Constitutive Modelling Of High Strength High Performance Concrete

High Strength/High Performance Concrete (HSC/HPC) continues to be the object of particular interest and extensive research, and its use in construction is increasing continuously. fib Bulletin 42 summarises the available information on the material behaviour of HSC/HPC, and develops a set of code-type constitutive relations as an extension of CEB-FIP Model Code 1990. Literature on experimental data and international guidelines, standards and recommendations were reviewed, and already-existing constitutive relations and models were evaluated. In addition to a number of material laws chosen and adjusted for this report, some new constitutive relations were developed based on the collected data. The criteria for the choice of the existing relations as well as the development of the new constitutive relations involved their simplicity and operationality (code-type mathematical formulations). Furthermore, they had to be physically sound and if possible describe the behaviour of both high-performance and normal strength concretes by a unique relation. Finally, compliance with the specifications given in the CEB-FIP Model Code 1990 was examined. This State-of-art report is intended for engineers and represents a summary of the relevant knowledge available to and possessed by the members of the Task Group at the time of its drafting.

Collection of selected, peer reviewed papers from the 10th International Symposium on High Performance Concrete – Innovation & Utilization (HPC 2014), September 16-18, 2014, Beijing, China. The 87 papers are grouped as follows: Chapter 1: High-Performance and Ultra-High Performance Concrete, Chapter 2: Concrete Durability and Mechanical Properties, Chapter 3: Fire Resistance, Chapter 4: Concrete Sustainability, Recycling and Utilization, Chapter 5: Mix Proportion Design and Hydration, Chapter 6: Self-Compacting Concrete, Chapter 7: Special Raw Materials, Concrete Composites and Additives, Chapter 8: Structural Performance and Modeling, Chapter 9: Testing Methods, Evaluation and Quality

This book presents the work done by the RILEM Technical Committee 227-HPB (Physical properties and behaviour of High-Performance Concrete at high temperature). It contains the latest research results on the modelling of concrete behaviour at high temperature. Some monographs on the subject have been published already but generally they do not cover the whole range of possibilities which are encountered in the literature as well as in practice. Moreover, there has been a rapidly increasing development of computational models during the last twenty years, which deserves attention. Therefore, it is the aim of this report to compile and present most of the tools that are proposed in the literature and are nowadays available for practice in some commercial computational packages. The book is divided in 3 main chapters dealing with: - engineering modelling - advanced modelling - constitutive parameters including hydral, thermal and mechanical parameters. The results presented especially target a group of users composed by universities and research laboratories, building material companies and industries, material scientists and experts, building and infrastructure authorities, designers and civil engineers.

CREEP, SHRINKAGE AND DURABILITY MECHANICS OF CONCRETE AND CONCRETE STRUCTURES contains the keynote lectures, technical reports and contributed papers presented at the Eighth International Conference on Creep, Shrinkage and Durability of Concrete and Concrete Structures (CONCREEP8, Ise-shima, Japan, 30 September - 2 October 2008). The topics covered

fib Model Code 2010 represents the state-of-the-art of code-type models for structural behaviour of concrete. It comprises constitutive relations and material models together with the most important explanatory notes. However the underlying normative work, i.e. the fundamental data as well as the considerations and discussions behind the formulas could not be given within the Model Code text. Based on various experiences gained after the publication of Model Code 1990 this lacking background information will lead in the following to numerous questions arising from Model Code users. Consequently the present bulletin claims to conquer this general weakness of codes in a way to guard against any future misunderstandings of the Model Code 2010 related to its chapter 5.1 (Concrete). It discusses the given formulas in connection with experimental data and the most important international literature. The constitutive relations or material models, being included in MC1990 and forming the basis and point of origin of the Task Group’s work, were critically evaluated, if necessary and possible adjusted, or replaced by completely new approaches. Major criteria have been the physical and thermodynamical soundness as well as practical considerations like simplicity and operationality. This state-of-the-art report is intended for practicizing engineers as well as for researchers and represents a comprehensible summary of the relevant knowledge available to the members of the fib Task Group 8.7 at the time of its drafting. Besides the fact that the bulletin is a background document for Chapter 5.1 of MC2010, it will provide an important foundation for the development of future generations of code-type models related to the characteristics and the behaviour of structural concrete. Further it will offer insights into the complexity of the normative work related to concrete modelling, leading to a better understanding and adequate appreciation of MC2010.

Within this work a material law was developed which correctly describes the creep and relaxation characteristics of young and mature normal strength and high-strength concretes. It is based on an aging thermodynamically sound rheological model and considers the complex nonlinear creep behavior under constant and variable stresses. In case of relaxation the corresponding integral relation is solved by means of a numerical algorithm.

The International Federation for Structural Concrete (fib) is a pre-normative organization. 'Pre-normative' implies pioneering work in codification. This work has now been realized with the fib Model Code 2010. The objectives of the fib Model Code 2010 are to serve as a basis for future codes for concrete structures, and present new developments with regard to concrete structures, structural materials and new ideas in order to achieve optimum behaviour. The fib Model Code 2010 is now the most comprehensive code on concrete structures, including their complete life cycle: conceptual design, dimensioning, construction, conservation and dismantlement. It is expected to become an important document for both national and international code committees, practitioners and researchers. The fib Model Code 2010 was produced during the last ten years through an exceptional effort by Joost Walraven (Convener; Delft University of Technology, The Netherlands), Agnieszka Bigaj-van Vliet (Technical Secretary; TNO Built Environment and Geosciences, The Netherlands) as well as experts out of 44 countries from five continents.