Editor’s Note

“Limitations in Structural Identification of Large Constructed Structures” by Catbas et al. discussed issues related to the system identification of a long-span bridge using detailed finite element modeling of the system. It is shown that a reasonable level of confidence can be achieved with a model that is calibrated using local and global structural monitoring data with a sufficiently high spatial resolution. A method for “Multiresponse Parameter Estimation for Finite-Element Model Updating Using Nondestructive Test Data” is developed by Bell et al. using both stiffness-based and mass-based error functions. An error function normalization technique that can mitigate some of the numerical issues encountered during the parameter estimation procedure is also developed. Application of the multiparameter estimation is demonstrated using available experiments on a benchmark laboratory grid model of a bridge deck. The development of a “Reference-Free NDT Technique for Debonding Detection in CFRP-Strengthened RC Structures” is presented by Kim et al. Debonding is detected without relying on past baseline data. The proposed diagnosis is based on the concept of time reversal acoustics. The potential of the proposed method is verified experimentally using monotonic and fatigue tests of large scale CFRP strengthened concrete beams.

The “Reliability Evaluation of Vehicle-Bridge Dynamic Interaction” is investigated by Xiang, Zhao, and Xu using a time domain transfer matrix method. An iterative scheme is adopted to deal with the coupled terms in the resulting dynamic equations of motion. The dynamic reliability of the bridge-vehicle system is studied using the first order reliability method in conjunction with the transfer matrix method. A technique for evaluating the seismic performance of structures by integrating physical and numerical simulations of substructures into a single test model is described in a two-part paper, “Real-Time Error Monitoring for Hybrid Simulation” by Mosqueda, Stojadinovic, and Mahin. The first part introduces the methodology and presents an energy-based error monitoring method that predicts the reliability of the test results in real-time. In the second paper, numerical simulations with induced systematic and random errors are used to study the effects of experimental error on the linear and nonlinear seismic response of structures, and to examine the relationship between the proposed energy-based error monitors and other common performance measures. A new “Evolutionary Parameter Hysteretic Model for Wood Shear Walls” and its application in the development of seismic fragility curves is demonstrated by Pang et al. The proposed model is validated using the results of two full-scale shake table tests and eight cyclic shearwall tests with varying wall configurations and loading protocols.

The “In-Plane Stability of Parabolic Arches with Horizontal Spring Supports” is evaluated in a two-part paper by Bradford et al. The first paper provides solutions for the in-plane antisymmetric bifurcation buckling load and the symmetric snap-through buckling load for shallow arches. The effects of the stiffness of the horizontal springs on the buckling behavior is also investigated. The companion paper reports short-term experimental studies on two shallow parabolic reinforced concrete arches whose supports are connected by a steel tie. The load deflection response and buckling loads are compared to theoretical predictions. Overend, Parke and Buhagiar compare the mathematical formulations of a number of existing failure prediction models in “Predicting Failure in Glass—A General Crack Growth Model.” A general crack growth model based on statistical failure theory is proposed and the performance of the proposed model along with other available models is investigated by comparison with physical and numerical simulations. The proposed model is shown to provide the basis for an accurate and automated method to determine the tensile strength of glass subjected to static loads for generalized geometry and varying support conditions.

van de Lindt and Dao present a concept for the formulation of an “Evolutionary Algorithm for Performance-Based Shear Wall Placement in Buildings Subjected to Multiple Load Types.” By modeling the shear wall structure as a mechanism with genes, and applying an evolutionary algorithm within the searching process, the authors demonstrate the efficiency and robustness of the optimization methodology for complex nonlinear problems. The proposed algorithm coupled with a three-dimensional finite element model is shown to have promise for many building subassemblies and components beyond shear walls.

The issue includes four technical notes. The first of these, by Luo, Xu, and Wu, deals with the development of an “Accurate Stiffness Matrix for Nonprismatic Members” using the transfer matrix method. Improving the performance of structural components is the overall objective of Pan, Ohsaki and Tagawa’s paper “Shape Optimization of H-beam Flange for Maximum Plastic EnergyDissipation.” Global optimal solutions are obtained through a process called simulated annealing in conjunction with nonlinear finite element analysis. The next technical note investigates the parameter identification problem of a linear dynamic system using “Biased Modal Estimates from Random Decrement Signatures of Forced Acceleration Responses” and is authored by Ku, Cermak, and Chou. The last technical note, by Zhu and Law, evaluates the “Nonlinear Characteristics of Damaged Reinforced Concrete Beam from Hilbert-Huang Transform.” The time history of the instantaneous frequency of the beam, obtained from the decomposition of the vibration signal into an intrinsic mode function, is found to correlate with the opening and closing of cracks.