摘要:

AbstractA scheme is proposed to calculate the effect of torsion on each lateral load resisting element of asymmetrical buildings in the context of the response spectrum technique. The scheme consists of: (i) Obtain the modal shear and torque on the building by the response spectrum technique, (ii) Compute the total modal shear forces on each frame by resolving the modal shear and torque on the building according to principles of structural mechanics. The shears on each frame due to the lateral load effect and torsional effect are combined algebraically, (iii) Obtain the total shear force on each frame by combining the total modal shears on that frame in a root sum square manner.Since the proper phase relationship between the lateral load effect and torsional effect is accounted for on a modal basis, it is believed that the proposed scheme provides a more realistic load estimate on the frames than the conventional approach. An example of a simplified mono‐symmetrical frame structure is chosen to illustrate the accuracy of the proposed scheme, using dynamic time‐history analysis as a standard for compari

ISSN:0098-8847    

DOI:10.1002/eqe.4290060502

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractWhen subjected to major earthquakes, core‐stiffened buildings may begin to tip. That is, the overturning moment on the core's footing becomes so large that the footing breaks contact with the ground and begins to rock. A method is described for including the effects of tipping in the analysis of multistorey core‐braced structures. Curves are presented which summarize the maximum response to both pulse and earthquake excitations; these data are elucidated via a typical design example. By comparison to fixed‐base behaviour, tipping greatly reduces the base shear and moment. This makes possible a more economical design. However, attention must be devoted to avoiding potential soil‐mechanics problems associated with the wobbling behaviour of the tippi

ISSN:0098-8847    

DOI:10.1002/eqe.4290060503

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThis paper presents some findings of an investigation into the dynamic behaviour of offshore gravity platforms excited by waves. Results obtained from a finite element model are presented in the form of dynamic magnification factor curves for two structures typical of current concrete platform designs. In order to facilitate interpretation of these results a simple two degree of freedom model is developed and the equivalent results presented. These are found to be very similar to those obtained from the more detailed idealization, and it is therefore concluded that the principal mechanisms involved in the dynamic behaviour of offshore gravity structures are adequately represented in the simple model. Several useful insights into this behaviour are then achieved by closer examination of the two degree of freedom configuration.

ISSN:0098-8847    

DOI:10.1002/eqe.4290060504

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe natural frequencies of the San Pedro‐Terminal Island Suspension Bridge were fairly accurately determined by measuring traffic‐excited vertical vibrations with sensitive seismometers mounted at various locations on the bridge. The Fourier amplitude spectrum of the recorded vertical movements was computed and plotted. The measurements revealed a wide band of natural frequencies. The results for the vertical and torsional natural frequencies were correlated with the computed frequencies. The results of the field measurements showed reasonable agreement with the computed values. Finally, further recommendations toward obtaining better results were also indica

ISSN:0098-8847    

DOI:10.1002/eqe.4290060505

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractIf earthquakes are modelled by a stochastic process, it is possible to interpret the associated response spectrum in terms of the statistics of extreme values of oscillator response to the process. For a stationary earthquake model this interpretation leads to a relationship between the power spectral density function of the process and the response spectrum. This relationship is examined in this paper and forms the basis for two methods presented to obtain the power spectrum of the earthquake process from its response spectrum. One of these methods is approximate but leads to an explicit representation of the power spectral density function in terms of the response spectrum. The other method is exact wherein an iterative scheme for the solution of the problem is established. An example problem is solved to illustrate the use of the two methods and it is shown that for small values of damping, the approximate derivation yields a fairly accurate solution.

ISSN:0098-8847    

DOI:10.1002/eqe.4290060506

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractGeneral expressions are derived for the numerical evaluation of Duhamel's integral and its derivative. The work comprises an extension (to unequal time steps) and an application (to a piecewise linear forcing function) of the numerical integration approach adopted by Cronin.1The application is particularly relevant to the digital computation of response spectra from strong motion earthquake records.

ISSN:0098-8847    

DOI:10.1002/eqe.4290060507

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060508

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060509

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060510

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060501

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY