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Article
Publication date: 1 May 1992

LIN JIAHAO and F.W. WILLIAMS

Because of the extensive use of long‐span structures in modern engineering, much attention has been given to the extent to which ground motion phase‐lags affect the…

Abstract

Because of the extensive use of long‐span structures in modern engineering, much attention has been given to the extent to which ground motion phase‐lags affect the internal forces of such structures. In this paper, this problem is studied from the aspect of random seismic analysis, i.e. the random seismic responses of long‐span structures are explored with the phase‐lags of the ground joints of the structures taken into account. The earthquake is regarded as a stationary random process. Formulae for calculating the random responses of the structural displacements and internal forces are derived. Numerical examples are presented which illustrate some basic features of such random response, and also show that the ground motion phase‐lags have considerable effects on structural safety analysis.

Details

Engineering Computations, vol. 9 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 4 March 2016

Pan Xiang, Yan Zhao, Jiahao Lin, D Kennedy and Fred W Williams

The purpose of this paper is to present a new random vibration-based assessment method for coupled vehicle-track systems with uncertain parameters when subjected to random…

Abstract

Purpose

The purpose of this paper is to present a new random vibration-based assessment method for coupled vehicle-track systems with uncertain parameters when subjected to random track irregularity.

Design/methodology/approach

The uncertain parameters of vehicle are described as bounded random variables. The track is regarded as an infinite periodic structure, and the dynamic equations of the coupled vehicle-track system, under mixed physical coordinates and symplectic dual coordinates, are established through wheel-rail coupling relationships. The random track irregularities at the wheel-rail contact points are converted to a series of deterministic harmonic excitations with phase lag by using the pseudo excitation method. Based on the polynomial chaos expansion of the pseudo response, a chaos expanded pseudo equation is derived, leading to the combined hybrid pseudo excitation method - polynomial chaos expansion method

Findings

The impact of uncertainty propagation on the random vibration analysis is assessed efficiently. According to GB5599-85, the reliability analysis for the stability index is implemented, which can grade the comfort level by the probability. Comparing to the deterministic analysis, it turns out that neglect of the parameter uncertainty will lead to potentially risky analysis results.

Originality/value

The proposed method is compared with Monte Carlo simulations, achieving good agreement. It is an effective means for random vibration analysis of uncertain coupled vehicle-track systems and has good engineering practicality

Details

Engineering Computations, vol. 33 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 November 1997

Jiahao Lin, Jianjun Li, Wenshou Zhang and F.W. Williams

Proposes a new approach for analysing the stationary random response of complex structures located in a non‐homogeneous stochastic field. The approach is a kind of…

Abstract

Proposes a new approach for analysing the stationary random response of complex structures located in a non‐homogeneous stochastic field. The approach is a kind of complete CQC method because the cross‐correlation terms between both the participant modes and the ground joint excitations are included in the response calculations. Also takes into account the effect of the loss of coherency between ground joints.

Details

Engineering Computations, vol. 14 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 21 May 2021

Xiang Gao, Jiahao Gu and Yingchao Zhang

This paper aims to investigate whether single-name options trading prior to earnings announcements is more informative when there exist real activity manipulations.

Abstract

Purpose

This paper aims to investigate whether single-name options trading prior to earnings announcements is more informative when there exist real activity manipulations.

Design/methodology/approach

Using 5,419 earnings announcements during 2004–2018 made by 208 public US companies with relatively high options volumes ranked by the CBOE, the authors uncover two regularities using predictive regressions for stock return.

Findings

First, the total options volume up to twenty days pre-announcement is significantly higher than that in other periods only for earnings management firms; moreover, after detailing options characteristics, the authors find these intensive pre-announcement trading to be concentrated in transactions of in-the-money call and long-term maturity put options. Second, an increase in the single-name call minus put options volume can positively predict the underlying stock’s next-day excess return much better in real earnings management firms, with a larger magnitude of effect in periods right before regular earnings announcement dates.

Originality/value

This paper makes a marginal and novel contribution by showing that real earnings management can serve as a proxy for the potential profit from informed trading in options as the return predictability of options volume becomes stronger for firms that have the manipulation motive and indeed perform manipulative actions.

Details

Pacific Accounting Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0114-0582

Keywords

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