Self-Compacting Concrete (SCC) for Prestressed Bridge Girders

Researchers conducted an experimental program to investigate the viability of producing self-consolidating concrete (SCC) using locally available aggregate, and the viability of its use in the production of precast prestressed concrete bridge girders for the State of Minnesota. Six precast prestressed bridge girders were cast using four SCC and two conventional concrete mixes. Variations in the mixes included cementitious materials (ASTM Type I and III cement and Class C fly ash), natural gravel and crushed stone as coarse aggregate, and several admixtures. The girders were instrumented to monitor transfer length, camber, and prestress losses. In addition, companion cylinders were cast to measure the compressive strength and modulus of elasticity, and to monitor the creep and shrinkage over time. The viability of using several test methods to evaluate SCC fresh properties was also investigated. The test results indicated that the overall performance of the SCC girders was comparable to that of the conventional concrete girders. The measured, predicted, and calculated prestress losses were generally in good agreement. The study indicated that creep and shrinkage material models developed based on companion cylinder creep and shrinkage data can be used to reasonably predict measured prestress losses of both conventional and SCC prestressed bridge girders.

In Situ Assessment of Structural Timber

ABOUT THIS BOOK
Wood is one of the most intriguing structural materials and the only one that is truly renewable. Along with stone, wood is the oldest structural material on the planet and has been extensively used throughout human history. Due to its aesthetical value and positive environmental impact, wood has experienced a renaissance in construction.

As a biodegradable, hygroscopic, non-isotropic material, wood presents special challenges for a professional working with it and requires thorough knowledge ranging from biology to continuum mechanics.

This state-of-the-art report reflects the current knowledge in the area of in situ assessment of the physical and mechanical properties of wood structures. Nondestructive, semi-destructive and destructive methods are described in a systematic manner where technology, equipment and limitations are discussed. Some of the discussed methods are used in other materials such as masonry and concrete. Most of the methods, however, are specific to wood and special qualifications are required to understand and apply these methods effectively. Existing methods are constantly improved and new methods are being developed. This report includes methods that are used in practice or have shown significant promise and have a body of knowledge that supports statements made in this report.

This is a useable tool for professionals, researchers, educators and students

Content Level » Research

Keywords » applications - individual methods - modern and historic buildings - structural timber - wood structures

Related subjects » Design - Engineering - Forestry

TABLE OF CONTENTS
Preface; List of Symbols and Abbreviations; List of Figures; List of Tables; Introduction; References ; 1 Stress Waves, by Bohumil Kasal, Gretchen Lear, and Thomas Tannert; 2 Ground Penetrating Radar, by Mehdi Sbarte; 3 Radiography, by Bohumil Kasal, Gretchen Lear and Ron Anthony; 4 Resistance Drilling, by Gretchen Lear, Bohumil Kasal and Ron Anthony; 5 Core-Drilling, by Bohumil Kasal; 6 Shear Test of Glue Lines, by Thomas Tannert; 7 Tension Micro-Specimens, by Bohumil Kasal; 8 Screw Resistance, by Nobuyoshi Yamaguchi; 9 Hardness Test, by Mariapaola Riggio and Maurizio Piazza; 10 Moisture Measurement, by Bohumil Kasal and Gretchen Lear; 11 Species Identification, by Nicola Macchioni; 12 Dendrochronology, by Olivia Pignatelli; 13 Review of Codes and Standards, by Nicola Macchioni, Clara Bertolini and Thomas Tannert; Key Words Index.