Karoumi, Raid

Thumbnail Image
Preferred name
Karoumi, Raid
Official Name
Karoumi, Raid

Research Output

Filters

3
Reset filters

Settings

Now showing 1 - 3 of 3
  • Publication
    Calculating an Influence Line from Direct Measurements
    (Institution of Civil Engineers, 2006-03)
    O'Brien, Eugene J. 
    ;
    Quilligan, Michael 
    ;
    Karoumi, Raid 
    The response of a bridge to a pre-weighed truck can be measured on site. This paper describes a mathematical method for converting the measured response of a load effect into an influence line for that effect. One influence ordinate is calculated for each scan of the data acquisition system. The vector of ordinates is found by solving a large set of simultaneous equations expressed in matrix form. The general form of the matrices is described, and the particular matrices for a three-axle truck are given. The technique is demonstrated using measured strain on two bridges using pre-weighed trucks with different numbers of axles.
      1581
  • Publication
    Estimation of nonlinearities from pseudodynamic and dynamic responses of bridge structures using the Delay Vector Variance method
    (Elsevier, 2016-01-01)
    Jaksic, Vesna 
    ;
    Mandic, Danilo P. 
    ;
    Karoumi, Raid 
    ;
    Basu, Biswajit 
    ;
    Pakrashi, Vikram 
    Analysis of the variability in the responses of large structural systems and quantification of their linearity or nonlinearity as a potential non-invasive means of structural system assessment from output-only condition remains a challenging problem. In this study, the Delay Vector Variance (DVV) method is used for full scale testing of both pseudo-dynamic and dynamic responses of two bridges, in order to study the degree of nonlinearity of their measured response signals. The DVV detects the presence of determinism and nonlinearity in a time series and is based upon the examination of local predictability of a signal. The pseudo-dynamic data is obtained from a concrete bridge during repair while the dynamic data is obtained from a steel railway bridge traversed by a train. We show that DVV is promising as a marker in establishing the degree to which a change in the signal nonlinearity reflects the change in the real behaviour of a structure. It is also useful in establishing the sensitivity of instruments or sensors deployed to monitor such changes.
      418Scopus© Citations 9
  • Publication
    Maximum total load effects in vehicle-bridge dynamic interaction problems for simply supported structures
    (European Association for Structural Dynamics, 2014-07-02)
    Cantero, Daniel 
    ;
    Karoumi, Raid 
    ;
    O'Brien, Eugene J. 
    This paper quantifies the underestimation of bending moment that results from exclusively considering the mid-span section of bridges when calculating vehicle-bridge dynamic interaction. A numerical model of a simply supported Euler-Bernoulli beam, traversed by a 1-DOF vehicle, is used to evaluate the differences. The simplicity of the model is justified by the additional insight that the results provide on the complex vehicle-bridge interaction problem. The results are presented using three dimensionless parameters that uniquely define the solution, taking into account the coupled system (vehicle and beam) frequencies and masses as well as the velocity of the passing vehicle. The results show that the overall maximum load effect occurs in the vicinity of the mid-span section and can be of significantly higher magnitude when compared to the maximum at mid-span.
      188