Studies On Ultimate Bearing Capacity Of Reinforced Concrete Arch Rib

The evaluation of the ultimate bearing capacity of reinforced concrete arch ribs is a significant issue in the design and construction of long-span reinforced concrete arch bridges. Aiming at the issue of the evaluation of the ultimate bearing capacity of long-span reinforced concrete arch ribs, this dissertation investigated the ultimate bearing capacity of reinforced concrete arch ribs on the basis of summarizing and absorbing the achievements in the pioneer works. The main research work is as follows:The failure criteria and tests of concrete were systematically summarized and dissected. According to the characteristics of the behavior of long-span reinforced concrete arch ribs, the basic parameters and failure models were determined for the collapse analysis of long-span reinforced concrete arch ribs.The characteristics and suitable scope of the constitutional relationship of concrete and reinforcement were analyzed in detail, then, the constitutional relationship of concrete and reinforcement were determined for the simulation analysis of long-span reinforced concrete arch ribs.The characteristics and suitable scope of the cracking models of reinforced concrete were dissected. With the applied demands for the collapse analysis of long-span reinforced concrete arch ribs, the cracking models of reinforced concrete were determined to imitate the behaviour of reinforced concrete arch ribs.The element models which had been used commonly to analyse the ultimate bearing capacity of bridge structures were summarized. The necessity of using special concrete solid element to the numerial analysis of ultimate bearing capacity of long-span reinforced concrete arch ribs was discussed; furthermore, the principles of the reinforced concrete solid element in ANSYS were dissected.The solution procedures for nonlinear equilibrium equations in structural analysis were systematically summarized. With some numerical examples, the policy on tracing the nonlinear equilibrium paths was determined, which was used for evaluating the ultimate bearing capacity of long-span reinforced concrete arch ribs.Comparing the experiment data of the reinforced concrete arch rib model and its numerical anlysis results on the basis of collapse theory, it was found that the numerical anlysis results are very close to the experimental data, and consequently the reliability of the numerical analysis procedures on the basis of collapse theory for evaluating the ultimate bearing capacity of reinforced concrete arch ribs was certified.The values of dominant parameters of long-span reinforced concrete arch rib were discussed. By means of the large-scale general software ANS YS, the collapse analysis models which were similar to the practical arch bridges were built to evaluate the ultimate bearing capacity of reinforced concrete arch ribs.Based on a large number of systematic simulating numerical experiments, this dissertation deduced a series of expressions to describe the effects of the dominant parameters on the ultimate bearing capacity of reinforced concrete arch ribs by means of mathematical statistic theory. The initial geometric imperfection, calculated span, rise span ratio, coefficient of arch axis and load types were included in these expressions.The applied evaluation methods, which are able to meet the precision request of civil engineering, were deduced to evaluate the ultimate bearing capacity of long-span reinforced concrete arch ribs. The initial geometric imperfection, calculated span, rise span ratio, coefficient of arch axis and load types were taken into account in the applied evaluation methods.This dissertation evaluated the ultimate bearing capacity of two practical bridges by means of the evaluation method, the finite element method and the design codes method, and consequenly some conclusions were reached by comparing with these evaluating results. The conclusions herewith can serve as reference to the design, construction and study of the ultimate bearing capacity of long-span reinforced concrete arch bridges.