| The structure formed by superimposing the prefabricated steel-concrete parts and the cast-in-situ components is called prefabricated steel-concrete structure.The prefabricated part can be poured in the prefabricated unit in advance and then transported to the construction site for pouring and stacking.It can greatly simplify the construction process.Currently,the research on the prefabricated components at the bottom of steel-concrete composite beams is not sufficient.The force performance of the bottom prefabricated component affects the safety and economy of the composite beam construction stage directly.Therefore,this paper selects 4 design parameters of shear span ratio,section form,concrete strength and section steel type.Designing and producing 18 specimens and conducts monotonic loading tests to explore the mechanical properties of the precast members at the bottom of the PSRC beam.The research includes the development state of the surface cracks of the specimen during the loading process,the failure type of the beam,the analysis of the load-mid-span deflection curve of the specimen according to the test data,the stress and strain of the specimen,and the influence law of design parameters on the bearing capacity of the specimen.Verification of the assumption of a peaceful cross-section.In addition,ABAQUS was used to perform finite element numerical simulation on 18 specimens.By comparing the test results with the simulation results,the cause of the error was explored and the rationality of the model was tested.Numerical simulation further expands the range of design parameters,and deeply analyzes the mechanical performance of the precast members at the bottom of the PSRC beam.The research came to the following conclusions.The following conclusions were obtained:(1)Under the monotonic static loading of the prefabricated component at the bottom of the PSRC beam,the main design parameter that affects the bearing capacity of the specimen is the shear-span ratio,which is 3.0 and 4.5.The bearing capacity of the specimens is low but the deformation capacity is good.The shear-span ratio is 1.5 for the specimens.High bearing capacity but poor ductility.The overall bearing capacity and deformation capacity of the rectangular cross-section specimens are better than those of the other two shape cross-section specimens.The concrete strength has little effect on the bearing capacity of the bottom prefabricated specimens.Compared with the solid web type steel specimen,the assembled honeycomb section steel specimen has high bearing capacity but poor deformation ability which belongs to brittle failure..(2)The simulation results of the load-mid-span deflection curve are close to the test results,indicating that the numerical model established in this paper can well simulate the mechanical performance of the precast member at the bottom of the PSRC beam under monotonic static loading.(3)Compared with the test curve,the simulated curve of load-span deflection does not have a falling section at the later stage,and the bearing capacity shows a rising trend,mainly because the concrete type in the simulation is homogeneous while the actual mixed concrete cannot be completely homogeneous,and the Embedded restraint used between the profile and concrete in the simulation does not consider bond slip,and the concrete falls off at the later stage of actual loading,while the numerical simulation does not simulate such situation(4)Through the numerical simulation of expanding the parameter value range,the following conclusions can be obtained: the bearing capacity of the specimen decreases with the increase of the shear-span ratio,but the deformation capacity increases;in the specimen that is dominated by compression,the concrete strength changes It has little effect on the bearing capacity of the test piece;the simulation result of the cross-sectional form is close to the test result;the deformation capacity of the solid web type steel specimen is obviously better than that of the honeycomb section steel specimen. |
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