Research On Key Technologies Of Design And Construction Of Large Span Prestressed Concrete Structure

In recent years,with the continuous development of prestressed concrete technology,prestressed concrete technology has been increasingly used in such ultra-long continuous structures as large convention and exhibition centers,super-large industrial buildings,and large underground garages.Due to the application of prestress,the internal force and stress distribution of the structure change,especially in the prestressed beam-column joint region,the stress change is more complicated;the prestressed concrete beam may have a larger load effect than the normal use phase during the construction phase;The construction technology of prestressed concrete structures is complicated,and it is difficult to avoid various difficulties in construction.Therefore,it is necessary to further study the stress performance of the prestressed concrete structure and the key construction technology.This is not only related to whether the design is reasonable,the construction is safe,but also directly affects the project schedule and cost.This paper is based on the exhibition hall of a convention and exhibition center.The main contents of the research are as follows:(1)Through the theoretical study,the bending moments of the beam ends and the middle span of the prestressed twisted beam under uniform load are provided for the reinforcement of the beam.Design Basis.(2)The two-node lap joint structure adopted by Midas FEA finite element software for prestressed continuous beams(one is the beam side twisted structure form,and the other is the beam top set tooth structure form)to establish a solid model.The stress distribution law of two lap joints is analyzed by contrast analysis.(3)The three different tension sequences of the prestressed secondary beam are analyzed and analyzed by Midas Gen finite element software.The order of tension is applied to the stress and displacement of the side beam,and a reasonable tension sequence is selected.(4)The reinforcement of the prestressed concrete beam-column joints makes the ordinary concrete difficult to pour and the prestressed tendons are easy to lay.Construction problems such as conflicts will be further studied to provideconstruction experience for similar projects in the future.Through the research in this paper,the main conclusions are as follows:(1)When the tension is applied by the beam-side twisting structure,the stress distribution of the joint is more gentle due to the increase of the stress-diffusing region on the beam side;(2)when the beam is used When the top tooth structure is tensioned,the stress curve changes suddenly in the tensioned end due to the change of the section shape,and the internal compressive stress is large due to the local compressive stress.(3)As far as the stress distribution is concerned,the prestressed tendon lap joint of the beam-column joint is better than the beam-side twisted structure.(4)Among the three different tensioning sequences selected,the least affected by the stress and displacement of the side beam is the tensioning sequence from the middle to the ends.(5)For the problem that the primary and secondary beams have more reinforcement,the beam-column joints are densely packed,and the ordinary concrete can not be poured,the self-compacting concrete technology is introduced,and the field test is carried out to verify that the self-compacting concrete meets the expected effect.Used in projects with similar problems in the future.