Diaphragm-Free Prefabricated Beam Bridge Wet Joint Crack Control
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Solution Overview
Problem
Conventional prefabricated bridges face challenges such as high safety risks, low efficiency, and high costs due to the need for intermediate diaphragms, suspended formwork, and negative moment tooth blocks, which result in extensive high-altitude suspension work and poor construction quality, particularly in the construction of wet joints and negative moment tendon anchoring.
Innovation Solution
An intermediate diaphragm-free, suspended formwork-free, and negative moment tooth block-free beam bridge design that eliminates intermediate diaphragms, suspended formwork, and negative moment tooth blocks by incorporating prefabricated main girders with integrated wet joints and thicker deck slabs, allowing direct anchoring of negative bending moment tendons and using cantilever slabs with cushion plates to reduce on-site workload and improve safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If intermediate diaphragms are used in conventional prefabricated bridges, then structural stability is improved, but construction safety deteriorates due to extensive high-altitude suspension work
Solution Approach 1:
The patent removes intermediate diaphragms from the bridge structure, extracting the problematic component that required extensive high-altitude suspension work. This eliminates the need for workers to perform dangerous suspended operations while diagonal reinforcement bars provide alternative structural support.
Solution Approach 2:
The patent replaces the mechanical support system of intermediate diaphragms with a reinforcement bar system (diagonal bars extending from pier caps to deck slab). This substitution maintains structural integrity while eliminating the need for intermediate diaphragm installation at height.
2Strength
If intermediate diaphragms are installed, then transverse structural support is improved, but construction efficiency deteriorates due to slow wet joint construction
Solution Approach 1:
The patent extracts intermediate diaphragms from the construction process, eliminating the time-consuming wet joint construction operations. Diagonal reinforcement bars provide the necessary transverse support without requiring formwork, rebar welding, concrete pouring, and formwork removal at multiple intermediate locations.
Solution Approach 2:
The diagonal reinforcement bars are pre-installed as part of the pier cap or deck slab construction, providing transverse support functionality in advance without requiring separate intermediate diaphragm installation operations during bridge assembly.
3Ease of operation
If suspended formwork is used for wet joints, then deck slab access passages are provided, but material waste increases due to concrete dead weight
Solution Approach 1:
The patent removes the suspended formwork system and associated wet joint concrete structures. Access between deck slabs is achieved through other means (such as gaps or alternative pathways) without requiring concrete-filled formwork, thereby eliminating the waste of concrete that serves only as dead weight.
Solution Approach 2:
Instead of using permanent or semi-permanent concrete formwork structures that become waste, the patent employs temporary access solutions or design features that provide construction access without creating substantial material waste.
4Strength
If rigid joints are used for wet joints, then structural connection is improved, but formwork requirements increase leading to higher measure costs
Solution Approach 1:
The patent eliminates intermediate diaphragms and their associated rigid joint requirements. Without intermediate diaphragms, the need for complex rigid joint formwork systems is removed, simplifying the overall formwork requirements while maintaining structural integrity through diagonal reinforcement.
5Manufacturing precision
If negative moment tendons are anchored in tooth blocks, then tendon anchoring is achieved, but construction safety deteriorates due to high-altitude suspension work
Solution Approach 1:
The patent removes tooth blocks from the deck slab underside, eliminating the need for high-altitude suspension work to install and anchor negative moment tendons. Tendons are instead anchored directly to the pier cap or through alternative positioning methods that ground-based operations.
Solution Approach 2:
The patent relocates the tendon anchoring function from the vertical dimension (tooth blocks hanging below the deck requiring suspended access) to the horizontal dimension (anchoring at pier cap level or using ground-based positioning equipment), eliminating the need for high-altitude work.
6Strength
If tooth blocks are installed for negative moment tendon anchoring, then anchoring capacity is improved, but prefabrication efficiency deteriorates
Solution Approach 1:
The patent extracts tooth blocks from the prefabrication process, eliminating the time-consuming installation and anchoring operations. Negative moment tendons are anchored more efficiently through alternative methods that do not require separate tooth block installation steps.
Solution Approach 2:
The patent integrates the tendon anchoring function directly into the pier cap or deck slab structure, merging multiple operations (anchoring, support, positioning) into a single integrated system that improves prefabrication efficiency.
Data Source
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AI summary
The present invention proposes an intermediate diaphragm-free, suspended formwork-free, and negative moment tooth block-free beam bridge, and a design method thereof. The beam bridge includes prefabricated main girders, a wet joint, lower structures, and pier cap transverse beams above the lower structures. The concrete deck slabs of adjacent prefabricated main girders are connected by the wet joint. The design method of the above beam bridge includes the following steps: S1, initial design of the main girders; S2, calculation of the non-uniform deflection of the main girders and the indirect transverse stress of the deck slabs; S3, calculation of the direct transverse stress of the deck slabs; S4, crack resistance verification of the deck slab; S5, optimization of bridge parameters to reduce the stress on the driving surface; S6, completion of the beam bridge design. The beam bridge and its design method effectively solve the problem that the existing intermediate diaphragm-free beam bridge is prone to longitudinal cracking at the joints, and realize the suspension tension without the wet joint suspended formwork of the deck slab and the negative bending moment tendon, and have better mechanical properties and better economic, environmental and social benefits, which can facilitate the promotion and application of such bridges in various types of highways , railways and municipal engineering.