A Fast Method For Evaluating Progressive Collapse Resistant Ability Of Steel-Frame Structures Under Blast Loading

Recently, explosion happens more frequently than ever all over the world. Whenthe building structure is subjected to blast loading, some important columns will bedamaged seriously, and the blast load will even cause progressive collapse of thebuilding structure, leading to a great deal of casualties and property loss. The commonnumerical method for assessing progressive collapse resistant ability of entirestructures is Alternate Load Paths Method and Direct Simulation Method, which bothrequire complicated modeling work of the whole building and extremelytime-consuming calculation. In this paper, the sub-structure method is combined withtwo methods for rapid evaluation of progressive collapse resistant capacity for steelframe structures. The main work and conclusions of this thesis are presented as thefollowing.(1)Assume that a column is damaged when the building structure is subjected toblast loading, allowable collapse regions caused by the failure of the column are givenin this paper. The principles of sub-structure selection applying to Alternate LoadPaths Method are proposed based on this. And the principles of choosingsub-structure applying to direct simulation method are proposed according toallowable collapse regions, damage evaluation and ratio of explosion energy.(2) There are complex interactions between the sub-structure and the reststructure. The effect of the rest structure acting on the sub-structure is simulated bysprings. Besides, to simulate the force between the sub-structure and the rest structure,loads are applied to the boundaries of the sub-structure. Considering thecharacteristics of Alternate Load Paths Method and Direct Simulation Method, themethods to obtain stiffness of the springs and loads are proposed in this paper.(3) Progressive collapse resistant capacity analyses of two five-storey steelframes are carried out using both the Alternate Load Paths method and the proposedmethod, and evaluate the progressive collapse resistant ability using the judgmentrules of progressive collapse and the evaluation methods of progressive collapseresistant ability applying to steel frame structures which is given in this paper. Theresults show that the proposed method could assess the progressive collapse resistantcapacity of the whole structure reliably and accurately with high computationefficiency.(4) Analysis of a five-storey steel frame is carried out using Direct Simulation Method and the method introduced in this paper, and evaluate the progressive collapseresistant ability using the judgment rules of progressive collapse and the evaluationmethods of progressive collapse resistant ability applying to steel frame structureswhich is given in this paper. The result shows that under the same conditions, dynamicresponse, the limit TNT equivalent weight and damage situation of the sub-structure isconsistent with the entire structure. And the example shows that the sub-structuremethod is very effective in increasing the computing efficiency, so the progressivecollapse resistant ability of the entire structure can be assessed simply and quickly.