Calculation method of creep under decreasing stress considering variation of natural environmental factors

Abstract

The actual structure is always in the state of natural changing environment and stress decreasing in the section. At present, there is little method for calculating the creep under decreasing stress which takes environmental variation into account. As excessive deflection becomes a serious problem for long span continuous rigid frame bridges during the operation period, in this paper, a creep calculation method is proposed for the continuous decrease of stress in most girder sections, and considers the environmental factors comprehensively. Firstly, the multifactor (temperature, relative humidity and reinforcement ratio) correction was made to creep model of the current code JTG D62. And five creep recovery models were compared and analyzed simultaneously. Based on the elastic creep theory and the superposition principle, the improved creep calculation method was proposed. Then theoretical calculation was carried out for the assumed structure. The results showed that the calculated value obtained by the proposed method were obviously different from those obtained by the code, and were significantly different from those obtained without considering creep recovery, which proves the superiority of the proposed method under the action of multiple environmental factors and decreasing stress.