Precast segmental pier reinforced with both conventional steel bars and high-strength steel bars

Abstract

A precast segmental pier reinforced with both conventional steel bars and high-strength steel bars according to one or more embodiments of the present invention includes a footing, a segmental pier, longitudinal bars and unbonded post-tensioned tendons, characterized in that: the segmental pier is comprised of one or more precast segments, the longitudinal bars are comprised of both the conventional steel bar and the high-strength steel bar, connecting the footing and the segmental pier together with unbonded post-tensioned tendons to form an entire pier.

Claims

1. A precast segmental pier reinforced with first steel bars and second steel bars having higher strength than the first steel bars, comprising a footing, a segmental pier, longitudinal bars and unbonded post-tensioned tendons, characterized in that: the segmental pier is comprised of one or more precast segments, the longitudinal bars are comprised of both the first steel bars and the second steel bars, connecting the footing and the segmental pier together with unbonded post-tensioned tendons to form an entire pier, wherein the first steel bars are HRB400, HRB500, HRBF400, HRBF500, HRB400E, HRB500E, HRBF400E or HRBF 500E, and the second steel bars are PSB785, PSB830, PSB930, PSB1080 or PSB1200.

2. The precast segmental pier of claim 1, wherein the ratio of the reinforcement ratio of the first steel bar to the reinforcement ratio of the second steel bars is 0.5 to 2.0, and the longitudinal bars are arranged symmetrically and/or at intervals in the cross-section.

3. The precast segmental pier of claim 1, wherein the upper surface and the lower surface of each precast segment are flat or be provided with one or more shear keys.

4. The precast segmental pier of claim 1, wherein the lower end of the second steel bar is used together with an anchor matched with it so as to enhance the anchorage performance.

5. The precast segmental pier of claim 1, wherein the lower end of the unbonded post-tensioned tendons are anchored in the footing, and the tendons sequentially pass through the ducts for post-tensioned tendons with smooth inner wall reserved in each precast segment when the pier is assembled, and the upper unbonded post-tensioned tendons are anchored in the recess for the anchor of post-tensioned tendons after tensioning; the unbonded post-tensioned tendons are steel strands, deformed steel bars or FRP bars.

6. The precast segmental pier of claim 1, wherein corrugated ducts are reserved in the footing and each precast segment.

7. The precast segmental pier of claim 6, wherein the embedded part of the metal corrugated pipe in the footing is no less than 36d, which d is the diameter of longitudinal bar.

8. The precast segmental pier of claim 6, wherein the corrugated ducts are realized by embedding a metal corrugated pipe in advance, the corrugated pipe is a circular metal corrugated pipe, the diameter of metal corrugated pipe is d, which d is the diameter of the longitudinal bar.

9. The precast segmental pier reinforced of claim 8, wherein the embedded part of the metal corrugated pipe in the footing is no less than 36d, which d is the diameter of longitudinal bar.

10. A precast segmental pier reinforced with both first steel bars and second steel bars having higher strength than the first steel bars, comprising a footing, a segmental pier, longitudinal bars and unbonded post-tensioned tendons, characterized in that: the segmental pier is comprised of two or more precast segments, the longitudinal bars are comprised of both the first steel bars and the second steel bars, connecting the footing and the segmental pier together with unbonded post-tensioned tendons to form an entire pier; the first steel bar and the second steel bar only pass through several precast segments of the lower part of the segmental pier, and are not arranged along the entire pier, wherein the first steel bars are HRB400, HRB500, HRBF400, HRBF500, HRB400E, HRB500E, HRBF400E or HR 500E, and the second steel bars are PSB785, PSB830, PSB930, PSB1080 or PSB1200.

11. The precast segmental pier of claim 10, wherein the ratio of the reinforcement ratio of the first steel bar to the reinforcement ratio of the second steel bars is 0.5 to 2.0, and the longitudinal bars are arranged symmetrically and/or at intervals in the cross-section.

12. The precast segmental pier of claim 10, wherein the upper surface and the lower surface of each precast segment are flat or be provided with one or more shear keys.

13. The precast segmental pier of claim 10, wherein the lower end of the second steel bar is used together with an anchor matched with it so as to enhance the anchorage performance.

14. The precast segmental pier of claim 10, wherein the lower end of the unbonded post-tensioned tendons are anchored in the footing, and the tendons sequentially pass through the ducts for post-tensioned tendons with smooth inner wall reserved in each precast segment when the pier is assembled, and the upper unbonded post-tensioned tendons are anchored in the recess for the anchor of post-tensioned tendons after tensioning, and the unbonded post-tensioned tendons are steel strands, deformed steel bars or FRP bars.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic longitudinal cross-sectional view of a precast segmental pier according to embodiment 1;

(2) FIG. 2 is a schematic 3D view of a single precast segment;

(3) FIG. 3 is a schematic cross-sectional view of a precast segmental pier;

(4) FIG. 4 is a schematic of the construction process of the precast segmental pier in the present invention;

(5) FIG. 5 is a schematic longitudinal cross-sectional view of a precast segmental pier according to embodiment 2;

(6) FIG. 6 is a schematic longitudinal cross-sectional view of a precast segmental pier according to embodiment 3.

DETAILED DESCRIPTION

(7) The invention is described in further detail below with reference to the following figures and embodiments:

(8) 1. Embodiment 1, as shown in FIG. 1, the invention provides a precast segmental pier reinforced with both conventional steel bars 10 and high-strength steel bars 11, comprising a footing 1, a segmental pier 2, longitudinal bars 6 and unbonded post-tensioned tendons 7. The segmental pier 2 is composed of one or more precast segments 4, and the footing 1 and the segmental pier 2 are connected together by unbonded post-tensioned tendons 7 to form a entire pier. Each precast segment 4 has a rectangular cross-section with the same cross-sectional dimension and the same segment height. The height of the segments is 1.5 to 4 times of the size of the long edge of the section, so that the plastic hinge of the precast segmental pier can be fully developed to ensure the energy dissipation capacity in seismic design, and the volume and the weight of a single precast segment 4 are small for assembling conveniently. As shown in FIG. 2, each precast segment 4 is provided with the same number of corrugated ducts 5 at the same cross-sectional position. Therefore, the corrugated ducts 5 and the ducts for post-tensioned tendons 8 can be achieved after assembly. After the precast segments 4 are assembled and the unbonded post-tensioned tendons 7 are tensioned, the longitudinal bars 6 are placed into the corrugated ducts 5. If the length of the single longitudinal bar 6 is smaller than the height of the segmental pier 2, the longitudinal bar 6 is extended in the approach of mechanical connection, welding or binding connection. The construction method of the precast segmental pier reinforced with both conventional steel bars and high-strength steel bars in the embodiment 1 is shown in FIG. 4: firstly, pouring the footing 1, and reserving the corrugated ducts 5 during pouring so as to insert the longitudinal bars 6 into the footing 1 for anchorage; Then, assembling the lower precast segments 4, and sequentially assembling the other precast segments 4 to enable the unbonded post-tensioned tendons 7 to through the ducts for post-tensioned tendons 8 of the precast segments 4; Tensioning the unbonded post-tensioned tendons 7 after the assembly is completed; And then, placing the longitudinal bars 6 into the the corrugated ducts 5, finally, pressure grouting is carried out in the corrugated ducts 5, and grouting quality is ensured. The longitudinal bars 6 are restrained by the surrounding grouting material, the metal corrugated pipes 9 and the steel hoops 12, so that the longitudinal bars 6 generally do not suffer from buckling failure under compression during an earthquake. The high-strength growing material confined by the metal corrugated pipe 9 can resist compression together with the concrete, so that the compression stress level and the degree of damage of the concrete can be lower. Therefore, the precast segmental pier has better durability and post-seismic performance than the cast-in-situ pier, and ensures the rapid recovery of the bridge traffic network in the earthquake disaster areas.

(9) 2. Embodiment 2, as shown in FIG. 5, the embodiment 2 is different from the the embodiment 1 in that the segmental pier 2 of the precast segmental pier reinforced with both conventional steel bars and high-strength steel bars has only one precast segment 4. When the slenderness ratio of the segmental pier 2 is no more than 6, the segmental pier 2 can be a single precast segment 4, so that the assembling efficiency can be improved. Moreover, when the slenderness ratio of the segmental pier 2 is no more than 6, the size and the weight of the segmental pier 2 are not too large to be transported and assembled. When the same or similar design and construction as in the embodiment 2 is adopted, it should be noted that the size and weight of the segmental pier 2 meet the related transportation regulations and do not exceed the limit of the hoisting equipment.

(10) 3. Embodiment 3, as shown in FIG. 6, the present embodiment is different from the embodiment 1 in that conventional steel bars 10 and high-strength steel bars 11 only pass through several precast segments 4 of the lower part of the segmental pier 2, and are not arranged along the entire pier. For a cantilever pier, the bending moment of the bottom of the pier is the largest under the action of an earthquake, and the bending moment is gradually reduced from the bottom of the pier to the top of the pier. In seismic design, longitudinal bar reinforcement ratio can be gradually reduced according to bending moment distribution of pier, and finally, the longitudinal bar is cut at a certain reasonable height. The cutting of the longitudinal bar 6 is in accordance with the corresponding seismic design specification. When the height of the precast segmental pier reinforced with both with conventional steel bars and high-strength steel bars is larger, the amount of conventional steel bars 10 and high-strength steel bars 11 can be effectively reduced by this method while the seismic performance is ensured, so that the economic benefit and the construction efficiency are favorably improved.

(11) Finally, the above embodiments are only used to illustrate the technical solution of the present invention and are not limited.