摘要:

AbstractIt is pointed out that local vibrations of certain members in earthquake excited offshore structures can induce substantial stresses that may often dominate the design of these members. Such vibrations are not accounted for in dynamic analyses of structural models with masses lumped at the joints. A practical, easy to implement solution to this problem is recommended and results from an actual structure, subjected to a three‐component real earthquake, are presented demonstrating the importance of local inertia effect

ISSN:0098-8847    

DOI:10.1002/eqe.4290100302

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDuring the 9 February, 1971 San Fernando earthquake, Building 41 of the Veterans Administration Hospital was in an area of very strong snaking; being directly over a portion of the causative fault; it is estimated that the building experienced a maximum base shear of 60 to 130 per cent of the weight of the structure. It survived with very minor structural damage, although designed with a lateral force coefficient of only 10 per cent. The study attempts to reconcile these facts by analysis of the transverse response of the building. A code‐oriented, lateral force analysis is only partially successful in this reconciliation in that it indicates first yield at lateral loads of 15–20 per cent of the weight of the structure, with a capacity of 35–45 per cent if redistribution of loads among the walls is permitted. The capacity against static overturning is 45–50 per cent. A dynamic analysis of a fixed‐base three‐dimensional linear model of the structure gives essentially the same results. A third study of a two‐dimensional, dynamic model incorporating partial uplift and soil yielding indicates that the successful response of the building is attributable to the large strength built into the structure and the beneficial effects of non‐linear soil‐stru

ISSN:0098-8847    

DOI:10.1002/eqe.4290100303

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn recent papers the author has shown that when determining optimum parameters for an absorber which minimizes the vibration response of a complex system, the latter may be treated as an equivalent single degree‐of‐freedom system if its natural frequencies are well separated. Emphasis was on minimizing the displacement response when the excitation was a harmonic force. In the present paper simple expressions for optimum absorber parameters are derived for undamped one degree‐of‐freedom main systems for harmonic and white noise random excitations with force and frame acceleration as input and minimization of various response parameters. These expressions can be used to obtain optimum parameters for absorbers attached to complex systems provided that optimization is with respect to an absolute, rather than a relative, quantity. The requirement that the natural frequencies should be well separated is investigated numerically for the different cases. The effect of damping in the main system on optimum absorber parameters is investigat

ISSN:0098-8847    

DOI:10.1002/eqe.4290100304

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA model for the random vibration of hysteretic and degrading plane frames to Gaussian shot noise or filtered shot noise is presented. The model, which combines the discrete hinge concept previously used in deterministic frame analysis with Bouc's smooth system hysteresis, results in a non‐linear set of differential equations which can be linearized in closed form without recourse to the Krylov‐Bogoliubov assumptions. Solution is iterative in the stationary case and by numerical integration with stepwise updates in the non‐stationary case. Numerical studies are presented of strong girder and strong column two storey, one bay frames. These studies indicate that the model can locate the sites of yielding and provide reasonable values of structural response as compared with simulation data. Moreover, the model can provide a joint by joint breakdown of the structure energy dissipation

ISSN:0098-8847    

DOI:10.1002/eqe.4290100305

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe dynamic responses of simple arch dams, with different radius to height ratios are analysed for three conditions: the dam alone without water, and the dam with full reservoir, considering water to be compressible in one case and neglecting water compressibility in the other case. The complex frequency response functions for accelerations at the dam crest due to the three components of ground motion—upstream‐downstream component, cross‐stream component and vertical component–are presented. Based on these results, the effects of dam‐water interaction, of water compressibility, and of bank motions on dam response are inv

ISSN:0098-8847    

DOI:10.1002/eqe.4290100306

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn this report, three different models in increasing order of complexity have been used to identify the seismic behaviour of a three‐storey steel structure subjected to arbitrary forcing functions, all of which excite responses within the elastic range. All of the models are constructed using system identification.In the first model, five parameters have been used to identify the frame. Treating the system as a shear building, we assign one stiffness coefficient to each floor and introduce Rayleigh‐type damping with two additional parameters. The mass, assumed to be concentrated at a floor level, is kept constant throughout the study. The parameters are established using a modified Gauss‐Newton algorithm. The match between measured and predicted quantities is satisfactory when these quantities are restricted to floor accelerations or displacements.To remove the constraint imposed by assuming that the frame deforms as a shear building, a second model with eight parameters is introduced, allowing rotations of the joints as independent degrees of freedom. Six of the eight parameters are related to the stiffness characteristics of the structural members while the remaining two are related to damping as before.In constructing the eight‐parameter model, we learned that it is the effective lengths of the members that change during optimization. We also found that the independent response quantities, floor accelerations and joint rotations, must be used in the cost function for the optimization algorithm to converge.The match between measured and predicted quantities for the eight‐parameter model is excellent. The set of parameters derived from the minimum squared error gives a model that shows very good correlation using information on the full duration of the pulse or only a portion of it. Also the same correlation exists between the coefficients obtained from different excitations.In an effort to explain the values of the parameters associated with the girders, an additional degree of freedom, namely, the pitching motion of the shaking table, is introduced as an additional degree of freedom. The paper presents, therefore, a five‐, an eight‐ and, finally, a nine‐

ISSN:0098-8847    

DOI:10.1002/eqe.4290100307

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractMeasurements have been made of vibrations induced in the 180 m high Emosson arch dam in Switzerland3by a system of mechanical eccentric‐mass vibrators and by the natural wind. Details are given of the dam itself, the tests and the experimental results obtained. Finite element calculations made before the tests, which include reservoir and foundation effects, are compared with the measurement

ISSN:0098-8847    

DOI:10.1002/eqe.4290100308

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractAt the present time, there is a need for a rational approach for the analysis and design of three‐dimensional structures subjected to multi‐component earthquake motions. In this paper, a general design criterion for multi‐component earthquake input is proposed. A new method for three‐dimensional dynamic analysis is presented which estimates maximum displacements, forces or stresses for specified points within a structure. For each maximum value calculated, the corresponding critical angle of earthquake input is evaluated. The method is readily incorporated into existing computer programs for earthquake analysis, allowing one computer run to produce mean maximum response values for all possible angles of earthquake input. Combined axial and bending stresses are calculated at the modal level. It is shown that combining modal stresses yields lower estimates than if stresses are evaluated from maximum axial forces and moments. In addition, the method can be used without modifications to perform design checks for arbitrary blast or seawave

ISSN:0098-8847    

DOI:10.1002/eqe.4290100309

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractSeismic response of cylindrical storage tanks anchored to rigid base slabs is considered. Finite elements are used for the liquid and tank wall, idealized as a thin shell. For steel tanks of practical dimensions, design charts are presented for natural frequencies, maximum shear and overturning moment on the foundation, and maximum stress resultants in the tank wall. Furthermore, an analytical expression for the superelevation of the free surface is presented.

ISSN:0098-8847    

DOI:10.1002/eqe.4290100310

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe resistance of a soil to horizontal harmonic vibration of a vertical, end bearing pile with circular cross‐section is theoretically investigated. The soil is considered to be a continuum with material damping of the hysteretic type. The motions of the soil and pile are expressed as series, and a resistance coefficient on each term in the series of the pile motion is found. The resistance is found to depend on the excitation frequency, the pile slenderness and on the material properties of the soil. Finally a study of the influence of the parameters is carried ou

ISSN:0098-8847    

DOI:10.1002/eqe.4290100311

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY