CN106284056A - Longspan Bridge elastoplasticity shock mitigation system - Google Patents

Abstract

The invention relates to an elastoplastic damping system for a long-span bridge, which comprises a pair of damping cables composed of elastic-plastic damping cables and a transverse viscous damper; there are two pairs of damping cables, one end of each pair of damping cables is anchored to the The main beam of the bridge is integrally cast on the anchor block, the other end is anchored on the main tower column on the other side, the two pairs of damping cables are symmetrically arranged, and one end of the viscous damper is anchored at the beam bottom of the main beam , and the other end is anchored on the beam of the main tower of the bridge. The shock absorption system can provide sufficient restraint stiffness and bearing capacity under normal use conditions, and has sufficient deformation capacity and energy dissipation under strong earthquake conditions, which can significantly improve the seismic performance of long-span bridges in strong earthquake areas.

Description

Elastoplastic damping system for long-span bridges

technical field

The invention belongs to the technical field of shock absorption of bridge engineering structures, and relates to an elastic-plastic shock absorption system of a long-span bridge.

Background technique

Long-span bridges are major transportation infrastructure projects. In order to reduce secondary disasters after earthquakes and ensure the safety of traffic lifelines, their seismic safety cannot be underestimated. With the implementation of my country's western resource development strategy and the "One Belt, One Road" national strategy, the construction of long-span bridges in high-intensity earthquake areas and active fault areas has become an inevitable and realistic demand. A lot of practice has proved that adopting proper seismic reduction and isolation design is an effective method to improve the seismic performance of long-span bridges. , can significantly reduce the inertial force transmitted to the substructure, and realize the mutual balance between the structure's seismic internal force and displacement response.

At present, the commonly used shock absorbers and isolation devices can be divided into two categories: one is the speed-dependent type, such as viscous damper, etc., the principle is to use the damping provided by the viscosity of the liquid to dissipate energy, but does not provide stiffness. The boundary constraints of the structure basically have no effect. Under dynamic conditions, due to the phase difference between the internal force response and the structural response, the force of the structure will not be significantly increased; the second is the displacement-related type, such as steel damping support, lead Core rubber bearings, high damping bearings, etc., mainly use the yield hysteretic properties of materials to absorb energy, and have initial stiffness and yield force. When the yield force is greater than the maximum internal force response under normal use conditions and less than the internal force under earthquakes Response, it can not only provide the restraint behavior under normal service conditions, but also provide large post-buckling deformation and energy dissipation characteristics under earthquake conditions.

Long-span bridges in strong earthquake areas are generally designed with floating systems in the longitudinal direction. Because their own stiffness can meet the needs of normal use, the shock absorbers mostly use velocity-dependent viscous dampers to provide the necessary energy consumption. In the past 20 years Most long-span bridges adopt this design system. However, in the direction of the bridge, due to the consideration of static forces such as wind loads, strong constraints need to be provided at the tower-beam and pier-beam connections to meet the normal use requirements, and the bearing capacity requirements of the tower-beam connections can generally reach several Under the action of earthquakes, when the design of shock absorption and isolation is adopted, there will be a large demand for deformation, especially the relative displacement between the tower and the beam, which can generally reach the order of tens of centimeters to tens of centimeters. Among the existing displacement-related dampers, steel dampers are the most widely used, but generally cannot meet the requirements of large bearing capacity and large displacement capacity at the same time, and their low-cycle fatigue life is significantly affected by initial micro-defects in materials and structures. The use environment and daily maintenance requirements are also relatively high; rubber products generally have a small vertical bearing capacity and poor durability. Therefore, at present, the transverse damping and isolation design of most long-span bridges is still limited to the pier-beam connection, and the non-shock-absorbing and isolation connection mode of the lateral wind-resistant support is used between the tower and the beam. It increases the seismic force demand and damage risk of the bridge tower to a large extent. The world-famous Lyon-Antirion Bridge in Greece adopts a combination of transverse viscous dampers and sacrificial devices in the transverse bridge direction in order to overcome strong earthquakes, but the structure of the large tonnage sacrificial device (350 tons) is complicated , the price is expensive, and in addition, the impact effect on the structure when the large-tonnage sacrificial device breaks is still unclear.

The elastic cable is a kind of elastic limit connection device, which does not provide energy dissipation capacity, and has certain applications in the longitudinal shock absorption design of early long-span bridges. For example, the Minggang Central Bridge in Japan has installed longitudinal steel hinge cables between the towers and girders to control the longitudinal displacement. The elastic cable is generally composed of high-strength steel wire or steel strand, so it can easily provide a large bearing capacity; but its effective elastic displacement is controlled by the cable length, and the maximum elastic deformation is generally 0.8% of the effective cable length. When a larger cable is deformed, a longer cable length is required. In the design of the Yongning Yellow River Bridge, the applicant proposed for the first time to combine elastic cables and viscous dampers for the lateral shock absorption design of the bridge and has been successfully applied, wherein the elastic cables are finished cable-stayed cables. However, limited by the width of the transverse bridge, its maximum deformation is only ±26cm. For this reason, the applicant proposes the design scheme of the elastic-plastic damping cable, so that it has both large bearing capacity and large deformation capacity, and also has a certain energy dissipation capacity, thereby greatly improving the shock absorption and isolation technology in high-intensity earthquake areas. The adaptability in long-span bridges provides a new solution for the shock-absorbing and isolation design of long-span bridges. However, the anchor head is the potential weak link of the current elastic cables and finished cable-stayed cables, which cannot ensure their stable plastic behavior; secondly, the cable-stayed cables used for bridge lateral There are great differences in the stress state of the cables, which have higher requirements for the connection structure such as rotation, etc. Objectively, it is necessary to develop new products according to the design purpose and use requirements of the shock-absorbing cables.

Contents of the invention

The object of the present invention is to provide an elastic-plastic damping system for large-span bridges under strong earthquake conditions, which has stable plastic properties, large bearing capacity and large deformation capacity, and is suitable for large-span cable ends and low tension The anti-slack construction design has excellent weather resistance and low maintenance requirements.

In order to achieve the above object, the solution adopted by the present invention is to provide a long-span bridge elastic-plastic damping system: it includes a damping cable pair (11) and a transverse viscous damper (12) composed of elastic-plastic damping cables. Composition: there are two pairs of damping cables, one end of each pair of damping cables is anchored on the anchor block (14) integrally poured with the main beam (13) of the bridge, and the other end is anchored on the main tower column ( 15), two pairs of damping cables are symmetrically arranged, and one end of the viscous damper (12) is anchored to the beam bottom of the main beam (13), and the other end is anchored to the main tower beam (16) of the bridge.

Preferably, the elastic-plastic damping cable is used between the main girder (13) and the main tower, auxiliary pier or transition pier.

Preferably, the bridge is a cable-stayed bridge, a suspension bridge, an arch bridge or a long-span girder bridge.

The elastic-plastic shock absorbing cable is characterized in that it includes an anchoring area (1), a redundant cable reinforcing section (2) and an effective cable section (3), and the redundant cable reinforcing section (2) is arranged in the anchoring area (1) and effective cable segment (3). Add redundant wires (4) in the anchorage area (1) and redundant wire reinforcement section (2), so that the number of wires in the anchorage area (1) and redundant wire reinforcement section (2) is greater than the effective The number of effective wires (5) in the cable section (3), the redundant wires (4) are cut off in the effective wire section (3), forming the anchorage area (4), the redundant wire reinforcement section (2) and the The difference in tensile capacity between the effective cable segments (3).

Preferably, the shock absorbing cable also includes a pressure ring (6), and the redundant wire (4) and the effective wire (5) control the pressure distribution in the pressure ring (6) in the pressure ring (6) to realize effective Gradual change of wire stress.

Preferably, there is a through-core spherical hinge support (7) in the anchorage area (1).

Preferably, the shock-absorbing cable is covered with a hot-extruded PE protective sheath (8).

Preferably, the shock-absorbing cable further includes a U-shaped bracket (9) and a protective hoop (10) for the cable body.

The elastoplastic damping system for long-span bridges proposed by the present invention provides a more concise, economical and efficient solution for the shock-absorbing and isolation design of long-span bridge tower girders in strong earthquake areas, and its beneficial effects are as follows:

1) The elastic-plastic damping cable has the advantages of large bearing capacity and large deformation capacity, which can not only provide sufficient initial stiffness to meet the constraint requirements under normal use conditions, but also provide greater deformation capacity under strong earthquake conditions and a certain energy consumption capacity;

2) The deformation capacity of the elastic-plastic cable can be increased by more than 3 times compared with the elastic cable, which can be used to adapt to larger and stronger earthquakes, and can also reduce the length of the cable, so it is suitable for various bridge widths and earthquakes Strength has better adaptability;

3) The elastic-plastic damping cable has the same durability and low maintenance requirements as the stay cable, and its material strength utilization rate is high, the weight is light, the connection structure is simple and reliable, and the replacement is convenient, so it also has better economy;

In a word, the present invention is mainly used in the transverse shock absorption design of long-span bridges, especially in high-intensity areas, and has excellent adaptability to strong earthquakes.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the design drawing of redundant wire reinforcement of elastic-plastic shock absorbing cable.

Fig. 2 is a design drawing of the U-shaped bracket of the elastic-plastic shock-absorbing cable and the protective hoop of the cable body.

Fig. 3 is the elevation view of the elastic-plastic shock-absorbing cable used in the concrete cable-stayed bridge.

Figure 4 is a three-view view of elastic-plastic damping cables used in concrete cable-stayed bridges.

In the figure: 1-anchor area, 2-redundant wire reinforced section, 3-effective cable section, 4-redundant wire, 5-effective wire, 6-pressure ring, 7-spherical hinge support, 8- PE protective sleeve, 9-U-shaped bracket, 10-cable body protection hoop, 11-elastic-plastic damping cable pair, 12-transverse viscous damper, 13-main beam, 14-anchor block, 15-main tower Column, 16-main tower beam, 17-steel support, 18-longitudinal viscous damper.

detailed description

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 and Fig. 2, the cable anchorage of the elastic-plastic damping cable of the present invention adopts a redundant design, and a redundant wire reinforcement section 2 is added between the anchorage area 1 and the effective cable section 3. The number of wires in the anchorage area and the reinforcement section is greater than the number of effective wires, and the redundant wire 4 is cut off in the effective wire section, forming a tensile capacity difference between the anchorage area and the reinforcement section 2 and the effective wire section 3, In order to avoid potential weak and damaged links from occurring in the anchorage area or the reinforcement section. The redundant cable 4 and the effective cable 5 control the pressure distribution in the pressure ring 6 in the pressure ring 6 to realize the gradual change of the stress of the effective cable, thereby avoiding the stress concentration and brittle fracture of the high-strength steel wire in the effective cable section, so that The plastic properties of the steel wire are fully exerted, and then stable plastic properties are obtained.

The test shows that the maximum strain of the cable designed according to the above scheme can reach 2.5%. It can be seen that the deformation capacity of the elastic-plastic cable can be increased to more than 3 times compared with the elastic cable. Combined with the large bearing capacity of the cable, it can be It has the characteristics of large bearing capacity and large deformation capacity, and has better adaptability to strong earthquakes.

As mentioned above, when the shock-absorbing cables are arranged upward on the cross bridge, the length of the cables will be limited by the width of the bridge. For the design of the floating system in the vertical direction, the shock absorbing cable must also be able to adapt to the longitudinal displacement of the main girder due to the influence of temperature and earthquake, which makes the cable end rotation angle of the shock absorbing cable much larger than that of ordinary stay cables. The present invention adopts the design scheme of the through-heart type spherical hinge support 7 at the anchorage place of the cable end. In addition, since the stress level of the shock absorbing cable is not high under normal use conditions, U-shaped brackets 9 and cable body protection hoops 10 are also designed to prevent stress relaxation or excessive sag.

Shock-absorbing cables are protected with the same hot-extruded PE sheath8 as stay cables, so they can have the same weather resistance and low maintenance as stay cables, which compares to viscous dampers, steel dampers, and rubber Such shock-absorbing products will be greatly improved.

As shown in Figures 3 and 4, a transverse damping design is adopted between the pylons and girders of a concrete cable-stayed bridge, and the adopted damping system consists of elastic-plastic damping cable pairs 11 (arranged in pairs) and transverse viscous dampers 12 . There are two pairs of shock-absorbing cables. One end of each shock-absorbing cable is anchored on the anchor block 14 integrally cast with the main beam 13, and the other end is anchored on the main tower column 15 on the other side. The two shock-absorbing cables are arranged symmetrically. . One end of the viscous damper 12 is anchored to the beam bottom of the main beam 13 , and the other end is anchored to the main tower beam 16 . It can be seen from FIG. 4 that the shock-absorbing cable pair 11 and the transverse viscous damper 12 are coordinated with the steel support 17 and the longitudinal viscous damper 18 in spatial layout without conflicting with each other.

As a transformation of the embodiment of the present invention, the parameters of the main tower (shape, section size, etc.), and the arrangement position of the elastic-plastic damping cables can be designed and adjusted as required.

As a transformation of the embodiment of the present invention, the elastic-plastic damping cable can be used between the main girder and the main tower, or between the main girder and the auxiliary pier and transition pier.

As yet another transformation of the embodiment of the present invention, the bridge structure may be a cable-stayed bridge, a suspension bridge, an arch bridge, or a girder bridge with a large span (50m or more single-span span).

The above-mentioned descriptions of the embodiments are not limitations on the solutions of the present invention. Therefore, the scope of protection of the present invention is not limited to the above-mentioned embodiments, and any modifications made according to the concept of the present invention are only formal and not substantive. And improvements, as long as the structure includes the shock-absorbing form of the elastic-plastic shock-absorbing cable, it should be considered as falling within the protection scope of the present invention.

Claims (8)

1. a Longspan Bridge elastoplasticity shock mitigation system, it is characterised in that it includes the damping rope that elastoplasticity damping rope is constituted Rope is to (11) and horizontal viscous damper (12)；It is two right that damping rope has, and every pair of damping rope one end is anchored in and described bridge On the anchor block (14) of girder (13) one-piece casting, the other end is anchored on the king-tower king-post (15) of opposite side, two pairs of damping ropes Being arranged symmetrically, viscous damper (12) one end is anchored at the bottom of the beam of described girder (13), and the other end is anchored in described bridge On beam of main tower (16).

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 1, it is characterised in that: described elastoplasticity damping Rope is between described girder (13) and king-tower, auxiliary pier or transition pier.

Bridge Seismic system the most according to claim 1, it is characterised in that: described bridge is cable-stayed bridge, suspension bridge, arch bridge Or the beam bridge of large span.

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 1, it is characterised in that: described elastoplasticity damping Rope includes that anchorage zone (1), redundancy rope silk strengthen section (2) and effective rope section (3), and redundancy rope silk strengthens section (2) and is arranged on anchorage zone (1) and between effective rope section (3)；Redundancy rope silk (4) is increased so that anchoring in anchorage zone (1) and redundancy rope silk strengthen section (2) District (1) and redundancy rope silk strengthen the quantity of effective rope silk (5) that the rope silk quantity in section (2) is greater than in effective rope section (3), superfluous Yu Suosi (4) blocks in effective rope section (3), forms anchorage zone (4), between redundancy rope silk enhancing section (2) and effective rope section (3) Resistance to tension differential.

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 4, it is characterised in that: described elastoplasticity damping Rope also includes pressure rings (6), described redundancy rope silk (4) and effective rope silk (5) in pressure rings (6) by control pressure rings (6) Interior pressure distribution, it is achieved the effectively change gradually of rope silk stress.

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 4, it is characterised in that: anchorage zone has in (1) The spherical hinged-support of punching (7).

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 4, it is characterised in that: also overlap outside described damping rope There is hot extrusion PE protective jacket (8).

Longspan Bridge elastoplasticity shock mitigation system the most according to claim 4, it is characterised in that: described damping rope also includes U-shaped support (9) and rope body protection cuff (10).