Experimental Study On Flexural Behavior Of Concrete Filled Aluminum Alloy Tube

This paper, starting from the experiment and theory, presents an experimental study on the mechanical behavior of concrete-filled aluminum alloy tubular(CFAT)members subjected to pure bending, and the theoretical analysis and deduction proceeded on this basis. The test results of ultimate bearing strength, failure modes,bending moment-displacement curves, bending moment-longitudinal deformation curves, overall displacement curve, and longitudinal vs. strain distribution curves of all specimens were reported. And inspected the influence of geometric parameters on the ultimate bearing capacity of CFAT.Firstly, a total of 28 circular CFAT specimens and 30 rectangular CFAT specimens and corresponding rectangular hollow aluminum alloy tubes(HAT) were fabricated and tested to investigate the relation of bending moment vs. deflection of the composite beam. Each group of specimens were divided into 2 and 3 groups,respectively, separated on the CFAT specimens at different geometrical parameters and competent to fill stress performance, failure mode, ultimate bearing capacity are investigated.The test results shows: For the circular CFAT specimens, the ductility, flexural stiffness and bearing capacity of circular C50 CFAT specimens have a great improvement with the corresponding circular C30 CFAT specimens. The concrete strength had no significant influence on ductility, flexural stiffness and bearing capacity. For the rectangular CFAT specimens, the ductility, flexural stiffness and bearing capacity of rectangular CFAT specimens have a great improvement with the corresponding rectangular HAT specimens. The concrete strength had no significant influence on ductility, flexural stiffness and bearing capacity. And the height, width,external diameter and wall thickness of specimen has a positive improvement on bearing capacity whether for circular C30 CFAT specimens, circular C50 CFAT specimens or rectangular HAT specimens.Secondly, considering the aluminum alloy and steel belongs to a high strength-to-weight ratio and lightness metal materials, the flexural stiffness of allCFAT beams can be calculated by analogously using using the AIJ(1997),BS5400(2005), Eurocode4(2004), AISC(2005) and DBJ 13-51(2005) specifications of the concrete-filled steel tubular(CFST) structures. It is shown that the BS5400(2005) specifications predictions were relatively identical for all specimens in the initial flexural stiffness and post-yield flexural stiffness aspect for the circular CFAT specimens. And the AIJ(1997) and Eurocode4(2004) specifications predictions were relatively identical for all specimens in the initial flexural stiffness and post-yield flexural stiffness aspect for the rectangular CFAT specimens, respectively.Then, the initial computational expressions of the flexural bearing capacity of CFAT specimens were got through theoretical analysis and deduction. And the calculation formulas of flexural bearing capacity were obtained by the method, binary linear regression. After the regression calibration, this paper get the formula with a certain precision, can provide a reference for practical engineering.Finally, this paper summarizes the deficiency in the entire research process, and proposed the future research directions in this field.