Unified Design Method Of Anti-progressive And Anti-seismic Collapse Of RC Frame Structures

Building structures may suffer from gas explosions,terrorist attacks,fire,hurricanes and other abnormal events during its service time,that often cause loacal damage of them.The local damage may result in a chain reaction mechanism spreading through the entire structure,which in turn lead to progressive collapse(PC).Time has witnessed the disastrous consequences of progressive collapses at home and abroad,such as the Ronan Point(London,1968),the bulidings of the World Trade Center(New York,2001)and Fengcheng Power Plant(Yichun,2016).In order to study the progressive collapse mechanism of reinforced concrete(RC)frame structures,a lot of experiments and numerical simulation have been carried out by many researchers all over the word.The influence of structural members such as beams and floors and non-structural members such as infilled walls on the progressive collapse resistance of structures has been discussed through these experiments and numerical simulation.Anti-progressive collapse design is the most effective way to avoid progressive collapse of buildings.In this paper,the anti-progressive collapse design method of RC frame structures is taken as the research object,including:(1)Collection and analysis of the progressive collapse tests of RC frame structures.A total of 49 double-span beam continuous collapse tests were collected,then the relationship between the load carrying capacity characteristics and deformation characteristics of these specimens and the beam span-height ratio is analyzed and a simple method for judging the ultimate deformation capacity of the double-span beams under PC is given.The fundamental characteristics of the PC resistance of the beam-slab substructures are given through analysis of the capability curve and failure characteristics of beam-slab substructures with different column removal conditions.It is found that RC plane frame with infills has higher stiffness and strength than without it through releated tests.The infills change the failure mode of the frame beam,but does not affect the ultimate deformation capacity of the specimen.(2)Development of methods for estimate the PC resistance of RC frame structures.The calculation method of the load carrying capacity of double-span beams in the arch action stage is collected.Define the peak load carrying capacity in compressive arch action(CAA)stage of RC double-span beam as its PC resistance and improving the method to estimate the CAA capacity of double-span beam so it will be easier.The method to determine the PC resistance of beam-slab substructures under different column removal conditions is given and a simplified linear model for calculating the PC resistance of substructures under the condition of demolishing side columns and middle columns is proposed.Single strut model of infill wall in RC frame structures is given and used in the computational procedure of the peak bearing capacity of RC plane frame with full height or partial infill wall.(3)Analysis of anti-progressive collapse performance of RC frame structure.The proposed simplified linear model in this paper is used to calculate the progressive collapse resistance of a test structure to verify the accuracy of it.The anti-progressive collapse performance of a 6-story RC frame structure was analyzed using numerical method and the results were compared with the calculation results of the simplified linear model to further verify the correctness of it.