Method and structural system for improving three-dimensional stress performance of large-span three-tower cable-stayed bridge

Abstract

The application discloses a method and a structural system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, and the method comprises the following steps: improving vertical stiffness of the three-tower cable-stayed bridge through auxiliary cables and longitudinal elastic cables on both sides of a middle tower; performing three-stage control on longitudinal static and dynamic responses of the three-tower cable-stayed bridge under temperature load, static force and most unfavorable load working conditions and earthquake working conditions through longitudinal elastic cables between the middle tower and a main beam and longitudinal viscous dampers on a first side tower and a second side tower; performing three-stage control on lateral static and dynamic responses of the large-span three-tower cable-stayed bridge through new damping and energy dissipation wind-resistant bearings between the middle tower, the first side tower, the second side tower and the main beam; and performing two-stage control on lateral static and dynamic responses of large-span three-tower cable-stayed bridge piers through friction pendulum seismic isolation bearings between first piers, second piers and the main beam.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bridge engineering, and more particularly relates to a method and a structural system for improving three-way stress performance of a large-span three-tower cable-stayed bridge. BACKGROUND

[0002] The cable-stayed bridge is a modern bridge type, has good economy and wide adaptability, and has now developed into a mainstream bridge type of large-span bridges. In the face of complex construction conditions such as deep water, soft foundation, and multi-channel navigation, the multi-tower cable-stayed bridge has strong competitiveness. At present, the three-tower cable-stayed bridge has been widely used in engineering.

[0003] The structural system of the three-tower cable-stayed bridge is directly related to the overall design of the bridge, the structural safety, and the realization of the function; compared with the double-tower cable-stayed bridge, although the three-tower cable-stayed bridge is similar in form to the double-tower or single-tower cable-stayed bridge, with the increase in the number of towers and the extension of the beam length, the stress characteristics of the multi-tower cable-stayed bridge have changed to varying degrees; the multi-tower cable-stayed bridge is higher, longer, and more flexible, the lack of effective longitudinal constraint on both sides of the middle tower of the three-tower cable-stayed bridge makes the structural stiffness smaller and the self-damping lower and lower, and only relying on the structural stiffness or damping or only relying on the external stiffness or damping cannot meet the requirements of structural safety and function; in addition, the three-tower cable-stayed bridge is more sensitive to static and dynamic actions such as vehicles, temperature, wind, and earthquakes, and the longitudinal displacement of the main beam, the vertical deflection of the main beam, the fatigue stress amplitude of the cable, and the tower bottom internal force are much larger than those of the double-tower cable-stayed bridge; compared with the conventional double-tower cable-stayed bridge, the most prominent technical problem of the three-tower cable-stayed bridge is the excessive temperature deformation and the insufficient vertical stiffness, and for the three-tower cable-stayed bridge in high-intensity regions, poor seismic performance is also a common technical problem. At present, the multi-tower cable-stayed bridge with a span not greater than 650m has been built, and the research on the structural mechanics behavior, the constraint system, and the device is not systematic, so it is a key problem in the design to select a reasonable structural system to slow down the temperature effect of the three-tower cable-stayed bridge, enhance the structural vertical stiffness, and improve the seismic performance, so as to achieve superior overall performance of the bridge and economical scale of the components, which is also the key to ensuring the structural safety and rationality of the three-tower cable-stayed bridge.

[0004] In view of the insufficient vertical stiffness of the three-tower cable-stayed bridge, domestic and foreign scholars have proposed some targeted measures, such as adding auxiliary piers, increasing the stiffness of the main tower, and setting cross cables, but the recommended longitudinal constraint system is mostly the form of fixed connection of the tower beam or the use of fixed bearings, and the research on the lateral constraint system of the three-tower cable-stayed bridge is very little. The Huangmaohai Bridge is a single-column tower double-surface three-tower cable-stayed bridge, the main beam adopts a split steel box beam, the bearing is difficult to set, and the tower beam fixed connection is difficult to process. Therefore, it is urgent to propose a structural system for improving the three-way stress performance of a large-span three-tower cable-stayed bridge in view of the stress characteristics of the three-tower cable-stayed bridge and taking into account the bridge landscape. SUMMARY

[0005] In order to solve the above defects or improvement needs of the prior art, the present application provides a method and a structural system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, three-level control of longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge is performed by longitudinal viscous dampers and longitudinal elastic cables, three-level control of transverse static and dynamic responses of the bridge tower of the large-span three-tower cable-stayed bridge is performed by new damping and energy dissipation wind-resistant bearings, two-level control of transverse static and dynamic responses of the bridge pier of the large-span three-tower cable-stayed bridge is performed by friction pendulum seismic isolation bearings, so that the stress of each level of the large-span three-tower cable-stayed bridge is clear and reasonable, the rationality and economy of the structural design of the large-span three-tower cable-stayed bridge are improved, and the bridge landscape is also considered; the problems of significant temperature effect, insufficient vertical stiffness of the structure and poor seismic performance of the large-span three-tower cable-stayed bridge can be solved.

[0006] In order to achieve the above-mentioned purpose, one aspect of the present application provides a method for improving three-way stress performance of a large-span three-tower cable-stayed bridge, comprising the following steps:

[0007] S1: improving the vertical stiffness of the three-tower cable-stayed bridge by auxiliary cables and longitudinal elastic cables arranged on both sides of the middle tower;

[0008] S2: performing three-level longitudinal control of the three-tower cable-stayed bridge under temperature load, static most unfavorable load working condition and seismic action working condition by longitudinal elastic cables arranged between the middle tower and the main girder along the longitudinal direction of the main girder and longitudinal viscous dampers arranged on the first side tower and the second side tower, and improving the longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge;

[0009] S3: performing three-level control of the transverse static and dynamic responses of the bridge tower of the large-span three-tower cable-stayed bridge by new damping and energy dissipation wind-resistant bearings arranged between the middle tower, the first side tower and the second side tower and the main girder along the transverse direction of the main girder, and improving the transverse static and dynamic responses of the large-span three-tower cable-stayed bridge;

[0010] S4: performing two-level control of the transverse static and dynamic responses of the bridge pier of the large-span three-tower cable-stayed bridge by friction pendulum seismic isolation bearings arranged between the first bridge pier and the second bridge pier and the main girder along the transverse direction of the main girder, and improving the transverse static and dynamic responses of the large-span three-tower cable-stayed bridge.

[0011] Further, the three-level longitudinal control of step S2 comprises:

[0012] S21: under the action of temperature load, the longitudinal viscous damper adapts to the displacement generated by slow movement of the temperature load, and does not affect the free expansion of the main girder, and the longitudinal elastic cable arranged at the temperature zero point of the middle tower will not generate temperature secondary internal force;

[0013] S22: under the static most unfavorable load working condition, the longitudinal elastic cable arranged on the middle tower is used to limit the displacement of the beam end of the main girder and reduce the scale of the expansion device on the main girder;

[0014] S23: under the action of earthquake, the longitudinal elastic cable arranged on the middle tower prevents the main beam from generating excessive longitudinal displacement, the longitudinal viscous damper arranged on the first side tower and the second side tower plays a damping and energy dissipation role in the free deformation within the stroke range thereof; by applying initial tension to the longitudinal elastic cable, it is ensured that the longitudinal elastic cable will not relax under the action of earthquake, thereby improving the longitudinal static and dynamic response of the long-span three-tower cable-stayed bridge.

[0015] Further, the three-stage longitudinal control of step S3 comprises:

[0016] S31: the initial internal force provided by the new damping and energy dissipation wind-resistant support limits the disturbance caused by the wind on the main beam by the vehicle and live load above the main beam, thereby ensuring driving comfort;

[0017] S32: under the action of a hundred-year cross wind, the elastic stiffness of the new damping and energy dissipation wind-resistant support within the limiting gap thereof ensures the limited movement of the main beam; when the deformation of the new damping and energy dissipation wind-resistant support is greater than the limiting gap thereof, the new damping and energy dissipation wind-resistant support forms a larger elastic stiffness to limit the larger lateral deformation of the main beam;

[0018] S33: under the action of lateral earthquake, the friction damper in the new damping and energy dissipation wind-resistant support realizes lateral damping and energy dissipation, reduces the seismic response of the bridge tower, and thereby improves the lateral static and dynamic response of the long-span three-tower cable-stayed bridge.

[0019] Further, the two-stage longitudinal control of step S4 comprises:

[0020] S41: the limiting shear pin provided by the friction pendulum seismic isolation support limits the lateral movement of the main beam, thereby ensuring driving comfort;

[0021] S42: under the action of lateral earthquake, the limiting shear pin in the friction pendulum seismic isolation support is sheared, and the friction plays a lateral damping and energy dissipation role, thereby reducing the seismic response of the bridge pier.

[0022] Another aspect of the present application provides a structure system for improving the three-way stress performance of a long-span three-tower cable-stayed bridge, the long-span three-tower cable-stayed bridge comprising a main beam spanning a first bridge pier and a second bridge pier arranged at intervals, a first side tower, a middle tower and a second side tower arranged in sequence on the main beam along the longitudinal center axis of the main beam, and a plurality of groups of cable stays arranged on both sides of the middle tower, both sides of the first side tower and both sides of the second side tower; the structure system comprises a longitudinal elastic cable arranged between the middle tower and the main beam, longitudinal viscous dampers arranged between the first side tower and the main beam and between the second side tower and the main beam, new damping and energy dissipation wind-resistant supports connecting the middle tower, the first side tower and the second side tower transversely to the main beam, friction pendulum seismic isolation supports connecting the first bridge pier and the second bridge pier to the main beam, and auxiliary cables arranged on both sides of the middle tower.

[0023] The vertical stiffness of the long-span three-tower cable-stayed bridge is improved through the auxiliary cable and the longitudinal elastic cable; the longitudinal static and dynamic responses of the long-span three-tower cable-stayed bridge are improved through the longitudinal elastic cable and the longitudinal viscous damper; the lateral static and dynamic responses of the long-span three-tower cable-stayed bridge tower are controlled in three levels through the novel damping and energy dissipation wind-resistant support, and the lateral static and dynamic responses of the long-span three-tower cable-stayed bridge pier are controlled in two levels through the friction pendulum seismic isolation support, so that the three-way stress performance of the long-span three-tower cable-stayed bridge is improved.

[0024] Further, the longitudinal elastic cables are symmetrically arranged on both sides of the middle tower, and the arrangement direction of the two longitudinal elastic cables is consistent with the longitudinal center axis direction of the main girder, i.e., arranged along the longitudinal direction of the main girder.

[0025] The height of the longitudinal elastic cable is flush with the height of the main girder.

[0026] Further, the longitudinal viscous dampers are symmetrically arranged on both sides of the first side tower and the second side tower, and the arrangement direction of the longitudinal viscous dampers is consistent with the longitudinal center axis direction of the main girder.

[0027] Further, the novel damping and energy dissipation wind-resistant supports are symmetrically arranged on both sides of the middle tower, both sides of the first side tower and both sides of the second side tower.

[0028] The arrangement direction of the two symmetrically arranged novel damping and energy dissipation wind-resistant supports is perpendicular to the longitudinal center axis direction of the main girder, i.e., arranged along the lateral direction of the main girder.

[0029] Further, the friction pendulum seismic isolation supports are laterally arranged between the first pier, the second pier and the main girder.

[0030] Further, the auxiliary cables are symmetrically arranged along the longitudinal center axis direction of the main girder on both sides of the middle tower.

[0031] One end of the auxiliary cable is fixed to the tower body of the middle tower, and the other end is fixed to the main girder.

[0032] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0033] (1) The method and structural system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, by additionally arranging auxiliary cables between the middle tower and the main beam and arranging longitudinal elastic cables on the middle tower, the vertical stiffness of the three-tower cable-stayed bridge is effectively improved, and the technical problem of insufficient vertical stiffness of the three-tower cable-stayed bridge is solved; the longitudinal viscous dampers and the longitudinal elastic cables arranged between the tower and the beam increase the longitudinal additional stiffness and additional damping of the three-tower cable-stayed bridge, control the displacement of the beam end of the large-span three-tower cable-stayed bridge under static and dynamic force, reduce the size of the expansion device, improve the internal force response of the structure under static and dynamic force, and improve the seismic performance of the three-tower cable-stayed bridge; the three-stage design of the shock-absorbing energy-dissipating wind-resistant support arranged transversely between the tower and the beam can control the transverse deformation of the bridge under the action of live load wind and temperature, and plays a buffering role between the main beam and the bridge pier; under the action of a hundred-year cross wind, the shock-absorbing energy-dissipating wind-resistant support can limit the transverse deformation of the main beam; under the action of an earthquake, the shock-absorbing energy-dissipating wind-resistant support can play a shock-absorbing and energy-dissipating role, and improve the stress performance of the structure; the two-stage design of the friction pendulum shock-absorbing and isolation support arranged transversely between the pier and the beam can limit the transverse deformation of the main beam under static force, and play a shock-absorbing and energy-dissipating role under the action of an earthquake, thereby improving the stress performance of the bridge pier; the problems of significant temperature effect, insufficient vertical stiffness of the structure, and poor seismic performance of the large-span three-tower cable-stayed bridge can be solved.

[0034] (2) The method and structural system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, by respectively and symmetrically arranging auxiliary cables and longitudinal elastic cables along the longitudinal center axis of the main beam between the two sides of the middle tower and the main beam, the vertical stiffness of the large-span three-tower cable-stayed bridge is improved; by respectively and symmetrically arranging longitudinal viscous dampers between the two sides of the first side tower and the main beam and between the two sides of the second side tower and the main beam along the longitudinal center axis of the main beam, and by respectively and symmetrically arranging longitudinal elastic cables between the two sides of the middle tower and the main beam along the longitudinal center axis of the main beam, the longitudinal static and dynamic response of the large-span three-tower cable-stayed bridge is controlled in three stages, and the longitudinal static and dynamic response of the large-span three-tower cable-stayed bridge is improved; by respectively connecting the novel shock-absorbing energy-dissipating wind-resistant supports between the two sides of the middle tower and the main beam, between the two sides of the first side tower and the main beam, and between the two sides of the second side tower and the main beam along the transverse direction of the main beam, the transverse static and dynamic response of the large-span three-tower cable-stayed bridge is controlled in three stages; by respectively arranging the friction pendulum shock-absorbing and isolation supports between the main beam and the first bridge pier and between the main beam and the second bridge pier along the transverse direction of the main beam, the transverse static and dynamic response of the large-span three-tower cable-stayed bridge is controlled in two stages, and the transverse static and dynamic response of the large-span three-tower cable-stayed bridge is improved; the stress of each level of the large-span three-tower cable-stayed bridge is clear and reasonable, the rationality and economy of the structural design of the large-span three-tower cable-stayed bridge are improved, and the landscape of the bridge is also considered. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1A side view structural schematic diagram of a structure system for improving three-way stress performance of a large-span three-tower cable-stayed bridge according to an embodiment of the present application;

[0036] Figure 2 A top view sectional structural schematic diagram of a structure system for improving three-way stress performance of a large-span three-tower cable-stayed bridge according to an embodiment of the present application;

[0037] Figure 3 A flowchart schematic diagram of a method for improving three-way stress performance of a large-span three-tower cable-stayed bridge according to an embodiment of the present application.

[0038] In all the drawings, the same reference signs represent the same technical features, specifically: 1-first pier, 2-second pier, 3-main girder, 4-middle tower, 5-first side tower, 6-second side tower, 7-cable-stayed cable, 8-longitudinal elastic cable, 9-longitudinal viscous damper, 10-new type shock-absorbing energy-dissipating wind-resistant support, 11-friction pendulum shock-absorbing support, 12-assistant cable. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in details below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict.

[0040] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, when an element is referred to as being “fixed to”, “disposed on” or “provided on” another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it can be directly connected to the other element or indirectly connected to the other element; the terms “mounting”, “connection”, “connecting”, “provided with” should be understood in a broad sense and for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, or can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0041] Furthermore, the terms "first", "second", "third", etc. are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or a significant difference from one another. Thus, features defined with "first", "second" etc. can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "a plurality" is two or more, unless explicitly specified otherwise.

[0042] As Figure 1 and Figure 2As shown, one aspect of the present application provides a structure system for improving the three-way stress performance of a large-span three-tower cable-stayed bridge, the large-span three-tower cable-stayed bridge comprising a first pier 1, a second pier 2 arranged at intervals, a main beam 3 arranged across the first pier 1 and the second pier 2, a middle tower 4 arranged on the main beam 3, a first side tower 5 and a second side tower 6 arranged on both sides of the middle tower 4, and a cable-stayed cable 7 arranged on both sides of the middle tower 4, both sides of the first side tower 5, and both sides of the second side tower 6; the cable-stayed cable 7 is arranged in multiple groups on both sides of the middle tower 4, both sides of the first side tower 5, and both sides of the second side tower 6; one end of the cable-stayed cable 7 is fixed to the tower body of the middle tower 4, the first side tower 5, and / or the second side tower 6, and the other end is fixed to the main beam 3; the middle tower 4 is arranged at the center of the main beam 3; the first side tower 5 is arranged between the middle tower 4 and the first pier 1; the second side tower 6 is arranged between the middle tower 4 and the second pier 2; the structure system for improving the three-way stress performance of the large-span three-tower cable-stayed bridge comprises a longitudinal elastic cable 8 arranged between the middle tower 4 and the main beam 3, a longitudinal viscous damper 9 arranged between the first side tower 5 and the main beam 3 and between the second side tower 6 and the main beam 3, a novel damping energy dissipation wind-resistant support 10 transversely connecting the middle tower 4, the first side tower 5, and the second side tower 6 to the main beam 3, a friction pendulum seismic isolation support 11 connecting the first pier 1 and the second pier 2 to the main beam 3, and an auxiliary cable 12 arranged on both sides of the middle tower 4; the longitudinal viscous damper, the longitudinal elastic cable, the novel damping energy dissipation wind-resistant support, the friction pendulum seismic isolation support, and the auxiliary cable are used to control the longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge in three stages, control the transverse static and dynamic responses of the bridge tower of the large-span three-tower cable-stayed bridge in three stages, control the transverse static and dynamic responses of the bridge pier of the large-span three-tower cable-stayed bridge in two stages, make the stress of the large-span three-tower cable-stayed bridge clear and reasonable, improve the rationality and economy of the structural design of the large-span three-tower cable-stayed bridge, and take into account the landscape of the bridge; the structure system has large vertical stiffness and good seismic performance, can successfully solve the problem of insufficient vertical stiffness of the three-tower cable-stayed bridge, effectively control the beam end displacement and reduce the size of the expansion joint, has a damping and energy dissipation effect under an earthquake, and effectively reduces the seismic response; and can solve the problems of significant temperature effect, insufficient vertical stiffness of the structure, and poor seismic performance of the large-span three-tower cable-stayed bridge.

[0043] Further, as Figure 1 and Figure 2As shown, the longitudinal elastic cable 8 is symmetrically arranged on both sides of the middle tower 4, the arrangement direction of the two longitudinal elastic cables 8 is consistent with the longitudinal central axis direction of the main beam 3, that is, the longitudinal arrangement along the main beam 3; the height of the longitudinal elastic cable 8 is flush with the height of the main beam 3; the longitudinal viscous damper 9 is symmetrically arranged on both sides of the first side tower 5 and the second side tower 6, the arrangement direction of the four longitudinal viscous dampers 9 is consistent with the longitudinal central axis direction of the main beam 3; the height of the longitudinal viscous damper 9 is lower than the height of the main beam 3; the novel damping energy dissipation wind-resistant support 10 is symmetrically arranged on both sides of the middle tower 4, both sides of the first side tower 5 and both sides of the second side tower 6; the arrangement direction of the two symmetrically arranged novel damping energy dissipation wind-resistant supports 10 is perpendicular to the longitudinal central axis direction of the main beam 3, that is, the transverse arrangement along the main beam 3; the friction pendulum seismic isolation support 11 is transversely arranged between the first bridge pier 1, the second bridge pier 2 and the main beam 3; the auxiliary cable 12 is symmetrically arranged along the longitudinal central axis direction of the main beam 3 on both sides of the middle tower 4, and the auxiliary cable 12 is preferably 5 pairs; one end of the auxiliary cable 12 is fixed to the tower body of the middle tower 4, and the other end is fixed to the main beam 3; the longitudinal elastic cable 8 is used to longitudinally connect the main beam 3 and the middle tower 4; the longitudinal viscous damper 9 is used to longitudinally connect the main beam 3 and the first side tower 5 and the second side tower 6; the novel damping energy dissipation wind-resistant support 10 is used to transversely connect the main beam 3 and the middle tower 4, the first side tower 5 and the second side tower 6; the friction pendulum seismic isolation support 11 is used to vertically connect the main beam 3 and the first bridge pier 1 and the second bridge pier 2; the auxiliary cable 12 and the longitudinal elastic cable 8 arranged on both sides of the middle tower 4 along the longitudinal direction of the main beam 3 are used to improve the vertical stiffness of the long-span three-tower cable-stayed bridge; the longitudinal elastic cable 8 arranged between the middle tower 4 and the main beam 3 along the longitudinal direction of the main beam 3 and the longitudinal viscous damper 9 arranged on the first side tower 5 and the second side tower 6 are used to improve the longitudinal static and dynamic response of the long-span three-tower cable-stayed bridge; the novel damping energy dissipation wind-resistant support 10 arranged between the middle tower 4, the first side tower 5 and the second side tower 6 and the main beam 3 along the transverse direction of the main beam 3 and the friction pendulum seismic isolation support 11 arranged between the first bridge pier 1, the second bridge pier 2 and the main beam 3 along the transverse direction of the main beam 3 are used to improve the transverse static and dynamic response of the long-span three-tower cable-stayed bridge.

[0044] As Figure 3 shown, another aspect of the present application provides a method for improving the three-way stress performance of a long-span three-tower cable-stayed bridge, comprising the following steps:

[0045] S1: The vertical stiffness of the three-tower cable-stayed bridge is improved by setting auxiliary cables 12 and longitudinal elastic cables 8 on both sides of the middle tower 4; specifically, the number of auxiliary cables added in the middle span is compared and selected, and it is found that the effect of using 5 pairs of auxiliary cables is better and relatively economical and reasonable; and the middle tower constraint system is compared and selected, and with the increase of the elastic constraint stiffness of the middle tower, the vertical stiffness of the three-tower cable-stayed bridge gradually increases, and when the longitudinal constraint stiffness is 1e5 kN / m, the effect of the longitudinal rigid constraint of the middle tower can be achieved. Finally, the method of adding 5 pairs of auxiliary cables in the middle span and setting longitudinal elastic constraints (6.5e5 kN / m) in the middle tower is selected to improve the vertical stiffness of the three-tower cable-stayed bridge;

[0046] S2: The three-tower cable-stayed bridge is subjected to three-level longitudinal control under temperature load, static most unfavorable load condition and seismic action condition by setting longitudinal elastic cables 8 between the middle tower 4 and the main girder 3 in the longitudinal direction of the main girder 3 and setting longitudinal viscous dampers 9 on the first side tower 5 and the second side tower 6, to improve the longitudinal static and dynamic response of the long-span three-tower cable-stayed bridge; specifically including the following steps:

[0047] S21: First-level control, under the action of temperature load, the longitudinal viscous damper 9 can adapt to the displacement caused by slow movement of temperature load, without affecting the free expansion of the main girder 3, the longitudinal elastic cable 8 is set at the temperature zero point of the middle tower 4 and will not generate temperature secondary internal force;

[0048] S22: Second-level control, under the static most unfavorable load condition, the longitudinal elastic cable 8 set on the middle tower 4 plays a role, limiting the displacement of the beam end of the main girder 3 and reducing the scale of the expansion device on the main girder 3;

[0049] S23: Third-level control: under the seismic action condition, the longitudinal elastic cable 8 set on the middle tower 4 plays a role to prevent the main girder 3 from generating excessive longitudinal displacement, the longitudinal viscous damper 9 set on the first side tower 5 and the second side tower 6 deforms freely within its stroke range and plays a role in shock absorption and energy dissipation, and in order to ensure that the longitudinal elastic cable 8 set on the middle tower 4 plays a role under the action of the earthquake, an initial tension is applied to the longitudinal elastic cable 8 to ensure that the longitudinal elastic cable 8 will not relax under the action of the earthquake;

[0050] S3: The three-level control of the transverse static and dynamic response of the long-span three-tower cable-stayed bridge is carried out by setting new shock absorption and energy dissipation wind-resistant bearings 10 between the middle tower 4, the first side tower 5 and the second side tower 6 and the main girder 3 in the transverse direction of the main girder 3, to improve the transverse static and dynamic response of the long-span three-tower cable-stayed bridge; specifically including the following steps:

[0051] S31: First-level control, the new shock absorption and energy dissipation wind-resistant bearing provides an initial internal force to limit the disturbance caused by the vehicle and live load wind on the main girder 3, and ensure the driving comfort;

[0052] S32: The second level control, under the action of the horizontal wind, the new shock-absorbing energy-dissipation wind-resistant support forms a smaller elastic stiffness in its limiting gap, which can ensure the limited movement of the main beam 3 and play a buffering role between the main beam 3 and the bridge piers (the first bridge pier 1 and the second bridge pier 2), when the deformation of the new shock-absorbing energy-dissipation wind-resistant support is greater than its limiting gap, the new shock-absorbing energy-dissipation wind-resistant support 10 forms a larger elastic stiffness, which limits the larger lateral deformation of the main beam;

[0053] S33: The third level control, under the action of the lateral earthquake, the friction damper in the new shock-absorbing energy-dissipation wind-resistant support 10 plays a role, realizes the lateral shock-absorbing energy-dissipation effect, and reduces the seismic response of the bridge tower.

[0054] S4: The lateral static and dynamic responses of the piers of the long-span three-tower cable-stayed bridge are controlled in two levels by respectively arranging the friction pendulum shock-absorbing supports 11 between the first bridge pier 1, the second bridge pier 2 and the main beam 3 in the lateral direction of the main beam 3, so as to improve the lateral static and dynamic responses of the long-span three-tower cable-stayed bridge; specifically including:

[0055] S41: The first level control, the limiting shear pin is provided by the friction pendulum shock-absorbing support to limit the lateral movement of the main beam and ensure the driving comfort;

[0056] S42: The second level control: under the action of the lateral earthquake, due to the large lateral horizontal force, the limiting shear pin in the friction pendulum shock-absorbing support is sheared off, the friction pendulum shock-absorbing support plays a role in lateral shock-absorbing energy-dissipation, and the seismic response of the pier is reduced.

[0057] The application provides a working principle of a structure system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, which comprises the following steps: setting auxiliary cables 12 and longitudinal elastic cables 8 symmetrically along a longitudinal center axis of a main beam 3 on both sides of a middle tower 4 and between the middle tower 4 and the main beam 3, so as to improve vertical stiffness of the large-span three-tower cable-stayed bridge; setting longitudinal viscous dampers 9 symmetrically along the longitudinal center axis of the main beam 3 on both sides of a first side tower 5 and between the first side tower 5 and the main beam 3, on both sides of a second side tower 6 and between the second side tower 6 and the main beam 3, and setting longitudinal elastic cables 8 symmetrically along the longitudinal center axis of the main beam 3 on both sides of the middle tower 4 and between the middle tower 4 and the main beam 3, so as to perform three-level control on longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge and improve the longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge; connecting new damping and energy dissipation wind-resistant supports 10 along the main beam 3 transversely between the middle tower 4 and the main beam 3, between the first side tower 5 and the main beam 3 and between the second side tower 6 and the main beam 3, so as to perform three-level control on transverse static and dynamic responses of the large-span three-tower cable-stayed bridge; setting friction pendulum seismic isolation supports 11 along the main beam 3 transversely between the main beam 3 and the first pier 1 and the second pier 2, so as to perform two-level control on transverse static and dynamic responses of the large-span three-tower cable-stayed bridge, and improve the transverse static and dynamic responses of the large-span three-tower cable-stayed bridge; setting auxiliary cables and longitudinal elastic cables on the middle tower, so as to effectively improve vertical stiffness of the three-tower cable-stayed bridge and solve the technical problem of insufficient vertical stiffness of the three-tower cable-stayed bridge; and the large-span three-tower cable-stayed bridge can solve the problems of significant temperature effect, insufficient vertical stiffness of the structure and poor seismic performance.

[0058] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the application and is not used to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A method for improving the three-dimensional stress performance of a long-span three-tower cable-stayed bridge, characterized in that, The application relates to a structure system for improving three-way stress performance of a large-span three-tower cable-stayed bridge, the large-span three-tower cable-stayed bridge comprising a main beam (3) crossing first and second piers (1 and 2) arranged at intervals, a first side tower (5), a middle tower (4) and a second side tower (6) arranged on the main beam (3) along a longitudinal center axis of the main beam (3) in sequence, and a plurality of groups of cable stays (7) arranged on both sides of the middle tower (4), both sides of the first side tower (5) and both sides of the second side tower (6); the structure system comprises longitudinal elastic cables (8) arranged between the middle tower (4) and the main beam (3), longitudinal viscous dampers (9) arranged between the first side tower (5) and the main beam (3) and between the second side tower (6) and the main beam (3), novel damping and energy dissipation wind-resistant bearings (10) connecting the middle tower (4), the first side tower (5) and the second side tower (6) with the main beam (3) transversely, friction pendulum seismic isolation bearings (11) connecting the first and second piers (1 and 2) with the main beam (3) respectively, and auxiliary cables (12) arranged on both sides of the middle tower (4); The vertical stiffness of the large-span three-tower cable-stayed bridge is improved through the auxiliary cables (12) and the longitudinal elastic cables (8); the longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge are improved through the longitudinal elastic cables (8) and the longitudinal viscous dampers (9); the transverse static and dynamic responses of the bridge towers of the large-span three-tower cable-stayed bridge are controlled in three stages through the novel damping and energy dissipation wind-resistant bearings (10), and the transverse static and dynamic responses of the bridge piers of the large-span three-tower cable-stayed bridge are controlled in two stages through the friction pendulum seismic isolation bearings (11), so that the three-way stress performance of the large-span three-tower cable-stayed bridge is improved; The method comprises the following steps: S1: the vertical stiffness of the three-tower cable-stayed bridge is improved through the auxiliary cables and the longitudinal elastic cables arranged on both sides of the middle tower; S2: the longitudinal static and dynamic responses of the three-tower cable-stayed bridge are controlled in three stages under the action of temperature load, the most unfavorable static load and the action of earthquake through the longitudinal elastic cables arranged between the middle tower and the main beam along the longitudinal direction of the main beam and the longitudinal viscous dampers arranged on the first and second side towers, so that the longitudinal static and dynamic responses of the large-span three-tower cable-stayed bridge are improved; S3: the transverse static and dynamic responses of the bridge towers of the large-span three-tower cable-stayed bridge are controlled in three stages through the novel damping and energy dissipation wind-resistant bearings arranged between the middle tower, the first and second side towers and the main beam along the transverse direction of the main beam, so that the transverse static and dynamic responses of the large-span three-tower cable-stayed bridge are improved; S4: the transverse static and dynamic responses of the bridge piers of the large-span three-tower cable-stayed bridge are controlled in two stages through the friction pendulum seismic isolation bearings arranged between the first and second piers and the main beam along the transverse direction of the main beam, so that the transverse static and dynamic responses of the large-span three-tower cable-stayed bridge are improved; The three-stage longitudinal control of step S2 comprises: S21: under the action of temperature load, the longitudinal viscous dampers adapt to the displacement generated by slow movement of the temperature load, do not affect the free expansion of the main beam, and the longitudinal elastic cables arranged at the temperature zero point of the middle tower do not generate temperature secondary internal force; S22: In the static worst load working condition, the longitudinal elastic cable arranged on the middle tower is used to limit the displacement of the beam end of the main beam and reduce the scale of the expansion device on the main beam; S23: In the earthquake working condition, the longitudinal elastic cable arranged on the middle tower is used to prevent the main beam from generating excessive longitudinal displacement, the longitudinal viscous damper arranged on the first side tower and the second side tower is used to realize the damping and energy dissipation effect in the free deformation range of the stroke, and the initial tension of the longitudinal elastic cable is applied to ensure that the longitudinal elastic cable will not relax under the action of the earthquake, thereby improving the longitudinal static and dynamic response of the long-span three-tower cable-stayed bridge; The three-stage longitudinal control of step S3 comprises: S31: The initial internal force provided by the new damping and energy dissipation wind-resistant support is used to limit the disturbance of the vehicle and the live load wind on the main beam, so as to ensure the driving comfort; S32: In the case of a hundred-year crosswind, the elastic stiffness of the new damping and energy dissipation wind-resistant support in the limiting gap is used to ensure the limited movement of the main beam; when the deformation of the new damping and energy dissipation wind-resistant support is greater than the limiting gap, the new damping and energy dissipation wind-resistant support is used to form a large elastic stiffness to limit the large lateral deformation of the main beam; S33: In the lateral earthquake, the friction damper in the new damping and energy dissipation wind-resistant support is used to realize the lateral damping and energy dissipation effect, so as to reduce the seismic response of the bridge tower, thereby improving the lateral static and dynamic response of the long-span three-tower cable-stayed bridge; The two-stage longitudinal control of step S4 comprises: S41: The limiting shear pin of the friction pendulum seismic isolation support is used to limit the lateral movement of the main beam, so as to ensure the driving comfort; S42: In the lateral earthquake, the limiting shear pin of the friction pendulum seismic isolation support is sheared, and the friction is used to realize the lateral damping and energy dissipation effect, so as to reduce the seismic response of the bridge pier.

2. The method for improving three-dimensional force performance of a long-span three-tower cable-stayed bridge according to claim 1, characterized in that: The longitudinal elastic cable (8) is symmetrically arranged on both sides of the middle tower (4), and the arrangement direction of the two longitudinal elastic cables (8) is consistent with the longitudinal center axis direction of the main beam (3), that is, the longitudinal arrangement along the main beam (3); The height of the longitudinal elastic cable (8) is flush with the height of the main beam (3).

3. The method for improving three-dimensional force performance of a long-span three-tower cable-stayed bridge according to claim 2, characterized in that: The longitudinal viscous damper (9) is symmetrically arranged on both sides of the first side tower (5) and the second side tower (6), and the arrangement direction of the longitudinal viscous damper (9) is consistent with the longitudinal center axis direction of the main beam (3).

4. The method for improving three-dimensional force performance of a long-span three-tower cable-stayed bridge according to claim 3, characterized in that: The new damping and energy dissipation wind-resistant support (10) is symmetrically arranged on both sides of the middle tower (4), both sides of the first side tower (5), and both sides of the second side tower (6). The arrangement direction of the two symmetrically arranged new damping and energy dissipation wind-resistant supports (10) is perpendicular to the longitudinal center axis direction of the main beam (3), that is, the lateral arrangement along the main beam (3).

5. The method for improving three-dimensional force performance of a long-span three-tower cable-stayed bridge according to claim 4, characterized in that: The friction pendulum seismic isolation support (11) is laterally arranged between the first bridge pier (1), the second bridge pier (2) and the main beam (3).

6. The method for improving three-dimensional force performance of a long-span three-tower cable-stayed bridge according to claim 5, characterized in that: The auxiliary cable (12) is symmetrically arranged along the longitudinal center axis direction of the main beam (3) on both sides of the middle tower (4); One end of the auxiliary cable (12) is fixed to the tower body of the middle tower (4), and the other end is fixed to the main beam (3).

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