long‐span cable‐stayed bridges when subjected to seismic loading is formulated. All possible sources of non‐linearity, such as cable sag, axial force‐bending moment interaction in bridge towers and girders and change of geometry of the whole bridge due to large displacements are considered in the analysis. Both cases of uniform and multiple‐support seismic excitations are considered in the non‐linear formulation of the problem. A tangent stiffness, iterative procedure is utilized to capture the the non‐linear seismic response. The non‐linear equations of motion are solved using a step‐by‐step integration technique in the real displacement coordinate space as well as in the modal coordinate space to

ISSN:0098-8847    

DOI:10.1002/eqe.4290190106

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe dynamic non‐linear behaviour of three‐dimensional long‐span cable‐stayed bridges under seismic loadings is studied. The cases of multiple‐support as well as uniform seismic excitations of these long and flexible structures are considered. Different sources of non‐linearity for such bridges are included in the analysis, as outlined in the companion paper. In this accompanying analysis a tangent stiffness iterative procedure is utilized to estimate the non‐linear seismic response. Numerical examples are presented in which a comparison between a linear earthquake‐response analysis (based on the utilization of the tangent stiffness matrix of the bridge at the dead‐load deformed state which is obtained from the geometry of the bridge under gravity load conditions) and a non‐linear earthquake response analysis using the step‐by‐integration procedure is made. In these examples two three‐dimensional bridge models representing recent and future trends in cable‐stayed bridge design are utilized. The study sheds some light on the salient features of the seismic analysis and design of these long contemporary bridges. In addition, parameters affecting the seismic response of these bridges are discussed: other factors considered are non‐linearity, uniformity and spatial variation of ground motion inputs

ISSN:0098-8847    

DOI:10.1002/eqe.4290190107

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractResearch engineers use two types of energy equations to study single‐degree‐of‐freedom (SDOF) systems subject to earthquake induced ground motions. The first method uses anabsolute energyformulation; the second method uses arelative energyformulation. While the relative energy formulation has been used in the majority of previous investigations, this study shows that the absolute energy equation is physically more meaningful. For a given ductility ratio, the input energy demands calculated by both methods are significantly different for both the short and long period ranges although the results are similar in the intermediate period range. A comparison between the analytically predicted absolute input energy of a SDOF system with the experimentally measured input energy of a six‐storey braced steel frame shows good corr

ISSN:0098-8847    

DOI:10.1002/eqe.4290190108

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe fundamental solution for a periodic point force in the interior of a three‐dimensional, homogeneous, isotropic, elastic half‐space is derived. The method of synthesis and superposition is employed to obtain the solution in the Laplace transform as well as the frequency domain. These correspond to the dynamic equivalent of Mindlin's static half‐space point force solutions. It is reduced, for certain limiting conditions, to the dynamic equivalent of Boussinesq's and Cerruti's problems of a normal and tangential periodic point force respectively, on the boundary of a half‐space. Also, static solutions of Mindlin, Boussinesq and Cerruti are recovered for small frequency parameters. Finally, results are presented and compared with other available so

ISSN:0098-8847    

DOI:10.1002/eqe.4290190109

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of the paper is to study the vibrational characteristics of the Flaminio Obelisk in Rome as part of general studies being performed for preservation purposes. The scope of the paper is limited to dynamic analysis using a finite element model and comparison of the results with those from the measured response to forced vibrations. The state of preservation of the monument is described as well as the sonic method used to evaluate the integrity of the sections. The results of the sonic tests are used to determine reductions in the cross‐sectional properties. A stick model including two rotational frequency independent soil springs at the basement level of the obelisk is developed. A good agreement between the numerical and the experimental results is obtained for the natural frequencies and for the modal shapes. A response spectrum and stress analysis according to the Italian Seismic Code is performed considering and evaluating the degraded characteristics of section

ISSN:0098-8847    

DOI:10.1002/eqe.4290190110

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe distortions of earthquake ground motions recorded in small instrument shelters as a result of soil‐structure interaction effects are investigated by means of a theoretical parametric study. A total of 12 foundation geometries varying in basal radius, embedment depth and extension above the ground surface and a number of soil profiles including uniform and layered soil models were considered. The results obtained show significant amplification and deamplification of the free‐field ground motion for sufficiently soft soils (β20

ISSN:0098-8847    

DOI:10.1002/eqe.4290190111

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of the paper is to study the applicability of stochastic methods for determining the response in the vertical plane of long‐span bridges to earthquakes. The bridges are of the modern type, with flexible towers, box‐decks and inclined hangers, Humber and Bosporus being used as the main examples, although some useful information is obtained by studying a small suspension footbridge. The input ground acceleration is that of the Pacoima Dam record of the 1971 San Fernando event, but use is also made of filtered white noise.Because the stochastic approach is essentially an attempt to abstract usable information which could otherwise be obtained from a lengthy time‐history approach, the procedure adopted here is to compare the same parameters obtained in these two ways, as far as possible. In particular, the maximum values of displacements and bending moments are considered.The essential question to be answered is whether the short length of earthquake records, coupled with the large natural periods of vibration of long‐span bridges, allows sufficient response information to be generated to make statistical parameters meaningful. The short‐span (50 m) footbridge gives no cause for concern here, but the detailed comparison with time‐history solutions shows that the stochastic approach for both Bosporus and Humber has to be cautiously assessed, particularly if some trailing zeros are not added to the earthquake record. However, general conclusions are not made, because only one earthquake record ha

ISSN:0098-8847    

DOI:10.1002/eqe.4290190112

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY