Cheng Su

Effect of Slip-Hardening Interface Behavior on Fiber Rupture and Crack Bridging in Fiber-Reinforced Cementitious Composites

AbstractA generic crack bridging model for short fiber-reinforced cementitious composites is developed aiming to analytically account for fiber tensile rupture at the pullout stage and two-way fiber pullout induced by both the slip-hardening interface behavior and the chemical bond and fiber tensile rupture at the debonding stage. Explicit solutions to the current model have been given in this paper. The predicted composite bridging-stress versus crack-opening relations as well as concerned composite characteristics such as the tensile strength and mean postfailure crack opening are shown to reasonably agree with the experimental results for a series of polyvinyl alcohol fiber-based engineered cementitious composites. The influence of slip-hardening interface behavior on fiber rupture and crack bridging is clarified by comparing current model with a previous model. It is found that the slip-hardening interface behavior-induced fiber rupture can significantly govern the crack bridging behavior, and it is e...

Aerostatic Reliability Analysis of Long-Span Bridges

The response surface Monte Carlo method (RSMCM) is proposed for reliability analysis of aerostatic response and aerostatic stability for different types of long-span bridges, in which the nonlinear effects due to geometric nonlinearity and deformation-dependent aerostatic loads are taken into consideration. The geometric parameters, the material parameters, and the aerostatic coefficients of the bridge girder are regarded as random variables in the proposed method. RSMCM has higher accuracy in comparison with the traditional response surface method and requires much less computational cost than the conventional Monte Carlo method. The proposed method is applied to reliability analysis of aerostatic response and aerostatic stability of the Hong Kong Ting Kau Bridge, and reasonable results illustrating effectiveness of the method are obtained.

Fast Equivalent Linearization Method for Nonlinear Structures under Nonstationary Random Excitations

AbstractAn efficient analysis procedure has been developed for the random vibration analysis of nonlinear structures subjected to nonstationary random excitations based on the equivalent linearization method and the time-domain explicit formulation method. When the equivalent linearization method is used for the nonstationary random vibration analysis of a nonlinear structural system, equivalent linear systems are constructed for different time instants and the analysis problem is transformed to a series of analyses of these linear systems. Because a large number of linear analyses must be conducted to get reliable results for the original nonlinear system, efficiency of the analysis algorithm for the linear analysis is crucial for its successful application. The time-domain explicit formulation method, recently proposed for the nonstationary random vibration analysis of linear systems, has much higher computational efficiency than other methods owing to the use of explicit expressions of dynamic response...

Green’s Function Method for Stability Analysis of Stochastic Structures

AbstractThe governing equations for the stability analysis of stochastic frame structures with small variations of the material and geometry parameters are established for the means and deviations of responses by including first-order terms. Taking advantage of the similarity between these equations and the governing equations for static analysis, a new Green’s function method based on the fundamental solutions for static problems is proposed for the stability analysis of stochastic structures in conjunction with multidomain techniques. The numerical examples presented show that there is good agreement between the results of the proposed method and those from Monte Carlo simulation for small variation situations, and that the new approach is more efficient than the perturbation stochastic FEM. Based on the numerical results, the effects of the covariance type, correlation scale parameter, coefficient of variation, and discretization of random fields, as well as the location of fictitious loads, are invest...

Reliability-Based Damage Identification Using Dynamic Signatures

AbstractBecause of the influence of the stochastic nature of structural properties and field measurements, the identification result of damage extent is, in essence, uncertain, causing possible deviations and affecting the reliability of the identification result. To give a probabilistic measure on the identification result of damage extent, a reliability-based damage identification method based on dynamic signatures is proposed in this study. The Monte Carlo simulation in conjunction with the response surface method is used to perform the reliability analysis of damage identification with given accuracy, and a trial-and-error procedure is proposed for conducting damage identification with acceptable reliability. The influence of both structural uncertainties and measurement noises on damage identification can be taken into account in the present approach. Meanwhile, the proposed method is capable of assessing the robustness of different types of dynamic signatures against noise and the sensitivity of var...

Analysis of Geometrical Non-Full-Similar Scale Model Based on Similarity Theorem

Applying similarity theory to study the characteristics of scale model for getting agreement between scale model test and prototype test. On the basis of the theoretical analysis of scale model test, a formula derivation of similarity condition was carried out based on similarity theory. A numerical example for joint of steel beam to CFST (concrete-filled steel tubular) was given to show the accuracy formula of similarity condition. The result showed that error results from non-full-similar geometrical properties was considerable between poorly-proportioned model test and prototype. For getting good agreement between scale model test and prototype test, the well-proportioned model should be calculated by the formula of similarity condition for the joint of beam to column.

A Spectral Representation Model for Simulation of Multivariate Random Processes

A model is proposed to simulate multivariate weakly stationary Gaussian stochastic processes based on the spectral representation theorem. In this model, the amplitude, phase angle, and frequency involved in the harmonic function are random so that the generated samples are real stochastic processes. Three algorithms are then adopted to improve the simulation efficiency. A uniform cubic B-spline interpolation method is employed to fit the target factorized power spectral density function curves. A recursive algorithm for the Cholesky factorization is utilized to decompose the cross-power spectral density matrices. Some redundant cosine terms are cut off to decrease the computation quantity of superposition. Finally, an example involving simulation of turbulent wind velocity fluctuations is given to validate the capability and accuracy of the proposed model as well as the efficiency of the optimal algorithms.