摘要:

AbstractParametric studies based on finite element simulations were conducted to establish the fundamental mechanisms by which tied‐back walls respond to travelling displacement pulses. Considering first linear elastic soil behaviour, we observed that the flexural stiffness of the wall hardly affects maximum transient displacements. Rather, the transient response is determined mainly by the ratio of pulse wavelength to wall height. The maximum load carried by the anchor was found to increase with increasing anchor stiffness. For short wavelengths, on the order of less than two times the wall height, the maximum displacements and displaced shapes are affected significantly by the inclination of the anchor. The importance of the anchor stiffness suggested by the linear elastic analysis was confirmed by the non‐linear analysis. A stiff anchor suppressed permanent displacements in the vicinity of the anchor, but did not substantially reduce permanent displacements elsewhere. As peak accelerations increased from 0.1gto 0.4g, permanent wall displacements increased significan

ISSN:0098-8847    

DOI:10.1002/eqe.4290200702

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA good response spectrum method, used for calculating the seismic design response for design inputs defined in terms of response spectra, should be able to include the effect of the higher modes, even though they may be truncated and not explicitly considered in the analysis. It should also be able to include the intercorrelation of the retained modes as well as their correlation with truncated modes. Herein one such method based on a suitable combination of the mode displacement and mode acceleration formulations of structural dynamics is proposed. Several numerical examples are presented to demonstrate the efficiency of the proposed approach vis‐a‐vis some other commonly used response spectrum approac

ISSN:0098-8847    

DOI:10.1002/eqe.4290200703

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA response spectrum method which combines the analytical advantage of the mode acceleration formulation and the practical advantage of the mode displacement formulation is developed for seismic response calculation of non‐classically damped structures. It reduces the error associated with the truncation of the high frequency modes without explicitly using them in the analysis. The method is especially effective for calculating the response of stiff structural systems and also for calculating the response quantities which are strongly affected by high frequency modes. Even with flexible structures, it is shown to provide more accurate response results than the results obtained with the mode displacement approac

ISSN:0098-8847    

DOI:10.1002/eqe.4290200704

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractIn foundation dynamics a most important effect, often overlooked, is that for a soil layer on rock a cutoff frequency exists, below which there is no radiation damping. Valuable insights into the nature of the cutoff frequency may be obtained without solving differential equations. Physically motivated wave‐propagation techniques enable modification of familiar unbounded cone models to represent layered soil. Echoes corresponding to the natural period of the layer appear to account for the cutoff frequency. The cone models have simple solutions in both the time and frequency domains.An investigation of the simplest system with a cutoff frequency, the shear bar on an elastic foundation, shows that, for radiation to take place, the radius of penetration of waves must extend to infinity. In order to reach infinity, the waves' displacement amplitude must die off in a special way, otherwise conservation of energy would be violated. These considerations reveal a general radiation criterion, namely, that the waves' amplitude must diminish in inverse proportion to the square root of the far‐field boundary surface. Using the radiation criterion, it is possible to derive transmitting boundaries for shear waves which replace the far fi

ISSN:0098-8847    

DOI:10.1002/eqe.4290200705

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe exact stationary solutions of the random response of two special vibration systems with impact interactions are formulated in this paper. Between the two systems, the Hertz contact law is used to model the contact process during vibration. A clearance is also introduced. The excitation is assumed to be a stationary white Gaussian process with zero mean and acting on the two systems independently. By assuming the ratio of the excitation and damping parameter of each system to be the same, the exact solutions can be found through solving the time‐independent Fokker‐Planck equation. The effects of contact stiffness, clearance and the system properties on the response are discussed probabilistically. From this study, it is found that, under some cases, the contact phenomena still play an important role on the response even when the clearance is larger than three times the root mean square response of the corresponding linear syst

ISSN:0098-8847    

DOI:10.1002/eqe.4290200706

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThis study presents the dynamic behaviour of a rigid block which rests on a footing supported by a spring and a dashpot on a rigid base. The response of the rigid body is examined carefully when the base is excited by a harmonic force. It is found that a periodic motion appears in three different modes: stick‐stick, stick‐slip and slip‐slip. The conditions that initiate the stick‐stick and slip‐slip modes are derived in explicit forms and the maximum sliding displacement is also obtained analytically. Useful dimensionless parameters are proposed for the presentation of the dynamic behaviour. The accuracy of results is confirmed by the response history computed by the Nigam‐Jenn

ISSN:0098-8847    

DOI:10.1002/eqe.4290200707

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractEnhancement of accuracy of the direct integration methods used in structural dynamic response analysis is presented. The accuracy achieved is obtained at the same time as the cost of the problem solution is reduced. The method presented is based on Richardson's extrapolation technique.

ISSN:0098-8847    

DOI:10.1002/eqe.4290200708

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290200709

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290200710

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY