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Experimentally determined dynamic responses of ten scale models of masonry infilled steel frames were compared with the results of three simple analytical models. Effects investigated included stiffening and strengthening contribution of the masonry infill, degradation of the system, motion intensity, frame stiffness, and rotational joint rigidity at slab-to-column intersections. Tests on one-third scale models, subjected to sinusoidal motions, revealed that masonry infill markedly increases the dynamic strength and stiffness of the system. At weak-to-moderate motions (below 0.5 g), models exhibited a nonlinear response before the final failure, while strong motions accelerated the system degradation rate. Stiffer frames and rotationally rigid joints resulted in significantly increased system dynamic strength. A braced frame model wherein cross-bracing replaces the panel action adequately predicted linear and lower-region nonlinear responses of infilled frames with flexible column-to-slab rotational conditions. Satisfactory predictions of the linear response of framed walls with rigid column-to-slab rotational conditions were made with a single degree of freedom model. The third analytical model based on an equivalent strut technique was found to be unsatisfactory for predicting dynamic response of masonry infilled frames. Key words: masonry panel, steel frame, shear, dynamic, analytical, experimental.

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Recently, the limit states approach using factored strength has been recommended in geotechnical design. Some recent research has indicated that the application of limit states design using recommended load and strength factors leads to conservative designs compared with the conventional methods. In this study the influence of sheet pile wall geometry, type of water pressure distribution, and different methods of analysis on the maximum bending moment and achor rod force are presented. Recommendations are made to make the factored strength design compatible with conventional design. Key words: factored strength, working stress design, ultimate limit state design, anchored sheet pile wall, bending moment, anchor rod force.

A numerical model is presented for predicting the natural frequencies of one-way stiffened plates with ribs having high ratios of flexural to shear rigidity. The model is based on the free interface modal synthesis method. Experimental validation using floors with wood I-joists and wood-based sheathing showed that the model has good numerical accuracy in the predictions of natural frequencies and mode shapes if analyses include shear deformation and rotatory inertia effects in ribs. Neglect of these effects can lead to large errors in the predicted natural frequencies for plates with ribs having high ratios of flexural to shear rigidity. Large errors can also be encountered in natural frequency prediction for plates with fairly low ratios of flexural to shear rigidity. This occurs with mode shapes that have multiple curvature along ribs if shear deformation and rotatory inertia effects are neglected. Key words: free flexural vibration, natural frequencies, ribbed plates, flexural rigidity, shear rigidity, modal synthesis.