Abstract
AbstractCreep and shrinkage are strongly influenced by the moisture content of concrete and by the ambient humidity. The effect of the latter is currently considered in models and design codes such as the fib Model Code 2010 by time-average considerations, thus totally neglecting cyclic changes in ambient humidity normally observed in outdoor structures. However, the influence of the cyclic ambient humidity on the long-term deformations of concrete compared to the constant mean humidity has barely been investigated. Therefore, the developments of creep and shrinkage of a normal-strength concrete C30/37 with three initial (before testing) moisture contents at constant humidity as well as cyclic humidity were investigated. Results demonstrate that the drying shrinkage and drying creep, but also the basic creep, are higher with higher initial moisture contents at constant ambient humidity conditions. Additionally, creep strains sharply increased up to plus 60% due to cyclic humidity compared to those due to corresponding average constant humidity. The influence of cyclic ambient humidity is more pronounced for concretes with lower initial moisture contents. Those strong deviations in the creep behaviour (compared to existing design models) may cause severe safety risks in prestressed concrete constructions. Therefore, existing creep models should be modified considering the influence of cyclic changes in humidity and the combined influence of the initial moisture content.
Funder
Deutsche Forschungsgemeinschaft
Gottfried Wilhelm Leibniz Universität Hannover
Publisher
Springer Science and Business Media LLC
Subject
Mechanics of Materials,General Materials Science,Building and Construction,Civil and Structural Engineering
Reference37 articles.
1. fib—Fédération Internationale du Béton (2013) fib model code for concrete structures 2010. Ernst & Sohn, Berlin. https://doi.org/10.35789/fib.BULL.0055
2. EN 1992-1-1 (2004) Eurocode 2: Design of concrete structures–Part 1-1: General rules and rules for buildings. CEN: Brussels
3. ACI Committee 209 (1992) Prediction of creep, shrinkage and temperature effects in concrete structures (ACI 209R-92) (Reapproved 2008). American Concrete Institute, Farmington Hills
4. Bažant ZP, Yu Q, Hubler MH, Křístek V, Bittnar Z (2011) Wake up call for creep, myth about size effect and black holes in safety: What to improve in fib model code draft. In: Proceedings of fib symposium: concrete engineering for excellence and efficiency, Prague, Czech Republic, June 8–10, 2:731–746
5. fib—Fédération Internationale du Béton (2013) Code-type models for structural behaviour of concrete: Background of the constitutive relations and material models in the fib model code for concrete structures 2010; state-of-art report. fib bulletin no.70, Lausanne, Switzerland. https://doi.org/10.35789/fib.BULL.0070
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献