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In contrast to the traditional uncertainty quantification of the modal parameters identified from the output‐only measurement data, this study develops an uncertainty propagation and quantification method for structural flexibility identified from input–output measurement data and then uses the derived flexibility matrix for structural reliability analysis. First, a novel procedure for variance estimations of the complete system matrix of the state‐space model is derived based on first‐order perturbation theory. Then, the mode scaling factors and integrated modal flexibility are subsequently derived and quantified. Finally, the predicted displacements and their uncertainty intervals are used to implement the reliability analysis in terms of the structural displacement serviceability limit state (SLS). The accuracies of the derived expressions are verified by a numerical example through the comparison of variance values estimated from Monte Carlo simulations. The simulation example also indicates that we can expect to identify structural parameters with higher reliability if the input force to the structure is measured, and the identified modal scaling and corresponding flexibility matrix undergo more uncertainty than those of the modal parameters. Finally, we apply the proposed uncertainty quantification method to a scaled three‐story frame structure to demonstrate its practicability. The proposed method bridges a gap between the identified structural flexibility and structural reliability analysis directly by the probability category. [ABSTRACT FROM AUTHOR]

Shape optimization is a pervasive tool for designing concrete free-form shells. However, the existing shape optimization approaches for free-form shells usually assume the material is purely elastic without considering material damage, which may produce undesired results in real-world structural applications, especially in the case of concrete structures. In this article, a framework is presented for performing the shape optimization of concrete free-form shells while considering concrete damage. In the proposed optimization algorithm, the Mazars model is coupled with finite element analysis for modelling structural responses subjected to material damage. Through a series of numerical examples, the proposed algorithm is validated and the effects of material damage on optimal results are investigated. It is demonstrated that the consideration of material damage leads to a more robust design, which highlights the importance of accounting for the material damage during the shape optimization process of concrete free-form shells. [ABSTRACT FROM AUTHOR]

To overcome the cumbersome of the vehicle-bridge interaction system when imposing road roughness, a fast-modeling method for the vehicle-bridge interaction system was proposed. The bridge displacement and the road roughness were applied to the vehicle system as the boundary condition. The vehicle loads were applied to the bridge system as the input. The interaction between the vehicle and the bridge was achieved simply and effectively. To verify the accuracy of the proposed method, a two-dimensional simulation model for the vehicle-bridge interaction system considering the vehicle speed and the road roughness was established, and the simulation results were compared with the theoretical solution. The results show that the bridge displacement error is less than 2%, and the bridge acceleration error is only about 4%, indicating that the proposed method can simulate the vehicle-bridge interaction system fast and accurately and the road roughness can be simulated effectively. It provides new guidance for modeling the vehicle-bridge interaction system. [ABSTRACT FROM AUTHOR]

A self-anchored suspension bridge balances forces internally without external anchorage requirements, making it suitable for sites where anchorages would be difficult to construct. It often adopts either a full-floating or a semi-floating tower-girder connection system, which may result in large displacement responses along bridge longitudinal direction during earthquakes. This study investigated the efficacy of using the fluid viscous damper (FVD) for seismic control of a single-tower self-anchored suspension bridge. First, the energy dissipation behaviors of the FVD under sinusoidal excitations were studied. It revealed that besides the damper parameters (i.e. damping coefficient and velocity exponent) of an FVD itself, the energy dissipation capacity also relies on the characteristics of external excitations. Therefore, optimum damper parameters added to a structure should be determined on a case-by-case basis. Parametric study was then carried out on the prototype bridge, which indicated a tendency of decreasing the longitudinal deck/tower displacements and tower forces with increasing damping coefficient C and decreasing velocity exponent α. Compared with the linear FVD, the nonlinear FVD with a smaller velocity exponent can develop more rectangular force-displacement loops and thus achieve better energy dissipation performance. With selected optimum damper parameters (i.e. C = 3 0 0 0 kN ⋅ m − 0. 3 s 0. 3 and α = 0. 3) for the two FVDs added between the deck and the tower, the longitudinal deck and tower displacements could be reduced by 54%, while the peak bending moment and shear force at the tower base could be reduced by 30% and 19%, respectively. It is concluded that the nonlinear FVD can provide a simple and efficient solution to reduce displacement responses of self-anchored suspension bridges while simultaneously reducing the bending moment and shear force in the tower. [ABSTRACT FROM AUTHOR]