6.1 Arch bridge types and structural behavior

Arch bridges are marvels of engineering, using their curved shape to transfer loads efficiently. From fixed to hinged designs, these structures showcase the power of geometry in load-bearing. Let's dive into the world of arches and discover how they stand strong.

Tied and spandrel arches offer unique solutions to thrust and aesthetics. We'll explore how these bridges work their magic, distributing forces and minimizing bending moments. Get ready to uncover the secrets behind these elegant and efficient structures!

Arch Bridge Types and Characteristics

Fixed and Hinged Arch Bridges

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  Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch Bridge View original

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  Frontiers | Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With ... View original

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  Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch Bridge View original

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  Frontiers | Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With ... View original

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Top images from around the web for Fixed and Hinged Arch Bridges

• 

  Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch Bridge View original

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• 

  Frontiers | Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With ... View original

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• 

  Frontiers | Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With ... View original

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• 

  Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch Bridge View original

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• 

  Frontiers | Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With ... View original

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• Arch bridges transfer loads through structural configuration and load-bearing mechanism
• Fixed arch bridges utilize rigid connections at both ends for high stability and efficient load distribution
• Two-hinged arch bridges employ pinned connections at supports allowing horizontal movement and reducing bending moments
• Three-hinged arch bridges incorporate an additional hinge at the crown providing greater flexibility and adaptability to temperature changes

Tied and Spandrel Arch Bridges

• Tied arch bridges use a horizontal tie to resist outward thrust of the arch eliminating need for massive abutments
• Open-spandrel arch bridges feature series of smaller arches or columns supporting deck (reduces dead load, enhances aesthetics)
• Closed-spandrel arch bridges have solid walls between main arch and deck offering increased stiffness but higher dead load
• Spandrel design choice impacts bridge's dead load, aesthetics, and maintenance requirements

Load Transfer in Arch Bridges

Axial Compression and Force Resolution

• Arch bridges primarily transfer loads through axial compression along curved arch structure
• Arch shape converts vertical loads into diagonal forces resolved into horizontal thrust and vertical reactions at supports
• Bending moments in arch bridges typically smaller compared to beam bridges resulting in more efficient material use
• Funicular arch shape closely follows line of thrust minimizing bending stresses and optimizing structural efficiency

Support Conditions and Live Load Effects

• Horizontal thrust at arch supports resisted by massive abutments or tie system to maintain equilibrium
• Structural behavior influenced by arch geometry, material properties, and support conditions
• Live loads cause deformations altering distribution of internal forces requiring careful analysis and design considerations
• Proper drainage systems within spandrel and fill areas prevent water accumulation and potential structural damage

Arch Shape and Performance

Geometric Considerations

• Arch shape significantly affects load distribution (common geometries circular, parabolic, catenary)
• Rise-to-span ratio critical parameter influencing magnitude of horizontal thrust and overall structural efficiency
• Lower rise-to-span ratios result in higher horizontal thrust but may be more aesthetically pleasing and provide better clearance
• Higher rise-to-span ratios lead to reduced horizontal thrust and improved structural efficiency but may present challenges in approach grades and visual impact

Span Length and Structural Efficiency

• Span length affects required depth and stiffness of arch rib to resist buckling and control deflections
• Relationship between arch shape and span influences distribution of bending moments and shear forces along arch
• Optimization of arch geometry leads to more efficient material use and improved overall bridge performance
• Interaction between deck and arch influences overall structural behavior and can be optimized to enhance performance

Design Elements of Arch Bridges

Spandrel and Fill Design

• Spandrel walls in closed-spandrel arch bridges provide lateral support to arch and help distribute loads from deck to main arch
• Fill material in closed-spandrel arch bridges contributes to overall stiffness of structure and helps distribute loads more evenly
• Choice between open and closed spandrel designs affects bridge's dead load, aesthetics, and maintenance requirements
• Proper drainage systems within spandrel and fill areas crucial to prevent water accumulation and potential structural damage

Deck Design and Load Transfer

• Deck serves as primary load-bearing surface for traffic and transfers loads to arch through spandrel structure
• Deck design must account for local bending and shear effects while ensuring proper load transfer to underlying arch system
• Interaction between deck and arch influences overall structural behavior and can be optimized to enhance performance
• Deck-arch interaction optimization improves load distribution and structural efficiency (deck stiffening, composite action)