Analysis Of Design And Construction Of Prestressed Concrete Structure With Large Span

In recent years，the demand for large space of industrial and civil architecturebecome more and more common, as the increasing requirements in function of use andproduction technology. The essence of large space is the floor without frame column,which requires large beam span. Prestressed frame beam can satisfy the requirement ofstress and deformation in case, as far as possible, to increase the span of the beam. Theuse of prestress can change the distribution of internal forces and stress of structures,makes best use of compression performance of high strength concrete and the tensileproperty of high-strength and low-relaxation reinforcement, to take full advantage ofmaterial properties. Additionally, the construction technique of prestressed concretestructures is complex, and load effect of structures in construction stage may be moreintense than normal use stage. Therefore, in-depth understanding of the mechanicalproperties of prestressed concrete structures not only concerns the rationality of designand security of construction, but also affects the project cost directly.In this thesis, a school multi-purposed teaching building which is a long spanprestressed concrete structure with beam-slab floor in Hefei is used as an engineeringexample. And the following contents are the key areas to explore in depth in thisarticle:Firstly, select the structure layout of large span concrete floor. According to differentways of behave, the author use three kinds of structural forms,(includingunidirectional prestressed primary and secondary beam structure, unidirectionalprestressed lattice girder structure and Bi-directional prestressed lattice girder structure)and six kinds of structure distributions for the long-span prestressed concrete floorstructure. Calculate the internal force and deformation of each structure form in orderto understand the mechanical properties and economic indicators.Secondly, build up finite element model for the whole structure, calculateprestressing effect with equivalent load method, do static elastic-plastic analysis of thestructure, to calculate seismic elastic-plastic reaction of prestressed concrete framestructure, find out sequence of appearance of member plastic hinge, and grasp failureshapes of structure and situation of each member at that time, to give a briefassessment to seismic capacity of the structure and conclude that prestressed latticegirder floor is the best program for those structure of similar spans in two directions.Thirdly, analysis the stress of the long-span prestressed concrete structure at construction phase, finding out that stress state in the process of construction isinconsistent with the design, even larger internal force and deformation would happento several members, this requires us to focus on and monitor during construction phase,then analysis and compare stress and deformation under different tension sequence ofprestressed beam to find a tension sequence with reasonable cost and convenientconstruction.At last, calculate duct wall friction coefficient μ and pipe local deviation coefficientk through monitoring prestress loss during actual tension process, compare them withvalue specified in code for design of concrete structure, and analysis factors that affectμ and k, furthermore, make some suggestions for its value.