Elastic Modulus Reduction Method For Evaluation Of Ultimate Load Bearing Capacity Of Concrete-Filled Steel Tubular Arch Bridge

Concrete filled steel tubular (CFST) arch bridges have been widely used in long-span Bridges, and the ultimate bearing capacity for the structures has been one of hot topics in engineering research field. Thus a lot of references have been found on analysis method of the ultimate bearing capacity on such complex structures at home and abroad. Especially, method of the Elastic Modulus Adjustment Procedure(EMAP) based on the plastic limit analysis theory, is developed rapidly, which has been widely used in pressure vessel and pressure pipeline engineering design and analysis. However, the EMAP method has some deficiencies on calculation accuracy, efficiency and applicability. In order to overcome these deficiencies, we proposed the elastic modulus reduction method (EMRM)to calculate the ultimate load bearing capacity of the structures. After that the corresponding theoretical and applied research are carried out. Based on the such research, the analysis method of ultimate bearing capacity of CFST arch is proposed finally in the paper, which is summarized as follows.(1) The homogeneous generalized yield function (HGYF) is established for CFST, which can overcome the shortcomings of precision and stability in the traditional generalized yield function. The corresponding calculating method is presented for the HGYF fitting and order choice.(2) EMRM for evaluating of ultimate load bearing capacity of CFST arch is established. By introducing the theory of CFST, a finite element model is established. And then according to HGYF for CFST, the element bearing ratio (EBR) of components is defined. Therefore, dynamic recognition method of the high bearing unit is obtained for CFST, and the structure elastic modulus reduction strategy is determined. Finally the EMRM for evaluating ultimate load bearing capacity of CFST is proposed, which shows good calculation accuracy, computational efficiency and stability of iteration.(3) The effect of concrete strength, steel ratio, rise span ratio and load condition on the ultimate bearing capacity of CFST is studied, and some useful results on engineering are summarized, which can provides reference for engineering practice.