Abstract
Many prestressed concrete bridges are reported to suffer from excessive vertical deflections and cracking during their service life. Creep softens the structure significantly, and therefore an accurate prediction of creep is necessary to determine long-term deflections in elements under eccentric axial compression such as prestressed concrete girders. This study proposes a modification to the creep damage model of Model Code 2010 to account for the effect of load eccentricity. The modified creep model considers damage due to differential drying shrinkage. Initially, the creep behaviour of small scale concrete specimens under eccentric compression load is investigated experimentally. Twelve small-scale concrete prisms were subjected to eccentric axial loading to assess their shrinkage and creep behaviour. The main parameters investigated include the load eccentricity and exposure conditions. Based on the experimental results, an inverse analysis is conducted to determine the main parameters of the modified creep model. Subsequently, a numerical hygro-mechanical simulation is carried out to examine the effect of load eccentricity on the development of shrinkage and creep, and on the interaction between drying, damage and creep. The results indicate that eccentric loading leads to different tensile and compressive creep through the cross section, which contradicts the current design approach that assumes that tensile and compressive creep are identical. The proposed model also predicts accurately the long-term behaviour of tests on reinforced concrete elements available in the literature. This study contributes towards further understanding of the long-term behaviour of concrete structures, and towards the development of advanced creep models for the design/assessment of concrete structures.
Highlights
Due to their structural efficiency and cost-effectiveness, prestressed concrete (PC) box girders are extensively used in the construction of long-span bridges (100–300 m)
This study proposes a modification to the creep damage model of Model Code 2010 to account for the effect of load eccentricity in concrete
This study proposed a new creep damage model based on modifications to the linear creep approach given in Model Code 2010
Summary
Due to their structural efficiency and cost-effectiveness, prestressed concrete (PC) box girders are extensively used in the construction of long-span bridges (100–300 m). Previous research has investigated the influence of second order effects [7, 8] and material nonlinearity [9,10,11] on the creep behaviour of such elements In these studies, the magnitude of tensile and compressive creep strains was assumed to be equal. Materials and Structures (2019) 52:119 damage [22, 23], where nonlinear creep is accounted for using the interaction between the growth of creep strain and damage over time Such models neglect the influence of shrinkage and drying-induced microcracking, which always occur during the service life of structures. The results of this study contribute towards developing a further understanding of the long-term behaviour of concrete structures, as well as towards the development of practical models to evaluate the serviceability of RC structures
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have