Finite Element Method For Post Tensioned Prestressed Concrete Structures

This book details the theory and applications of finite element (FE) modeling of post-tensioned (PT) concrete structures, and provides the updated MATLAB code (as of 2019). The challenge of modeling PT prestressed concrete structures lies in the treatment of the interface between the concrete and prestressing tendons. Using MATLAB, this study develops an innovative nonlinear FE formulation which incorporates contact techniques and engineering elements to considerably reduce the need of computational power. This FE formulation has the ability to simulate different PT frame systems with fully bonded, fully unbonded or partially bonded tendons, as well as actual sliding behavior and frictional effects in the tendons. It also allows for the accurate simulation of anchor seating loss.

This book details the theory and applications of finite element (FE) modeling of post-tensioned (PT) concrete structures, and provides the updated MATLAB code (as of 2019). The challenge of modeling PT prestressed concrete structures lies in the treatment of the interface between the concrete and prestressing tendons. Using MATLAB, this study develops an innovative nonlinear FE formulation which incorporates contact techniques and engineering elements to considerably reduce the need of computational power. This FE formulation has the ability to simulate different PT frame systems with fully bonded, fully unbonded or partially bonded tendons, as well as actual sliding behavior and frictional effects in the tendons. It also allows for the accurate simulation of anchor seating loss.

In Finite Element Design of Concrete Structures: practical problems and their solutions the author addresses this blind belief in computer results by offering a useful critique that important details are overlooked due to the flood of information from the output of computer calculations. Indeed, errors in the numerical model may lead in extreme cases to structural failures as the collapse of the so-called Sleipner platform has demonstrated.

Inhaltsangabe:Introduction: This dissertation is an investigation into the behaviour of externally prestressed structures, focusing on bridge box girders, at the ultimate limit state. The main objective is the ductility and the tendon stress increase up to failure of externally prestressed structures. Their behaviour will be compared to internally prestressed structures. The dissertation may have valuable information for the first stages of the design process for medium span bridges as the study is concerned about the overall safety and efficiency of prestressed concrete bridges by the means of ductility. The aim is also to provide information about the tendon stress at failure, which is required for the detailed design. Inhaltsverzeichnis:Inhaltsverzeichnis: AcknowledgementsVIII NotationIX 1.Introduction1 1.1Definitions1 1.2Significance of this study3 1.3Scope of the project5 1.4Historical overview and typical characteristics of external prestressing6 1.5Further structural applications of external prestressing9 2.Behaviour of externally prestressed structures10 2.1Tendon layout considerations10 2.2Behaviour at serviceability stage12 2.3Fatigue problems14 2.4Behaviour at ultimate limit stage14 2.4.1Influence of tendon slip on the ultimate limit state18 2.4.2Influence of the arrangement of the deviators on the behaviour at ultimate limit state19 2.4.3Influence of simply support and continuous support on the ultimate limit state20 2.4.4Precast segmental and monolithic bridges21 3.Collapse analysis23 3.1Investigated bridge types and their differences23 3.2Original bridge data28 3.3Simplified bridge data as basis for the calculations30 3.4FE Calculation32 3.4.1Technical aspects33 3.4.2General approach34 3.4.3Geometric model39 3.4.4Element specifications40 3.4.5Constitutive models45 3.4.6Ordinary reinforcement59 3.4.7Prestress60 3.4.8Material and geometric non-linearity63 3.4.9Kinematic constraints66 3.4.10Discrete crack propagation analysis of the precast segmental type with gap elements68 3.4.11Summary of the dividing features of the different structure types for the FE analysis72 4.Results73 4.1Load deflection behaviour73 4.2Tendon stress increase up to failure76 4.3Other results78 5.Discussion of the results85 5.1Interpretation of the results85 5.2Discussion of the exactness of the FE calculations by comparing to the full scale test89 5.3Comparison to other FE calculations and test results93 6.Conclusion and [...]

The book combines history with academic notes for use at the university level, presenting design examples from actual jobs with applications and detailing for the practicing engineer. Chapter 1 tells the history of post-tensioned concrete as only Ken Bondy can tell it. Chapters 2-8 are the notes Dirk Bondy uses to teach Design of Prestressed Concrete Structures at UCLA and Cal Poly-San Luis Obispo. Chapters 9-13 are design examples that address many of the decisions faced by practicing engineers on typical projects. Chapters 13-14 cover the art of detailing and observing the construction of post-tensioned concrete. This knowledge was obtained over many years of working on our own projects and listening and learning from the the pioneers of post-tensioned concrete. Chapter 15 covers the slab on grade industry, which represents more sales of post-tensioning tendons than all other post-tensioning applications combined. Chapter 16 discusses the challenging application of post-tensioning-external post-tensioning.

This collection contains 10 papers discussing finite element analysis of reinforced concrete structures presented at an international workshop held in New York, New York, June 2-5, 1991.

Non-linear computer analysis methods have seen remarkable advancement in the last half-century. The state-of-the-art in non-linear finite element analysis of reinforced concrete has progressed to the point where such procedures are close to being practical, every-day tools for design office engineers. Non-linear computer analysis procedures can be used to provide reliable assessments of the strength and integrity of damaged or deteriorated structures, or of structures built to previous codes, standards or practices deemed to be deficient today. They can serve as valuable tools in assessing the expected behaviour from retrofitted structures, or in investigating and rationally selecting amongst various repair alternatives. fib Bulletin 45 provides an overview of current concepts and techniques relating to computer-based finite element modelling of structural concrete. It summarises the basic knowledge required for use of nonlinear analysis methods as applied to practical design, construction and maintenance of concrete structures, and attempts to provide a diverse and balanced portrayal of the current technical knowledge, recognizing that there are often competing and conflicting viewpoints. This report does not give advice on picking one model over another but, rather, provides guidance to designers on how to use existing and future models as tools in design practice, in benchmarking of their models against established and reliable test data and in selecting an appropriate safety factor as well as recognising various pitfalls. fib Bulletin 45 is intended for practicing engineers, and therefore focuses more on practical application and less on the subtleties of constitutive modelling.

Shows the unifying generality of the proposed approach and the reliability of the ensuing computer package, for which the sole input is the specified cylinder strength of concrete and the yield is the stress of steel. This book offers an understanding of structural concrete behaviour, and illustrates the revision required for improving methods.