Development and validation of the model B4 for concrete creep and shrinkage

An analysis of 69 recorded bridge deflection histories reveals that the existing formulations for the creep and shrinkage of concrete structures greatly underestimate the multi-decade creep deflections of structures, often designed for lifetimes >100 years. Despite having the correct form, the existing model B3 (a 1995 RILEM Recommendation) markedly underestimates the multi-decade deflections. So does the new fib Model Code 2010. Presented is a new model, labeled B4, which overcomes two main shortcomings of the ACI, CEB, JSCE and GL models. First, the new model is calibrated using the collected bridge deflection data to ensure the proper terminal slope of the compliance function in logarithmic time. Second, model B4 extends the scope of prediction to modern concretes with various types of admixtures and high strengths