摘要:

AbstractWhereas an increase in material yield stress beyond the code specified characteristic value enhances plastic capacity, it may cause a reduction in overall ductility and energy absorption capability of steel frames. Since quality control of various shapes of sections used on site is difficult to impose, the effect of this random variability on design response parameters should be accounted for in earthquake‐resistant regulations. Moreover, the required weak‐beam/strong‐column design principle in particular, and failure mode control in general, could be undermined if the yield stresses in beam and column assume two opposite extremes in a random sample. This paper addresses the problem of defining the expected range of response parameters in a steel frame with randomly varying yield stress. A simple portal frame is designed using code specified characteristic values and verified by non‐linear transient dynamic analysis. The influence of yield stress variability, including the degree of correlation between beam and column material properties, on several response parameters is assessed through a Monte Carlo simulation study. Results are presented from both univariate and bivariate statistical analyses that quantify the relationship between input (material) and output (response) parameters. Assessment of the interdependence of output parameters given a particular model for yield stress variability is also undertaken. It is shown that certain response parameters exhibit more favourable statistical properties than others. Thus, the implications for seismic code design are discussed in the light of these

ISSN:0098-8847    

DOI:10.1002/eqe.4290200202

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractSimple methods of analysis are developed for computing the dynamic steady‐state axial response of floating pile groups embedded in homogeneous and non‐homogeneous soil deposits. Physically‐motivated approximations are introduced to account for the interaction between two individual piles. It is found that such an interaction arises chiefly from the ‘interference’ of wave fields originating along each pile shaft and spreading outward. For homogeneous deposits the wave fronts originating at an individual pile are cylindrical and the interaction is essentially independent of pile flexibility and slenderness. For non‐homogeneous deposits the wave fronts are non‐cylindrical and ray‐theory approximations are invoked to derive pile flexibility‐dependent interaction functions.Results are presented for the dynamic stiffness and damping of several pile groups, as well as for distribution of the applied load among individual piles. For deposits with modulus proportional to depth, the agreement with the few rigorous solutions available is encouraging. A comprehensive parameter study focuses on the effects of soil inhomogeneity and pile‐group configuration. It is demonstrated that the ‘dynamic group efficiency’ may far exceed unity at certain frequencies. Increasing soil inhomogeneity tends to reduce the respective resonant peaks and lead to smoother interaction functions, in qualitative agreem

ISSN:0098-8847    

DOI:10.1002/eqe.4290200203

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAn Active Mass Driver (AMD) system is proposed to suppress actively the response of a building to irregular external excitations such as earthquakes and typhoons. This system has been introduced to an actual ten‐storey office building for the first time in the world. The system controls the motions of a structure by means of an external energy supply. It consists of an auxiliary mass installed in a building and an actuator that operates the mass and produces a control force which counters disturbances to the building. The design method of the AMD system, including the location of the installation and the capacity and stability of the system, is proposed. Simplification of the control algorithm is also describe

ISSN:0098-8847    

DOI:10.1002/eqe.4290200204

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAn Active Mass Driver (AMD) system is proposed to suppress actively the response of a building to irregular external excitations such as earthquakes and typhoons.1This system has been introduced to an actual ten‐storey office building constructed in Tokyo in August, 1989. The proposed analytical methods utilize circuits of the system and mechanical characteristics to understand the real control effect of the system. Simulation analyses are also performed to verify the analytical model and the control effect during observed earthquake

ISSN:0098-8847    

DOI:10.1002/eqe.4290200205

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractCriteria to be used for the analytical prediction of collapse of R/C buildings subjected to earthquake excitation are suggested. It is attempted to include in the criteria as many of the parameters involved as possible, while keeping the complexity, as well as the cost of analysis reasonably low. Two combined collapse criteria are finally suggested, corresponding to member failure and storey failure. Using these criteria, quantitative estimations can be obtained of the actual values of behaviour factors (q‐factors) used in modern seismic codes. The ground motion dependence of these factors, as well as the sensitivity of their calculated values to the assumption made about the stiffness of R/C members, is illustrated with reference to two typical structure

ISSN:0098-8847    

DOI:10.1002/eqe.4290200206

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAn analytical methodology for estimating the values of behaviour factors (q‐factors), suggested in a companion paper, is applied to two typical reinforced concrete structures, a frame and a dual system, designed according to current European trends in seismic design. The two case studies clearly indicated the need to consider both local and overall collapse criteria, since either one can be critical for the determination of the behaviour factor, depending on the type of the structure. The calculated values ofq‐factors were close to, but higher than those specified by modern seismic codes, the larger discrepancy occurring in the case of the dual sys

ISSN:0098-8847    

DOI:10.1002/eqe.4290200207

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWhen solving the equations of structural dynamics using direct time integration methods, algorithmic damping is useful to control spurious high‐frequency oscillations. Ideally, an algorithm should possess asymptotic annihilation of the high‐frequency response, i.e. spurious oscillations are eliminated after one time step. Numerous one‐step algorithms, spectrally equivalent to linear multistep (LMS) methods, have been developed which include controlled numerical dissipation. This paper proves that the only unconditionally stable, second‐order accurate, 3‐step LMS method possessing asymptotic annihilation is Houbolt's method, which is known to be overly dissipative in the low‐frequency regime. Thus, using LMS methods, obtaining asymptotic annihilation with little low‐frequency dissipation requires at least a

ISSN:0098-8847    

DOI:10.1002/eqe.4290200208

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290200209

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290200201

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY