ISSN:0098-8847    

DOI:10.1002/eqe.4290090502

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA response spectrum method for stationary random vibration analysis of linear, multi‐degree‐of‐freedom systems is developed. The method is based on the assumption that the input excitation is a wide‐band, stationary Gaussian process and the response is stationary. However, it can also be used as a good approximation for the response to a transient stationary Gaussian input with a duration several times longer than the fundamental period of the system. Various response quantities, including the mean‐squares of the response and its time derivative, the response mean frequency, and the cumulative distribution and the mean and variance of the peak response are obtained in terms of the ordinates of the mean response spectrum of the input excitation and the modal properties of the system. The formulation includes the cross‐correlation between modal responses, which is shown to be significant for modes with closely spaced natural frequencies.The proposed procedure is demonstrated for an example structure that is subjected to an ensemble of earthquake‐induced base excitations. Computed results based on the response spectrum method are in close agreement with simulation results obtained from time‐history dynamic analysis. The significance of closely spaced modes and the error associated with a conventional method that neglects the modal correlations are al

ISSN:0098-8847    

DOI:10.1002/eqe.4290090503

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the dynamic interaction between soil, pile and structure when subjected to harmonic excitation at the base rock level. The structure to be analysed is an isolated tall bridge pier with deep group pile foundation. The dynamic substructure approach is taken, dealing first with the pile‐footing substructure and the pier superstructure independently; and then integrating these at the interface. Since the soil profile is multi‐layered, the transfer matrix scheme is applied to extend the relevant continuum solution proposed by earlier researchers for pile analysis in a homogeneous viscoelastic medium.Using a numerical example, the importance of the soil layer vibration modes which exert forces on the pile varying along the pile length is pointed out together with the soil‐structure inertial interaction in the structural response. The latter concerns the dynamic characteristic of the complete system whereas the former relates the driving force to it. Also examined is the applicability of the approximate soil reaction based on the plane strain assumption, which simplifies the formulation and requires much less computing time in the response ana

ISSN:0098-8847    

DOI:10.1002/eqe.4290090504

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractAn evaluation is made of response spectrum techniques as applied to seismic analysis and design of steel template offshore platforms. Such structures are designed as braced space frames for several loading conditions, including the simultaneous action of three earthquake components. Base shears as well as gross forces and combined stresses in members of three different platforms are computed for 30 real, three‐component earthquakes and response spectrum predictions, obtained by several modal‐spatial combination methods, are compared to time history solutions. Results are presented in the form of error statistics.The three approximations examined are: (a) combination of modes for one component input, (b) combination of the three partial responses to obtain estimates of total response and (c) combination of gross forces to derive maximum design stresses at a section. Attention is focused on corner piles because these are among the most heavily penalized members by three‐component excitations.It is shown that commonly used spatial combination rules may underestimate gross forces in design controlling corner members by 15–30 per centon the average. This is attributed to correlations between motion components that create additive effects along certain directions. Typical estimates of combined stresses, however, are found to be slightly conse

ISSN:0098-8847    

DOI:10.1002/eqe.4290090505

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractIn this paper we present numerical results representing the response of an elastic cylindrical shell to disturbances in an elastic half‐space. These numerical results show the radial displacement at the middle surface of the shell and the hoop stress in the shell. The incident disturbance is in the form of a plane dilatational wave or a Rayleigh wav

ISSN:0098-8847    

DOI:10.1002/eqe.4290090506

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractIt is known that the maximum danger of flutter‐type aerodynamic instability for suspension bridges occurs during the early erection phases of the deck.The effectiveness of two different provisional measures for increasing the instability critical windspeed in such conditions is evaluated for a long span suspension bridge with flat box stiffening girde

ISSN:0098-8847    

DOI:10.1002/eqe.4290090507

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe response of a rigid rectangular foundation block resting on an elastic half‐space has been determined by considering first the displacement functions for any position on the surface of an unloaded half‐space due to a harmonic point force. The influence of the foundation has been taken into account by assuming a relaxed condition at the interface, i.e. a uniform displacement under the foundation and that the sum of the point forces must equal the total applied force. The three motions of vertical, horizontal and rocking have been considered and numerical values for the in‐phase and the quadrature components of the displacement functions are presented for a Poisson's ratio of 0.25. The effect of the mass and inertia of the foundation can be allowed for by an impedance matching technique. Response curves and non‐dimensional resonant frequency curves are given for a square and a rectangular foundation for different mass and inertia ratios and for several values of Poisson's ratio. These curves are for design purposes and are an addition to similar published curves for circular and infinitely long rectangular foundations. Some of the calculated results have been verified by a laboratory exp

ISSN:0098-8847    

DOI:10.1002/eqe.4290090508

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290090509

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290090510

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290090511

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY