Research On Key Technologies For Prefabricated Concrete Frame Structure Based On Rapid Construction

Under the background of building industrialization,informatization and intelligence,the disadvantages of traditional concrete structure construction modes in industrial technology,resource and energy utilization,environmental protection,etc.are increasingly prominent,which are already quite difficult to adapt to the development requirements of China’s construction industrialization,and it is urgent to change the traditional construction modes of concrete structures.As an important part of the development of construction industrialization,concrete structure assembly construction modes have become a research hotspot in the field of construction industrialization.However,China’s concrete structure assembly construction market is still in the policy-driven passive development stage,and high construction cost is the main factor hindering the application of assembly construction technology in engineering.In order to improve the market advantage of assembly and construction technology of concrete frame structures,this paper analyzes the assembly and construction processes,structural separation and assembly schemes of concrete frame structure,puts forward a set of efficient assembly and construction process for concrete frame structures,and carries out systematic tests on the core content of bearing capacity of core column of frame column assembly joint at very early ages under this construction process.The bearing capacities for concrete-filled steel tubular(CFST)core columns and concrete filled steel tubular(CFST)columns confined with FRP at very early ages are studied in this paper.The main research work and conclusions are as follows(1)Based on the construction objectives of structural safety,rapid construction and controllable construction cost,from the structural technology level of concrete frame structures,the relationship between assembly scheme,detailed design of assembly joints,construction process and construction speed,and construction cost is established.The construction speed,standardization and generalization of assembly joints,and very early age components of prefabricated concrete frame structures are determined.Based on this,a set of self-assembly process is constructed to optimize the performance of concrete assembly.In accordance with the new rapid construction process of prefabricated concrete frame structures,the integrated design technology for prefabricated concrete frame structures and the detailed design technology for assembly joints such as columns,beams and floors are thoroughly analyzed.(2)As required by the bearing capacity of the core column of the frame column assembly joint at very early age,16 concrete-filled steel tube core column specimens of the frame column assembly joint are made,and the axial compression bearing capacity of the core columns are tested.The P-S curves,P-ε curves,axial compression bearing capacity,axial compression stiffnesses and ductility of core column specimens are studied by taking the loading age,steel pipe wall thickness and section shape as varying parameters.The results show that the bearing capacity and ductility of concrete filled steel tubular core columns are high at very early ages.According to the test results,the calculation method for axial compression bearing capacity of concrete filled steel tubular core columns at very early ages is discussed.(3)In order to meet the requirements of high stress levels in very early ages of assembly joints under high-efficiency construction technology,the scheme of using frame column assembly joints with FRP confined concrete core columns at very early ages is proposed innovatively.30 specimens of concrete filled steel tubular(CFST)columns confined with FRP are fabricated and tested for their axial compression behavior at very early ages.The P-S curves,P-ε curves,axial compression bearing capacity,axial compression stiffnesses and ductility of core column specimens are studied by taking loading age,section shape and FRP layers as varying parameters.The results show that: the bearing capacity and ductility of FRP confined concrete-filled steel tube core columns are high and ductility is good.Before the column reaches its peak load,quite some sound of fine fiber fracture are made as warning,which can well meet the functional requirements of frame column assembly joint core columns.According to the test results,the calculation method for axial compression bearing capacity of FRP confined concrete filled steel tubular core columns is discussed.(4)In order to correctly evaluate the influence of the axial compression history of the core column in its very early ages on the axial compression performance of the core column in its mature stage,experimental study on the axial compression performance of 12 steel tube restrained and 8 FRP steel tube composite restrained concrete core columns with high stress bearing history at very early ages are carried out.Taking the loading age,the number of FRP layers and the wall thickness of steel tube as varying parameters,the P-S curves,axial bearing capacity,axial compression stiffnesses and other mechanical properties of the core column specimens are studied by multiple loading and unloading.The results show that the axial compression bearing capacity of the core columns with high stress bearing history is higher than that of the specimens without loading history under the same curing conditions.The specimens show favorable "performance recovery" and "bearing capacity hardening" effects after curing,which reflects the feasibility and safety of the development and utilization of the early bearing capacity of confined concrete core columns,which can provide important technical support for the efficient construction of prefabricated concrete frame structures.The above research results show that: through the combination of structural technology analysis and construction benefit analysis,a set of rapid assembly construction process and design technology for concrete frame structures can be established,and the high stress bearing performance of concrete filled steel tube core columns at very early ages,the early warning function of local small FRP fracture and the,"performance recovery" and "bearing capacity hardening" of confined concrete after curing with high stress loading history,the goal of rapid assembly and construction of concrete frame structures can be achieved.The results of this paper can provide technical support for the application of new efficient assembly and construction technology schemes for concrete frame structures in pilot projects,and promote the development of concrete structure assembly construction technology to a technology driven stage.