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STATIC AND DYNAMIC BEHAVIOR OF PINNED-BASE PORTAL FRAMES.
NAVAL CIVIL ENGINEERING LAB PORT HUENEME CALIF
Tests were performed on four steel portal frames, 8 feet high and 12 feet long, fabricated from 12WF27 rolled sections. The frames were constant in cross section and hinged at their bases. Maximum static and dynamic loads of 75,000 and 80,000 pounds, respectively, were applied over one column of each frame to simulate a horizontal, travelling, blast wave. The rise times of the dynamic loads were approximately 2 to 3 milliseconds. The loads then decayed exponentially to zero in about 1 second. An equivalent triangular load-time function was used for analysis. After several dynamic loads were placed on one column of one frame, the opposite column was loaded to determine the effect of repeated and reversed loading. The applied loads and the resulting deflections, strains, and accelerations were measured. The reduced data are presented in graphical and tabular forms. The multiplemode, the simplified, and the response-chart methods of dynamic analysis were performed, and the results were compared with the experimental values. The multiple-mode analysis proved to be the only method that can be used to predetermine the locations of plastic hinges, however, the single-degree of-freedom system adequately described the maximum displacement of the frame in both the elastic and inelastic ranges. Good correlation was obtained between theoretical and experimental values for both the static and dynamic tests. The dynamic response factor and the dynamic shear factors were 1.9 and 1.4 respectively. Author
Final rept. for Mar-Oct 61,