tailieunhanh - Timber Bridges

Timber Bridges Introduction Timber as a Bridge Material • Past, Present, and Future of Timber Bridges Properties of Wood and Wood Products Physical Properties of Wood • Mechanical Properties of Wood • Wood and Wood-Based Materials for Bridge Construction • Preservation and Protection Kenneth J. Fridley Washington State University Types of Timber Bridges Superstructures • Timber Decks • Substructures Basic Design Concepts Specifications and Standards • Design Values • Adjustment of Design Values • Beam Design • Axially Loaded Members • Connections Introduction Wood is one of the earliest building materials, and as such often its use has been based more on tradition than on principles of engineering | Fridley . Timber Bridges Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 20 Timber Bridges Introduction Timber as a Bridge Material Past Present and Future of Timber Bridges Properties of Wood and Wood Products Physical Properties of Wood Mechanical Properties of Wood Wood and Wood-Based Materials for Bridge Construction Preservation and Protection Types of Timber Bridges Superstructures Timber Decks Substructures Basic Design Concepts Kenneth J. Fridley Specifications and Standards Design Values Adjustment of Design Values Beam Design Washington State University Axially Loaded Members Connections Introduction Wood is one of the earliest building materials and as such often its use has been based more on tradition than on principles of engineering. However the structural use of wood and wood-based materials has increased steadily in recent times including a renewed interest in the use of timber as a bridge material. Supporting this renewed interest has been an evolution of our understanding of wood as a structural material and our ability to analyze and design safe durable and functional timber bridge structures. An accurate and complete understanding of any material is key to its proper use in structural applications and structural timber and other wood-based materials are no exception to this requirement. This chapter focuses on introducing the fundamental mechanical and physical properties of wood that govern its structural use in bridges. Following this introduction of basic material properties a presentation of common timber bridge types will be made along with a discussion of fundamental considerations for the design of timber bridges. Timber as a Bridge Material Wood has been widely used for short- and medium-span bridges. Although wood has the reputation of being a material that provides only limited service life wood can provide long-standing and serviceable bridge structures when .