Continuous rigid frame bridges possess significant advantages in terms of structural performance and economic benefits. They have large bending stiffness in the longitudinal direction and torsional stiffness in the transverse direction, which allows them to adapt to the displacement caused by the shrinkage, creep, and temperature changes of prestressed concrete. This makes them suitable for large-span bridges that require both crossing ability and structural strength. Additionally, continuous rigid frame bridges exhibit better seismic performance compared to continuous beam bridges, as horizontal seismic forces can be evenly distributed among the piers, whereas continuous beam bridges require expensive seismic isolation devices or braking piers .

The design of high-pier continuous rigid frame bridges often involves the following considerations:

1. Pier Stability and Wind Load Resistance: High piers are typically located in large canyon areas where wind effects are significant. To ensure stability and resist wind loads, the following design strategies are adopted:

   - Piers should have adequate longitudinal compressive stiffness to accommodate deformations caused by temperature changes and concrete shrinkage.

   - Transverse stiffness of the pier columns should be designed to resist wind loads and reduce lateral displacement, thereby enhancing driving comfort.

   - Efforts should be made to minimize the pier's cross-sectional windward area and improve aerodynamic shapes to reduce the wind load coefficient.

   - For construction convenience, high piers are often built using slipform or climbing formwork techniques, and simple shapes are preferred .

2. Pier Types and Selection: High-pier continuous rigid frame bridges usually employ either monolithic or separated pier designs. Due to their height, these piers often adopt thin-walled box sections. Single-box single-leg piers provide strong bending and torsional stiffness but may exhibit larger longitudinal compressive stiffness, which limits their adaptability to longitudinal deformations. Conversely, double-leg piers are better suited for accommodating longitudinal deformations and are commonly used for spans up to 50 meters. They offer several advantages:

   - Greater overall bending stiffness compared to single-leg piers, ensuring safety during the cantilever construction phase.

   - Adjustable longitudinal compressive stiffness through modifications such as changing leg section sizes, spacing of tie beams, or tie beam stiffness.

   - Improved adaptability to multi-span continuous systems by adjusting pier stiffness without altering the pier top geometry.

   - Reduced windward area and smaller wind load coefficients, beneficial for resisting transverse winds in mountainous canyon areas.

   - Economic advantages in the superstructure due to larger longitudinal spacing between legs, which reduces the effective span of the box girder and its internal forces .

3. Design Considerations for Thin-Walled Piers: For thin-walled piers, factors such as wall thickness, pier stiffness, and local stability must be carefully considered. By limiting the width-to-thickness ratio, designers can ensure that local stability issues do not dominate the overall structural design .

4. Construction Techniques: High-pier continuous rigid frame bridges often utilize cantilever construction methods, which eliminate the need for temporary pier connections during the transition from continuous beam to rigid frame systems. This approach simplifies construction and reduces maintenance costs .

5. Economic and Technical Advantages: Compared to other bridge types like cable-stayed or suspension bridges, continuous rigid frame bridges generally have lower construction costs. They also require less material and maintenance compared to traditional simple-supported beam bridges. The use of high piers can optimize bridge economics by reducing the overall span length while maintaining structural integrity .

High-pier continuous rigid frame bridges represent a highly efficient solution for large-span bridge construction, particularly in challenging environments such as deep valleys or mountainous regions. Their design focuses on optimizing structural performance, adaptability to environmental loads, and economic efficiency.