Comprehensive Database for Concrete Creep and Shrinkage: Analysis and Recommendations for Testing and Recording

Hubler, Mija H.; Wendner, Roman; Bažant, Zdeněk P.

doi:10.14359/51687453

Cited by 74 publications

(87 citation statements)

References 26 publications

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“…Although thousands of measured shrinkage curves are available in the new NU database of creep and shrinkage [10], only the shrinkage data sets of Burg and Ost [11] and of Wittmann and Bažant [8,9] feature the minimal range of different specimen sizes, necessary to appraise the proposed method.…”

Section: Test Data Used For Evaluationmentioning

confidence: 99%

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Extrapolation of short-time drying shrinkage tests based on measured diffusion size effect: concept and reality

Bažant¹,

Dönmez

2015

Mater Struct

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To check the shrinkage of the concrete considered for a design and construction project, only a limited time such as 1-3 months is usually available. So, a short-time shrinkage test must be extrapolated to much longer times, which has been known to be a difficult problem. To obtain a dependable extrapolation, it was proposed to use weight measurements of the water loss of the test specimens. However, recently some problems with this concept have been identified. The present article proposes another concept relying on the diffusion size effect in shrinkage. In a much smaller companion specimen, it is possible to reach within 1-3 months the concave part of the shrinkage curve plotted in logarithmic time scale, in which the asymptotic value is closely approached. The method is examined using the available published data on the shrinkage of specimens of different sizes. Because the size difference in the available data is too small, the method is also examined using artificial small-size data obtained by scaling according to the diffusion theory. Both cases indicate overall improvement in predicting the final asymptotic values. However, although the extrapolation is clearly better than the traditional extrapolation ''by eye'' or by fitting a formula to one-size data, some non-negligible discrepancies are still observed, and it is not clear whether the size effect method is better than the water loss method. In the face of this reality, further studies are recommended using tests of combined drying and autogenous shrinkages, with greater size differences of drying specimens and a refined evaluation taking into account secondary influences such as differences in cracking, hydration aging, and the inevitable effect of autogenous shrinkage in the specimen core before it is reached by the drying front. Until such studies clarify the problem, taking the more conservative result from the extrapolations by the size-effect and weight-loss methods is recommended as better than intuitive extrapolation ''by eye''.

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Section: Test Data Used For Evaluationmentioning

confidence: 99%

“…-d Shrinkage data of Bažant and Wittmann[10,11] and their extrapolations 6 Optimal fitting, extrapolation and evaluation of artificially shifted data…”

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confidence: 99%

Extrapolation of short-time drying shrinkage tests based on measured diffusion size effect: concept and reality

Bažant¹,

Dönmez

2015

Mater Struct

Self Cite

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“…Creep may be a welcoming feature of structures if well designed and understood, as it relieves tensile stresses that might otherwise lead to cracking. However, this is not always the case and even for the case of concrete, the creep behavior is still subject to ongoing research that just recently yielded two new creep models, the RILEM recommendation B4 and the fib model code based on laboratory data and multidecade structural evidence . The main driving forces are often structural failures but also the increasing availability of long‐term experimental campaigns and new insights gained from lower‐scale investigations …”

Section: Mechanical Backgroundmentioning

confidence: 99%

Uncertainty analysis of the power law extrapolation techniques for adhesive anchors

Podroužek

Wan‐Wendner

2018

Structural Concrete

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Modern construction industry is increasingly utilizing postinstalled adhesive anchors as an alternative to traditional mechanical anchors. Although the application of adhesive anchors under sustained load offers many advantages, the associated approval guidelines based on a power law extrapolation technique have a number of ambiguities and limitations, which are shortly reviewed in this paper and subjected to uncertainty quantification and sensitivity analyses. Some of the observations presented may be considered as specific to the available experimental database of sustained load test, while some recommendations are universal, as they relate to the underlying creep phenomena and robust measures in regression. It is further shown, how a regression based safety factor could be derived from an experimental database and a possibilistic set of plausible choices.

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“…The hydration degree is directly related to the development of mechanical properties such as compressive strength, Young's modulus, tensile strength and fracture energy. Furthermore, hydration influences time dependent processes such as shrinkage and creep [11,12] and is influenced by environmental conditions such as temperature and humidity. In this respect, the evolution of material properties has been described by [13], where a coupled chemo-mechanical model is proposed.…”

Section: Exposurementioning

confidence: 99%

Design for lifecycle robustness of fastening systems

Podroužek

Vorel

Wan‐Wendner

2018

Beton und Stahlbetonbau

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The future requirements on faster and automated construction, improved life‐cycle performance and sustainability of infrastructure in general increasingly promote the use of fastening technology. This paper addresses the concept of lifecycle robustness by introducing an ensemble of technical and management measures, covering the entire life span from design, construction, operation and decommissioning. Although a significant research on robustness and performance indicators has been performed in related areas, such as bridges or nuclear power plants, a framework for the quantification of lifecycle robustness of fastening systems is still not available. The presented proposals are based on the synthesis of theoretical and technological progress, established engineering design approaches and communication procedures, and experimental evidence, all originating from in‐house research and industrial partners. Rather than discussing particular technical aspects, this paper focuses on the uncertainty management and hazard mitigation policies through the entire life span of the fastening systems.

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Comprehensive Database for Concrete Creep and Shrinkage: Analysis and Recommendations for Testing and Recording

Cited by 74 publications

References 26 publications

Extrapolation of short-time drying shrinkage tests based on measured diffusion size effect: concept and reality

Extrapolation of short-time drying shrinkage tests based on measured diffusion size effect: concept and reality

Uncertainty analysis of the power law extrapolation techniques for adhesive anchors

Design for lifecycle robustness of fastening systems

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