Ricky Hwa’s scientific contributions

This document presents the results of the tests of a mechanism that can be used to prevent progressive and catastrophic collapse of steel structures in the event of a blast attack and elimination of one of the exterior columns. The concept that was tested and verified is proposed by the Skilling, Ward, Magnusson, Barkshire (SWMB), Structural and Civil Engineers, Seattle to be used in a new building. The concept consists of placing horizontal cables in the floors and on top of the top flange of the girders along the exterior column line. By using Catenary action of the cables, the load of the eliminated column can be transferred to the rest of the structure. The test specimen was full-scale representative of one floor of a typical steel building structure with its floor slab, steel deck, supporting beams, girders and columns. The specimen was designed by the SWMB and the test set-up was designed jointly by SWMB and UC-Berkeley engineers and researchers. The size of the specimen was 19'x60'x6'. The test plans consisted of constructing the specimen inside the UC-Berkeley, Civil Engineering laboratory in Davis Hall, adding instrumentation to the specimen, removing a middle column, pulling the bam-column joint of the removed column down, observing and collecting data on performance of the structure after removal of the column. A total of four tests were conducted which were 19.8-inch, 21-inch, 24-inch and 35-inch drop of column. The tests indicated that after removal of the column the Catenary action of the cable-supported floor was able to support 110 kips, 140 kips, 160 kips and 190 kips of column load respectively for 19, 21, 24 and 35 inches of drop of the column joint. These load values were based on using hydraulic actuator to apply the load. The corresponding gravity loads that could be applied to the column were 85, 108, 123 and 146 kips.