| Aluminum alloy has the advantages of lightweight,high corrosion resistance,green environmental protection,strong formability non-magnetic and low maintenance cost,has been widely used in national defense engineering and Marine engineering.Because of the small elastic modulus,it is easy to deformation and instability when aluminum alloy beams are used as loadbearing member.In this regard,foreign scholars proposed the form of Aluminum Alloy Concrete Composite beams（ACC beams）,and it was found through experimental studies that the stiffness and bearing capacity of ACC beams were significantly improved.At present,there are few studies on the shear capacity of ACC beams and their main influencing factors at home and abroad.In order to promote the application of ACC beams in engineering structures,it is necessary to study the shear resistance.In this paper,a new type of ACC beams is proposed.Through theoretical research and finite element analysis,the section form of ACC beams,the influencing factors of shear capacity and the derivation of calculation formula are analyzed and studied.The main research contents and conclusions are as follows:（1）10 groups of 6061-T6 aluminum alloy were tested by DNS300 electronic universal testing machine.The mechanical parameters such as non-proportional extension strength,elastic modulus and tensile strength and σ-ε relationship curves were obtained by sorting out the test data.The strain hardening index was obtained by combining the Ramberg-Osgood model and Stein Hardt’s suggestion.Finally,the constitutive model of 6061-T6 aluminum alloy in this paper was obtained.（2）Two ACC beams with different section forms were designed for finite element analysis to explore the difference of the stress of ACC beams when the shear connectors was located on the web and the lower flange.By comparing the load-displacement curve,load-slip curve and shear performance,it is found that when the shear connectors is located at the bottom flange,the ACC beams bears an increased load,decreases the relative slip value and has a good shear resistance.Therefore,the subsequent parameter analysis was carried out based on the section form of the shear connectors located at the bottom flange.（3）Twenty-two ACC beams models were established for finite element analysis.Through the analysis of different parameters,the influence of each variable on shear capacity is studied.When the strength of concrete is increased,the maximum increase of shear capacity is 6.55%.The maximum shear strength increases by 25.6% and 7.45% when the ratio of height to thickness of web is increased.The maximum increase of shear capacity is 2.6% when the diameter of the bolt is increased.When the stirrup spacing is reduced,the maximum increase of shear capacity is 5.41%.When the shear span ratio increases from 1 to 3,the shear bearing capacity of ACC beams decreases.When the shear span ratio is greater than 3,the decline trend slows down.（4）By analyzing the shear mechanism of ACC beams,it can be concluded that the shear capacity of ACC beams mainly includes three parts: aluminum alloy beams web,concrete and stirrup.The stress transfer path of concrete was obtained according to the improved tension and compression rod calculation model,and the prediction formula of ACC beams shear capacity was obtained by superposition method.The calculation formula was compared with the finite element value and the error was found to be large.The strength reduction coefficient was used to modify the formula by referring to relevant literature.The average value of the ratio between the solution and the finite element value of the modified formula is 1.018,and the standard deviation is 0.151,indicating that the discreteness of the prediction formula for shear bearing capacity is small,and the formula is feasible. |
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