Experimental Research On Compressive Torsion Hysteretic Behavior Of Square Concrete-filled CFRP-steel Tubes

The concrete-filled steel tube has been developed for more than one hundred years and has become an important branch of structural engineering.In order to know mechanical essence,scholars have carried out a lot of research on concrete-filled steel tube in the field of scientific research.Because of excellent mechanical properties,convenient to construction and high economic efficiency,it's applied to industrial plants,high-rise buildings,bridge structures and underground structures in the civil engineering field.As use widely,the thickness of the steel tube is gradually increased so as to increase the bearing capacity of the member,the outer surface of the steel tube require certain corrosion resistance in special circumstances.Carbon fiber reinforced polymer(CFRP)is a new type of material formed by mixing carbon fiber sheets with epoxy resin.Due to light weight,high strength,good corrosion resistance and great durability,it has also been introduced into the field of civil engineering.The concrete-filled CFRP-steel tube is formed by adhering CFRP on the outer surface of the concrete-filled steel tube,which has higher bearing capacity,better ductility and excellent corrosion resistance.This paper mainly studies the compression-torsion hysteretic behavior of concrete-filled CFRP-steel tube,the main contents include:(1)Set the axial compression ratio,the transverse CFRP layers and the steel containing ratio as the main parameters,design and fabricate nine specimens.Measure the property of materials such as steel and concrete.Assembly the test devices.Measurement and acquisition of test datas such as torsion,rotation angle and strain of specimens.(2)Analysis of test results showed that the shape of curve is very full,the phenomenon of"pinch" is not obvious.Through stress-strain curves of specimens,it is found that the steel tube and the concrete have good cooperative working performance.Specimens have good ability of energy consumption,Stiffness degradation is obvious,strength degradation is not obvious.(3)Establish the model of compression-torsion hysteretic behavior square concrete-filled CFRP-steel tube by finite element software.The simulated results and test results were compared to verify the accuracy of the model.