PC Binding Articulation for Earthquake Resilient Concrete
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Solution Overview
Problem
Current earthquake-resistant design methods for prestressed concrete constructions suffer from residual deformation, damage, and high repair costs due to plastic deformation during earthquakes, and the use of unbonded prestressing tendons leads to issues like oil separation and reduced corrosion control, making them unsuitable for high seismic intensity events.
Innovation Solution
A PC binding articulation construction method that incorporates a secondary prestressing tendon with a grout bond designed to break at specific load levels, allowing the binding joint to open and rotate, absorbing energy within a resilient range and maintaining the structure's integrity, while a secondary prestressing tendon at the column base provides additional support and seismic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unbonded prestressing tendons are used for PC binding juncture, then the construction allows lifting of column-beam junction interface during earthquakes, but oil separation occurs and corrosion control is reduced
Solution Approach 1:
The prestressing tendon system is segmented into bonded and unbonded portions. The tendon is divided into a bonded portion near the column-beam junction and an unbonded portion extending into the beam, allowing different functional zones within the same tendon system.
Solution Approach 2:
Different bonding conditions are applied at different locations along the prestressing tendon. The portion requiring stability and corrosion resistance (near the junction) is bonded with grout, while the portion requiring movement freedom (in the beam) remains unbonded.
2Loss of energy
If coupling reinforcement rods are disposed on upper and lower portions of beam to bear large deformation, then deformation energy is absorbed, but residual deformation remains after earthquake
Solution Approach 1:
The mechanical system for energy absorption is replaced from plastic deformation of reinforcement rods to elastic deformation of prestressing tendons. The prestressing tendons, positioned near the neutral axis, absorb deformation energy through elastic stretching rather than plastic yielding.
Solution Approach 2:
The stress-strain relationship of the energy absorption mechanism is changed from plastic (permanent deformation) to elastic (reversible deformation). The prestressing tendons are designed to remain within the elastic range during earthquake deformation, ensuring full restorability.
3Strength
If prestressing tendon is arranged near neutral axis for binding function, then damage is small during earthquake, but the tendon must withstand large tensile forces
Solution Approach 1:
The tendon system is segmented into bonded and unbonded portions with different functional requirements. The bonded portion near the junction provides stable anchorage and corrosion protection, while the unbonded portion in the beam allows free movement and reduces anchorage complexity.
Solution Approach 2:
Grout is introduced as an intermediary material between the prestressing tendon and the surrounding concrete. The grout provides corrosion protection and stress transfer in the bonded portion, while its absence in the unbonded portion allows direct interaction between the tendon and concrete for simplified anchorage.
4Reliability
If the binding joint portion opens and rotates during earthquake, then energy is absorbed within resilient range, but the bond between prestressing tendon and grout must break
Solution Approach 1:
The bond between the prestressing tendon and grout is designed to break at a predetermined load level before the main structural elements fail. This controlled bond failure occurs in advance during the earthquake loading process, allowing the joint to rotate and absorb energy while protecting the primary structure.
Solution Approach 2:
The bonded portion of the prestressing tendon acts as a cushioning element that breaks beforehand to protect the main structural members. The bond failure serves as a sacrificial mechanism that absorbs excess energy and prevents more severe damage to the column and beam.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method prevents damage to construction members, reduces residual deformation, and allows for easy repair by maintaining the structure in a resilient state, achieving superior earthquake resistance and cost-effectiveness by reducing the need for extensive repairs and maintaining structural integrity during high seismic events.
Implementation Method 1
the column, the beam, and the prestressing tendon are deformed within a linear resilient range
Implementation Method 2
designing bond between the prestressing tendon and the grout to be broken within a vicinity of the binding joint portion when a load exceeds a predetermined earthquake load design value
Data Source
AI summary
In an earthquake resisting design method of a PC construction, a column and a beam, which are high-strength precast prestress concrete members, are joined by binding juncture with a prestressing tendon. A grout is filled and bonded. A first stage linear resilient design is employed, where all construction members are not damaged, for earthquakes up to a predetermined earthquake load design value. A second stage linear resilient design is employed, where earthquake energy is absorbed by breakage of the bond of the grout, and principal construction members are not damaged, for earthquakes exceeding the predetermined earthquake load design value. By employing a non-linear resilient design in which the first stage linear resilient design and the second stage linear resilient design are combined, an earthquake-resisting design level is significantly increased, and the construction can resist earthquakes exceeding a seismic intensity 6 upper.