摘要:

AbstractThe equations of motion are derived for the first mode response of a linear multistorey structure having a linear vibration absorber attached to the roof. Furthermore, the variance of the first mode response to a gaussian white noise lateral base acceleration (as a model of earthquake excitation) is determined. Smallest possible values of the variance of the response along with corresponding absorber parameters are established using an optimization program. It is demonstrated that the absorber is quite effective in reducing first mode response for 5‐ and 10‐storey structures even with relatively small values of the absorber mass. Moreover, minimal responses for the randomly excited single‐degree‐of‐freedom system have been determined, and a design example is presented. The absorber system has potential application not only in earthquake engineering but also in aerospace and terrestrial vehic

ISSN:0098-8847    

DOI:10.1002/eqe.4290020402

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractSeveral significant parameters that could affect interaction in a dam‐foundation system are discussed. These parameters are: (1) Fundamental periods of the dam and the foundation layer. (2) Lateral extent of the dam. (3) The material properties of the dam and the foundation layer. Five cases are analysed to illustrate the influence of these parameters on interaction. An interaction ratio,R1, relating the response of the dam‐foundation system at the base of the dam to the free field response is introduced and interaction effects are expressed in terms of this ratio; the smaller this ratio, the less are the interaction effects. For very small values ofR1, it is shown that the dam‐foundation system could be decoupledThe results of the studies presented in the paper suggest that the interaction effects cannot be uniquely related to either the ratio of the period of the dam to the period of the foundation layer, or to the material properties of the dam and foundation layer. However, for the limited number of cases investigated, the interaction effects were found to be uniquely related to the ratioD/B, whereDis the depth of the foundation layer andBis the width of the dam section. For values ofD/Bless than unity, strong interaction effects were obtained and the dam‐foundation system could only be analysed as a coupled system. For values ofD/Bgreater than unity, the interaction appeared negligible and the dam and its foundation layer could be decoupled. It should be noted, however, that for very small values ofD/Bthe interaction effects would decrease becaase asDapproaches zero, there would be no interactionThe use of the interaction ratio,R1, and the parameterD/Bshould aid in assessing the need for analysing the response of the dam‐foundation as a coupled or as a decoupl

ISSN:0098-8847    

DOI:10.1002/eqe.4290020403

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe importance of inelastic action of frame structures subjected to strong ground motions has been recognized by engineers for many years. However, the dynamic analysis of buildings undergoing inelastic deformations requires the solution of many theoretical problems, as well as the development of computer software which makes such analyses economically feasible in a design office–in spite of the extraordinary amount of computation involved. In this paper, some of the principal theoretical problems are briefly described. These are the load‐deformation relationship, yield capacity reduction, ductility,P– δ effect, viscous damping, panel zone distortions, numerical integration techniques, energy analysis and the effect of non‐structural elements. Special consideration is given to questions associated with the practical implementation of this theory. These questions arose during the development of a computer program, called NLDYN, capable of analysing the non‐linear dynamic behaviour of tall buildings in an engineering office environment. The capabilities of this computer program are illustrated with the results of the analysis of a 60 storey office building currently under construction in downtown L

ISSN:0098-8847    

DOI:10.1002/eqe.4290020404

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA new technique to enhance the earthquake resistance of tall reinforced‐concrete bridges is introduced whereby the tall piers are allowed to ‘step’ during a severe seismic attack. This means that each pier is free to rock from side to side with vertical separation of parts of the pier from the supporting foundations. This stepping action limits stresses in the reinforced‐concrete piers to values below the yield levels and this should lead to a substantial reduction in the cost of providing earthquake resistanceAs part of a feasibility study, a 200 feet‐high stepping pier is defined and its displacements are calculated for the ground accelerations of the 1940 El Centre earthquake, N‐S component. With no damping present the computations give many ‘stepping’ separations of rather large extent. When the effects of internal structural damping are included in the analysis, there is little reduction in the stepping motions at the level of damping expected in the pier. However, when the computations include the effects of some energy‐absorbing devices of a recently‐developed type, installed between the pier and its foundations, the amplitude and number of the stepping cycles are c

ISSN:0098-8847    

DOI:10.1002/eqe.4290020405

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAn understanding of the precise nature of the non‐linear response of structures is essential for future improvement of earthquake resistant design procedures. This paper presents a summary of observations of dynamic behaviour which were made on two typical modern buildings during a period of about ten years. These structures underwent numerous tests and experienced three strong earthquake ground motions. The data presented should prove useful for calibration of parameters in theoretical non‐linear modelsFor buildings having an apparent soft‐spring‐type non‐linearity, a partial or complete recovery of the structural stiffness appears to occur following the large strains created by strong ground shaking. The rate and extent of this recovery appear to depend strongly on the strain levels throughout the e

ISSN:0098-8847    

DOI:10.1002/eqe.4290020406

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe time‐dependent failure of rock subjected to repeated loading can be explained in terms of the residual strength locus: catastrophic failure occurs when the accumulation of deformation is such that the residual strength locus is intercepted. In a preliminary experimental study of the fatigue characteristics of rock masses, highly idealized models of jointed rock were subjected to a series of cyclic uniaxial compression tests. The results of these experiments show that intact and failed models of jointed rock are extremely susceptible to cyclic fatigue failure, and that in these cases the residual strength locus interpretation of time‐dependent failure is corr

ISSN:0098-8847    

DOI:10.1002/eqe.4290020407

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290020408

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290020410

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290020401

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY