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TL;DR: In this paper, free and restrained shrinkages were measured on self-consolidating concrete for three different relative humidities: 30, 50% and 70%. A maximum value of drying shrinkage was observed for the intermediate relative humidity.
32 citations
Dissertation•
16 Nov 2004
Abstract: Effective determination of long-term prestress losses is important in the design of prestressed concrete bridges. Over-predicting prestress losses results in an overly conservative design for service load stresses, and under-predicting prestress losses, can result in cracking at service loads. Creep and shrinkage produce the most significant time-dependent effect on prestress losses, and research has shown that high performance and high strength concretes (HPC and HSC) exhibit less creep and shrinkage than conventional concrete. For this reason, the majority of traditional creep and shrinkage models and methods for estimating prestress losses, over-predict the prestress losses of HPC and HSC girders. Nine HPC girders, with design compressive strengths ranging from 8,000 psi to 10,000 psi, and three 8,000 psi lightweight HPC (HPLWC) girders were instrumented to determine the changes in strain and prestress losses. Several creep and shrinkage models were used to model the instrumented girders. For the HPLWC, each model over-predicted the long-term strains, and the Shams and Kahn model was the best predictor of the measured strains. For the normal weight HPC, the models under-estimated the measured strains at early ages and over-estimated the measured strains at later ages, and the B3 model was the best-predictor of the measured strains. The PCI-BDM model was the most consistent model across all of the instrumented
15 citations
TL;DR: In this paper, a damage-plasticity model was extended to account for the effects of simultaneously occurring stiffness degradation, residual deformation, and creep, assuming the additivity of small strains.
Abstract: A damage-plasticity model is extended to account for the effects of simultaneously occurring stiffness degradation, residual deformation, and creep. Assuming the additivity of small strains...
14 citations
TL;DR: In this paper, the authors used nonlinear moisture diffusion analysis to determine the shape effect on the shrinkage rate of cylinders and showed that the mass loss and drying shrinkage of cylinders showed higher rate and ultimate values than the prisms, for the same effective cross section thickness.
10 citations
TL;DR: In this article, an exact method for estimating the time-dependent strain in reinforced concrete (RC) members is presented, which can be used to estimate the time dependence of reinforced concrete members.
Abstract: Time-dependent strains in reinforced concrete (RC) members are usually estimated using approximate algebraic methods. This paper presents an exact method for estimating the time-dependent s...
8 citations