A Bayesian methodology to construct probabilistic seismic demand models for the components of a s... more A Bayesian methodology to construct probabilistic seismic demand models for the components of a structural system is developed. Existing deterministic models and observational data are used. The demand models are combined with previously developed capacity models for reinforced concrete (RC) bridge columns to estimate the seismic fragilities of bridge components and systems. The approach properly accounts for all relevant uncertainties, including model error. Application to two bridge examples typical of modern California practice is presented.
To improve the accuracy of the assessment for existing bridge performance, evaluating upto-date s... more To improve the accuracy of the assessment for existing bridge performance, evaluating upto-date structural properties is essential. In this paper, we propose a methodology to update the structural properties of a bridge using modal data. Modal data can be easily extracted from a vibration testing conducted on a bridge, making the proposed methodology of practical value. There are three steps in the developed framework for an existing bridge: 1) to build a preliminary finite element model (FEM) based on the bridge design drawings; 2) to update the preliminary FEM to a baseline model using a Bayesian model updating approach with the modal parameters measured from the existing bridge; and 3) to identify local structural stiffness damage using the damage index method with the mode shapes of the existing bridge and of the baseline structure found in the previous step. The proposed framework makes use of the advantages of the Bayesian model updating method and the damage index method, compensating for their drawbacks. Then the proposed framework is illustrated with a simulated finite element model of the Lavic Road Overcrossing bridge, a typical box-girder RC highway bridge in California.
This paper proposes a probabilistic formulation to assess the effectiveness of the fiber reinforc... more This paper proposes a probabilistic formulation to assess the effectiveness of the fiber reinforced polymer (FRP) retrofit schemes in enhancing the structural performance of reinforced concrete (RC) bridge columns. Two probabilistic models are proposed to predict the deformation capacities of retrofitted columns. One deformation model corresponds to the flexural failure and the other considers the bond failure in the lap-splice region. A Markov Chain Monte Carlo (MCMC) simulation method is used to estimate unknown model parameters in the context of a Bayesian updating approach. The probabilistic capacity models are used to estimate the fragility curves of three example columns. In this paper, fragility is defined as the conditional probability of failure for given deformation demand. The results compare the column fragilities before and after the application of the retrofit measure. The results from the example columns indicate that the use of FRP composites considerably reduced the fragility for the bond failure mode and is also beneficial but with a moderate impact when considering the flexural failure.
A Bayesian methodology to construct probabilistic seismic demand models for the components of a s... more A Bayesian methodology to construct probabilistic seismic demand models for the components of a structural system is developed. Existing deterministic models and observational data are used. The demand models are combined with previously developed capacity models for reinforced concrete (RC) bridge columns to estimate the seismic fragilities of bridge components and systems. The approach properly accounts for all relevant uncertainties, including model error. Application to two bridge examples typical of modern California practice is presented.
To improve the accuracy of the assessment for existing bridge performance, evaluating upto-date s... more To improve the accuracy of the assessment for existing bridge performance, evaluating upto-date structural properties is essential. In this paper, we propose a methodology to update the structural properties of a bridge using modal data. Modal data can be easily extracted from a vibration testing conducted on a bridge, making the proposed methodology of practical value. There are three steps in the developed framework for an existing bridge: 1) to build a preliminary finite element model (FEM) based on the bridge design drawings; 2) to update the preliminary FEM to a baseline model using a Bayesian model updating approach with the modal parameters measured from the existing bridge; and 3) to identify local structural stiffness damage using the damage index method with the mode shapes of the existing bridge and of the baseline structure found in the previous step. The proposed framework makes use of the advantages of the Bayesian model updating method and the damage index method, compensating for their drawbacks. Then the proposed framework is illustrated with a simulated finite element model of the Lavic Road Overcrossing bridge, a typical box-girder RC highway bridge in California.
This paper proposes a probabilistic formulation to assess the effectiveness of the fiber reinforc... more This paper proposes a probabilistic formulation to assess the effectiveness of the fiber reinforced polymer (FRP) retrofit schemes in enhancing the structural performance of reinforced concrete (RC) bridge columns. Two probabilistic models are proposed to predict the deformation capacities of retrofitted columns. One deformation model corresponds to the flexural failure and the other considers the bond failure in the lap-splice region. A Markov Chain Monte Carlo (MCMC) simulation method is used to estimate unknown model parameters in the context of a Bayesian updating approach. The probabilistic capacity models are used to estimate the fragility curves of three example columns. In this paper, fragility is defined as the conditional probability of failure for given deformation demand. The results compare the column fragilities before and after the application of the retrofit measure. The results from the example columns indicate that the use of FRP composites considerably reduced the fragility for the bond failure mode and is also beneficial but with a moderate impact when considering the flexural failure.
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Papers by Qindan Huang