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A practical and efficient optimization procedure for designing reinforced concrete frame structures with improved resistance to seismic loading was developed. The design methodology used the optimality criteria method in an iterative analysis-and-redesign scheme. A damage ratio–based procedure was proposed by employing the inelastic component rotations from nonlinear dynamic analysis to strengthen the severely damaged components in each iteration. The optimization approach is intuitive, simple, and easy to apply, since only analysis tools are required. The approach was applied to optimize the seismic response of two prototype frames, and sensitivity analysis established the relationship between seismic performance and the additional material cost of strengthening. The proposed method can substantially reduce the maximum interstory drift for a slight increase of material cost, indicating that the proposed method is a feasible design procedure for improving the earthquake resistance of reinforced concrete frame structures. Also, the procedure can deal with the cases of single and multiple ground motions. The effectiveness of the proposed method was also verified through extensive time-history analyses. [ABSTRACT FROM AUTHOR]

With a scale of 1:100, an experimental model was set up to investigate the dynamic responses of a bridge tower subjected to ocean waves and wave-currents. The bridge tower was designed for a sea-crossing bridge. Based on a pile-group foundation, it was designed to be a typical gate-type structure. Wave-induced base shear forces on the foundation and motion responses of the tower were measured and analyzed. The experimental results show that when a wave period is close to the natural period of the structure, an obvious resonance will be induced on the structure. For different wave action angles, the longitudinal incident waves induced the largest longitudinal base shear forces on the foundation and the greatest dynamic motions on the upper tower of the structure. Because of the pile-group effectiveness, the incident directions of the waves and the wave periods affect the acting forces on the foundation of the structure. For wave-current actions, forward currents increase the forward wave forces on the foundation and decrease the backward forces, but do not significantly affect the motion responses of the upper tower. The experimental results can be used as the verification data for numerical calculations. With the structural forms of the pile-group and the gate-type tower being typical, the results given in this study can be used as a reference for similar engineering designs. [ABSTRACT FROM AUTHOR]

Realistic problems restrict the application of many existing structural damage detection methods. Due to the requirement of a comparison between two system states, lack of appropriate baseline data may become one of the limitations to undertake structural health monitoring strategy. This article suggests a non-baseline damage detection approach based on the mixed measurements and the transmissibility concept and demonstrates it in truss structures. The algorithm uses the measurement data from the strains of the truss elements and the displacements of the truss joints, in which the displacements are utilized to estimate the baseline strains based on the transmissibility matrix from an initial finite element model. Wavelet-based damage-sensitive features are extracted from both estimated and measured strains to detect damages of the target elements. Numerical and experimental studies are performed to investigate the feasibility and effectiveness of the proposed approach. It is concluded from the instances that the robustness of the algorithm is realized when handling the measurement noise, modeling errors and the operational condition variability. These permit the potential development of the damage detection method for real structures in site. [ABSTRACT FROM AUTHOR]