CN105603870A - Pier energy-consuming and crush prevention structure internally provided with energy-consuming rebars and sticky elastic material layers - Google Patents

Abstract

The invention discloses an energy-dissipating and anti-crush structure of a bridge pier with built-in energy-dissipating steel bars and a viscoelastic material layer. The structure is assembled with two ultra-high performance pieces on the four sides of the pier's vulnerable area of the dry joint segment, that is, the bottom segment. Concrete (Ultra? High? Performance? Concrete, UHPC) slab, a viscoelastic material layer is set between the bottom section of the pier and the UHPC slab, and the UHPC slab and the bottom section are combined into a whole by using pre-stressed rolled threaded steel bars. Holes are reserved between UHPC panels for placement of energy-dissipating steel bars. The present invention utilizes the property of "cracking but not breaking" of UHPC due to the incorporation of steel fibers to prevent the internal bottom segment from being crushed under the excitation of earthquake action, and utilizes the compact structure of UHPC to prevent the energy-consuming steel bars in the tunnel from corroding At the same time, the UHPC around the hole can prevent the buckling failure of the energy-dissipating steel bars under compression, and the energy-dissipating steel bars and the viscoelastic material layer are used to improve the energy dissipation capacity of the piers assembled with dry joint segments under earthquake excitation.

Description

Energy-dissipating and anti-crush structures of bridge piers with built-in energy-dissipating steel bars and viscoelastic material layers

technical field

The invention relates to a rapid construction technology and an anti-seismic design method of a bridge in a medium-high intensity area, in particular to a segmental assembly technology, an external prestressing technology and a shock absorption and isolation technology using metal materials to consume energy, and belongs to the field of civil engineering.

Background technique

Due to the advantages of rapid construction and self-resetting ability, dry joint segmental assembled piers have been applied in some river-crossing and sea-crossing bridges, including the Hong Kong-Zhuhai-Macao Bridge and the Canadian Confederation Bridge. This type of bridge pier divides the pier body into several sections vertically, the longitudinally stressed steel bars are broken at the joints of the sections, and the sections are connected by "dry joints" or filled at the joints. Epoxy resin is used to improve the durability of the piers, and then the segments are connected into a whole by post-tensioning. Scholars at home and abroad have found through experiments and theoretical studies that dry-joint segment-assembled piers have poor energy dissipation capacity under earthquake excitation, and are prone to crushing at the bottom segment.

In order to improve the energy-dissipating capacity of dry-joint segment-assembled piers, the most widely used method in engineering practice and scientific research is to build energy-dissipating steel bars in dry-joint segment-assembled piers. Although this method can improve the energy dissipation capacity of the bridge piers, it will also increase the residual deformation of the bridge piers after the earthquake, and the built-in energy dissipation steel bars are not easy to replace after the earthquake.

Aiming at the problem that the bottom section of piers assembled with dry joint sections is easy to be crushed under earthquake excitation, the most widely used method in engineering is to add constraints to the concrete at the bottom section to improve the deformation capacity of the concrete, including adding constraints to the concrete at the bottom section The amount of stirrups, the use of concrete-filled steel tubes to make the bottom segment, or wrapping FRP outside the concrete of the bottom segment can indeed reduce the damage of the bottom segment under earthquake excitation, but the damaged concrete is also difficult to replace after the earthquake question.

Contents of the invention

Technical problem: The purpose of this invention is to provide a bridge pier energy dissipation and anti-crush structure with built-in energy-dissipating steel bars and viscoelastic material layers, and use replaceable UHPC boards with built-in energy-dissipating steel bars to improve the performance of dry joint segment assembled bridge piers in earthquakes. The energy dissipation capacity under the action excitation and the anti-crushing bottom segment crushing, the use of this structure can not only improve the energy dissipation capacity of the dry joint segment assembled bridge piers under the earthquake excitation and prevent the bottom segment crushing, but also can pass through the After the earthquake, replace the damaged UHPC board and the built-in energy-dissipating steel bars and viscoelastic material layer to quickly repair the damaged pier and restore the bridge's function in time.

Technical solution: The present invention is an energy-dissipating and anti-crush structure of a bridge pier with built-in energy-dissipating steel bars and viscoelastic material layers. A viscoelastic material layer is set between the section and the UHPC slab, and a hole is reserved between the two UHPC slabs for placing energy-dissipating steel bars; the finished-rolled rebar crosses the pier bottom section and the UHPC slab transversely, and the two ends of the finished-rolled rebar Anchored by high-strength nuts and steel gaskets respectively, the UHPC plate and the bottom section of the bridge pier are combined into a whole by applying prestress to the finished threaded steel bars; the energy-dissipating steel bars are respectively connected to the The upper section is connected to the pre-embedded steel bars of the cap; the bottom section of the pier and the UHPC plate and the upper section need to be provided with a rubber cushion to prevent the upper section from being caused by the collision of the bottom section of the pier under the excitation of the earthquake. If the section is damaged, the wall thickness of the upper section should be increased at the joint with the bottom section of the pier, and the wall thickness will gradually decrease upward.

The diameter of the reserved channel is slightly larger than the diameter of the energy-dissipating steel bar.

The UHPC board is made using UHPC mixed with fine steel fibers,

Beneficial effect: compared with the prior art, the present invention has the following advantages:

1. The invention adopts the principle of capacity protection to separate the vulnerable area from the protected area, and uses pre-stressed rolled threaded steel bars to combine the UHPC plate as the vulnerable area with the inner bottom segment as the protected area, which can After the earthquake, the fast replacement of the damaged UHPC plate is realized through the relaxation and re-tensioning of the fine-rolled threaded steel bars.

2. UHPC board is used in the vulnerable area, which can make full use of the "cracked but not broken" property of UHPC due to the incorporation of steel fibers and the corrosion resistance due to its compact structure.

3. A viscoelastic material layer is set between the bottom section of the pier and the UHPC slab. Through calculation, only a small relative displacement occurs between the bottom section of the pier and the UHPC slab under earthquake excitation, and the viscoelastic material is used to generate shear. The working principle of energy dissipation during deformation can increase the energy dissipation capacity of the bridge pier. At the same time, the viscoelastic material layer is only cemented with the UHPC plate, and has no bond with the bottom section of the bridge pier. After the earthquake, the UHPC plate is replaced to realize the viscoelastic material layer. replace.

4. Set up two replaceable UHPC plates on the four sides of the bottom section of the pier, and set the reserved holes for placing energy-dissipating steel bars between the two UHPC plates. It is also beneficial to prevent the corrosion of energy-dissipating steel bars, and the UHPC around the tunnel can prevent buckling damage of energy-dissipating steel bars under compression.

5. The diameter of the energy-dissipating steel bar should be slightly smaller than the diameter of the reserved channel. The upper and lower ends of the energy-dissipating steel bar are respectively connected with the pre-embedded steel bars of the upper segment and the cap through steel sleeves, which is beneficial to the damping of the steel bars after the earthquake. The replacement of the device also ensures that the mandrel can deform freely under the excitation of the earthquake.

6. A rubber cushion is required between the bottom section of the pier and the UHPC plate and the upper section of the dry joint segment assembly to prevent damage to the upper section due to the collision of the bottom section under the excitation of the earthquake, thus ensuring the pier The possible damage is only concentrated on the replaceable UHPC board, which is conducive to the timely restoration of the bridge's use function after the earthquake and wins time for earthquake relief.

Description of drawings

Fig. 1 is a structural sectional view of an embodiment of the present invention;

Fig. 2 is a top view of the structure of the embodiment of the present invention;

Explanation of symbols in the figure: 1- pier bottom section, 2-UHPC plate, 3-viscoelastic material layer, 4-reserved hole, 5-energy-dissipating steel bar, 6-finish-rolled threaded steel bar, 7-high-strength nut, 8- Steel gasket, 9-steel sleeve, 10-upper segment, 11-embedded steel bar, 12-rubber cushion.

detailed description

The present invention is a structure that improves the energy dissipation capacity of dry joint section assembled bridge piers under earthquake excitation and prevents the bottom section from being crushed by using replaceable UHPC board built-in energy dissipation steel bars and viscoelastic material layers. It is necessary to use replaceable UHPC plates, viscoelastic material layers, energy-dissipating steel bars, precision-rolled threaded steel bars, high-strength nuts, steel gaskets, steel sleeves, embedded steel bars, and rubber cushions.

The replaceable UHPC boards are respectively provided with two pieces on the four sides of the bottom section of the pier, and a viscoelastic material layer is arranged between the UHPC board and the bottom section of the pier, and the viscoelastic material layer and the UHPC board are connected by cementation, and connected with the bottom section of the pier. The force is transmitted between the sections through frictional force, and holes are reserved between the two UHPC plates for placing energy-dissipating steel bars, and the holes are symmetrically distributed with respect to the center of the pier.

The replaceable UHPC plate and the inner bottom segment are combined into a whole by prestressing the finished rolled threaded steel bar, and the thickness of the replaceable UHPC plate is obtained through calculation, and UHPC has the property of "cracking but not breaking" due to the incorporation of steel fibers , to ensure that the replaceable UHPC board after the earthquake is only partially damaged and not crushed in a large area. At the same time, the inner bottom segment remains intact, which is sufficient to support the upper dead load and the prestress applied by connecting different segments. After the earthquake, the UHPC board can be replaced The piers can be restored quickly.

The friction coefficient between the viscoelastic material layer and the bottom section of the pier should be smaller than the friction coefficient between the UHPC slabs. By applying appropriate prestress, it is ensured that only the bottom section of the pier and the UHPC slab are under earthquake excitation. Small relative displacement occurs, and the viscoelastic material layer can undergo shear deformation to generate energy dissipation, and there is no relative displacement between the two UHPC plates.

The diameter of the energy-dissipating steel bar is slightly smaller than the diameter of the tunnel, and the upper and lower ends of the energy-consuming steel bar are respectively connected with the pre-embedded steel bars of the upper segment and the cap through steel sleeves, and the dry joint segment assembled pier is under the excitation of the earthquake. It will swing in the horizontal direction, causing the soft steel mandrel to undergo elastic-plastic deformation due to repeated tension and compression, so as to achieve the purpose of energy consumption. Among them, the UHPC around the reserved holes plays a role in preventing the buckling and damage of the energy-dissipating steel bars. The diameter of the holes is slightly larger than that of the energy-dissipating steel bars, which reserves space for the energy-dissipating steel bars to expand under compression.

There are 20 channels and energy-dissipating steel bars in the replaceable UHPC board.

The dry joint segment assembled pier bottom segment and the UHPC slab and the upper segment need to be provided with a rubber cushion to prevent the upper segment from being damaged due to the collision of the bottom segment under the excitation of the earthquake. The wall thickness of the upper section should be increased at the joint with the bottom section, and the wall thickness should be gradually reduced upward, so as to ensure that when the UHPC boards are replaced sequentially after the earthquake, the pier can still effectively transfer the upper dead load and prestress to the bearing platform .

The concrete implementation process of the present invention is as follows:

Step 1: Transport the sections of the pier assembled with dry joint sections from the prefabrication plant to the construction site. After the sections are placed vertically and in sequence on the cap platform, the rubber cushion has been bonded to the bottom of the upper section 10. 12. Connect each segment into a whole through post-tensioning prestressing;

Step 2: place a UHPC board 2 on the four sides of the bottom segment 1 sequentially, and the viscoelastic material layer 3 has been bonded to the UHPC board 2 in the prefabrication plant as shown in Figure 2;

Step 3: Place the energy-dissipating steel bar 5 in the groove of the UHPC board 2, and connect it to the upper segment 10 and the pre-embedded steel bar 11 in the cap through the steel sleeve 9;

Step 4: Place another UHPC board 2 on the four sides of the pier bottom section 1 in turn, as shown in Figure 2. The two UHPC boards 2 are aligned at the reserved tunnel 4. At this time, the energy-dissipating steel bar 5 is just placed in the reserved tunnel 4;

Step 5: Pass the finished-rolled threaded steel bar 6 through the holes reserved on the pier bottom section 1 and the UHPC plate 2, according to the "Technical Specifications for Highway Bridge and Culvert Construction" JTG/TF50-2011 about tensioning and finishing-rolled threaded steel bar 6 It is stipulated that prestressing is applied to the finish-rolled rebar 6 by relevant equipment, and high-strength nuts 7 and steel washers 8 are used to anchor them.

In this embodiment, the UHPC plate 2 described in step 2 is made of UHPC mixed with fine steel fibers, and the thickness of the UHPC plate 2 is obtained by calculation, and the calculation principle is to ensure that the inner bottom segment 1 does not suffer damage.

In this embodiment, the friction coefficient between the viscoelastic material layer 3 described in step 2 and the pier bottom section 1 should be smaller than the friction coefficient between the UHPC plates 2 to ensure that only the pier bottom section 1 is under seismic excitation. There is a small relative displacement between the two UHPC boards 2 , the viscoelastic material layer 3 can undergo shear deformation to generate energy dissipation, and there is no relative displacement between the two UHPC boards 2 .

In this embodiment, there are 20 reserved channels 4 and energy-dissipating steel bars 5 in the UHPC board 2 described in step 3, and the diameter of the reserved channels 4 is slightly larger than the diameter of the energy-dissipating steel bars 5. When the bridge pier undergoes horizontal deformation under the excitation of the earthquake, the entire energy-dissipating steel bar 5 can be freely deformed to give full play to the energy-dissipating capacity.

As stated above, while the invention has been shown and described with reference to certain preferred embodiments, this should not be construed as limiting the invention itself. Various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (3)

1. the power consumption of the bridge pier of built-in power consumption reinforcing bar and viscoelastic material layer and an anti-crush texture, is characterized in that,This structure is in bridge pier coxopodite section (1) four each two blocks of UHPC plates (2) that are superimposed, the bridge pier coxopodite section of arranging in outside, limitAnd viscoelastic material layer (3), preformed hole between two blocks of UHPC plates (2) be set between UHPC plate (2) (1)Road (4) is used for placing power consumption reinforcing bar (5); Finish rolling deformed bar (6) is horizontally through bridge pier coxopodite section (1) and UHPCPlate (2), high-strength nut (7) and steel plate washer (8) anchoring, institute are passed through respectively in the two ends of finish rolling deformed bar (6)The UHPC plate (2) of stating applies prestressing force by both groups with bridge pier coxopodite section (1) by finish rolling deformed bar (6)Synthetic entirety; Described power consumption reinforcing bar (5) by threaded steel bushing (9) respectively with upper segment (10) andThe embedded bar (11) of cushion cap is connected; Described bridge pier coxopodite section (1) and UHPC plate (2) and upper segment (10)Between need to arrange rubber spacer (12), prevent under geological process excitation because the collision of bridge pier coxopodite section (1) causesUpper segment (10) is damaged, and upper segment (10) will increase wall thickness with bridge pier coxopodite section (1) seam crossing,Reduce gradually to wall thickness.

2. the power consumption of the bridge pier of built-in power consumption reinforcing bar according to claim 1 and viscoelastic material layer and anti-crushing knotStructure, is characterized in that described reserving hole channel (4) slightly larger in diameter is in the diameter of power consumption reinforcing bar (5).

3. the power consumption of the bridge pier of built-in power consumption reinforcing bar according to claim 1 and viscoelastic material layer and anti-crushing knotStructure, is characterized in that, described UHPC plate (2) uses the UHPC that mixes micro steel fiber to make.