There is provided a method of introducing prestress into a beam-column joint of PC construction to make it into a triaxially compressed state, in which the beam-column joint is made into a triaxial compression state and reasonable prestress is introduced into cross section areas of the ends of the members forming the beam-column joint. A tensile introducing force is generated by tensionally anchoring PC cables passed through the beam-column joint to introduce prestresses into the cross section areas of the ends of the members forming the beam-column joints in respective axial directions to make triaxial compression state, to satisfy the following conditions (1) and (2): (1) no tensile strength is generated, with respect to long term design load, in cross-section areas of the members forming the end of the beam and the end of the column, which ends are in contact with the beam-column joint; and (2) upon occurring of extremely large scale earthquake (very rarely occurred earthquake), in the beam-column joint, no generation of diagonal cracks is allowed to be generated but diagonal tensile stress intensity caused due to shear force inputted by seismic load is made less than allowable tensile stress intensity of concrete.

Precast construction elements are described suitable for use in high seismic areas. The precast construction elements can be precast, pre-topped double tees. The precast construction elements incorporate a passive energy dissipation device in a flange. The energy dissipation device provides a ductile connection having a deformation capacity of larger than 0.6″. Adjacent elements are connected to one another at joints that include the passive energy dissipation device. Passive energy dissipation devices can be passive hysteretic dampeners, such as U-shaped flexural plates. Passive energy dissipation devices can be bar dissipaters (e.g., grooved dissipaters). Also described are passive hysteretic dampers that include U-shaped flexural plates held in conjunction with a reinforcement element that defines a circle around which the flexural plate can bend.

An anti-seismic reinforcement structure using a panel zone reinforcing fixture, according to the present invention, comprises: panel zone reinforcing fixtures which are coupled, to reinforce an existing frame consisting of a column and a beam as existing members, to one side of the frame and which are respectively fixed to sides of the column and the beam at a panel zone where the existing column and the existing beam are joined to each other; a reinforcing column which is installed at one side of the column and has opposite ends thereof fixed to the panel zone reinforcing fixtures; and a reinforcing beam which is installed at one side of the beam and has opposite ends thereof fixed to the panel zone reinforcing fixtures.

The joint has a prefabricated-reinforced-concrete column, a reinforced-concrete foundation, a column anchoring longitudinal bar, a grouting sleeve and a foundation anchoring steel bar. The foundation anchoring steel bar and the column anchoring longitudinal bar are connected by a seam filling material filling the grouting sleeve. A splicing seam between the reinforced-concrete foundation and the prefabricated-reinforced-concrete column is filled with the seam filling material. The foundation anchoring steel bar includes a vertical portion and a horizontal portion. The vertical portion includes an upper-portion anchoring section protruding out of an upper surface of the reinforced-concrete foundation, a middle-portion non-adhesive section buried within the foundation and a lower-portion anchoring section. An exterior of the middle-portion non-adhesive section is provided with an isolating sheath for isolating the middle-portion non-adhesive section and the concrete adhesion.

Precast construction elements are described suitable for use in high seismic area. The precast construction elements can be precast, pre-topped double tees. The precast construction elements incorporate a passive energy dissipation device in a flange. The energy dissipation device provides a ductile connection having a deformation capacity of larger than 0.6″. Adjacent elements are connected to one another at joints that include the passive energy dissipation device. Passive energy dissipation devices can be passive hysteretic dampeners, such as U-shaped flexural plates. Passive energy dissipation devices can be bar dissipaters (e.g., grooved dissipaters). Also described are passive hysteretic dampers that include U-shaped flexural plates held in conjunction with a reinforcement element that defines a circle around which the flexural plate can bend.

Although Fiber Reinforced Polymers (FRPs), as alternatives for the corrosive steel reinforcement in concrete structures, have shown promising performance under gravity loads, their performance under reversal cyclic loading is still one of the main concerns. The linear behavior of FRP reinforcement has a two-sided effect on the seismic performance of FRP-reinforced concrete (RC) moment-resisting frames. Although the linear nature of FRP reinforcement could be advantageous in terms of limiting the residual damage after an earthquake event, it lowers the energy dissipation of the structure which can compromise its seismic performance. Disclosed herein is the addition of steel plates at selected locations in moment-resisting frames to improve seismic performance of FRP-RC structures while still being able to take advantage of its linear behaviour (minimal residual damage after earthquake). The effectiveness of the proposed solution was tested both experimentally and analytically.

There is provided a method of prestressing a beam-column joint with an appropriate ratio among the magnitudes of compression in the directions of X, Y, and Z axes. The method introduces prestress in a beam-column joint with a tensile introducing force generated by tensionally anchoring prestressing tendons that are arranged in PC beams extending along two horizontal directions (or X axis and Y axis) and PC columns extending along the vertical direction (or Z axis) and passed through the beam-column joint to bring the beam-column joint in triaxial compression, the prestress being introduced such that a diagonal tensile force T generated by an input shear force due to a seismic load of an extremely great earthquake that may occur very rarely will be cancelled completely or partially so as not to allow diagonal cracks to occur. The ratio of the prestresses introduced in the directions of the respective axes satisfies the following equation (1):
σx:σy:σz=1:1:0.3−0.9   (1)
where σx, σy, and σz are prestresses introduced in the directions of the X axis, the Y axis, and the Z axis respectively.

Disclosed is a buttress assembly located outside side walls comprising non-bearing walls located in a long side direction of an existing building and comprising concrete, the buttress assembly including a plurality of reinforcing steel structures extending in a short side direction of the existing building, connected to the existing building by anchors, and arranged in a vertical direction of the side walls.

There is provided a method of introducing prestress into a beam-column joint of PC construction to make it into a triaxially compressed state, in which the beam-column joint is made into a triaxial compression state and reasonable prestress is introduced into cross section areas of the ends of the members forming the beam-column joint.

A tensile introducing force is generated by tensionally anchoring PC cables passed through the beam-column joint to introduce prestresses into the cross section areas of the ends of the members forming the beam-column joints in respective axial directions to make triaxial compression state, to satisfy the following conditions (1) and (2): (1) no tensile strength is generated, with respect to long term design load, in cross-section areas of the members forming the end of the beam and the end of the column, which ends are in contact with the beam-column joint; and (2) upon occurring of extremely large scale earthquake (very rarely occurred earthquake), in the beam-column joint, no generation of diagonal cracks is allowed to be generated but diagonal tensile stress intensity caused due to shear force inputted by seismic load is made less than allowable tensile stress intensity of concrete.

The column-base joint includes a prefabricated-reinforced-concrete column and a reinforced-concrete foundation, and further includes a coating-steel-plate sleeve that is integrally prefabricated with the concrete column and encloses an exterior of a column base. A gap is between a bottom end of the coating-steel-plate sleeve and an upper surface of the foundation. An outside of the gap is provided with a plugging material. The joint further includes an annular rib plate all of whose edges are horizontally and seamlessly connected to an inner wall of the coating-steel-plate sleeve and whose middle portion is provided with a rib-plate opening. The annular rib plate is provided with a sleeve opening that matches with the grouting sleeve device.