| Carbon fiber sheet has the advantages of light weight, high strength,corrosion resistance, high efficiency of construction and so on, so the carbon fiber confined concrete is increasingly widely applied in the field of ground structural engineering. As a kind of new supporting structure,this concrete arch has not appeared in the underground engineering support. Therefore, it is of innovative and promotional significance to study the compressive and bending property of such archmembers as well as the calculation method for their bearing capacity.Through the axial compression test of carbon fiber confined concrete short columns, this paper analyzed the influence laws of failure characteristics and bearing characteristics of compressive members influenced by height-diameter ratio, strength grade of concrete, carbon fiber sheet constraint layers and external constraint layer categories. The results showed that with the increase of concrete strength and carbon fiber constraint layers and the decrease of height-diameter ratio, the bearing capacity of members increased and damage degree reduced.Compared with the specimen with the strength grade of C30, the bearing capacity of specimen C40 and C50 increased by 25.4% and 73.7%respectively; when the constraint layers increased from 1 to 3, the bearing capacity enhanced by 4.5%, 16.4% and 26.8% respectively in contrast with the specimen without carbon fiber constraint; when the height-diameter ratio reduced from 3 to 2.25 and 1.8, the bearing capacity improved by 84.7% and 192% respectively; and the effect of change in constraint layer categories on bearing capacity and failure mode was not obvious.The pure bending tests for confined concrete beam were carried out and the influence of carbon fiber sheet constraint layers and core concrete categories on flexural and bearing capacity of bending members was studied: the flexural and bearing capacity increased with the increase of constraint layers. When the carbon fiber sheet constraint layers were 1, 2 and 3, compared with the specimen without carbon fiber constraints, the peak load increased by 70.1%, 183.7% and 347.1%respectively; when the core concretes were changed from ordinary concrete to steel fibrous concrete, the peak load increased by 26.2%, the midspan displacement increased by 61.2% and the steel fibrous concrete significantly improved the deformation capacity of flexural members;the influence of carbon fiber layers’ change on the bearing capacity of flexural members is greater than that of compressive members.Based on the test results and some influencing factors, the modified axial elastic modulus of confined core concretes was deduced and then the computational formula for bearing capacity of cylindrical confined short column was obtained. The compressive strength of this concrete was introduced, the computational formula for flexural capacity of flexural members in the circular cross-section was deduced and the formula was modified according to the influence laws of fiber constraint layers on the error. The computation result was roughly consistent with the test result.The stress and deformation characteristics of compressive members and flexural members were simulated by means of ABAQUS and the simulated result and test result of load-displacement curve for concrete specimen showed a consistent changing trend, but the strength of simulation value after yield reduced slowly with a gentle curve.Influence laws of different factors were accordant with the test results:for compressive specimen, the peak load increased with the increase of concrete strength and carbon fiber constraint layers and reduced with the increase of height-diameter ratio, among which the effect of height-diameter ratio is the most obvious, then the concrete strength and that of carbon fiber constraint layers is the least. For flexural specimen,the peak load increased with the increase of carbon fiber constraint layers. |
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