Research On Collapse Performance Of Prefabricated Concrete Structure

With the development of China’s economy and society,the industrialization of construction and assembly has actually become more apparent.And the prefabricated frame structure has the characteristics of high-quality components,short construction time and low environmental pollution.Compared with the traditional cast-in-place concrete structure,the overall stress performance of fabricated concrete structures,especially the collapse resistance,has gradually attracted the attention of scholars.Under the occasional load,the destruction of local structural members may cause the overall collapse of the structure.Due to the various structural measures of the fabricated structure,there are many factors affecting its collapse performance,and its progressive collapse resistance remains to be studied.In response to the above problems,this paper has carried out the following research work on the progressive collapse performance of the prefabricated concrete frame structures:(1)Designed six single-story and double-span reinforced concrete structures with 1/4 scale,including one cast-in-place structure,five prefabricated structures.Simulate the dynamic collapse of the structure by quickly removing the pedestal under the center column.The experiment results show that,the dynamic response of prefabricated structure is less than that of cast-in-place structure through DIF(35),experiments show that the DIF(35)of prefabricated structures are between 1.04 and 1.40,which can provide a reference for the design of the dynamic collapse in the future.Increasing the span will reduce the dynamic response of the structure and shorten the distance between the splicing area and the side column and applying prestress will increase the dynamic response of the structure;after the experiment,the fundamental frequency of prefabricated structure has been reduced by 64.9% higher than that of the cast-in-place structure,indicating that the prefabricated structure has greater damage during dynamic collapse,the large span and changing the position of the splicing area cause the fundamental frequency of structures to drop by 76.5% and 69.7%,respectively,indicating that the damage of structure under load impact is more serious.Experimental results show that this prefabricated structures have desirable strength to mitigate progressive collapse.(2)Using software ANSYS/LSDYNA to establish fourteen prefabricated frame structures to conduct comprehensive parameter study.The simulation results show that compressive arch action and catenary action will be mobilized successively to resist progressive collapse.Increasing the reinforcement ratio and pre-stressed specimens in the prefabricated segment can make ultimate load increase by 13%;increasing the structural span-to-height ratio can postpone the failure time of prefabricated column segment reinforcement and reinforcement strength of prefabricated beam segments developed more fully,therefore,the ultimate load of the specimen with the largest span increased by 11.4%.The position of the splicing area has a little effect on the load mechanism,but it will affect the deformation of the structure,if the position of the splicing area moves away from the frame column,the structural ultimate load can increase by 24.3%.Compared with the DIF(35)of structures obtained by dynamic experimental measurement between 1.04～1.40,using energy method to calculate the DIFp of structures in static experiment are between 1.11～1.80,the results obtained by the two calculation methods are less than the recommended values.(3)Eight prefabricated reinforced concrete frame structures are established through parameters about span-to-height ratio and position of splicing area to analyze the collapse resistance of structures and the internal force of stressed members.The result shows that,more floors will restrict the final deformation of structure,which has a weaker effect on large span;changing position of splicing area will not affect mechanical performance but it will reduce final deformation of structure;the stress performance of adjacent structure in the failure area changes with the number of floors,the lower floor is affected by structure force transmission mechanism,and the upper floor is affected by structural deformation;the internal force of the remaining structure is only redistributed in the same floor;the internal force of bottom column is significantly improve after center column has failed,and the strength reserve of bottom column should be increased.The research work in this paper can provide reference for collapse resistance of fabricated structures with similar assembly method.