Prefabricated UHPC Slab Arch Rib for Lower-Weight Bridge Construction
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Solution Overview
Problem
Conventional concrete-filled steel tube stiff skeleton arch bridges face issues with large self-weight, high construction costs, low efficiency, quality challenges, material waste, and durability concerns due to shrinkage and creep of externally encased concrete, particularly in mountainous terrain.
Innovation Solution
Employing an externally encased prefabricated UHPC slab with a concrete-filled steel tube stiff skeleton, where UHPC slabs are prefabricated off-site and connected on-site, reducing on-site concrete pouring by over 70% and minimizing the need for wooden formwork, while ensuring high mechanical strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cast-in-situ ordinary concrete is used for externally encased concrete, then the structure achieves sufficient strength, but the self-weight of the whole structure increases significantly
Solution Approach 1:
The patent changes the material parameter from ordinary concrete to ultra-high-performance concrete (UHPC), which has significantly higher strength density. This allows the externally encased concrete to maintain sufficient structural strength while reducing the volume and weight of concrete required, directly resolving the contradiction between strength and self-weight
Solution Approach 2:
The patent employs composite construction by combining the steel tube structure with externally encased UHPC. This composite approach leverages the high strength-to-weight ratio of UHPC to reduce overall structural weight while maintaining or enhancing strength characteristics compared to ordinary concrete
2Strength
If cast-in-situ ordinary concrete is used for externally encased concrete, then the structure achieves sufficient strength, but the construction period increases due to heavy workload
Solution Approach 1:
The patent applies preliminary action by pre-casting UHPC panels in a controlled factory environment before installation at the construction site. This preparatory work is performed off-site with optimized conditions, significantly reducing the on-site construction period while ensuring high-quality outcomes that meet structural strength requirements
Solution Approach 2:
The patent divides the externally encased concrete into standardized pre-cast UHPC panel segments that can be manufactured independently and assembled on-site. This segmentation enables parallel production activities and reduces the sequential construction time required for traditional cast-in-situ concrete
3Strength
If cast-in-situ ordinary concrete is used for externally encased concrete, then the structure achieves sufficient strength, but the construction efficiency decreases due to high formwork precision requirements
Solution Approach 1:
The patent uses pre-cast UHPC panels with precision manufacturing performed in advance at the factory. This preliminary fabrication under controlled conditions eliminates the need for complex on-site formwork operations and high precision field construction, thereby improving construction efficiency while maintaining structural strength
Solution Approach 2:
The patent extracts the formwork operation from the on-site construction process by pre-fabricating the externally encased concrete elements in the factory. This removal of the formwork step from field operations eliminates the associated precision requirements and time consumption, significantly improving construction efficiency
4Strength
If large-volume externally encased concrete is poured at the construction site, then the structure achieves sufficient strength, but the pouring quality becomes difficult to guarantee
Solution Approach 1:
The patent transfers the concrete pouring operation to the factory environment where it is performed in advance as part of panel fabrication. This preliminary action under controlled factory conditions ensures consistent and high-quality concrete placement, curing, and finishing, eliminating the quality control difficulties associated with on-site pouring
Solution Approach 2:
The patent extracts the concrete pouring operation from the on-site construction process and relocates it to factory-based pre-casting operations. This removal of pouring from the field eliminates the quality assurance challenges of monitoring and controlling large-volume on-site concrete placement
5Strength
If cast-in-situ ordinary concrete is used for externally encased concrete, then the structure achieves sufficient strength, but micro-cracks form due to shrinkage and creep affecting durability
Solution Approach 1:
The patent changes the material composition and properties from ordinary concrete to ultra-high-performance concrete (UHPC), which has fundamentally different shrinkage and creep characteristics. UHPC exhibits significantly reduced shrinkage and creep due to its refined microstructure and composition, preventing micro-crack formation and enhancing long-term durability while maintaining structural strength
6Strength
If cast-in-situ ordinary concrete is used for externally encased concrete, then the structure achieves sufficient strength, but a large number of disposable wooden formwork are required causing material waste
Solution Approach 1:
The patent extracts the formwork operation from on-site construction by pre-casting UHPC panels in the factory. This removal eliminates the need for disposable wooden formwork at the construction site, preventing material waste while still achieving the required structural strength through the pre-fabricated panels
Solution Approach 2:
The patent eliminates the need for disposable formwork by using reusable factory-based casting operations. The permanent molds and formwork systems used in factory pre-casting can be reused multiple times, preventing the material waste associated with single-use wooden formwork while maintaining structural strength quality
Data Source
AI summary
An externally encased prefabricated ultra-high-performance concrete (UHPC) slab arch bridge with a concrete-filled steel tube stiff skeleton is provided. The arch bridge includes a concrete-filled steel tube stiff skeleton arch rib segment, where the concrete-filled steel tube stiff skeleton arch rib segment is arranged at four corners inside a concrete-filled steel tube stiff skeleton externally encased prefabricated UHPC slab arch rib segment, and the concrete-filled steel tube stiff skeleton externally encased prefabricated UHPC slab arch rib segment includes two web structures, where the top and bottom of the two web structures are respectively connected to a roof structure and a floor structure through a cast-in-situ UHPC longitudinal joint and a cast-in-situ UHPC transverse joint. The stiff skeleton externally encased concrete is prefabricated into a UHPC slab and then transported to the site for assembly, the UHPC is used as externally encased concrete to reduce the self-weight of the structure.